Roller Tip Rockers- FE390 427 etc

[Jac Mac]

Got caught with a set of Comp Cams Rockers ( pn 1046-16 ) this weekend that could have been a disaster had it been allowed to run much longer-15 minutes total. Six of the sixteen rockers had not been machined with adequate clearance in the area where the pushrod meets the rocker adjusting screw. Was able to salvage them with a bit of careful die grinder use. This message is to advise any of you who may have recently installed a set or have bought them for your future engine build to check the whole sixteen for clearance. If your in the USA you will probably be able to address the problem with them -Comp Cams-, unfortunately that was not an option for me at this time but I will be advising them of this problem. Pics show the area of concern etc. & yes, I am giving myself a hard time for not checking the whole set prior to fitting & the six hours wasted today doing a partial teardown to check out any other possible problems that might have resulted from it are a painful reminder as I write this!

 

[Keith]

Were there any discernible "symptoms" Jac or was it a case of Serendipity?

I have used most of Comp Cams products in the past and have always found them to be of good quality but I'm not sure how much stuff they actually manufacture themselves these days.... if anything.

 

[Jac Mac]

More serendipity but a bit of both Keith, I had a 'gut' feeling it was not 100%, but as it was its first start & running at about 2500 on a test stand with open exhausts and a cross ram with twin 4bbls etc that were an all new combo I was just busy enough. Discovered it this morning when I removed the rocker shafts to retorque. Only fouled the pushrod/rocker from about 50% lift upward, so did not show when adjusting lash etc.

 

[speed220mph]

JacMac: We always do a preassembly to recheck clearances just for this reason, especially the valve train. Fat aluminum rocker arms, large-diameter pushrods and high-lift cams combine to close up clearances at the pushrod and valve-spring retainer, so we check clearances with the valve on the seat and fully open. We do this check regardless of rocker-arm manufacture.

Similar to the problem you found, here's a roller rocker we found to have a pushrod-to-rocker interference in the valve open position. We clearanced the rockers using a light touch with a die grinder and burr.

 

[Keith]

More serendipity but a bit of both Keith, I had a 'gut' feeling it was not 100%, but as it was its first start & running at about 2500 on a test stand with open exhausts and a cross ram with twin 4bbls etc that were an all new combo I was just busy enough. Discovered it this morning when I removed the rocker shafts to retorque. Only fouled the pushrod/rocker from about 50% lift upward, so did not show when adjusting lash etc.

Thanks for the info. Phew :stunned: - that looks like a close call....

Gut feeling backed up by solid experience = 'Engine Guru' :thumbsup:

 

[egoman/ Shawn Wedge]

It looks like the use of a shorter pushrod may have cured this also.

 

[Jac Mac]

It looks like the use of a shorter pushrod may have cured this also.

At first glance one could draw that conclusion from the pics and it is hard to 'see' the difference between the correct/incorrect rockers at first glance. The damaged areas resulted from the pushrod cup literally 'shaving' the alloy while running rather than pounding into a solid area, even if the pushrod was 0.050" shorter it would still have interfered on the 'bad' rockers, also that would give a less than optimum wear pattern on the valve end and when the adjustment screw is extended to match a shorter pushrod it increases the chance of it coming loose in service from the extra side loading @ full lift. The other rockers that had been correctly machined for clearance have 0.040" clearance between pushrod cup and rocker body thru the full lift cycle. I have simply modded the 'bad' rockers to match the good ones. As installed now the 'wear' pattern on the end of the valve stem is 0.050" wide and centered.

 

[egoman/ Shawn Wedge]

I am sorry Jmac did you say that there were two different spec rockers sent to you in the same shipment?

 

[Jac Mac]

I am sorry Jmac did you say that there were two different spec rockers sent to you in the same shipment?

Egoman, refer post #1, Six of the Sixteen rockers in the set were not machined correctly in the area of concern. Thats the reason I posted the info so that anyone who might have purchased a set of these for their motor can check now and save themselves some future aggro. It would be all to easy for someone to simply bolt a set on and drive off to have the whole thing turn to custard a few miles down the road. Extended use damage could be $$$expensive. Driver says something like, can you hear that different noise? and his mate says' Oh just turn the radio up!

I am now in contact with a Tech rep at Comp Cams who is very concerned & eager to rectify the problem.