I am at a cross roads, and am wondering. I have a 1986/87 350 chevy engine. I also have a 283. I want to some day put the 283 back in the truck, but it needs a rebuild. The 350 I just dropped in has valve issues. Block is fine. Knowing this here is the question. If I redo the 86/87 350 heads, will they work on a 1965 283. What will I gain if anything. The 283 heads have 1.70 intake and 1.49 exhaust valves.
the 350 heads will work on the 283 but they will drop the compression way down. Like 6 to 1 down. I know becuase I had 350 heads (79cc if i remember right)on a 283 about 6 months ago. It ran fine but had no low end torque and would almost die when it shifted to second under normal driving conditions. I found a rebuilt set of 305 heads (58cc) and it runs so much better.
350 heads don't work on a 283. Listen to the guys that know. maybe their 283s were not running well because the valves were hitting the cylinder? Unless your 283 is punched .125 you have to relieve the top of the cylinder to successfully run a 350 head on it.
Not only will your compression be lowered which results in less lower rpm torque, but the bigger valve size does the same thing. Smaller valves (within reason) tend to increase low rpm flow charateristics, which will help torque.
Depending on which 283 heads you have, you might be better to rebuild the 283 heads and put them on your 350. It will pull pretty good but due to the smaller valves it will begin to "run out of air" at likely anything above 5000 rpm (which you might not get to). But watch the compression ratio! If it ends up being to high, you can run into detonation problems.
I was studying chamber size and realized as well that it wouldnt be a good idea. 305 heads are the way to go. Thanks all
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