VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1925 Chevy head

My 1925 Chevrolet cylinder head is cracked along the valve guide on number 3 cylinder and runs down the side of the head. I have a spare head that is also cracked in the same way. I was wondering if anyone else experienced the same problem and if they got them fixed or not. I called one place that claims to be in business for 30 years and they said they couldn't fix it. The damage was too extensive.

RichW, That's very common. You can use a 1928 cylinder head which has a 2 port exhaust and isn't prone to cracking as much as the single exhaust port head.

Thanks, Steve. That's good to know.

While a '28 head can fit and they are more common, I would encourage you to continue searching for a "correct" head, so that when people look at the vehicle it will look like a true 1925 Chevrolet, not something cobbled together. The '25 has the one-year-only two piece valve covers, and is nice to see correctly done. Heads are out there, and the chase is part of the "fun." Hershey is less than a month away - and an advertisement in the G&D will take a while to appear in print, but might very well generate some leads.

Chevyguru, Thanks for the reassurance that there are heads still out there. It is always my goal to do a correct restoration. Hopefully, I'll get lucky at Hershey but I still haven't given up with searching for a repair shop or part sources.

I agree with Chevyguru. The single port head is part of what makes a '25 a '25. Good ones do show up and it is worth the hunt, in my opinion.

If you prevent a single port head from getting really, really hot, they are as reliable as a twin port. If you do get one hot, don't add cold water too quickly, take your time.

Regards
Al

Thanks Al. So far I contacted 2 machine shops and both want nothing to do with the heads. I was considering having one cast although I'm not sure of the price. I just don't want to be stuck with a vehicle that's going to end up being a trailer queen or yard ornament.

Rich - I am sending you a regular email with the Newsletter from the Model H group attached. See page 11 for a short article about cast iron repairs to heads. You might try contacting Ray Moot, who is the Director of the group, and even possibly he could pick up a head from you at Hershey and carry it back to the guy in the article, not sure how you both might want to proceed, if at all. But it's a lead. If you contact Ray Moot, mention my name, Don Williams.

Thanks, Don, I'll do that.

Do you have a picture of the head with the two valve covers on it?

I have a set of the '25 valve covers with felts in real nice condition that came in some 4 cyl parts I bought. Are they worth much?

I found someone who says he can fix this type of crack. I took both heads to him to repair. He's located in Massachusetts about 3 hrs. away from me. He stitch welds. To get around the valve guide he cuts a piece of the guide away to access the area. He says after new valve guides are inserted replacing the missing piece is an easy fix for a machine shop. If anyone is interested in contacting him his name is Frank Casey, tel. 508-865-6613. He does really nice work. Incidentally, after disassembly. I found both heads that I have were cast in April 1925.

Good news!

Congrats, Dean

Excellent.

Familiar conversation for we inflicted with single port heads. Interesting place for the cracks to appear and maybe a freezing crack? After collecting 34 of the blighters,I have only ever seen them cracked inside the exhaust port, from heat. One has to carefully check apparently good heads in this area because they can look to be OK yet a simple blast from a grit blaster will reveal all and then if OK it pays to finally use crack testing dyes in case there are hair line cracks starting.
Another word of advice is that nearly all the heads that turn up (lying around) are doing that because they are cracked and have been removed from service.
We Chev people have been indeed slow to get improved versions remade, especially as one head could be made to fit all models to '28. I suspect Fraud owners would have acted by now for sure. Better material alone would likely fix the problem.
But with due respects, despite some pretty awful machining alignment with valve guide boring, the heads we cut in sections to see what might be possible for repairing, were beautifully cast and very consistent in wall thickness etc. Even opened sections would not weld inside the port area, so yes they are indeed not repairable.
Happy searching, but check carefully.

I have been told that the problem with trying to weld the heads is excess carbon in the crack and pores of the cast iron. Burning it out has allowed some to weld the cracks.

Attached is s a link to photos of the better of the two heads showing the crack. Frank seems confident that he can fix it. I will update as to whether he can or can not repair it.

Thanks for the photo. Very clear.
I hope you have success with the repair and would suggest that it is likely given the crack location on the outside where it can be got at to be "stitched". But if a crack is also on the inner jacket wall then short of removing a large piece of the outer wall to allow access then it is curtains. I can only imagine that crack being caused by freezing, a rare event here.
I might mention that of the 34 heads we collected in our search for a good one, not one was useable, all being cracked inside the port area (nearly always a single crack up the back face then becoming smaller and fanning out across the top face in several directions). So I am not so sure about the "fun of the chase", perhaps frustration would be a better term.
It would appear likely that the best way to get a good head is to get an assembled engine because it is likely it was still functioning when last used, but of course whole unmolested engines are just about as rare these days.
Does masochist come to mind?
Cheers.

Hey Rusty Relic,

Just finding 34 single port Chev 4 heads would be a task beyond many of us, especially here in OZ. I can only imagine the frustration of one cracked one after another.

Cheers

Ray

I went through 8 heads and found only one good head. IT WAS AN AFTERMARKET HEAD MANUFACTURED IN THE LATE 30S. This one is a keeper in case I ever lost a head on my other 4-cylinder cars.

I wonder about some of those cracked heads. If we took the time to bolt them up they may be a useable head. Even with the cracks across the center (between #2-#3 cylinders) of the head.

Has anyone tried to groove out the crack across the middle of the head and pack with JB Weld?

Who rebuilds or sells these RAX carbs..I have one pre 28 although the motor chugs the carb isnt right....I have a 28 ab motor.

Lucky you Ray. Interesting that it was an after-market head that was good. We had those too and now I wonder if in fact they may have been sourced from the US. You can be sure of one thing that would have made that attractive, and that is that GM would have been ripping us off here. Parts were always very expensive for all cars. Still holds true today for just about anything. Harleys, Triumphs etc are all 60+% dearer than anywhere else, and you need a bank manager with you to venture into Toyota parts departments. Apparently we are wealthy!
Among the collection of heads we had were 4 after-market jobs, two definitely OZ made. Alas all were cracked inside the port as for the genuine jobs. So the rumours I have always heard for 40 years that these local heads will fix the problem seem to not be true.
Interesting question about JB weld. Seems to fix just about anything. Would it hold under expansion and contraction? Hope someone has tried.
As an aside, my nephew is a pattern maker at a place that makes all manner of new parts for the racing world among other limited specialised replacement parts for industry etc. They said no worries for new Chev heads. Expect a bill for $30K for all the moulds. Now if I win the lottery then that will look like chicken feed and in the interests of Chev 4 owners sanity I will have a heap made. In the meantime scrounge on chaps.

Good news. I spoke to Frank today. Of the two heads I sent to Frank one is definitely repaired. The other one has a 4 inch crack inside the exhaust port. He says he can fix that one too. Frank says the good news is that the metal is thick inside so the repair will hold better. I don't know how he did it but I'll know more in about 2 weeks when I pick them up. I also picked up a 1928 head with the exhaust manifold at Hershey last week. It looks to be rebuilt. I'll keep that for an emergency or I'll put it on my Model T. Lol. When I get the heads back I'll post pics of the repairs.

I got both heads back today. Both were pressure tested. One was at 40psi and the other at 50psi and both passed with no leaks. The original head from the engine was the best one of the two. It had no internal cracks. The other one had an internal crack and it was repaired. This man is amazing I have to say and his prices didn't break the bank. He showed me some of the stuff he worked on and is working on and I don't think there is anything this guy can't fix.