403 or 350 heads

[mustangboi]

Just wondering if anyone knew... I have an Olds 403 motor im rebuilding, The heads are not the greatest but I have a set of 350 Olds heads. Would I be better off finding another set of 403 heads? Would the 350 heads ruin performance? What are my pros and cons about using the 350 heads?

[BNaylor]

Welcome to AF.

The forum you posted in is reserved for GM N body cars and your issue is generic in nature so it has been moved to Oldsmobile Non-Specific.

[xeroinfinity]

What year is the 403 and whats the year on the heads, aproximatly.

IMO 403's are kinda dogy anyways .

[mustangboi]

The 403 is out of a 79 Olds, it has been gone through totally. I do have the original heads that have not been machined yet, but also have a set of heads from a 75 Cutlass 350 that are perfect. I was told at one time the 350 heads on a 403 is a better combination creating a bit more snap.

[xeroinfinity]

Originally Posted by mustangboi

The 403 is out of a 79 Olds, it has been gone through totally. I do have the original heads that have not been machined yet, but also have a set of heads from a 75 Cutlass 350 that are perfect. I was told at one time the 350 heads on a 403 is a better combination creating a bit more snap.

Sorry I didnt get back to ya sooner, I didnt get an email notification stating you posted again.

On with the heads, the 350 heads add better performance for sure. A friend of mine has a 79' TA w/403 which has 350 heads and he said its quicker and he gets a little better mpg, which we all love

[mustangboi]

Hey thanks dude, I will go with the 350 heads then. I can always go back to the stock heads if need be.

[relic7680]

you could keep the stock 4A heads and bump compression by swapping out the factory dished pistons....some mild porting would help flow. this is what i plan to do on mine.