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MG MGB Technical - head problem

Hi All, Is there a problem with "B" heads cracking? If so how , why and where. Thanks.
s page

The short answer is yes - Peter Burgess will give you chapter and verse.
Roger W

They usually crack in between the valves of #2 or #3 cylinders, or beneath the spark plugs. Running the engine on low-octane fuel is the chief contributor to this problem.
Stephen Strange

I think, in a nutshell, you have answered the question Roger and Steve. The heads crack all over the place, as years go by and the heads get older and more fatigued we see cracks in places we haven't before. If you want a head working on take it to someone who knows what they are on about in terms of work capability and knowledge of failure. Pressure testing and penetrative die crack testing does not always show the cracks. The crack problem with B series and A series 1275 heads can be very stressful to a customer, that is why we offer a 'stunning' guarantee. If we work on a customer's head and it cracks within a couple of years we will redo the work free on a customer supplied casting. If we supply an outright casting we would replace the casting and work if it were to crack in a couple of years.

Peter
Peter Burgess Tuning

Hi Peter,
I hope you bounce back to this thread sometime, I wanted to ask you if in your opinion if you thought(other than standard or irregular abuse) heads crack from cycling thermally or if you thought it was due to the influence of time changing the materials bond. Ive got a good crack tested 1622 head used but unmachined. Im just hanging on to it because there getting harder to find over here and sometimes collectors pay a bit more if you have one they need.
If its just left on the shelf in a dry area it wont develope cracks... what do you think. I know its kind of a stupid question... just looking for an opinion.
Steven Devine

I cannot see storage cracking a head. If the crack is there it will show up at some time. Have a close look around the ex valve and up over onto the head face opposite the spark plugs. 1622 heads very prone to cracking here, doesnt always show on crack testing so we skim/mill the heads before we do any real work on 'em.


Talking about rarity of heads, we had a quiet few days modded headwise so we prepared some modded Mini heads, a couple of these sold almost straightaway. Another quiet couple of, days so we prepared a head suitable for an MGA 1500 and one for a 1622. I thought these would go 'overnight' as people are always asking me if we have castings they can buy.....these have sat on the shelf for 5 weeks without a nibble, such is life :)

Peter
Peter Burgess Tuning

Thanks for taking time out of your day for the advice!
Sounds like Muphys law again! You do this and you get that!
Steven Devine

The cylinder head on my 79 cracked between #2 & #3 all the way to the valve guide. Remedied with a new Aluminum Alloy head and has been trouble free since, even with an overheat due to a temp cooling fan sensor failure. This was appox. 10 years and 15,000 miles ago.

FWIW

Cheers

Gary

79 mgb
gary hansen

This thread was discussed between 24/03/2013 and 01/04/2013

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