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Sun Nov 08, 2009 5:14 pm

Wow! That's rough when you can't recognize or find a reason for failure. Hope something is better this time.

Sun Nov 08, 2009 5:23 pm

The lifters definitely aren't sticking. When I had the 1 and 2 pistons off, I twisted the crank and watched the lifters on the 3 and 4 side go through their rotations; there's not enough lift on this cam to push the lifters all the way up into their bores to get them wedged in there, so that's good.

I did notice that the oil pick-up was loose. One of the six studs that the oil plate bolts onto runs through the case, and the backside of it is threaded so it can hold down the pick-up. I don't think my studs were screwed into the case far enough, so I didn't see the end of it sticking up past the pick-up, nor the fact that it was missing a nut. I remedied this problem on this assembly. I did notice a nice little wear pattern on the top of the dome of the pick-up from where the cam lobe had smacked into it, so it was jumping around at least a little. If air was getting sucked into the oil system, would I notice it from a sudden PSI drop, or would it even register on a gauge?

Sun Nov 08, 2009 5:33 pm

no - you still had oil pressure but it gets foamy. The air escapes the first place it can find. That is often #2 rod journal and the cam galleries. Ask any road course racer who has lost an engine to sucking small amoubts of air and they will hold up a piece of #2 rod bent at 90 degrees and sometimes #3 rod. We lost an engine at Holtville at 9.000 RPM sucking air. This is how I know this. It made a huge ball of flame as the aerated oil hit the red hot headers - sort of like a giant flame thrower. Holtville (if it is still used) is a flat track and turn 9 used to be scattered with remnants of engines. Lots of rod parts and cast steel from blocks ventilating.

Do take the camshaft, case and parts to your machinist so they can look at them too. There may be several things going on but the cam should not be hitting the oil pickup.

Mon Nov 09, 2009 12:32 am

I have had to run a cam line bore tool in case's sometimes. The center cam bearing gets warped and you put a new cam and bearing in when you crank down the nuts and bolts the cam get's hard to turn. some builders don't notice that this happens and just run's it and that's what happen's it tare's up the bearing. It's a very handy little tool but dosn't get much used.

Mon Nov 09, 2009 4:46 am

Get another set of cam brngs and fit just cam in case and check how cam spins/play. This past summer i found a set that would tighten up the cam,hard to spin,got another brand and all was well. Loose fuel pump rod,lots of play, can knock.

Mon Nov 09, 2009 2:23 pm

I have found this tight cam thing in blocks I have had to line bore in the bigger size's. and always in the middle bearing. I do prefit the cam also to make sure I don't have a tight one.