sticky valve burning 100LL

[Bob Wood]

I am  running a 37HP Mosler Comp/Ratio 8:1.  I am now running 100ll thru all testing and my current 6 hours of flight time. I am experiencing a sticky exhaust valve in #2 in the mornings until things get warmed up...I am thinking 100LL is not helping me with this.

I was running premium (no ethanol of course) during testing and exhaust was sooty , (which i now realize is normal) and I wanted to set jets, and just ended up using 100ll to jet the carbs and all testing, as the VW was all new to me.

I went thru this with my 57 tripacer since the mid 80's. I found it ran smoother and  less plug fowling with Premium. We always ran marvel Mystery oil for upper end lube.  All went very well, only had issues on trips when I could not get Mogas... The 0-320 is 7:1 C/Ratio

So with my 8:1 which seems to be borderline for 100LL, should I try to mix 1/2 and 1/2 mogas and 100ll, or am I ok for 100% Mogas??

also will my jetting change?? I ended up with a 130 & 150 jet to obtain 1200 EGT in both sides.

Thanks for your help!!

Bob

[Steve]

I am  running a 37HP Mosler Comp/Ratio 8:1.  I am now running 100ll thru all testing and my current 6 hours of flight time. I am experiencing a sticky exhaust valve in #2 in the mornings until things get warmed up...I am thinking 100LL is not helping me with this.

Run Mo gas... Make sure the rocker is hitting the valve stem eccentrically so the valve is rotating in the guide... The adjustment is shimming the rocker side to side with washers...

[Bob Wood]

Thanks Steve, well this turned out to be a dinged up Swivel foot adjuster.(Not a stuck valve)...I took the head off and it was perfect  When I adjusted the valves I saw a ridge or burr on the swivel foot.  This hump have been rotating causing all sorts of problems exhaust wise....So my line up is off between valve stem and swivel foot. 

When i cut my push rods( when I lowered my compression) I changed to swivelfeet. I have 1 shim under the base and a matching washer under the side support e of the rocker shaft. Somehow the stem and foot are not lining up right and it hammered the smile ridge into the foot.....Exhaust valve only was bad, the intake had a little mark but not bad...

Any guidelines on how to line these up. It looked to me that it was hitting just off center to allow the valve to turn like when using the standard adjusting screw. Maybe a couple more shims?? to move everything up?? Cannot really find much in the books i have...

Thanks,
Bob

[Steve]

When i cut my push rods( when I lowered my compression) I changed to swivelfeet. I have 1 shim under the base and a matching washer under the side support e of the rocker shaft. Somehow the stem and foot are not lining up right and it hammered the smile ridge into the foot.....Exhaust valve only was bad, the intake had a little mark but not bad...

Any guidelines on how to line these up. It looked to me that it was hitting just off center to allow the valve to turn like when using the standard adjusting screw. Maybe a couple more shims?? to move everything up?? Cannot really find much in the books i have...

Thanks,
Bob

I think Scott Casler would be a go-to person with a question...

[Dan_]

Any guidelines on how to line these up. It looked to me that it was hitting just off center to allow the valve to turn like when using the standard adjusting screw. Maybe a couple more shims?? to move everything up?? Cannot really find much in the books i have...

Thanks,
Bob

This may help...  a drawing attached from one place and a procedure from another...  




The pic shows you want the valve stem perpendicular to the center line of the rocker shaft at half lift.



This link describes how to get there.

Then there is pushrod length.

And clearance for the swivel foot...

[Bob Wood]

Thanks for this info Dan & Steve. I do have a inquiry out to Scott C.

Thanks,
bob

[Bob Wood]

I updated this thread to Rocker geometry, as I determined i had no sticky valve.

Does anybody know what engine symptoms will show up caused by poor rocker geometry?

I looked at the info below and and going to recut my push rods to improve things. Mine are not terrible but not correct either...

Would this cause the engine to run rougher than if correctly set up? What improvements will I expect to see after  the push rod recut?

Thanks,
Bob