engine rebuilding

[daveid]

Over the last couple months ive been pondering what to do with my chevy 400 and i know ive posted in muscle cars about it, but it is gonna be my first tear down and rebuild. I was going to go and put in a hp type kit, but i dont know how good these ones are for 500-1000 bux. Also, all thats wrong with the engine is it needs new rings. Do you guys think i should just replace the rings and keep it like that so its a basic rebuild to get myself familiar with taking it apart and putting it back together, or go all out?

My other problem is i dont have much money for it right now so i cant afford real high performance stuff.
Like this kit right here? What do you guys think of it?
http://www.northernautoparts.com/Pro...ctModelId=1669

Also, id have to buy a gasket kit even to just replace the rings right?

Thanx
david

PS. If i need new rings and i dont know what brand piston they are how can i tell or can you put a different companies ring on a different piston.

[curtis73]

While its apart, definitely have it hot tanked and bored. You might be able to get away with just rehoning it, but I highly doubt it.

The bores wear and get larger. They also wear unevenly and get out-of round. Just putting new rings in might make it worse since the old rings have worn with the bores. New rings would be perfectly round and not seal very well.

The hot tank and bore should be under $200. I think my latest one was $135 for a bore and hone and $35 for the hot tank.

Things like rings, bearings, and other peripherals are all interchangeable. There are better names and constructions, but for the most part, any ring manufacturer will do just fine for you. If they are made for the same application, one brand will fit just as well as the next. The Hastings rings spec'd in that kit will do quite well.

Usually, re-ringing a block can only happen if its a low-mileage block, like a fresh assembly that turned up a cracked ring or a bum piston pin. You can usually disassemble and re-ring with possibly a light honing to it and be fine, but after break in, usually its not much of an option.

Yup, you'll need a complete gasket kit, but check with northernautoparts. The kit says "felpro gasket." That might be a full kit.

You can bet that the main and rod bearings are almost toast, and even if you just ran the engine 10,000 miles, they've probably affected the crank. Therefore I also strongly suggest having the crank checked. The crank journals wear in an egg-shaped pattern since they are subjected to forces from only one side.

If you're worried about cash outlay, I submit this: That old saying of "it costs less in the long run to do it right." is never more true than with engine work. Just the act of pulling and engine is more labor than I care to do, but doing it twice in one project is a pain. Not to mention, re-buying gaskets, draining fluids, new break-in periods... grr.

You might be bux ahead to take a mild step down in components and spend that money on some more machine work. I'm not talking about porting or fancy stuff, just things like machining the crank, boring the block, resizing rods, and refurbishing heads. In a trade off (since you're not going over the top with power) you can step down to hypereutectic or cast pistons and save a couple hundred to offset the extra machine work.

Although, $585 is pretty cheap for a kit that inclusive

Just to put it in perspective, I took my 454 to a top notch machine shop that was known for expensive but good work. My original stuff I had done: bore and hone, new cam bearings, hypereutectic pistons with coated skirts, main and rod bearings, rings, piston pins, resized rods, rebuilt heads with new springs, seals, and a valve job, resized crank, and new ARP wave-loc rod bolts and main bolts, and I had to have my crank snout rethreaded. That's pretty inclusive of a high-quality rebuild from stem to stern and it came in at just under $1000. Of course, I tore it apart and I assembled it so that saved some money. The parts I ordered individually were; gasket set, cam, lifters, pushrods, oil pump, intake and some other hi-po goodies, but the whole project was well under $2000 for 400 hp. Since you have a small block, parts are a little cheaper, too. Given the price of that kit you are looking at, you could have all of that done for about $1500, less if you used some cheaper brand fasteners and cheaper pistons.

You're going to run into one snag so I'll just prepare you for it. Your machine shop won't know how far they have to overbore until they see it, and they can't finish honing it until they have the pistons. You'll have to give them the block, get the verdict, then order your kit. Then they can precisely measure the pistons and finish hone accordingly. You could just go ahead and order the .060"-over pistons since 60 almost always cleans it up, but that is sort of a waste if you don't need it that far.

Edit: One thing I forgot. Don't forget to take all the hardware with you to the machine shop. In specific, take the main bearing caps and bolts, head bolts, rod nuts, etc. They need all of that to check clearances and the machining they do turns out more true if those fasteners are torqued in place during the work.

[MagicRat]

Ho-hum, another stunning and very inclusive curtis post

I might add that whenever I tear down an engine I pay close attention to the 'ridge' at the top of the cylinder bore. Although the piston goes to the top of the cylinder, the rings dont, so the top 1/16 to 1/8 of an inch receives no wear. If you can feel a ridge, the cylinder walls have descernable wear and you should consider a rebore.

[daveid]

thanx a lot for the help guys. I had a 454 build by a friend of mine and i put top of the line stuff in it but i dont live near him anymore and i want to do this on my own and learn cuz it has alawys been a passion of mine. Therefore, thats why i lack money. LOL.

Anyways i know you also get what you pay for but and like you said curtis, it sucks to do a job twice!!!
The engine i got when i bought my old truck just to have an engine to roll around in. I only drove it about 20 miles and pulled it out.
Since i went so extensive on my 454, its more of a race engine used for the street. On this one i eventually want to make a hot 406, thats made comepletey made for STREET. But i want the experiance before getting in over my head and spending a couple grand.
Also right now to come up with money it would be like 100 here and 100 there. So back to that engine kit too, Your saying its worth it? I also know that you cant have an engine worth anything unless you have it machined correctly which i know you guys are saying as well.
Also too, sorry i know im all over the place in my subjects but since your saying all the stuff i will need to do to it i mine as well try and hop up the motor right now. And that being said, about how much hp do you think this kit would make with the stock heads? or with stock heads ported?

Anyways, thanx again for all the help.
david

[daveid]

or what about this kit?

eBay item 7954632145 (Ends Apr-15-05 09:30:04 PDT) - High Performance Engine Kit for 400 Chevy W/ Hyd. Cam

[curtis73]

Its a little hard to guess... what heads are they? If you can tell me the heads I can maybe find some flow numbers and we'll see.

For now I'll stab at some guesses. If you're sticking to a street-only 406, (and since its a stock compression assembly) I'd stick with the Crane 266 option in the northern auto kit (or something similar; comp makes a 262 and a 268, etc)

Anyway, with stock, unported heads I would think around 300 hp/380 tq. If you mildly port them, 340 hp/425 tq. You could step up in cam a touch but then I would highly recommend more like 9.5:1 compression. Then you're looking at something like 375/430. Those are just vague guesses using Desktop Dyno (which I'm not sure is working properly right now) but if you want, get your ducks in a row, decide on a cam, get me head numbers, and I'll plug in some more accurate parameters in DD and give you some numbers.

[daveid]

you want the serial #'s? Ya id like to bump it up to like 9.5 comprssion like you said. I want a street engine with some hp but id make it street/race but i just dont want to have to deal with cooling problems thats all. And if i have some wicked engine then id want to start messing with the gear ratio's and stuff to see how fast it really could go but id like around 400-450 hp but anyways, ill get you the head #'s soon and ill look at some cams tonight.

Thanx for the quick responses curtis.

david

[daveid]

the casting #'s on the head that i can see is right next to the bottom side of the head and i see 450 6. I dont know if thats it or where else to find them. i looked all over the heads.As for the cam, you think the 284 would be too much?
I like the sounds of that one, but i dont know how itd stack up to the rest, lol. Since you said to maybe get less expensive pistons, they do have the same package but with hypereutectic ones. heres the link.
http://www.northernautoparts.com/Pro...ctModelId=1670

thanx again curtis,
david

[curtis73]

I like that kit. The hypereutectics are actaully preferable in some cases (in my opinion) If you don't need the ultimate strength of forged, the hypers provide a lightweight, strong middle ground. They also expand and contract more uniformly with the block so cold start blowby is reduced. Forged pistons expand more so they have be given a little more bore space so that they have the right clearance when hot. Its really only a big deal for emissions, but if you do any short trips it could shorten the life of your oil and accelerate bore wear slightly.

I'm pretty sure you have to pull the valve cover to get the casting number. It is probably between the rockers and has 6, 7, or 8 digits.

284 cam is getting pretty stout. Less is more on the street. The other thing that concerns me is its 106 LSA. You'll won't have adequate vacuum levels for power brakes and your climate controls, and carb tuning will be on the expert level. The Crane 278 might do OK since it has a 110 LSA. You want more LSA on a street engine (in general) since it will smooth out the idle and add vacuum. But still with the 278 you'll need more head work and a 2700 stall converter (depending on the car). Streetable? yes. Easy to live with daily? not for me. Its up to you, though. I see a guy drive by my place every single day in a Nova with a small block. The cam sounds about like a 278; noticable idle, dual 2.5" exhaust, 2700 stall or so, and he seems to do fine in it. He probably gets 8 mpgs and has no power accessories, but that seems to be fine for his daily driver. I couldn't deal with the high stall all day and no power brakes

Just my 2 cents, but my experience is based entirely on heavy cars. If this is going in a vega its a different story Someone else here a better cam picker?

[daveid]

ok. No i see exactly what your saying. Ya and i dont want to be screwing with the thing every couple days and messing with the carb, let alone hire someone to fix it. lol.
As for driving it and stuff, id say id probly be driving it a couple days a week and about 35 miles on most of those days.
Ill look for those casting #'s asap, which could end up being tonight or sunday evening.
Do you think itd be worth going for the 406? or just staying at whatever it needs to get the cylinders cleaned up? Like i said id like 400 hp but i totally agree with you that if its going to be all that work and dealing with that stall then id rather go like 25 hp lower to not deal with it.

Hey thanx again curtis
david

[daveid]

ok. the casting # is 376450

[curtis73]

Although my sources are a little old, those appear to be non-original heads. They are small chamber heads from 262, 305, 350 engines. At any rate, they are a pretty low performance piece from my research, but information was sketchy at best.

I plugged in some numbers on desktop dyno with the flow numbers I came up with and I got 300 hp/400 tq. Less than we had hoped. I think you can still buy vortec heads for about 300 each fully assembled. They should push you to 350/425 as-cast. Ported vortec heads would put you back up to more like the 375/430 I was talking about earlier.

This is where my head runs out of info. I haven't done any small block chevy research in years, so I don't have any more info in my head. At the end of this post I'll give you some links of where I got my info and you can maybe take it from there. The problem with just putting vortec heads on a 406 is that it might shove your compression too high. You might have to choose slightly dished pistons or flat tops with four valve reliefs or something. I can tell you this: In general, the more effective combination will be found (as far as chevy's are concerned) with a flat-top piston and the proper chamber volume. This maximizes quench and swirl which is a good thing for detonation tolerance and efficiency. The next best combo is a dished piston to get your proper compression if you have a chamber that's too small. The last choice I would make (although not an issue in your case) would be using a domed piston to compensate for a chamber that's too big. It kills quench and slows flame speed, but you don't need to worry about that.

These finer points you can either hash out yourself, or talk with your machinist. SBCs are common enough that he should know what heads provide nice flow and the proper chamber size for your compression goals. Do enough of your own homework that you'll know if he's blowing smoke up your arse, but if you have a good rapport with him you can trust the fine details to him.

http://users.erols.com/srweiss/tablehdc.htm
http://www.chevyhiperformance.com/techarticles/41598/
http://www.kendrick-auto.com/head_flow_figures.htm
http://www.mortec.com/castnum.htm
http://www.dw1977.cz28.com/photo2.html
http://www.angelfire.com/tx5/randysr...Headguide.html
http://www.kendrick-auto.com/chevrol..._number_re.htm

[daveid]

cool thanx curtis. ill definatly use those and check them out. well that second kit i beleive had flat tops.

[curtis73]

Originally Posted by daveid

Do you think itd be worth going for the 406? or just staying at whatever it needs to get the cylinders cleaned up?

I just noticed a question I missed... You could just bore it as much as it needs for a cleanup, but in general the least that would be is .030" For that reason, common piston sizes include .030", .040", and .060" oversized. Some also have a .020" over, but probably not for your 400. .030" overbore is 406 cubes, so I think you'll be getting 406 anyway since .030" is the smallest piston that is the next size up for your engine.