305 Heads

[Copdogcorvettes]

Hi everyone; Here is my Question:
The 78 350 is one of the lowest compression engines ever in a Corvette. The HP rating was only 5 hp over the 80 305. Now I have had an 80 305 Vette and like it very much. It could use a little more torque. But back to the question, Using the 305 small chamber head on the 78 350. The chamber are 58cc a bit small than the 350 heads. Exh. valve are the same and intakes are 1.84. Which is not that much smaller than the 1.94 in the 350 heads. Compression rato should be up from 8.5 to 9.2 with just the head change. Sounds like easy HP gain to me.

So, what do you think? :confused

Thanks for any input on this.
Gary

 

[TimAT]

It will help a little, but the gain will likely be offset by the lack of airflow. The 305 heads just won't breathe too well.

 

[Copdogcorvettes]

Well the ports don't look to bad; and a little porting should help the flow. Maybe? Most other 305s used 1.72 intake valve and they didn't flow that well. So, what make them flow so poorly; besides the small intake size?

Good points.

 

[rgtrough]

Hey copdog, I think it is worth a try. If you already have the heads and are doing the work yourself. You may have a detonation issue to deal with (I always did with 305s). If you don't have the heads look into some of the after market cast units (if your trying to maintain some originality?) that are for sale on ebay or craigslist. Using a .015" head gasket could help even more if you're not using one already. Hell go for we put big blocks in Vegas

 

[Copdogcorvettes]

I have the heads. A friend gave them to me thinking they were 172s. I checked the intakes and they are 184s and the valves have the double springs. I was just finshing a set of 350 194 head. Porting with all new valves; just needed to get all the seat & valve ground to match. So, I was thinking of just porting the 305 heads; put the stainless exhuast valve in. Then some screw in stud and my set of full roller rockers. Unless there is some problem I don't know about should be a nice HP gain.

Gary