Home Forums General Discussion Technical Questions Maxton UC4 harsh opening

Hi all!

I have adjusted many valves before, but I need extra help for this one. The valve seems to be adjusted properly, but if the car sits idle for more than a few minutes the next up opening is very harsh. By UP opening I mean even before the UA (UP Acceleration) because I can definitely feel the UA to full speed and it is nicely adjusted. It almost feels as if the valve is internally losing its "prime". Any ideas?

Thanks,

S

Tight packing will cause a rough breakaway. This can’t be compensated for with valve adjustments.

I usually apply CAT oil directly to the piston to buy me a few days of smoother operation until the packing can be replaced. The Cat oil will smooth out the take off within a couple runs but ultimately the packing has to be replaced with a fresh set. Kind of sucks when you have to replace a packing that does not leak a drop.

Definitely packing related. Check for sticky varnish or rings from the oil getting overheated. Try cleaning this off with a strong hand cleaner, Scrubs in a Bucket work good. You can also scuff the piston with Emory cloth or even install a sanding ring but I wouldn’t go that far unless a re-pack doesn’t solve it.

"Breakaway" that's the word I was looking for! Thanks for the input guys. As Ranger said it is a shame to replace a packing when it doesn't leak at all, but if that's what the problem is so be it. I'll order a new one. Thanks for the tips guys.

S

Try putting some STP on packing and piston if it's sticking. Used to work great on Otis selectors stop lugs.