RB30/26DETT exhaust cam wear

[Stu UK]

Hi all,

I seem to have a re-occurring exhaust cam/lifter wear problem on my RB30/26 and was wondering if anyone else has seen this ?

Originally cams were Kelford 182E's with Tomei lifters and after 500 miles or so the engine started making a increasingly loud ticking noise. After pulling the cam covers off I found some of the exhaust cam lobes and liftere were showing signs of wear. One lobe and lifter in particular was very bad (near cap 5). The lifter had actually mushroomed as can be seen in the pictures below.There seemed to be plenty of oil in the cam covers so I was advised it may be a material hardness issue on the cam or lifter. The inlet cam/followers were ok.

The cams were replaced with Tomei cams/lifters and after around 2000 miles the same wear is apparent on one of the new exhaust cam lobes but in a different position this time - lobe/lifter 2. Again plenty of oil seems to be up there but I'm wondering if this must be some sort of oil supply issue to the exhaust cam area. Again the inlet cam is fine. Checked valve clearances and most are within tolerance still apart from number 2 exhaust lobe/lifter which now has a big clearance and rather than mushrooming it looks like the lifter now has a slight bowl in its top.

The engine has a N1 oil pump with wide drive collar and blocked of rear feed to head and Tomei front oil restrictor to head. Plenty of oil pressure measured in the block.

Anyone seen this before ?

Cheers 

Stu