I am planning on buying some Edelbrock RPM 64cc heads for Christmas.Will I see significant improvement over my 882 heads and what compression will I have with 4 relief flattop pistons.Also how much of a horsepower increase should I expect?

Thanks in advance and Happy Holidays!!!!!!

You will see a definite increase in power over your 882 heads. I do not know what the combustion chamber size is on the 882 but would gues that it is 76cc. Just bumping up the compression will generate an additional 10-15 hp. My guess is that with the components you already have, 30 hp should not be out of the question.

Your compression should fall between 9.5:1 to as much as maybe 10.25:1 depending on the deck height, gasket thickness and the size of those valve releifs. IF the motor we are talking about is the one in your signature, the XE 284 cam is pretty darn large for what you have and there should be a rather large increase over 4500rpm. With the additional compression and better flowing head, I would not be surprised by at least 50 additional horsepower or more if your heads arent ported. Id go for a 4.10 gear with that cam, not a 3.73, but I guess the 3.73 will work well enough, and about a 3200-3500rpm converter would be more optimum.