VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1953 to 62 235 head Evolution??

Gene or anyone else that has any input, maybe you can clear up the history of the mid 50’s and up 235 heads. We’ve had a discussion going on about the 3835913 (casting no.) head that was on the 1954-55 early 235s. The head appears to have been changed in 1956 and from what I’ve been able to figure out a couple of times till they settled on the 848 head. The parts books I have access to only list the 3836848 head as a replacement for 1953 on up and it seems to be the head most sought after.
Any info that would help clear this up in my mind would be appreciated.
Denny Graham
Sandwich, IL

1953 head casting # 3701887. 7.5 to 1 compression ratio.* No provision for side type valve cover screws. Cover held down with center studs. If you drilled holes for the 1954 valve cover on the left side casting was thin and you struck water. Don't ask me how I know.

* Cr on cast iron piston engines 7.1 due to lower piston height

1954 head, casting number not in 1954 book but has the same 7.5 CR but provisions in casting to accept valve cover screws.

1955 head casting # 3835913, 7.5 CR no real changes from 1954 head.

1956 head casting # 3836948, 8.0 CR and provsion for larger eletric temp gauge sender requiring change is casting. Would suspect change is combustion chamber to raise CR

1957 head the same

1958 head raised to 8.25 CR , smae casting number, would assume "shaved" slightly to raise CR

1959-1062 heads the same as 1958.

When a new head was purchased and was the 848 head it came with the adaptor for the old style temp sender so would cover all engines. If you had a 1953-55 you got the higher CR.

For a 1953 it would have the four screw location for the newer valve cover but the old valve cover and studs could be used.

Thanks Gene, I somehow knew you’d be the one to come thru on this one. Couldn’t’ find that info in the reproduction literature or on line and I don’t have much original literature at my disposal. If those original casting numbers aren’t in the parts books how could one verify that from the GM literature? I can’t find engineering changes or service notes for ”˜56 thru ’62 anywhere.

So that was the Slooooow evolution of the head. I’m surprised they didn’t come up with those changes a little quicker when they brought out the new block.
So the valves and ports are pretty much the same and they just made minor changes to mount the sheet metal and temp gauge over the first few years. It sounds like the 848 head was Chevy’s final solution for the full pressure 235. And if one isn’t hung up on casting numbers being correct it sounds like it would be advantageous to use the 848 head on a ’54 235 to bump up the hp a bit. Or just mill the 913 head a bit to bring the CR up to the 848 standard.

For 1956 can I assume you meant #3836848 instead of #3836948 ?
Thanks again,
Denny Graham
Sandwich, IL

Yes - 848 is correct.

The 848 head would be the replcement for both 235 engines in 1953 and the old dipper engine and the modern full pressure engine both used the same heads.

The only thing changed and improved upon through the years was the material the exhaust valves were made from. By some strange quirk the exhaust valves interchange with the small block V-8's also so the small block valves are the best ones to use. They also fit 1950-53 216 engines.
Burning exhaust valves was always a problem on the 216 and early 235. With a set of the better valves they would go five times as long between valve jobs. The better valves is all I stocked in the parts dept. for replacement.

Did you ever give your 216 a complete rebuild?

I did both 216 heads I have here a couple of years ago. One I've been running on the 1950, 3604 and one is on the shelf as a spare. Both got mill work, hard seats, guides, new V8 X-valves, Magnaflux and pressure tested, spring pressures matched and shimmed.

I'm doing the short block this summer, just got off the phone with my engine shop and all they need to deliver it this week is the plugs for the oil galleries. He says they are a real odd ball size and he had to special order them.
Had it bored .020" over, alum pistons from EGGE, rods reworked for inserts, cam brg and timing gear, crank polished and the whole rotating mass balanced.

This past month I picked up a 1954, 3604 (can't seem to get away from those 3/4 ton trucks) that was a virtual one owner. In fact the guy that owned the truck up till this summer was a 14-year-old farm boy from central Nebraska in April of 1954. His dad bought the truck for him to drive to High School because there was no bus service out in the country back then. Of course the truck also had to carry its weight doing farm chores. This engine is the one that raised the questions about the 3836913 head. I haven’t had the truck long enough to do a full evaluation of it. It runs nice, needs some front-end work and a good clean up and eventually will get all of those dings and dents removed. It was garaged most of it’s life and the only rust is small hole at the drivers cab corner were there were some rags and dirt that had accumulated there.
I’ve got a book of receipts from 1954-6-7 for delivery of hogs and cattle in the dad and son’s name and a hand full of registrations over the years. It has most of the original paper work in the glove box, i.e., owner’s manual, service policy, break-in/tire chart card certificate of title. He said they registered and insured it in his, (the son’s) name back then because it was cheaper than having it in his dads name. The real kicker is the guy is ’70 now and lives a mile away from me and says he has pictures of the truck being used on the farm. http://www.pbase.com/dennygraham/1954_3604_chevy_truck&page=all
So I’ve got a good starter for the next project after the ’50.

Denny Graham
Sandwich, IL