Sheered cam cover stud

[ALAN COCHRANE]

Hi Everyone

After a successful day in the garage changing the dual silencers I stupidly decided to try and tighten the cam cover nuts in an effort to stop an oil seep. Result-I sheered the front stud on the exhaust cam cover-part no C6727/1. It sheered flush with the cover. This is one of the shorter studs which only holds the cover down.

There should be enough thread left to fix a nut to it and remove it. Is this particular stud difficult to remove?

Cheers

Alan

[abowie]

If this is one of the little 1/4" ones then it should be easy to get out. It is a UNC thread into the aluminium of the head. A pair of pliers should do the trick.

Reassembly. Use spray Hylomar on the new paper gasket. I use a small dab of silicone in the corners of the rear seal.

Clean up all you copper washers and heat them cherry red over the gas stove and let them cool in the air. This softens them. Then wire wheel the soot off them.

Reassemble and take the nuts down to 4 lbft. If the cover subsequently leaks take it down to a maximum of 7 lbft. More and you can crack it.

If it still leaks after this, remove the cover and put a bead of silicone maybe 1mm thick around the outer edge of the sealing face of the cover. Reassemble with the gasket. Snug the cover down but do not tighten it. Let the silicone cure for a couple of days, THEN tighten it down to 4 lbft. this can help if you don't have properly flat covers.

[ALAN COCHRANE]

Thanks Andrew

I might try the silicone route for my leaking cam oil feeds as well.

Cheers

Alan

[mgcjag]

Hi Alan....I would be vary wary useing silicone around the cam feed pipes.....it would be easy for any bits that squeeze out to get into the very narrow pipes and block the oil feed to the cam.......ensure that the surface on the back of the block is absolutely flat and the banjo mating surface is also flat......are you useing the very thin shaped crush copper sealing washers or just a flat one......Steve

[christopher storey]

I agree with Steve. Use of silicon sealant on any part of the oil system is fraught with danger , and someone on this board managed to block his exhaust cam feed in exactly that way. IIRC he was lucky enough on this occasion to get away without permanent damage, but.......

[abowie]

I agree with Christopher and Steve. Allowing bits of silicone sealant into the oil is bad.

The trick with the cam covers is to put the bead on the outer rim of the cover face, and not squash it, so that it can't get inside the engine. Once it's gone off then you can compress it. I only use it if I can't get the standard gasket to seal, which is uncommon.

The cam oil pipes can be made to seal. You need flat faces on the banjo, softened copper washers, a flat sealing surface on the head and the courage to do the bolts up far tighter than you think you need to. I'm talking a good strong arm on an 8" ring spanner. Maybe 20 lbft at a guess. I've not stripped one yet but if you did a Helicoil would fix it, albeit it would be hard to do with the head on the engine in the car.

[Moeregaard]

Andrew's approach to leaky cam covers is similar to mine and works extremely well. I apply a thin coat of that glorified rubber cement sold by Permatex to both sides of the gasket, with a small amount blue Hylomar in each corner at the rear.

Regarding the cam oil feeds, be very careful bringing up the torque on the banjo bolts. The threads in the cylinder head are easily stripped and most aren't in the best of shape after fifty-plus years. I once had to remove the head from a freshly overhauled engine and install Helicoils on the cam-feed ports after one of the threads gave up the ghost when the banjo bolt was little more than hand-tight.

[christopher storey]

The JEC used to , and I hope still do , sell extra long cam feed bolts which used the threads which are tapped far deeper into the head than the standard bolts extend to ( syntax!? ) . These solve the problem of stripped threads

[ALAN COCHRANE]

Thanks for all the advice gents. On closer inspection the main oil leak is coming from the cam covers. Both are leaking profusely along the whole of the lower sides and front and back as well.
This may explain the reason I had to put four pints of oil into the engine after only 1200 miles.
On the plus side the front crank seal is bone dry, the gearbox does not have a major oil leak from the bell housing and the cams seem to have a very healthy oil supply!
I’ve ordered a tube of Permaflex and will let it semi cure before tightening down the cam cover bolts.
The cam feed has turned out to be a minor leak which I fixated on. I have inserted a nitrite O ring in between the copper washer and the cylinderhead which seems to have slowed the leak considerably.
I’ll let you know how I get on.

Cheers

Alan

[Mich7920]

You may be able to buy one of these glass shelves thick enough to regain the flatness of the cam cover.
The glass is obligatorily flat.
GR400 / 600 or 800 grit sandpaper with oil on the glass and gently rub the cam cover over the sheets.
Thats what I did and I reduced the leaks dramatically.
Mich