[mega_fly]

Hello Everyone,

I have been trying to find some info about using 350 heads on a 305.

I have a 1980 TA that has a 305 but is not the original motor. I also have a rusty 350 long block in my garage. The heads are GM cast number 3947041. Found this on the internet:

3947041....69-70...302/350......"Right angle" casting identifier, 64cc chamber, accessory holes, good HP head

If i had the heads cleaned and ready to install, do you think they would work on the 305? I am thinking of maybe using these heads with a Edelbrock Performer intake and Headers to let the motor breath better.

[mega_fly]

Hello Everyone,

I have been trying to find some info about using 350 heads on a 305.

I have a 1980 TA that has a 305 but is not the original motor. I also have a rusty 350 long block in my garage. The heads are GM cast number 3947041. Found this on the internet:

3947041....69-70...302/350......"Right angle" casting identifier, 64cc chamber, accessory holes, good HP head

If i had the heads cleaned and ready to install, do you think they would work on the 305? I am thinking of maybe using these heads with a Edelbrock Performer intake and Headers to let the motor breath better.

[surfnbird]

Well here's what I think I would do,,,,,
I'd take that rusty 350 block you've got in the garage to a reputable machine shop and have them prep it for you, slap them heads on it and build yourself a motor (or let them do it for you). You'll be a whole lot happier and it will probably save you from just wanting to do it later.

I know,,,, opinions are like assholes, Everybodys got one!

[mega_fly]

thats the eventual plan. but i dont have the cash for it now. I figure that since i have to have the heads done anyway, i could just do that part now and then when the 350 is done just swap them over. Any idea on how much machine shops to do heads. 100-200 $?

Here is my thinking:

HEad work = $200
Edelbrock intake = $100
Headers = $200

500 bucks and i would have another 30 to 40 horse, move the horse power peak way up and have the parts ready for when the 350 or 383 stroker is done.

Im a young family man have pity!

[surfnbird]

I know exactly how it is, I'm in the middle of a 462 stroker build up right now, I'm $6500. into the project and not quite finished yet. Anyway head work will probably cost you about $300. of your $500. But the thing is when you go to build youe 350 motor your going to have to freshen up those heads all over again. Just food for thought.

[mega_fly]

gotcha, thanks for the input. ill leave them out of the equation for now

[TA454]

Yes 350 heads will work on a 305 you just need to run 350 head gaskets with them

[connman]

dont brmember the correct cc but a 305 is at about 53 55 cc and that will take u'alls compression way way down on an already compression less motor why not do a simple rebuild on the 350 turn crank about 120 bucks put new bearings and new rings in it and reseal it I know that every one will tell u;all that it needs boring and ect but I have done it many a time also those old 041 heads are the best closed chamber heads that chev made and if the motor is original u should have a steel crank in it rebuilding a chev the old fashion way can be done really cheap I put a crank kit 350 cast crank kit in a 305 {racers tip just dont put a 305 crank in a 350} put in new rings and bearings put on tulip valve guide seals and gasket set for less than 250 bucks I just lapped the valves in as I went If u want to talk to me go to [email protected] and leave message just mention 350 build up so I dont delete u A chev motor has no real problens with rebuilding if u follow the motors manual

DRIVE IT LIKE U'ALL STOLE IT!

[mega_fly]

Hello all. I have been thinking about the low compression issue with the 350 heads. However, it seems that this is just the right environment for a roots type blower putting out some boost. With the better airflow of the heads and intake and the high level of boost i could run with a blower, i would think this 5 liter could put out some descent reliable power.

WADDAYATHINK?

[PLAY400]

I don't know all the details but I've been told by a few Chebby guys that the 305 head is now desirable. Has something in common with older performance heads but I can't remember what but they are supposed to be making good power with them.

[mega_fly]

Well i got a pair of those hi-po heads available RIGHT NOW!! Available to the highest bidder! Shall we start the bidding at 600 hundred? Do i hear 7?

[bonneville Joe]

305 heads have a smaller chamber than a 350 head. If you but a 305 head on a 350 it will bump the compression up. I've heard this a few times. I had a guy tell me that if I got ahold of a 350 block to replace my 305 in my GTA to reuse the 305 heads for that reason.

[Bill Eveland]

305 heads won't flow as good as the 350 head without some work, so your defeating your purpose by swapping the heads just to add compression.

[mega_fly]

So a 1980 305 w/ stock heads i believe has around 8.5 to 1 compression. The heads are 55 or 50-something cc? Using 64cc vortec heads would lower the compression to ?? Anyone?

[mega_fly]

Turns out that this motor was a 350 the whole time. The heads are '882' castings w/ 1.94 intake valves.

[impish]

yup 64cc's will lower compression on a 305 AND 350's of the 80's if it has dished pistons it is a low comp 58cc head motor

[impish]

i re read your post, 882's? that is like a 71-78 motor?

[Jeff Walker]

The 882 castings were used on 75 up to somewhere around 79-80. they have about a 72cc chamber and I have seen then with the 1.94 intake valve and also the smaller size 1.72 intake. If the engine in you car still has the dished pistons the 64cc 350 heads would bring the compression up to about 9.00 to one.

[Carl S]

Jeff

This is great. I can get Chev tech assistance on a Pontiac forum!!!

I am building a bracket car with some teenage kids, and we are on a budget. We have a set of stock 350 pistons for a 75 engine (dished) and will be getting a set of 65 327 heads, I believe 64 cc. Does that mean we will end up with about 9.00 to 1? I couldn't find a calculator anywhere that would tell me. We plan to shave them a touch if that is what it gives us stock.

Thanks

Carl

[Jeff Walker]

LOL Yeah a person learns a thing or two about most all makes when he has spent most his life turning wrenches for a living and as a hobby.

If the 327 heads are the 64cc chamber, using them on a 350 with dished should put you in that range for compression. Here is a link that you might find useful: http://www.prestage.com/