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MGA MGA Crankshaft

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DElimon

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Does any mga owner have any idea why a eighteen month old crankshaft would crack in half?? Beginning to wonder if the three main engine is worth putting back on the road, I wonder if the quote professional mechanic messed up the installation. /ubbthreads/images/graemlins/lol.gif
 
Did you have the crank Magnafluxed before it was rebuilt?
Were the mains cut undersize?
Did the rebuilder properly radius the fillets on the journals?
Was Plastiguage used to doublecheck the rebuilder?
Were the correct bearings installed and properly lubed?
Was the torque sequence followed?
Did you follow the break-in?

Too many variables and too little information to help you.
 
Scott, you've posted all I deleted several times.

Thank you!
 
Just did.
 
Can you post a picture?

I have seen a lot of OE MGA cranks endure obscene amounts of sadistic torture.

Most of the bad ones were culled out of the herd before I was born.

I don't respect my crank as much as I should....It has always been there for me though.

I'm going to talk to mine today.....Thank You! /ubbthreads/images/graemlins/grin.gif
 
The crank was a remanfactured crank kit, it was magnafluxed, bearings were checked or plasti gauged, all work was done by a very experienced english car mechanic who is a professional mechanic and owns a very sucessful repair business, he also owns english cars!
/ubbthreads/images/graemlins/nonod.gifDid not get one thousand miles until it snapped in half-Now I am thinking that it would be foolish to try to make a three main engine preform for any lenght of time!!
 
Check the Main bearing tunnel for alignment.

Why was the new crank put in in the first place?

The "B" series engine is as bullet proof as the pomms ever built, if it broke that quikly, something was wrong somewhere.
 
Sounds like a flawed crank - magnafluxing isn't perfect.

You don't say which engine you have. The 1500/1600 crank is inherently weak and ill-suited to competition use.

The 1622 crank seems to hold up much better, although for street use, it shouldn't make any difference - they should all give reasonable service.

Remember that the cranks are all 40 years or more old and have seen varied previous use unless you find a NOS part.

Personally, my preference for a street MGA is a 3 main MGB engine!
 
Thanks for the information, the crankshaft was put in to replace one that was known to have been raced. The engine is a 1622 engine, I discussed alignment with mechanic, they did not have the old crank aligned when they installed it.
I guess I am debating switching to a 1800 five main engine, what do other A owners think, should I stay with the 1622??
 
Denny...it does not make any difference as to what other A owners think...this is YOUR MGA.

Upgrade or repair as YOU see fit.
 
[ QUOTE ]

what do other A owners think, should I stay with the 1622??

[/ QUOTE ]
NO....Go w/ the 1800 & sell all of the unexploded 1622 bits to me. /ubbthreads/images/graemlins/grin.gif
 
Somehow I thought that might be suggested. heh.
 
Dr E.....You know I'm just trying to help. /ubbthreads/images/graemlins/devilgrin.gif
 
Oh yeah, Dave. You're a paragon... my hero. /ubbthreads/images/graemlins/thumbsup.gif
 
Seriously consider a 3 main MGB. It can be made to look exactly like a 1622 and is the easiest to swap in, including the mechanical tach drive.

That's what I use in my 1962 coupe, and have used in several race cars (less main bearings means slightly more power through lower frictional loss).
 
Thanks for the advise on three main, guess I will leave the three main 1622 engine in her. Still cannot figure out why the crank snapped, I guess I just got a bad remanfactured cank, even the main bearing surfaces have ridges!! Block is in machine shop for crank alignment check and fit up with a new crankshaft!!!!
 
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