Found a set of heads that were ported but the guy that has them for sale says they measure 70cc now I know 83cc is stock. He ran KB flat tops. He said the KB pistons even though flat top were .8cc? Thought most flat tops were -1.5cc? Even with flat tops at 70cc I would think there would be a risk of piston to valve clearance especially running a .030 HG. He also said his build had a .028 squish. Thought .030 was the lowest most would wanna go with a street carbed evolution. Thanks
I know nothing most the time but my guess is you are way way safe
Unless you are running all sorts of lift/overlap.
Measure and you will know.
I'll be running a Woods W6H cam. Have Jim's rollers new tappers from Larry and brand new S&S tappet blocks. I am milling the pistons a little to achieve zero deck height with a 030 HG. With my current heads which are 73cc I'd be in the 9.8 to 1 range but I know the 6H likes 10.2 so if I used these heads I'd be much closer. I'm also wondering about the Keith Black flat tops. Online says they are +.8cc but then they list their domed pistons - vs everyone else lists their domed + example 12.9cc on a Weisco and a KB domed lists -9.9cc for a domed piston. Just want a little clarification I'm not engine builder thanks
Sounds like a candidate for compression releases
Ok let me ask this my heads measure 74cc can I have them milled to 70cc without any issues? I already have releases
Quote from: ReapersWG on September 15, 2020, 07:13:12 PM
Ok let me ask this my heads measure 74cc can I have them milled to 70cc without any issues? I already have releases
May need to surface intake manifold pads, and increase valve reliefs in the pistons.
What is the measurement, top to bottom?
3.750" is the O/A dimension for the thickness of OE Evo, and T/C heads.
3.770"
https://harleytechtalk.com/htt/index.php/topic,111382.msg1340636.html#msg1340636
I disagree.
I have measured them more times than I can ever remember.
That dimension is in fact 3.750", unless a mis-machined from HD.
A Screaming Seagull performance head will usually measure 3.690". (minus .060"), and the intake pads are also cut deeper. :smile:
Have a set on a bike that measures 3.590 no problem fitting. being running for ten years plus. All the stock ones seam to measure 3.750, had a couple old ball ones that measure bigger.