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.
So I started to assemble my 110" TC with Hillside stage 4 heads and the T-man 660-PS2 cams.. I had Scott install 2.02" intakes and 1.65" exhausted. He also took approximately .080" off the surface of the heads to get me to 85 cc's.
First thing I did was take a set S&S lifters and take all the oil out of them so I could completely collapse them into a solid to be able to take an accurate valve to piston clearance..
I used the old .030" head gaskets and reassembled everything with playdough in the valve reliefs.. I set the pushrods to zero lash and turned the motor over several times just to make sure there was no interference.. The motor rolled over without issue..
I disassemble everything and removed the cylinders heads to measure the playdough/clay and on the front cylinder the actual clearance on the intake valve relief was about .030" and the rear was at .040".. The radius seemed pretty good but I'm not the most comfortable with the clearance..
I'm going to open the valve reliefs a little.. I think if I add .030" to both front and rear I should be good..
These measurements are from a solid lifter so even if the lifter pumps up completely I think I should still have the clearance I need..
I have at least .060" on the exhaust both front and rear so I should be good there.. The exhaust valves just barely contacted the playdough..
Looking for a little confirmation, thanks...
The Red playdough is the rear cylinder and the multi color is the front.. Wish I had some plain old grey clay...
Last edited by 98hotrodfatboy; Apr 19, 2024 at 05:20 PM.
I find it's better to leave the clay in place and cut it in half with a razor blade. That way I can see exactly the profile the valve made. Also pulling off clay that is really thin, it's possible to stretch the clay and give a bad reading. Also I would take a reading on your ACR. Since the heads are machined 0.080", you want to make sure you have room for the ACR to open. Sometimes you have to shim them up.
I would think that 0.060" as a minimum clearance on the valve flat, I prefer to see more. The radius is ok at 0.030".
Maybe I'll set it up again but by looking at you your second pic it looks like where the valve touched the clay to be almost identical to mine.... The only place the valve touched was out at the radius of the valve relief.. I think I might be ok.. The only other thing I could think of is that the only time it'll ever get that close to the piston is if the lifter pumps up completely and I doubt that's ever going to happen unless that is the valve floats... My spring pressure on the seat is 180 and at .660 is 384.. I think I'll be okay..
Last edited by 98hotrodfatboy; Apr 19, 2024 at 06:13 PM.
Thanks.. I think I'll give it another shot.. Also I forgot to mention that I will not be using the ACR'S.. I had manuals installed so I could do away with the Auto's..
Also I wipe a little light weight oil (household oil) on the valves and head surfaces that I don't want sticking to the clay. I wipe it on by my finger, just a slight amount.
If what you are using is playdough, I wouldn't.. I use the stuff shown. Get it at any good arts and crafts store.. BTW, the old green one is about 48 years old.. You can resurrect the stuff by adding vegetable oil and kneading it but it was getting kind of small.
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.
Valve To Piston Clearance...
