Small Block Chevy Build for Reliability & Longevity
petef
01-02-2010, 12:30 AM
I'm going to be buying a a rebuilt 305 engine for my 1985 G20 Van and I'm wondering if it's worth the added expense of modifying the engine with such things as roller rockers or a full roller cam setup, double roller timing chain & gears (as opposed to the stock nylon coated gears), or anything else that would increase the reliability and longevity of the engine.
Rebuilt 305 Engine
http://www.autoguide.net/apf/chevy-car_engines/gmc_305lb_2.html
I'm thinking that the valve train is the weakest link for premature engine failures in a chevy small block so making these mods could substantially extend the life of the engine or keep me from having to do repairs.
What do you think?
---pete---
Rebuilt 305 Engine
http://www.autoguide.net/apf/chevy-car_engines/gmc_305lb_2.html
I'm thinking that the valve train is the weakest link for premature engine failures in a chevy small block so making these mods could substantially extend the life of the engine or keep me from having to do repairs.
What do you think?
---pete---
MrPbody
01-02-2010, 10:49 AM
When buying a remanufactured engine, one is rolling the dice. If you buy strictly on price and how "good" the warranty is, you'll be needing that warranty, almost invariably. You may wish to look at local shops and find the the better smallblock guys. You don't need a "race" engine or anything like that, but you DO need a reliable and efficient engine. Just beware if the price seems to good. In comparison, our 305 "customs" go out the door around $2,500. But again, those are custom-built for specific applications and the overall cost wasn't as important to the customer as the end result.
305 is a decent little engine. Operative word "little". If economy is more important than power, 305 is a good choice. If you need more (or want) power, 350 is a more logical choice. It bolts right in where 305 was, and is a more efficient package.
For the 3/4 ton van, unless it's just highway driving and SOME light work, 305 with the stock cam will be under-powered. If you want it to "pull a load" (trailer, heavy cargo, whatever), have them use a "torque cam" (NOT a high perormance cam). This will enhance low-end power and increase fuel economy. Some call it an "RV" cam. Putting an aftermarket intake (like Edelbrock "Performer") and small-tube headers will inrcease both power and efficiency, as well. A SMALL 4-bbl. carb would "top it off" (pun intended...). A well-tuned small 4-bbl. will use less fuel than a 2-bbl. IF one practices "right foot control".
Jim
305 is a decent little engine. Operative word "little". If economy is more important than power, 305 is a good choice. If you need more (or want) power, 350 is a more logical choice. It bolts right in where 305 was, and is a more efficient package.
For the 3/4 ton van, unless it's just highway driving and SOME light work, 305 with the stock cam will be under-powered. If you want it to "pull a load" (trailer, heavy cargo, whatever), have them use a "torque cam" (NOT a high perormance cam). This will enhance low-end power and increase fuel economy. Some call it an "RV" cam. Putting an aftermarket intake (like Edelbrock "Performer") and small-tube headers will inrcease both power and efficiency, as well. A SMALL 4-bbl. carb would "top it off" (pun intended...). A well-tuned small 4-bbl. will use less fuel than a 2-bbl. IF one practices "right foot control".
Jim
petef
01-02-2010, 03:10 PM
Jim, your advise seems centered on power and efficiency which are important, but what I was referring to was more in terms of longevity and reliability. I focused mainly on the valve train because it's been my experience with Chevy small blocks that the valve train is usually the first thing to fail or give repeated problems.
In other words, I'd be willing to sacrifice power and efficiency for the sake of having an engine that would last longer. For example, valve guide wear is probably much less when using roller rockers because the valves have less side to side wear and they run more true within the guides.
If that is true, then a roller cam & roller rockers might help an engine last longer without needing a valve adjustment because there is less wear on the parts. It's been my experience with Chevy small blocks that I need to adjust the valves every few years to quiet them. That's what made me consider a roller cam & rocker. Not for high performance, but for high reliability. I could be wrong since there are more moving parts that could possibly fail. I really don't know and this is why I asked the question.
Another example is the timing chain and gears which I've often seen fail prematurely when the nylon coated gears wear prematurely. So my idea is to use a double roller timing chain and all metal gears for reasons of longevity.
Am I on the right track here?
----pete---
In other words, I'd be willing to sacrifice power and efficiency for the sake of having an engine that would last longer. For example, valve guide wear is probably much less when using roller rockers because the valves have less side to side wear and they run more true within the guides.
If that is true, then a roller cam & roller rockers might help an engine last longer without needing a valve adjustment because there is less wear on the parts. It's been my experience with Chevy small blocks that I need to adjust the valves every few years to quiet them. That's what made me consider a roller cam & rocker. Not for high performance, but for high reliability. I could be wrong since there are more moving parts that could possibly fail. I really don't know and this is why I asked the question.
Another example is the timing chain and gears which I've often seen fail prematurely when the nylon coated gears wear prematurely. So my idea is to use a double roller timing chain and all metal gears for reasons of longevity.
Am I on the right track here?
----pete---
MagicRat
01-02-2010, 08:59 PM
Here are some thoughts:
First the timing chain. Nylon timing chain components are used to slightly reduce engine noise and are occasionally (but not always) installed as original equipment. But they are almost unheard of in the aftermarket. The vast majority of replacement timing chain sets are all-steel, and I am pretty sure a rebuilder would never use a nylon set because of their rarity and their poor reputation.
But, it is a good idea to go for a "true roller" (not a cheapie, fake, look-alike roller) timing chain. The good, expensive ones seem to last longer.
Next, valve guides.... I do not think stock valve guides are a big issue. Older SBC's often burned oil due to the design of the valve seals. This burning sometimes was mistaken for worn guides. But in my experience, the guides generally last as long as the rest of the engine. And newer, upgraded seals last longer.
Next, roller rockers. IMO the stock steel rocker arms are the most reliable and longest-lasting option.
But if you simply must have a roller, go with the steel rocker arms with a roller tip. These are slightly more efficient and reduce valve guide loads slightly. But stay away from roller rockers where the fulcrum is a roller. These have slightly less friction but are unreliable, and short-lived, especially the aluminum design.
Roller cams...... these are slightly more efficient (less drag) but do not necessarily last longer than conventional lifters. Some SBC's, especially the 305's from the very early '80's sometimes had a problem with developing flat lobes on the cams. But this was due to machining inaccuracies, and not due to the design itself. Blocks that developed this problem were mostly scrapped years ago.
Imo the most reliable, longest-lasting engine is one which has the most careful assembly, not the fanciest parts. All critical clearances, such as the cylinder bore, piston ring end-gap, bearing clearances, etc. all have a tolerance range. Careful machining and assembly can ensure that all clearances are at the 'tight ' end of the tolerance range. This takes time and effort, something most rebuilders are unwilling to do, because it costs them money.
This kind of careful assembly is called "blueprinting". But BEWARE. Most engines are 'blueprinted' to ensure loose clearances, not tight ones. A loose engine has slightly less internal friction, and thus more power, which is good for performance and racing. But a loose engine is much like a worn-out engine, and has a shorter lifespan than a 'tight' one.
So, if you want a "blueprinted" engine, specify that you want tight clearances. .
A 'tight' engine will have a longer break-in period and, when new, be slightly less fuel-efficient, due to higher internal friction. But efficiency improves as the engine is broken in.
Finally, after a 1000-mile break-in, use synthetic engine oil, and change the oil fairly often.
Finally, it's a really good idea to go for a 350. I currently own a 1984 G20 van with a 305 4bbl. It's likely almost identical to yours. I have been able to get about 20 extra hp by some careful tuning and careful, but free modifications. Send me a private message if you want details.
But even with the mods, it is underpowered for heavier work.
I used to own a '79 G20 van with a 350 4bbl, which again, was stock, but carefully tuned. The 350 was significantly more powerful and more capable. Now, since the cost of rebuilding a 305 and 350 are virtually identical, imo it's money better spent to go for a 350.
That site you listed is suspect, imo. That's a very, very low price for a rebuild. I would think thay are cutting corners somewhere. As noted above, if you want reliability, you should visit some local shops and go with one that is clean, well equipped, established and with knowlegable staff. Talk to them about some procedures etc. It will defintely cost you more than $1139, (+shipping) but reliability costs money. :)
First the timing chain. Nylon timing chain components are used to slightly reduce engine noise and are occasionally (but not always) installed as original equipment. But they are almost unheard of in the aftermarket. The vast majority of replacement timing chain sets are all-steel, and I am pretty sure a rebuilder would never use a nylon set because of their rarity and their poor reputation.
But, it is a good idea to go for a "true roller" (not a cheapie, fake, look-alike roller) timing chain. The good, expensive ones seem to last longer.
Next, valve guides.... I do not think stock valve guides are a big issue. Older SBC's often burned oil due to the design of the valve seals. This burning sometimes was mistaken for worn guides. But in my experience, the guides generally last as long as the rest of the engine. And newer, upgraded seals last longer.
Next, roller rockers. IMO the stock steel rocker arms are the most reliable and longest-lasting option.
But if you simply must have a roller, go with the steel rocker arms with a roller tip. These are slightly more efficient and reduce valve guide loads slightly. But stay away from roller rockers where the fulcrum is a roller. These have slightly less friction but are unreliable, and short-lived, especially the aluminum design.
Roller cams...... these are slightly more efficient (less drag) but do not necessarily last longer than conventional lifters. Some SBC's, especially the 305's from the very early '80's sometimes had a problem with developing flat lobes on the cams. But this was due to machining inaccuracies, and not due to the design itself. Blocks that developed this problem were mostly scrapped years ago.
Imo the most reliable, longest-lasting engine is one which has the most careful assembly, not the fanciest parts. All critical clearances, such as the cylinder bore, piston ring end-gap, bearing clearances, etc. all have a tolerance range. Careful machining and assembly can ensure that all clearances are at the 'tight ' end of the tolerance range. This takes time and effort, something most rebuilders are unwilling to do, because it costs them money.
This kind of careful assembly is called "blueprinting". But BEWARE. Most engines are 'blueprinted' to ensure loose clearances, not tight ones. A loose engine has slightly less internal friction, and thus more power, which is good for performance and racing. But a loose engine is much like a worn-out engine, and has a shorter lifespan than a 'tight' one.
So, if you want a "blueprinted" engine, specify that you want tight clearances. .
A 'tight' engine will have a longer break-in period and, when new, be slightly less fuel-efficient, due to higher internal friction. But efficiency improves as the engine is broken in.
Finally, after a 1000-mile break-in, use synthetic engine oil, and change the oil fairly often.
Finally, it's a really good idea to go for a 350. I currently own a 1984 G20 van with a 305 4bbl. It's likely almost identical to yours. I have been able to get about 20 extra hp by some careful tuning and careful, but free modifications. Send me a private message if you want details.
But even with the mods, it is underpowered for heavier work.
I used to own a '79 G20 van with a 350 4bbl, which again, was stock, but carefully tuned. The 350 was significantly more powerful and more capable. Now, since the cost of rebuilding a 305 and 350 are virtually identical, imo it's money better spent to go for a 350.
That site you listed is suspect, imo. That's a very, very low price for a rebuild. I would think thay are cutting corners somewhere. As noted above, if you want reliability, you should visit some local shops and go with one that is clean, well equipped, established and with knowlegable staff. Talk to them about some procedures etc. It will defintely cost you more than $1139, (+shipping) but reliability costs money. :)
petef
01-03-2010, 01:34 AM
Here are some thoughts:
Finally, after a 1000-mile break-in, use synthetic engine oil, and change the oil fairly often.
MagicRat, thank you sooooooooooo much for the detailed reply. You have answered so many of my questions and concerns on rebuilt engines. Great post!
I believe the oil type & change frequency issues are critical for me. I've always used Castrol 10-40 motor oil of the conventional type. Normal oil pressure would be between 40 and 60 PSI. I often judge the condition of the engine if it will maintain 30 to 40 PSI at idle in the hot summer months here in NJ.
My problems with small block Chevy engines usually occur after I notice the oil pressure dropping below 30 PSI at idle. Sometimes I'll try to compensate by using Castrol 20-50 motor oil in the hot summer months in order to keep that oil pressure from going too low. It seems that my rebuilt engines fail due to valve train problems caused by the engine oil sludging up. I operate a service business and do mostly short trips of 15 to 20 minutes driving at a time 60% highway miles and 40% city miles. I try to change my oil every 3k to 5k miles. I use the van for very light duty. No towing. Occasionally I load it heavily to haul some wood or lumber but just for very short distances. I rarely drive for more than 45 minutes of continuous driving.
Ok, with all that said, what should I be doing different to keep my engine from sludging up? Is synthetic oil less prone to sludging? Should I be doing a regularly scheduled engine flush? Should I be using a detergent oil?
---pete---
Finally, after a 1000-mile break-in, use synthetic engine oil, and change the oil fairly often.
MagicRat, thank you sooooooooooo much for the detailed reply. You have answered so many of my questions and concerns on rebuilt engines. Great post!
I believe the oil type & change frequency issues are critical for me. I've always used Castrol 10-40 motor oil of the conventional type. Normal oil pressure would be between 40 and 60 PSI. I often judge the condition of the engine if it will maintain 30 to 40 PSI at idle in the hot summer months here in NJ.
My problems with small block Chevy engines usually occur after I notice the oil pressure dropping below 30 PSI at idle. Sometimes I'll try to compensate by using Castrol 20-50 motor oil in the hot summer months in order to keep that oil pressure from going too low. It seems that my rebuilt engines fail due to valve train problems caused by the engine oil sludging up. I operate a service business and do mostly short trips of 15 to 20 minutes driving at a time 60% highway miles and 40% city miles. I try to change my oil every 3k to 5k miles. I use the van for very light duty. No towing. Occasionally I load it heavily to haul some wood or lumber but just for very short distances. I rarely drive for more than 45 minutes of continuous driving.
Ok, with all that said, what should I be doing different to keep my engine from sludging up? Is synthetic oil less prone to sludging? Should I be doing a regularly scheduled engine flush? Should I be using a detergent oil?
---pete---
silicon212
01-03-2010, 03:24 AM
Castrol is excellent oil but there's a caveat - more on that later. First, regarding viscosities - don't run 10w40 oil at all - it's widely known to be the oil that breaks down the easiest, and this may be the source of the sludge. Castrol is a highly detergent oil and when I used it (back in the SJ and older days), running it kept the engine very clean on the inside. I only ever used the 20w50 variant (I live in sunny Mesa, AZ where winter falls on a Thursday this year).
You mentioned a quest for valvetrain longevity and this is where the above mentioned caveat comes into play - the SJ variety was the last that contained sufficient levels of ZDDP (zinc phosphate, necessary for cam lobe lubrication w/ flat tappet lifters) to keep the lifters lubed up. If you're going to run a roller cam/lifter combo, then disregard this but if you are going to run a flat tappet setup, two things you MUST follow - the proper oil and the proper lifters. Many of the lifters on the aftermarket are cheap crap from China and will not live in an engine, especially one with the wrong oil. The only lifters I would put in my engine today are made by COMP, Sealed Power or AC/Delco (not so sure about the latter these days, but they are the OEM). Ignore the rest! That being said, there are oils available today that do contain plenty of ZDDP but they are not 'mainstream' oils for gasoline applications. See, the government wants the end of ZDDP in oil, because it may weaken the action in a catalytic converter over a period of several tens of thousands of miles. ZDDP forms a 'sacrifical layer' on the cam lobe that gets scraped off, and replenished with lubrication - thus keeping the actual cam lobe and lifters apart and extending their lives.
You can get regular SM oil and use it as long as you use a zinc additive such as ZDDPlus, or you can run racing oil (Valvoline Racing) or diesel engine oil (Rotella-T, Delo etc) as these still have high levels of ZDDP.
Since 2006 I have only run Rotella-T in my engine. It's got over 300k miles on it and is on its second cam (only because I wanted to change the engines' power band). Of course, the lifters are the same age as the cam but the rest of the valvetrain has around 320k miles on it - and it's never been adjusted on either end of the cam swap (which occured at around the 100k mile mark).
You mentioned a quest for valvetrain longevity and this is where the above mentioned caveat comes into play - the SJ variety was the last that contained sufficient levels of ZDDP (zinc phosphate, necessary for cam lobe lubrication w/ flat tappet lifters) to keep the lifters lubed up. If you're going to run a roller cam/lifter combo, then disregard this but if you are going to run a flat tappet setup, two things you MUST follow - the proper oil and the proper lifters. Many of the lifters on the aftermarket are cheap crap from China and will not live in an engine, especially one with the wrong oil. The only lifters I would put in my engine today are made by COMP, Sealed Power or AC/Delco (not so sure about the latter these days, but they are the OEM). Ignore the rest! That being said, there are oils available today that do contain plenty of ZDDP but they are not 'mainstream' oils for gasoline applications. See, the government wants the end of ZDDP in oil, because it may weaken the action in a catalytic converter over a period of several tens of thousands of miles. ZDDP forms a 'sacrifical layer' on the cam lobe that gets scraped off, and replenished with lubrication - thus keeping the actual cam lobe and lifters apart and extending their lives.
You can get regular SM oil and use it as long as you use a zinc additive such as ZDDPlus, or you can run racing oil (Valvoline Racing) or diesel engine oil (Rotella-T, Delo etc) as these still have high levels of ZDDP.
Since 2006 I have only run Rotella-T in my engine. It's got over 300k miles on it and is on its second cam (only because I wanted to change the engines' power band). Of course, the lifters are the same age as the cam but the rest of the valvetrain has around 320k miles on it - and it's never been adjusted on either end of the cam swap (which occured at around the 100k mile mark).
petef
01-03-2010, 09:58 PM
All good points on oil types. Thank you.
Sounds like Synthetic Oil is the way to go along with frequent oil changes.
I'm guessing at 5k mile intervals or 1 year, whichever comes first. Correct?
I found some more useful info on Synthetic Oils
Synthetic oils are resistant to sludging.
http://en.wikipedia.org/wiki/Synthetic_oil
For my particular situation, sludging seems to be the biggest problem to overcome because my first rebuilt engine failed at about 30k miles/4 years use and my second rebuilt engine failed at about 60k miles/15 years use and both had valve train failures I can attribute to sludging and poor oil circulation in the top end of the engine.
If my general use of the vehicle makes the engine more prone to sludging, what EXTRA measures should I take to ensure it does not sludge up?
As a preventative maintenance measure, what is a good way to monitor the level of sludging and clean it before serious problems occur?
---pete---
Sounds like Synthetic Oil is the way to go along with frequent oil changes.
I'm guessing at 5k mile intervals or 1 year, whichever comes first. Correct?
I found some more useful info on Synthetic Oils
Synthetic oils are resistant to sludging.
http://en.wikipedia.org/wiki/Synthetic_oil
For my particular situation, sludging seems to be the biggest problem to overcome because my first rebuilt engine failed at about 30k miles/4 years use and my second rebuilt engine failed at about 60k miles/15 years use and both had valve train failures I can attribute to sludging and poor oil circulation in the top end of the engine.
If my general use of the vehicle makes the engine more prone to sludging, what EXTRA measures should I take to ensure it does not sludge up?
As a preventative maintenance measure, what is a good way to monitor the level of sludging and clean it before serious problems occur?
---pete---
j cAT
01-03-2010, 10:00 PM
I'm going to be buying a a rebuilt 305 engine for my 1985 G20 Van
What do you think?
---pete---
the 305 engine is a small reliable motor in a light weight vehicle.
when used in an application such as a van with more load and wind resistance, the engine won't last as it will be worked to death..
the 350 can be modified if it is required to produce more power..the 305 is not designed to produce more power..it is a poor design ..for this power increase...
the use of 10-40wt is a poor oil choice..this viscosity will cause engine wear..this has been known since the early 1980's GM TSB..10-30wt is the correct lube.....
the cost of a 305 should be less than the 350 as the 305 does not have much use/demand.
What do you think?
---pete---
the 305 engine is a small reliable motor in a light weight vehicle.
when used in an application such as a van with more load and wind resistance, the engine won't last as it will be worked to death..
the 350 can be modified if it is required to produce more power..the 305 is not designed to produce more power..it is a poor design ..for this power increase...
the use of 10-40wt is a poor oil choice..this viscosity will cause engine wear..this has been known since the early 1980's GM TSB..10-30wt is the correct lube.....
the cost of a 305 should be less than the 350 as the 305 does not have much use/demand.
silicon212
01-04-2010, 12:04 AM
J cat -
There are MILLIONS of 305s on the road. While it's true that most enthusiasts would rather have a 350, it's kind of like the computer world in that enthusiasts want - if not the most powerful CPU/memory/mainboard combo, then one that's a step or two behind it but still out ahead of most everything else. The general computer user is happy with a rather pedestrian Dell computer that's not upgradeable to our standards. I would say the same thing applies to cars - you and I and most others here want the 350 but I would be willing to wager that 7 out of 10 people would be happy with the 'pedestrian' 305 powering their Caprice or other similar large car (Cadillac Fleetwood, anyone?).
It does not cost more to buy general rebuild/overhaul parts for a 305 as it would for a 350, but if one were to buy a preassembled crate engine, the 350 would probably be a little cheaper.
To say that the 305 has less use/demand as a 350 would be incorrect, to say the least. Especially in this economy with energy prices being what they are - at this point I'd probably be happy with a 305 in my own car if I weren't so 'intoxicated' by the off-the-line acceleration (read: torque) of the 350.
There are MILLIONS of 305s on the road. While it's true that most enthusiasts would rather have a 350, it's kind of like the computer world in that enthusiasts want - if not the most powerful CPU/memory/mainboard combo, then one that's a step or two behind it but still out ahead of most everything else. The general computer user is happy with a rather pedestrian Dell computer that's not upgradeable to our standards. I would say the same thing applies to cars - you and I and most others here want the 350 but I would be willing to wager that 7 out of 10 people would be happy with the 'pedestrian' 305 powering their Caprice or other similar large car (Cadillac Fleetwood, anyone?).
It does not cost more to buy general rebuild/overhaul parts for a 305 as it would for a 350, but if one were to buy a preassembled crate engine, the 350 would probably be a little cheaper.
To say that the 305 has less use/demand as a 350 would be incorrect, to say the least. Especially in this economy with energy prices being what they are - at this point I'd probably be happy with a 305 in my own car if I weren't so 'intoxicated' by the off-the-line acceleration (read: torque) of the 350.
MrPbody
01-04-2010, 08:26 AM
My response focused on efficiency simply because, overall, there ARE no longevity issues with a properly built SBC. Most of the old problems have been solved through experience and engineering. Valve guide problems ended in the mid '70s. Valve TRAIN problems? Only in "high revvers". SBC is among the most popular engines ever built by anyone for a lot of good reasons, none of which are because they're "cheap". They're "cheap" because they're the most popular...
Mainly, the best way to increase the longevity of a SB in a 3/4 ton van is to use the largest CID you can... And more importantly, as pointed out by Magic Rat, the quality of the BUILD is key.
Jim
Mainly, the best way to increase the longevity of a SB in a 3/4 ton van is to use the largest CID you can... And more importantly, as pointed out by Magic Rat, the quality of the BUILD is key.
Jim
j cAT
01-04-2010, 09:10 AM
my 305 is not very effecient..the most I ever got was 18mpg..84 camaro.
the 350 is a design with power increases and parts widely available for this engine..the 305 has a restricted intake issue ,,not designed for power increases..
the poster asked about a 305 in this van..my response is not enough power...the engine will be over worked and the tranny will suffer..
the computer analogy is a good one...any componet not up to speed and the preformance will suffer..memory , buss , processor,hard drive, and even how the motherboard was designed..
both engines with proper care are reliable ..as we all know many are still running...still the 350 engine is in demand...even with the cost of fuel rising..Its not like there using these engines in small vehicles, they just need the power for use in a truck , van, or boat...then the parts available.
the 350 is a design with power increases and parts widely available for this engine..the 305 has a restricted intake issue ,,not designed for power increases..
the poster asked about a 305 in this van..my response is not enough power...the engine will be over worked and the tranny will suffer..
the computer analogy is a good one...any componet not up to speed and the preformance will suffer..memory , buss , processor,hard drive, and even how the motherboard was designed..
both engines with proper care are reliable ..as we all know many are still running...still the 350 engine is in demand...even with the cost of fuel rising..Its not like there using these engines in small vehicles, they just need the power for use in a truck , van, or boat...then the parts available.
MagicRat
01-04-2010, 09:21 AM
MagicRat, thank you sooooooooooo much for the detailed reply. You have answered so many of my questions and concerns on rebuilt engines. Great post!
I believe the oil type & change frequency issues are critical for me. I've always used Castrol 10-40 motor oil of the conventional type. Normal oil pressure would be between 40 and 60 PSI. I often judge the condition of the engine if it will maintain 30 to 40 PSI at idle in the hot summer months here in NJ.
My problems with small block Chevy engines usually occur after I notice the oil pressure dropping below 30 PSI at idle. Sometimes I'll try to compensate by using Castrol 20-50 motor oil in the hot summer months in order to keep that oil pressure from going too low. It seems that my rebuilt engines fail due to valve train problems caused by the engine oil sludging up. I operate a service business and do mostly short trips of 15 to 20 minutes driving at a time 60% highway miles and 40% city miles. I try to change my oil every 3k to 5k miles. I use the van for very light duty. No towing. Occasionally I load it heavily to haul some wood or lumber but just for very short distances. I rarely drive for more than 45 minutes of continuous driving.
Ok, with all that said, what should I be doing different to keep my engine from sludging up? Is synthetic oil less prone to sludging? Should I be doing a regularly scheduled engine flush? Should I be using a detergent oil?
---pete---
All good posts here.
A couple of things....... a hot idle pressure of less than 30 psi is not a problem. This is common and is okay as an engine gets older.
In stock, old-technology engines like yours, the rule of thumb is allow for a minimum of 10 psi for every 1000 rpm. So this means approx. 10 psi at idle, 20 psi at 2000 rpm etc.
20W-50 is simply too thick for most normal engines. Some race engines use this, only because they have been 'blueprinted' for loose clearances. But that oil is simply too thick to get into the tiny clearances found in bearing journals, especially on a cold-start up. In such cases, oil flow is better than oil pressure. Therefore, using 20W-50 may cause more harm than good.
Engines develop sludge for 2 reasons:
1. If conventional oils get overheated regularly - something which almost never happens with SBC's.
2. If the oil is not changed often enough and accumulates contaminents.
Your driving situation is not good for engine life. Short trips (15-20 minutes) tends to not allow the engine oil to warm up fully. This means that sludge-producing contaminets, like condensation, blow-by gases etc will accumulate in the oil, because the oil will not get hot enough to 'boil-off' these contaminents.
Therefore, an annual oil change is a bad idea, regardless of oil type. Synthetic oils accumulate sludge-producing contaminents as fast as conventional oils. Change the oil frequently, This is the most important thing you can do to prevent sludge build-up. Change it minimum every 3 months. If the engine gets several short trips every day, consider changing the oil every 2 months, regardless of mileage. Of course, this gets expensive if synthetics are used. So use a conventional 10W30, and do your own oil changes (if you don't do so already.)
As Silicon 212 mentioned, oils with a high zinc content are best. These are found primarily in oils intended for diesel engines exclusively. (not diesel and gas). Unfortunately, most diesel engine oils are 15W40, which is too thick. You can find diesel-only oils that are 10W30. Penzoil makes one, that I use. But its a bit rare and hard to find :( so don't get worried if you can't find it.
BTW if you change the oil yourself, fill the oil filter first before installing it. Mechanics almost never do this, but its important. It takes 2 minutes to do this, but it means the engine is not starved for oil when you start it up next.
Finally, check your PCV valve and hoses. They are vital to preventing sludge build-up. If you have never changed it it may be blocked and be contributing to your sludge problems. Consider changing it once a year if it looks dirty.
I believe the oil type & change frequency issues are critical for me. I've always used Castrol 10-40 motor oil of the conventional type. Normal oil pressure would be between 40 and 60 PSI. I often judge the condition of the engine if it will maintain 30 to 40 PSI at idle in the hot summer months here in NJ.
My problems with small block Chevy engines usually occur after I notice the oil pressure dropping below 30 PSI at idle. Sometimes I'll try to compensate by using Castrol 20-50 motor oil in the hot summer months in order to keep that oil pressure from going too low. It seems that my rebuilt engines fail due to valve train problems caused by the engine oil sludging up. I operate a service business and do mostly short trips of 15 to 20 minutes driving at a time 60% highway miles and 40% city miles. I try to change my oil every 3k to 5k miles. I use the van for very light duty. No towing. Occasionally I load it heavily to haul some wood or lumber but just for very short distances. I rarely drive for more than 45 minutes of continuous driving.
Ok, with all that said, what should I be doing different to keep my engine from sludging up? Is synthetic oil less prone to sludging? Should I be doing a regularly scheduled engine flush? Should I be using a detergent oil?
---pete---
All good posts here.
A couple of things....... a hot idle pressure of less than 30 psi is not a problem. This is common and is okay as an engine gets older.
In stock, old-technology engines like yours, the rule of thumb is allow for a minimum of 10 psi for every 1000 rpm. So this means approx. 10 psi at idle, 20 psi at 2000 rpm etc.
20W-50 is simply too thick for most normal engines. Some race engines use this, only because they have been 'blueprinted' for loose clearances. But that oil is simply too thick to get into the tiny clearances found in bearing journals, especially on a cold-start up. In such cases, oil flow is better than oil pressure. Therefore, using 20W-50 may cause more harm than good.
Engines develop sludge for 2 reasons:
1. If conventional oils get overheated regularly - something which almost never happens with SBC's.
2. If the oil is not changed often enough and accumulates contaminents.
Your driving situation is not good for engine life. Short trips (15-20 minutes) tends to not allow the engine oil to warm up fully. This means that sludge-producing contaminets, like condensation, blow-by gases etc will accumulate in the oil, because the oil will not get hot enough to 'boil-off' these contaminents.
Therefore, an annual oil change is a bad idea, regardless of oil type. Synthetic oils accumulate sludge-producing contaminents as fast as conventional oils. Change the oil frequently, This is the most important thing you can do to prevent sludge build-up. Change it minimum every 3 months. If the engine gets several short trips every day, consider changing the oil every 2 months, regardless of mileage. Of course, this gets expensive if synthetics are used. So use a conventional 10W30, and do your own oil changes (if you don't do so already.)
As Silicon 212 mentioned, oils with a high zinc content are best. These are found primarily in oils intended for diesel engines exclusively. (not diesel and gas). Unfortunately, most diesel engine oils are 15W40, which is too thick. You can find diesel-only oils that are 10W30. Penzoil makes one, that I use. But its a bit rare and hard to find :( so don't get worried if you can't find it.
BTW if you change the oil yourself, fill the oil filter first before installing it. Mechanics almost never do this, but its important. It takes 2 minutes to do this, but it means the engine is not starved for oil when you start it up next.
Finally, check your PCV valve and hoses. They are vital to preventing sludge build-up. If you have never changed it it may be blocked and be contributing to your sludge problems. Consider changing it once a year if it looks dirty.
silicon212
01-04-2010, 11:23 PM
"BTW if you change the oil yourself, fill the oil filter first before installing it. Mechanics almost never do this, but its important. It takes 2 minutes to do this, but it means the engine is not starved for oil when you start it up next. "
EXCELLENT ADVICE that's worth repeating - I've been doing that since I was a kid (yes I used to maintain the family cars even when I was 10 years old!), only since I can't think of much worse you can do to an engine than give it a 'dry start', especially the types who like to goose the gas pedal when they start the engine - say 'auf wiedersehen' to the bottom end!
EXCELLENT ADVICE that's worth repeating - I've been doing that since I was a kid (yes I used to maintain the family cars even when I was 10 years old!), only since I can't think of much worse you can do to an engine than give it a 'dry start', especially the types who like to goose the gas pedal when they start the engine - say 'auf wiedersehen' to the bottom end!
petef
01-07-2010, 03:58 AM
Your driving situation is not good for engine life. Short trips (15-20 minutes) tends to not allow the engine oil to warm up fully. This means that sludge-producing contaminets, like condensation, blow-by gases etc will accumulate in the oil, because the oil will not get hot enough to 'boil-off' these contaminents.
Therefore, an annual oil change is a bad idea, regardless of oil type. Synthetic oils accumulate sludge-producing contaminents as fast as conventional oils. Change the oil frequently, This is the most important thing you can do to prevent sludge build-up. Change it minimum every 3 months. If the engine gets several short trips every day, consider changing the oil every 2 months, regardless of mileage. Of course, this gets expensive if synthetics are used. So use a conventional 10W30, and do your own oil changes (if you don't do so already.)
As for my sludging problem I think your advise above is probably the best. For oil change frequency I see now the need to monitor time, not mileage. Or more simply put, change the oil every 3 months or every 3k miles, whichever comes first. Sounds like I also need to switch from 10W40 to 10W30 for my 305 Chevy engine and to stick to the conventional Castrol GTX oil for the sake of expense with such frequent oil changes.
I'll change that PVC valve annually too. :)
Thanks for the advise. This entire thread is
full of great advise and useful info.
As for monitoring the level of sludge, I guess I can
occasionally remove the oil filler tube from the valve
cover and explore with my finger for any evidence of
sludging.
---pete---
Therefore, an annual oil change is a bad idea, regardless of oil type. Synthetic oils accumulate sludge-producing contaminents as fast as conventional oils. Change the oil frequently, This is the most important thing you can do to prevent sludge build-up. Change it minimum every 3 months. If the engine gets several short trips every day, consider changing the oil every 2 months, regardless of mileage. Of course, this gets expensive if synthetics are used. So use a conventional 10W30, and do your own oil changes (if you don't do so already.)
As for my sludging problem I think your advise above is probably the best. For oil change frequency I see now the need to monitor time, not mileage. Or more simply put, change the oil every 3 months or every 3k miles, whichever comes first. Sounds like I also need to switch from 10W40 to 10W30 for my 305 Chevy engine and to stick to the conventional Castrol GTX oil for the sake of expense with such frequent oil changes.
I'll change that PVC valve annually too. :)
Thanks for the advise. This entire thread is
full of great advise and useful info.
As for monitoring the level of sludge, I guess I can
occasionally remove the oil filler tube from the valve
cover and explore with my finger for any evidence of
sludging.
---pete---
MagicRat
01-07-2010, 09:12 AM
As for my sludging problem I think your advise above is probably the best. For oil change frequency I see now the need to monitor time, not mileage. Or more simply put, change the oil every 3 months or every 3k miles, whichever comes first. Sounds like I also need to switch from 10W40 to 10W30 for my 305 Chevy engine and to stick to the conventional Castrol GTX oil for the sake of expense with such frequent oil changes.
I'll change that PVC valve annually too. :)
Thanks for the advise. This entire thread is
full of great advise and useful info.
As for monitoring the level of sludge, I guess I can
occasionally remove the oil filler tube from the valve
cover and explore with my finger for any evidence of
sludging.
---pete---
It looks like you are on the right track here. My family, friends and I do just this and have never had any signs of oil sludging, even when I have removed the odd valve cover or oil pan, ( to replace a gasket etc. )
I'll change that PVC valve annually too. :)
Thanks for the advise. This entire thread is
full of great advise and useful info.
As for monitoring the level of sludge, I guess I can
occasionally remove the oil filler tube from the valve
cover and explore with my finger for any evidence of
sludging.
---pete---
It looks like you are on the right track here. My family, friends and I do just this and have never had any signs of oil sludging, even when I have removed the odd valve cover or oil pan, ( to replace a gasket etc. )
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