VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1926 Chevy Head Cleanup / Testing

Good Evening everyone, Im hoping I can get some insight on the do's and dont's of cleaning up my spare '26 head.

First of all, the head has MASON cast between the oil wells on the top of the head. Any ideas on what this refers to? Aftermarket possibly?

Second, the head is covered in rust. Not scaly rust but just weathered. There is some scale coming out of the water passages but nothing major.

Whats the best way to clean up? I was planning on abrasive blasting the head but was wondering if I should be worried about the valve guides? Should I put rubber plugs in the guides to keep the sand out? Just blast them too?

Then when its cleaned up, how do I go about pressure testing the head for cracks, or is this something best left to a professional? What pressures are we talking here, and any suggestions on how to seal everything up?

Thanks for any help you can provide!
Frank

Franky.
I use glass beads as it is less abrasive and doesn't produce the "etching" like other blasting media and it does a great job of removing the rust. However I don't think using garnet sand will hurt anything if you do use it. Some of the more knowledgeable folks here can advise better but I don't believe the head originally had valve guides. My recommendation is once you have cleaned the head up take it to a good machine shop and let them install valve guides, resurface the deck, pressure check and do a valve job. That way you will have a good solid head for your rebuild. These heads are notorious for cracking! The name MASON was the name of an engine company - it was not a foundry. The Mason Co. was merged into Chevrolet and became the Motor & Axle Division on December 31, 1917
Tom

You could get a sheet of 3/16-1/4 inch rubber material and mount it between the head and a spare block. Using a tire valve stem and enough of the old inner tube clamp it to the water outlet with a hose clamp after you have filled the head with water. When I did a 28 head I found it only took a few pounds to see the external leaks. If you wanted to check for leaks and cracks in the valve chamber areas you would have to make a steel plate with cutouts around the valve area. Because Chevrolet only used 8 bolts you would want to go with a fairly thick plate material to prevent any warping. If your head has the atomizers in the intake ports, you might want to take them out for cleaning and better view of the insides.
As far as cleaning, you could have it baked, acid cleaned or just sand blasted. I would install plugs in the spark plug holes (sand blasting) and remove the freeze plugs between 2 and 3 cylinders.

Thanks for the reply everyone! Been real busy lately and havnt had a chance to do anything with the head. I still have an overheating problem with my '26 and pulled the water pump today to do a rebuild with a new baffle plate. Old impeller was grinding away at the baffle plate. Hopefully this will make a difference. Making a phone call tomoro for parts.

I like using Evapo-Rust, it is a liquid that works extremely well and isn't overly expensive. Its on Amazon if you can't find it in local stores. Just submerge the head in it and leave it for a few days to a week and rinse with water. Makes way less work and you are not trying to clean out sand after or being worried about etching. For your cracks, most engine shops can Magnuflux. It is a strong magnet and powder and it is a pretty thorough way of finding cracks.

I was wondering how well magnaflux would work on the exhaust side of the head...it would be challenging to see in there, eh? between the end two exhaust valves

TSC, Tractor Supply sell Evapo-Rust here in the USA if you have one close.