I was wondering if ZZ4 heads would work on a 305. S/R torquers have the same valve sizes and chamber cc volume. the only difference is in the intake volume(ZZ4 is 25 cc bigger). so, will these heads work on a 92 305 TPI with headers, full cat back exhaust and ported intake?

 

Yes they will work, they are the aluminium vette L98 heads. If you do a search you will see they are pretty popular upgrade for the 305.

 

Youre going to run into a few issues, none all that bad but issues regardless. Theres probably still a missing accessory bolt hole in the passenger head, that can be remedied with a drill and tap. The intake bolt pattern is the 86-earlier style, so the 4 center bolts on the intake wont fit unless you elongate the bolt holes in the intake. Simple way is with a drill, nice way is to mill it or have a machine shop do it. Theres also no heat riser, which means the EGR will no longer function. If the EGR is an emissions concern where you are, you'd need a vette or aftermarket base and a tube from the RH exhaust manifold to the back of the intake manifold for the EGR to work.

 

Howabout the larger valve problems? Wont there be a problem with the valves hitting the cylinder walls?

 

Not unless someone changed the valves to 2.02/1.60, which I really doubt.

 

Ahh, so the stock valves will work with a 305... just what I wanted to hear!

 

If I have an '86 intake, they should just bolt right up, right?

If they do, Where can I get some? I really would like to go with aluminum heads when I get them, but I don't want to have hundreds of dollars of machine work done before I can mount them up, ya know?

I have a 305, so most aftermarket heads are too big.

 

I would check all your local junk yards to see if you could score a used set. If you can't find a set, or if you just want new ones, check www.sdpc2000.com .

 

Yea, the 86 base will bolt up just fine.

I picked up some used ones in really good shape years ago for $300. I ported them and did the valve job myself, so cost wise I have very little in them. I'd say with patience you should be able to pick up a decent set for not too much $$$$. Try calling a few machine shops, most have stuff like that in the shop they will sell.

 

madmax,

Ok, so what's the deal here with 2.02/1.60 valves on a 305? I thought that they wouldn't fit and that 1.94/160 was the max due to the small bore. However, I'm getting this on another post telling me that they will fit!?!

https://www.thirdgen.org/techbb2/sho...932#post611932

So which is it? I'm thinking the max is 1.94/160 combo.

As for the vette heads, I have em on my 305