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CVO Technical => EVO => Topic started by: ltank on May 09, 2013, 11:34:35 PM

Title: Machining EVO Heads to Raise Compressio
Post by: ltank on May 09, 2013, 11:34:35 PM

I bought my son a 94 FXSTC with 27k miles. Wanting to raise the compression a few points to 9.5:1How much to shave off heads if using .030 gaskets?  The cam DM500 likes 8.5:1 to 9.8:1 ratio.
Cast pistons have longer life. What are the best options? Should we replace his lifters too?
I will replace the cam bearing and plastic breather gear if it has one.
Thanks
Ltank

Title: Re: Machining EVO Heads to Raise Compressio
Post by: prodrag1320 on May 10, 2013, 07:46:49 AM

the heads should be CC`ed to find how much will have to be machined off.if you want to go with cast pistons,theres really not much choice besides HD.no reason to replace the whole lifter,just replace the rollers

Title: Re: Machining EVO Heads to Raise Compressio
Post by: ltank on May 12, 2013, 10:16:58 AM

I found new Screaming Eagle EVO heads for 680 bucks. They have 72 CC chambers,  with stock flat top pistons it should have 9.5:1 compression. For double the price of forged pistons I get the compression and better flowing heads with bigger valves. I plan to use the Dave Mackie DM500 cam. 240 in. 240 ex.
22/38 intake,52/12 exhaust timing. It should run well.  Cam says 8.5 to 9.8 compression. My son better be happy. I hopped up his TC from 88 to 95" with DM TC510L cans but he lost it wife!!!!
Thanks
Ltank

Title: Re: Machining EVO Heads to Raise Compressio
Post by: HILLSIDECYCLE.COM on May 15, 2013, 08:11:37 PM

Those s/e heads have -.060" off the surface, vs the OE head.
Not barn-burners as far as the flow rates either.
Scott