When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
I'm building a 95" project (ex 2000 88"), Andrews 21 camshafts, JE 324712 pistons (9.25 static c.r.), 0.005 deck height, 0.030 Cometic gasket.
The calc says I'll get a ccr of 8.88.
But I'd like a 9. Can I mill the heads?
If the pistons were flattops it would be clear, but these pistons have a shallow dome.
What measurements do I need to take to figure out how much I can mill to keep the piston from hitting the head?
Or is this a bad idea and best to leave it as is?
Several ways to get there.
1. Reduce chamber volume to 83cc; a .015" cut should do that. This would require that the cylinder chamber volumes be measured for a starting volume. As has been advised, always a good idea to measure piston to valve clearance but, in this case, that shouldn't be an issue.
2. Advance the cam 4*.
3. Replace the Andrews 21 cam with the S&S 509; which, IMHO is a better choice.
Several ways to get there.
1. Reduce chamber volume to 83cc; a .015" cut should do that. This would require that the cylinder chamber volumes be measured for a starting volume. As has been advised, always a good idea to measure piston to valve clearance but, in this case, that shouldn't be an issue.
2. Advance the cam 4*.
3. Replace the Andrews 21 cam with the S&S 509; which, IMHO is a better choice.
Thanks a lot.
Ironically, I have S&S 509's sitting on my shelf I was thinking they would give high cold cranking compression. But the calculator says 189. As I remember, up to 190 cold cranking compression is quite acceptable. Am I right?
Last edited by SeeR; Aug 1, 2023 at 01:03 PM.
Reason: typo
Thanks a lot. Ironically, I have S&S 509's sitting on my shelf I was thinking they would give high cold cranking compression. But the calculator says 189. As I remember, up to 190 cold cranking compression is quite acceptable. Am I right?
Yes; 190psi is fine.
190psi, for me, is on the cusp of needing compression releases but many run that CCP without them. These days, some are running CCP at 200+ with no issues; I run a 98" motor at 212psi with no issues; just requires a very good tune. You can get by without CRs but if you have the heads off, investing in a set of manual compression releases would be worth it and will extend battery and starter life. They are not that expensive and the machine work for them is also not that expensive; IIRC, $125 would probably cover it.
I think you will like the 590s. I hope the bike is carbureted and not the troublesome MM EFI. Good luck with the project.
Yes; 190psi is fine.
190psi, for me, is on the cusp of needing compression releases but many run that CCP without them. These days, some are running CCP at 200+ with no issues; I run a 98" motor at 212psi with no issues; just requires a very good tune. You can get by without CRs but if you have the heads off, investing in a set of manual compression releases would be worth it and will extend battery and starter life. They are not that expensive and the machine work for them is also not that expensive; IIRC, $125 would probably cover it.
I think you will like the 590s. I hope the bike is carbureted and not the troublesome MM EFI. Good luck with the project.
Yes the bike is on a S&S Super E carb with Dynatek ignition module.
Thank you very much
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.
Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.
Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.
Milling and dome pistons
I was thinking they would give high cold cranking compression. But the calculator says 189. As I remember, up to 190 cold cranking compression is quite acceptable. Am I right?
