I have an s2000 which is completely built. Somehow the other night all five tower caps that hold the cams in place cracked. Each were torqued correctly according to spec and the car motor was being broken in. This occurred after about 40 miles. There was no harm at all done to the valve assembly or the bottom end because the car had actually stalled right before as i place it in neutral . Once I fired it up again, I heard the noise so we immediately shut it off. After pulling it apart there seems to be some problem with the cam chain tensioner because one of the plastic guide for the chain was chewed up a bit.

Honda does not sell the caps separately because it comes with the head. I was able to locate another set through Greg Samaroo (thanks buddy). I will change both the cams and the caps since the cams do have slight scores on the lobes. Although it is not ideal to interchange the caps from head to head, it has been done numerous of times since the tolerance are so similar. Hopefully once checked upon assembly line honing may not be necessary.

Any thoughts on what caused the damage? The cracks were more predominant on the exhaust side also. The car utilizes AEM, the head was built by Joe Alaniz and Earl Laskey. We did the build up on the cams and caps. Since this was done during testing we did not go over 5K and there was no boost. Thank you for any input.

 

were the cams stock? or radical aftermarket? what about the springs? are they very tight? what about coil bind? there are a few things to check.

 

yes, stock cams, springs were aftermarket but nothing radical. They have worked fine on other applications. At this point things point to the cam tensioner, but I am trying to check all possiblities before we button her back up. Thank you for your input

 

Sounds like an oiling issue, how badly are the journals scored up? I don't see how the timing chain tensioner would cause all the caps to break, do you? Maybe some machining debris was lodged in an oil orfice and starved the head for oil....

 

actually no oiling issues, the journals were fine with the exception from some scores which attributed to the malfuction of the cam caps...There was also plenty of oil in the surroundings. I am lost too on this. If the tensioner was bad could there be excessive force being pulled on the cam which caused the caps to crack?

 

any thoughts? thanks

 

if you use caps from a different head you ar egoing to have problems....you should align bore the head....somethings wrong with the setup...caps dont just break for no reason.....Are you sure they werent already from a different head?
were they put on wrong? you need to also check the oil pressure when you get it back together

 

thanks, oil pressure and oil temp was fine. I have an in dash guage. These caps were indeed from another head, but cleared spec. Many f20c head have swaped out the towers and caps unlike the B series heads. I will take the suggestion and bore the new set.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blues2k3 &raquo;</TD></TR><TR><TD CLASS="quote">thanks, oil pressure and oil temp was fine. I have an in dash guage. These caps were indeed from another head, but cleared spec. Many f20c head have swaped out the towers and caps unlike the B series heads. I will take the suggestion and bore the new set. </TD></TR></TABLE>

This may be your problem right here. You definately want to align bore with the new caps on the head. The clearance may have been right at the spot where you Plastigauged it, but the journal was probably either out of round or had a little lip where the new cam overhung the cam journal or vice versa. I have swapped plenty of caps on B series, but have always align bored and never once had a problem.