I was wondering if I could install these heads http://store.edelbrock.com/83ccperfo...ralfinish.aspx
on Evo with a 83 bolt on kit. It seema like a great price for great heads if they would work.

HH

 

From what I understand, those heads have 83CC's (Cm^3) of volume in the combustion chamber, and are designed for S&S 100 Cubic Inch (Inch^3) motors. If you're not running a 100 inch S&S motor, I don't think it would work out right. Piston top volume would also figure into it. It would be "complicated."

 

Thanks so I should look more at the 72cc heads?

 

I dunno what your motor is, nor am I an authority on such things, just an amateur. I just have a philosophy of buying stuff that is meant to work together. I don't know what an 83 bolt on kit is. Is that 83 cubic inches? Is that top end only (pistons/cylinders)? What heads and combustion chamber size do the manufacturer recommend? If I was to take a SWAG, I'd say that the stock head volume would probably be just fine with only ~3 cubic inch increase, but again, it would depend on what the piston tops were like. What compression ratio are you looking for? All that plays into it.

 

If you want to improve performance you would be better finding a local Harley expert and talking through would you want. He can advise what to use and port your existing heads to match everything, so you get the most from your motor. As it says in the advert "contact your engine builder for recommendations". Unless you have a 4" bore motor they are no good to you whatever!

 

They're for big bore applications, on an 80"er they would suck...or not suck very well, the extra large valves and 83cc combustion chamber would slow down your intake charge, port velocity and VE would really drop off most likely giving less than stock performance....bigger ain't always better.... like grbrown said, talk to a porter and tell him what you're after(there are lots of really good ones out there)and he could recommend what needs to be done to your stock heads along with a cam, intake and exhaust so you'll have a package that works well together for a good boost in power in the RPM range you want it in.