i was reading that they would fit but i also read someplace that they wouldn't fit- something about the bore size or something of the sort. will the vette 113 d-port heads bolt up and work ok on a 305 block? my friend has a 305 in his car and a set of the 113 heads that he has for his engine he is eventually going to build- but he wants to put these on his 305 for the time being.

 

They fit fine, except for 2 details, possibly 3.

They have no provision for EGR; so if you have smog inspection tha trequires it, they won't pass, unless you use the Vette-style tube that plumbs from a manifold to the intake. And, being aluminum, they will lower the compression below where you would really want it to be. The 3rd possibility is that they have the 86-back intake bolt pattern so if it's a 87-up intake, you'll have to elongate the center 2 bolt holes.

 

They'll fit. No particular problem with the smaller bore of the 305 (valves will be slightly more shrouded than on a 350, but that's the case regardless of what heads you use).

They don't have the exhaust cross-over passages, so the standard method of feeding the EGR valve won't work.

The effective compression will be lowered. Both the 305 cast iron and aluminum L98 heads have 58cc chambers. Since the aluminum were intended for a 350 to produce the same effective compression as 64cc heads do on a 350, the heads should be shaved to 52-54cc in order to produce the same effect on a 305. But, if there's ever a 350 in the future for the heads, leave them alone.

 

(Dang, RB beat me to it again...)

 

at the risk of sounding stupid- what do you mean about the 58cc vette head chambers having the same compression as the 64cc heads? for example- the stroker kit powerhouse has for a 305- says that the compression for a 58cc head is 10:1. are you saying that since the head being used is for a 350 bore that the compressionwould be lower? i thought 58cc was 58cc

i think i am thinking about this a little too much and thus confusing myself

 

"Effective" compression, not static compression ratio.

Heat is transferred more readily through aluminum than through cast iron. Heat = energy, so to regain the lost energy, raise the static compression ratio. Since pinging is at least partially a function of combustion chamber temp, the higher static compression ratio with aluminum doesn't lead to more pinging.

The reason for the 10:1 with the Powerhouse 305 stroker when using 58cc heads is due to the increase in cylinder volume (being compressed into the same combustion chamber volume). All other things being equal, a 305 bored .030" over will have a higher compression ratio than a stock bore 305.

 

I wanna add to this.

I'm thinking of the vette heads..

I'm running iron sportsman-II's with 72cc chambers. WIth my TRW-L256F30 pistons, my static c/r should be like 8.96:1.

MY camshaft is 280/288 .502/.510 lift 110dlsa, so the overlap may bleed off a little compression.

I see 145-155psi on each cyl during a compression check.

With my pistons, suposedly a 58cc chamber head produced 10.40:1 compression ratio. (which is high!).

Assuming stock deck height, and this static compression ratio, my camshaft specs, what would you assume my "effective" compression raio to be?

Keep in mind, I'm boosted, have a vortech S-Trim. I wouldn't mind lowering the boost a little, but I'd like to still make around 6-8psi.

Thanks!

-- Joe