head queston from the new guy

OK this is what I got 84 GMC pickup 305 2wheel drive 4spd auto,(tuck was a 350).First off how can I tell one engine from another(305,350,327),the cubic inches shuold be on the block,, right?, can 350 heads be used on a 305,and will it change the compression(because of chamber size),I ask because I can get a set of 350 heads for free and I can redo them and then swap them on in a day.I use this truck daily so I cant have any down time.I'm not a Chevy guy so go easy on me,this was one of those I can't pass up deals and I needed a pickup,thanks ,,,speedfreak340.:smokin:

First off how can I tell one engine from another(305,350,327),the cubic inches shuold be on the block,, right?,

No, the cubes are not displayed on the block, so to speak. You need to find the block casting # (located on the back of the block, drivers side, above the bell housing attach point). Then you need to find the engine serial #'s (these are stamped in) located on the front passenger side just below the head/block mating surface. Then you need to check this site.

http://www.mortec.com/

can 350 heads be used on a 305,and will it change the compression(because of chamber size),

Yes, the heads are interchangeable but not sure about different chamber sizes. The web site above may give you more info on that. You'll also need the casting #'s and casting dates off the heads to help decifer the head info.

Hope this helps and welcome to the forum.

Ok 777stickman this sheds some light on things,thank you for your reply,as for chamber size I'll talk to my local speed shop. thanks again,,,speedfreak340.

Aside from checking the casting number there really isn't anyway to tell the CID of Chevy SB engines, even then you still have to do some work to figure them out.

When Chevy created the SB back in the 1950's they wanted a common platform from which they could use parts (same oil pan, valve covers, etc.) which saved them a lot of money. So with that in mind all the SB engines had identical external dimensions from the 265 all the way to the 400cid.

The way they came about getting different CIDs was all the the bore and stroke (and some creative casting methods with the 400), in some cases the bore was the same for two different engines but the stroke was different, by changing the stroke you can create a 327 or 350 out of the same block, there was a 302 made out of the same block it was basically a racing engine with a LARGE amount of breathing room.

Very cool ideas indeed, but to get back to the point... if a casting number says that it is either a 305 or a 350 the easiest thing to do is measure the bore, 305's bore is probably going to be narrower than a 350s, but in other cases they still shared the same bore. Then you get into looking up part numbers for the crank shafts, which hopefully will tell you what it is, but even then 307 or 327 (same stroke).

Then you start researching by year and find out when that particular casting number was in use to narrow it down even further until you finally get down to your engine.

Welcome to the world of Chevy :-)

Wow,,,,holy involvement batman,,I found it to be a hassle to change the starter,is it a long nose or sort?I told the guy behind the counter I have no idea.At the time I first bought the truck I was told it was a 350,the starter told me it was a 305.No 350 starters would fit,long or sort,so I told them give me one for a 305 and wala it fit. My mopar buddies are ribbing me big time, I told them the more I learn the dumber it makes you guys,then we chuckle and take another hit of beer,,,speedfreak340. :popcorn:

Well if u want the 305 to be weak as shit go ahead and throw on some 350 heads as they will drop compression, find yourself a set of 416 heads (416 being the last 3 digits of the casting #) these are ho heads and are the beast head chevy made for these engines.

Echoing MikeRWK, most 350 heads are going to be 'smog heads' with chambers in the 76cc range. Most stock 305s are 58-62cc and as such, the 76cc chamber will result in a substantial compression loss - on the order of 1-2 whole points! A factory 305 has its power issues but if you drop it down to 7:1, you will go nowhere fast.

The 416s are a good head - if you want aftermarket you can go with a set of World Performance S/R Torquer 305s. These even have 1.94 intakes and large volume ports and will do a good job at waking a 305 up. I've personally seen 305s run that will give a good run to a 350 in both HP and torque, but you have to invest a little in it.

Here's a little something from another site:
If you already have the 305 engine or at least it's short block, it's probably the cheapest and easiest way to 300 HP. Any more than that or if you want more low end torque it will be better to get a 350. If you can get a 350 without shelling out more than a few hundred bucks it's probably a good idea to get it, otherwise stick with the 305. Here's a setup that should get you close to the 300 HP mark:

Holley/Demon 600 cfm carb
Edelbrock RPM Air Gap manifold
Comp Cams XE262 cam (218/224 @ .050, .462/.469 lift)
14014416 casting 305 heads - these are the best of the 305 heads
1-5/8" headers with at least 2-1/2" single or 2-1/4" dual exhaust
Aftermarket HEI Ignition (Mallory, Accel, etc.)

http://www.hioutput.com/tech/343hp/343hp.html

Check out this link for a 343 HP 305.

They used a higher compression ratio, slightly ported heads, and a little lumpier cam than the combo I suggested.

The reason most attempts at building a good 305 end up being an exercise in futility is because many don't have the 14014416 casting heads. These heads have a tall short side radius, a smoother exhaust runner, and a larger 165cc intake port. If you don't have the 14014416 heads I wouldn't try building a 305.

Either will make a nice motor :D