Cracks at the base of rocker studs

[sdilts]

Looking for some assistance... rebuilding my 1275 and noticed these cracks (see photos) at the base of the studs for the rockers. Has anyone had these repaired with any success? If so, how and where? If it ends up being a boat anchor, I'll be looking for a used race 1275 head for street use in my '67 Mini Cooper S.

 

[Bob Hess]

Had one crack on a 948 head. Left the stud in and had the best welder I've ever seen weld it up. That was 25 years ago and it's still good. Welding cast iron is not complicated but you have to know what you are doing. I've used brass to repair cast iron but it didn't seem to be proper for this kind of problem. Puts too much heat on it for too long with brass.

 

[sdilts]

Do the cracks in mine look much different than the issue you had back then?

 

[Bob Hess]

No. I'm guessing the previous owner exceeded the torque range. We torque ours to 20 lbs using ARP lube and 25 lbs with oil.

Bob

 

[keithdeg]

no threads left exposed so the full diameter of the stud entered the hole

 

[sdilts]

no threads left exposed so the full diameter of the stud entered the hole

How can this be avoided if the torque is correct?

 

[sdilts]

I've received a quote from Crow Custom Cast Welding in Wisconsin. 150-200 for each stud to be repaired. Reportedly the valve guides will need to be removed, but the hardened seats will not need to be replaced after the work (which would be a good thing). Just wondering if this estimate is in line... and does anyone see a problem if the studs end up being welded in place during the repair work?

 

[Bob Hess]

I wouldn't weld in the stud unless everything else tried has failed. You don't have to weld all the way into the threads to repair most cases so leaving the stud in supports the welding process. If you need to weld into the thread area then plan on recutting the threads or if required put a Helicoil in. I think the repair cost is more than fair for that kind of work.

 

[sdilts]

Bob -- Thank you for your helpful comments! I appreciate you assistance with this issue.

 

[Bob Hess]

Bob -- Thank you for your helpful comments! I appreciate you assistance with this issue.

Any time. Just paying forward all the help and ideas I've gotten over all these years of building and repairing cars.

 

[jbecker]

If you need a 1275 head for your Cooper S I may have either an original S head or a 12g940 big valve head.

 

[Bob Hess]

Just to shed some light on weird repairs on the BMC engines we bought a 948 14.1 cr engine that had one of the intake chambers break through into the water jacket. It was repaired with JB Weld and we didn't find that out until we had raced the engine for 5 years. It's still in there.

 

[Al Seim]

Devil's advocate - if the cracking is just at the very top and is caused by the unthreaded major diameter running down into the threads exerting a bursting force at the surface, is it possible that it does not need to be repaired? Depends, I suppose, on how deep the threads go.