Rebuilding the top end on a 1990 FLT EVO. with 70000 miles on it.
I will be having the valves done and am replacing the cam and roller/tappetts and blocks.
Would like any info. regarding a good match of cam to compression ratio .
Am leaning towards the venerable Andrews EV27 and was wondering about milling the heads to attain a better compression ratio for this cam grind.?
This EVO is 8.5-1 stock and i would like to know what would be the best comp. ratio for this type of cam.
As i understand , the heads can be milled to attain up to approx. 10-1 comp.ratio but i dont know how far to go ?
Im thinking 9 to 9.5 comp. ratio to be able to use pump gas with no detonation troubles .?
Any help is appriciated as im a newby to HD.

 

that cam would love to be in a motor with 9.5 -10:1 Had the same set up in my old 98 Fatboy.. the EV27 was basically the same as the cam that started it all for the EVO's.. the EV-3, just a little faster ramps... real nice all around cam. I would go 10-1 if it were me.

 

I wouldn't machine the heads, as that is not reversible. An EV27 will be fine with stock heads, a little better with a slight increase in CR. With 70k miles up you could rebore the cylinders a little and use slightly higher CR pistons, which would be my preference.

 

Wrong thread.....

 

Used the EV27 in 2 FXR`s way back when

Was pleased with results