Having isues setting tappets

[doz]

Right bare with me this is gonna be a bit long winded. I apologise in advance maybe worth getting a brew and if need the loo best go now :shock:

I rebuilt my 1600tp motor about 2.5 k miles ago, spec is

1835cc
Engle 110 cam
1.25:1 ratio rockers
Balanced std crank, rods and flywheel
HP Oil pump with external cooler
Chome moly push rods
Vintage speed exhaust
Twin Kadrons jetted and kaddie shack ventures
Old school ported, polished ex drag car cylinder heads with 30cc combustion chambers

Everything was great. Cam burn done, and run in. Unfortunately recently I had a spark plug break up and knack the barrel and when I stripped the motor down the heads had cracked. So I set about doing a top end build. New p&b's with cb performance heads. As the heads were some what taller due to my old heads being heavily fly cut I replaced the pushrods again cutting them to correct length and making sure the rockers were shimmed correctly.

So engine rebuilt and running in again, I've covered about 400 miles. Problem is I've had to set the tappets 4 times since the rebuild. Everytime the gap gets to big. Ive tried 0.004" gaps and 0.006" gap and both end up with same issue. When the barrels were off I checked the cam followers and cam for wear but they looked in excellent condition.

It didn't act this way when I first built the engine but then the heads were second hand but reconditioned. Could this constant gap issue just be down to everything bedding in? I would of thought the gaps were more likely to close up ith new valve seats etc not keep getting bigger.

I've set the tappets the same way I've always done them. Dizzy cap off, rotate engine until dizzy arm is pointing to the ht lead I want to check then set the gaps on that particular cylinder. Rotate dizzy through one complete turn then recheck the gaps. Am I doing something wrong maybe?

 

[Alex VW Heritage]

Have you checked the oil for signs the cam or followers may be failing?

with cromo pushrods I have always set them when the engine is on a colling down cycle and set them so I can spin the pushrod but actually with zero gap.

theory being that the cromo push rods will not expand as much as the rest of the engine so the gap will only increase when the engine is warm.

hope this helps a little and good luck.

 

[doz]

Okay the enjin is on the bench in bits and I'm diving into a bottle of JD. So before I get too bollixed to type this what I found. The cam and cam follower face are perfect. However the face where the push rods fit, the little dimple area are smashed up :shock: . I've done some measurements across the followers from the top edge and the variation in the distance is massive! I'm looking at 18mm on a good one to 23mm to the worse one. So the follwers are wearing very quickly. Tonight I checked the clearances again and it was pointless. I had run out of thread adjustment. When I first cut the pushrods I calculated the length with the adjuster 1 and half turns out. So in a matter of say 400 miles I was all the way out.

So a rebuild again after only few thousand miles. At least all the other bearings are okay. So was I just unlucky and got a set of badly made followers or have I ballsed something up? I'm loath to rebuild it again if it's something I'm doing wrong. Out of all the recites I've got I can't find the one for the followers so got no idea who made them.

 

[madjack]

Hi I had a similar problem with tappets as I was running a 110 Cam with high lift pro comp rockers and snapped the mounting studs after reading on the net Gene Berg does not recommend running high lift cams with hi lift rockers as it just causes to much stress . Reverted back to just the high lift cam and standard pushrods and rockers and now runs a lot better . sure others may have other comments.