Anybody have any problems with broken cam caps on any of the DOHC engines? B18a/b or D16a1 or ZC? Just trying to trace down a problem. I built two virtually identical engines for a couple circle track racers using D16A1 heads. Engine 1 works great, set track record and won points championship. Engine 2 used an unported head and won track championship at a different track. I then ported the head and had Crower regrind the stock cams and I am using slightly longer than stock valves. Engine 2 dynoed with more HP than Engine 1, two weeks later 4 intake and 4 exhaust cam cap split down the middle and also broke the snout off the intake cam. No galling on any of the caps, the cam journals are within .001 of a stock cam, no unusal wear patterns, no bent valves. I looked at another head here and found what look like hairline cracks on a few of those caps. The only thing that really comes to mind is the more agressive cam created some kind of hamonics when using the stock valvesprings. The grind is similar to the Crower Stage 1 for B18A/B which specifies stock springs. Called them and they don't have anything to say about it, not even an actual spring pressure recommendation for the cams they ground for me. As it is I have 42#/110# intake and 32#/95# exhaust. Even if it was not enough spring pressure I would think the valves would float giving some hint of trouble. Revved crisp and clear to 7200 rev limiter. What do you think?

 

That's weird, I've never heard of that happening.:dunno:

 

Couldn't find any more possibilities other than the more aggressive ramping rate of the cam was beating up the caps. I'll make a girdle for them like the GSR heads. I think that should work.

 

ughh, I hate crower. Just recently my exhaust cam broke into 4 peices and demolished my head. Its at the machine shop right now because I am having cylinder head sealing problems after words. Are you sure the cam didnt fail causing the cam caps to split??? You just swapped cams without swapping valvetrain?? And they cant recommend what to use with there cam??? hmm, why didnt you go with a zex cam instead or do they do custom profiling. Is it possible you experianced some coil bind at high rpm?

 

Not a whole lot of cams out there for the ZC that aren't regrinds. After speaking with a bunch of people the only thing we could come up with was the lobe shape was too aggresive and was slapping the valve open causing a bad harmonic and beating on the caps. I managed to massage the caps from another head to fit on this one for the last race of the season and it ran fine using the stock cams. If we run it next year I'll start with another head and make a cap girdle like the GSR stuff. We did manage to win another track championship though - that's 4 track championships and two track records this year - WHOOHOO!

JFDMAS you might have your machine shop deck your block. I have had probs sealing these engines unless I decked the blocks. If you had the block sleeved then make sure the sleeve has not dropped below the deck surface.