TheSamba.com :: View topic - Very tight valve clearance on rebuilt engine

Sat Apr 30, 2016 5:36 pm

Perhaps its time to split the case and do the oil pump clearance the
proper way.. :idea:

I t really won't take much time and you will be hours ahead labor-wise
and not have to 2ndquess your work.

Also, are you using double thrust cam bearing in BOTH case halves?

Chris

Sat Apr 30, 2016 5:40 pm

so now pull the cover. see if it spins freely with the cover off. Next, measure across the pump with a straight edge while the pump and gear are in. Does the gear extend past the edge of the pump body? If yes then pull the pump out and see if that is true also with the pump out. If so the tang is not going in far enough. If the pump is still proud of the body with the pump out then something changed if you have been using the pump before. I have see pumps where the idler was not seated and that cocked the idler causing the gears to bind.

Sat Apr 30, 2016 8:57 pm

Snug the pump to the case minus the cover and then check the clearance of the drive gear. It sounds to me like you might have negative clearance.

Sat Apr 30, 2016 10:52 pm

I really have a problem with ANY gear on a 'FIXED SHAFT' wobbling as the it
is impossible with a thrust surface.....and, in the case that would be the pump cover or housing.

The DRIVE gear tang length is the problem or, the pump is a piece of crap.

Sun May 01, 2016 6:06 am

So, measured negative clearance on drive gear after torquing pump to case with cover off (about .020). Engine turns smoothly by hand...Will post some pics if that helps...

Sun May 01, 2016 8:53 am

Others will probably chime in here but assuming that everything else is right, if you grind .040" off of the drive tang you would be golden. Depending on the design of the gear you could also push the shaft .040" further into the gear.

Someone who knows more than I might know if it is possible for the cam to somehow be positioned wrong.

Sun May 01, 2016 8:54 am

orwell84 wrote: So, measured negative clearance on drive gear after torquing pump to case with cover off (about .020). Engine turns smoothly by hand...Will post some pics if that helps...
That is too much. Measure the gasket. IIRC it is only like .007".
.020-.007=.013 interference.

Mark the position of the drive gear. Remove it and Put some grease on the face of the oil pump tang. Align it and slide it back in. Is it bottoming out in the cam slot?

Sun May 01, 2016 2:54 pm

So I greased the end of the drive shaft tang and pushed it in. Grease was removed from the front end of the tang except in the very middle, which I assume means it bottomed out. The slot in the gear is not square, but rounded, so I assume I did this correctly. Will post a pic if my explanation doesn't make sense. Thanks, I really appreciate this...

Sun May 01, 2016 3:19 pm

Sun May 01, 2016 4:00 pm

when you built the engine did you do the steps of checking cam endplay and lash?

The old cam may have worn into the thrust bearing so that it sat farther back.

Sun May 01, 2016 4:36 pm

Good point, but new cam, new cam bearings...

Sun May 01, 2016 7:48 pm

I would say to clearance the end of the shaft. Grind off the end until until the gear will bottom in the pump housing and then grind off another .020" or so. Measure the overall length of the gear and shaft with some calipers so that you know what length you started with.

Mon May 02, 2016 3:48 pm

^^^^^^^
You may want to radius it to fit the cam slot as well.

Tcash

Wed May 04, 2016 4:02 pm

That wasn't so bad...took my time...measured, filed, measured, tried out the gear, of course cleaning off any filings before trying it in the pump body. Did not radius the gear, but beveled it like it was. It's a CB performance pump. I noticed Shadek was stamped inside the pump body. Anyway, it fits nicely and turns smoothly. Thanks!

Wed May 04, 2016 5:03 pm

orwell84 wrote: That wasn't so bad...took my time...measured, filed, measured, tried out the gear, of course cleaning off any filings before trying it in the pump body. Did not radius the gear, but beveled it like it was. It's a CB performance pump. I noticed Shadek was stamped inside the pump body. Anyway, it fits nicely and turns smoothly. Thanks!

Hope you gave it a bit of extra clearance. Things will change shape as the engine heats and cools and the cam may move around a bit as the thrust surfaces wear.

Wed May 04, 2016 6:42 pm

Did my best mate. Just me at the kitchen table with a file..clearenced the same with other gear...

Thu May 05, 2016 8:52 am

Quote: clearenced the same with other gear...

?????

Fri May 06, 2016 4:02 am

I meant that both gears now have the same clearance with the top of the pump body. Did not remove metal from the other gear...

Tue May 17, 2016 9:25 am

I did a test fit of my rocker arms and it seems I still have the valve clearance issues I began with in spite of having new heads and new pistons and cylinders. As I mentioned in an earlier post, Webcam lifters are longer than stock, making the pushrods too long. I know others have not had such issues with these lifters. I solved this in my last rebuild by shimming the rocker shafts. I still may take that route, but since it's on the bench and I have an adjustable push rod, I might as well measure for correct pushrod length. I assume you measure the pushrod tool at its ideal length and send the measurements to have new pushrods custom cut....

Thanks...

Tue May 17, 2016 9:30 am

my webcam 142 and lifters were a perfect fit with perfect geometry out of the box. Was the head fly cut or the case decked?