I got a set of 416 58cc 305 heads given to me. I want to replace my late 70s 76cc heads with them, I was told its a cheap way to hp. Anyone done this before?

I think you'll notice a gain in low end torque, but the engine will run out of breath quite quickly due to the small runners and valves.

The "cheap way to hp" comes from the smaller chambers yielding higher compression (often too high). I guess it works but you will not be stunned by the performance. Only aftermarket heads can do that, really.

You'll hear a few proponents of the 305 heads, but like I said; a few. Flat not worth it... IMHO Why do you think you got them for free? ::confused:

What engine you want to put them on and also what's it's compression ratio??

And then we can talk about this better..

Please get back so I can try to help you..

pdq67

1978 350ci 76cc heads 8.1 compretion