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MG MGB GT V8 Factory Originals Technical - Factory V8, cracked manifold

I finally got my brakes working OK (who designed the mountings for the master cylinders cover? They need a slap!) and fitted my new exhaust.

I ordered a replacement stainless system, that uses the standard manifolds (couldn't quite stretch to tubular manifolds at the moment). However, There's a small crack in one of the stud mounts (where manifold meets exhaust). Fortunately, I was able to drop a bolt through the hole for the stud, and clamp it all together adequately. It looks as if it ought to work OK, but only time will tell.

Couple of questions:

- I've heard these manifolds are prone to cracking, but where do they normally crack?

- Are these manifolds common to any other vehicle? Are they different to Land/Range Rover manifolds? I thought I'd ask, so I know what to look for at an autojumble.
Darren Ainsworth


They are unique to the factory MGB V8 and I have a pair with cracks. One of these cracks is exactly where you describe. The castings are very thin.

However they can be repaired by a specialist welder prepared to repair cast manifolds. Repairs are generally quite effective.

Ian Buckley

They do come up occasionally, but only slightly more often than rocking-horse poo.

Tubulars have their own problems including cracking, warping, down-pipes falling off them ...
Paul Hunt

But tubulars are 100 times easier to R & R!
Ian Buckley

I have one piece of rocking horse poo - I think it is the LHS manifold - available for what it cost me (a customer changed his mind!)

If anyone is interested I will check which side it is - e-mail me.
Chris at Octarine Services

One of the problems was that the manifold could expand & press against the block where the engine number casting is.......If it's in the same place as an SD1 that would be between 2 middle N/S might be worthwhile checking that you have clearance there.

Cast manifolds in good condition are very rare...I did see a pair for sale at Silverstone but no price on of my friends has just built a V8 roadster using exclusively V8GT parts, and he had to have the manifolds I'll stick to stainless RV8 manifolds.

Michael barnfather

Thanks for all the replies. At the moment, the exaust is pretty quiet and I like the sound. I guess I'll keep an eye on them, and perhaps have them repaired if possible, or replace them with tubular ones if it's not cost effective to have them welded.

Darren Ainsworth

This thread was discussed between 25/08/2004 and 26/08/2004

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