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MG MGB Technical - 6,500 RPM + old age = trouble

I just had the unpleasant experience of breaking a cam follower (tappet) in half! Had just finished a hillclimb run where I went over the finish line at 6500 rpm, got back to pits and the engine was missing. Found a loose push rod on No 2 inlet valve, further investigation found the cam follower had broken in half at the oil drain hole (light weight tappets - 39 grams, Harland Sharp roller rockers, Cr-Mo push rods), the bottom section of the follower has cocked sideways in the block. Not sure if there is any damage to the cam at this stage. Plan to now remove the engine and give a freshen up. Does anyone have a recommendation on cam followers?
For those who have followed my saga with the overdrive not disengaging I now have a chance to inspect the OD internals.
Mike

Mike Ellsmore

A view of the remaining bit of follower jammed in the block!

Mike Ellsmore

Judging by the wear pattern on the follower, it looks like there may be a bit of "slop" as the follower is reciprocating. Either wear in the block, follower or under-sizes followers or both. Check the bore dimensions and the shape of the follower guides in the block. I acquired a block recently which proved unusable because of oval guides.
My 3 pennyworth on followers is to purchase them from the same source as the camshaft. At least then you have some comeback if things go wrong and they are more likely to be matched for hardness.
Allan Reeling

the followers from an MGC are bigger in diameter, you can bore the block to that sice.
Siggi
Siggi

Mike I use the APT and have found them great. You can get them from Moss or APT direct. Full 60R test and the correct curve on the cam surface. I just did a complete rebuild on my supercharged engine which had a SC cam by Clive Cam's and APT followers over two years ago and they were completely unmarked, and I mean "as new". They went straight in again and this was a no expense spared rebuild. The cam is 289* so their working a bit.
Denis
Denis4

Thanks Denis,
I was planning on the APT followers also but was interested to hear what others think. My push rods are 5/16" - 10 5/8" long with Moss high ratio roller rocker set up (are these Harland Sharp manufacture?). When I finish getting the engine out and stripped I will make a trip to Clive Cams also. Progress has been slow as it has been around 95-100 F every day for the last week (lucky I like beer). Are you in Melbourne, Denis?
Mike
Mike Ellsmore

Mike I am on the Murray (beside it) between Strathmerton and Bearii which you most likely have never heard of.
About 75km north of Shepparton. Its been pretty hot hear as well, one day at 46*. I have been very happy with Clive's cam which is not a regrind but a billet. Denis
Denis4

Interesting.

The earlier pedestal style follower were considerably heavier, but I have to say I've never seen a failure like that on one of them.....
Bill Spohn

This thread was discussed between 09/03/2013 and 12/03/2013

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