So it looks like I've stumbled across an '848 head. We currently have an 887 head on our 235. Current engine/head is in decent shape, but the 848 head seems to be the one to get from what I've read. Any reason not to make the switch? I'm not in any rush to do it, but it's a good price, and I'll send it out to a shop to inspect, etc. and eventually we'll swap it out. Is there any particular valves or springs to look for or avoid (it's a bare head)? Engine has solid tappets if that makes a difference. There seems to be some NOS valves still kicking around.
That’s a good question, I’ll have to dig up some pics and hopefully see. I don’t have a low pressure 235. Truck is a Canadian GMC and supposedly they came factory with the Chevy 235 that American trucks got in ‘54. So it’s not low pressure but has the 2 acorn cover.
USA 1953 high-pressure 235s (in Corvettes) had the two bolt valve cover.
I cannot remember if the 1953 USA 235 Powerglide-equipped car engines were high pressure, but they had the two-bolt valve cover, as did all 1953 216/235 car/truck engines.
USA 1953 high-pressure 235s (in Corvettes) had the two bolt valve cover.
I cannot remember if the 1953 USA 235 Powerglide-equipped car engines were high pressure, but they had the two-bolt valve cover, as did all 1953 216/235 car/truck engines.
Yes, the '53 Powerglide cars were high pressure engines (2-bolt valve cover) and had hydraulic lifters, and all '54 engines were high pressure (4-bolt valve cover). Interesting the Canadian truck engine has a 2-bolt valve cover, which would not have been the case for '54 US engines. The '53 US truck engines (2 bolt valve cover) were all low pressure.
The 848 head was introduced for the 1956 pass cars. I have one that was cast late 55 so for the 56 production. I am not sure if they were ever installed on a truck motor, although they were installed on the Canadian Pontiac 261 pass car motors. A lot of years ago now, I was on the phone with Tom Langdon while he was still at GM and he looked up some head casting numbers for the chamber cc. The 848 head was theoretically 79.1 cc. The compression ratio for the 56-57 passenger cars was 8.0 to 1. That ratio was upped a little, 58 I think, but 59 for certain, to 8.5 to 1. I have never cc’d a 56-57 head and a 58 and 59 head to see if there is a difference in the combustion chamber volumn, or the piston to deck height of the various year motors to see if there was a difference. So I don’t know why the difference in compression ratio. At any rate, every one wants an 848 head to get that supposed .5 compression increase.
Milling the low compression 235 head 3/32" (.090") gives the same compression ratio as an 848 head, but some monkey motion with intake valve seating depth and rocker arm geometry has to happen as well to keep the intake valves from hitting the pistons. Jerry
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Were Canadian casting numbers different from US casting numbers? Your head looks like a 53 or later US 235 head. Even though all 235s were redesigned for 53 with 18 head bolts, etc., the trucks and stick-shift cars still had the oil nozzles, troughs, rod dippers and lower oil pressure. Which is weird, I think.
So just to update the thread, I did not pick up the head mentioned in my first post. However I was just travelling for work this week and did just pick up an overhauled 848 head. It was apparently overhauled awhile ago and is showing some signs of surface corrosion from sitting for so long. I know the cc's for an 848 head, but does anyone know the cc's for a 3701887 head? I can't find it in any threads I search on here. After the deal for the first head fell through, I wasn't in a rush for another one but noticed our head gasket was leaking a little. I retorqued the head bolts and that seems to have fixed it for now, but I do prefer to replace the head gasket at some point and I'd like to go through all the rockers anyway. I decided to look on Kijiji for various items before I traveled for work and saw this for sale on there and bought it.
