The Stovebolt Site Forums The Shop Area Engine Shop 54 235 engine work

Decided to start with the engine on my 54 GMC 150 truck, then work my way towards the transmission, rear end, brakes, etc.

I can turn the 54 Chevy 235 engine by hand and noticed it stops about halfway, assuming I have a stuck valve. Going to remove the valve cover and side plate to see what is stuck. Any suggestions to freeing stuck valves and/or lifters? Not sure if solid or hydraulic. Once I can spin the engine freely, I'll do a compression test and go from there. Was sitting since early/mid 70's. Don't want to ruin the engine by mistake.

I have the original 248 GMC engine already torn apart and looking for manuals and rebuild kits, etc.

TIA

If the stamped serial number by the distributor confirms that it's a 54 truck engine, the only option available then was a solid lifter cam. Passenger car engines in front of Powerglide automatics were the only ones with hydraulics. Don't waste any more time turning the engine- - - -pull the cylinder head. You've either got a very rusty cylinder, some stuck valves, or both. I've spent untold hours on getting a sticky engine to finally make a full turn- - - -even got a few of them to run- - - -and still ended up doing a rebuild in the end. You might as well bite the bullet and cut to the chase!
Jerry

Make a good point on the engine. From what I was told thru here or another forum, it's a 54 235 from a 3100 series truck #00II242F54X CON1 K5 is what's on the side of the block, heads are 6835913.
Starting to keep better notes to where and how I got this info as well as future work. Should have done this the first time. Have the 248 engine which I'd like to put back in the truck.

Will be taking the engine to the machine shop to have it checked out to make sure it's rebuildable, etc. First project truck for me and learning as I go. Wanted to try to get it running to see what all I need to do before I do a full on restore when I get garage built. Right now using the shop at work on weekends when I have time.
Looking for rebuilding parts for these engines, etc.

I'll be going back out to a friends place where I had gotten the truck and engines from, will look for more spare parts I can use as most of the stuff he will be selling or junking.

If you find a 302 or 270 GMC engine, it will fit right in place of the 248, cost about as much to rebuild, and give you more power.

Ed

I read somewhere that the 235 can be converted to a 260? If so, would anyone know where to find that info?

Not converted, made as 261 from factory, looks just like 235, look them up to see differences. HRL on here makes modified ones using different parts.

Ed

It's a different block with a much larger cylinder diameter: 3.75" vs. 3.5625", almost an 11% increase in displacement.

RP14 A friend at the junkyard gave me a 235,it seemed to be wore-out took some time with it,runs fine today. Soak your valve guides,leave side cover on,soak cylinders with MMO. If it's stuck valve can locate and free-up pretty easily. If not probably a tear-down.

RP14 An .080 over 261 will be a 272 using over the counter parts,for what it costs to get much more probably not worth it .

Read somewhere about converting. Might have misunderstood. Been years since I have worked on engines, mostly V8. Will keep the 235 stock and any minor upgrades. First thing first, disassembly and check the damage.

With a stroker crankshaft, and some highly modified NASCAR connecting rods, I can get close to 270 cubic inches from a 235, or around 300 from a 261. Unless you have your own machine tools, including a crankshaft grinder (I do) or know a machinist who works pro bono, it's not a very practical way to get more displacement. A bored-out 261 would be a lot simpler to build.
Jerry

Been a while since I have done much to the truck. Got the rear half of the frame blasted and painted, axle seals replaced and getting ready to put on the brake lines, etc.

The 235 engine broke free, not sure what it was but was an easy thing by rocking the fan back and forth. Checked all the valves for proper movement, compression was around 95's, no spark. Found the new set of points wasn't making any contact on the contact itself, replaced it and got spark. Poured some fuel down carb and it started right up without hesitation and ran smoothly for maybe 5 seconds or so.

Not sure what to do next on the engine that has been sitting for 40 plus years, should I pull engine and replace rings, gaskets, etc? Oil does flow good thru the rockers and was the original oil (clean).
Is there any way to check the block for any cracks without taking to machine shop? Or should I run the engine till hot and see if anything leaks?


Thank You

Run it for a while at normal operating temp and see what it does. If it isn't burning oil or leaking or anything, drive it.

A quick way to clean up an engine that has been idle for a long time is to use Diesel fuel. Change the oil, using whatever inexpensive "bottom shelf" generic stuff is available at Walmart, and add 3 quarts of Diesel to the crankcase so the crankshaft counterweights and connecting rods can dip down into the oil/Diesel mixture. This will splash the mix around like the agitator in a washing machine, and break loose any sludge or other debris, as well as possibly dissolving carbon deposits under the piston rings, etc. Run the engine at a fast idle for 15-20 minutes after it reaches normal operating termperature. DO NOT DRIVE THE VEHICLE OR PUT ANY LOAD ON THE ENGINE- - - - -1,000-1,500 RPM max. Drain the mixture while it's hot, taking dirt, sludge, and debris with it. Refill with good oil, (I like 15W-40) and change the filter, if the engine is equipped with one.

This will accomplish one of two results- - - -you'll either have a good running engine you can drive, or you'll create an oil burner that needs to be rebuilt because the piston rings are worn out, and all that was holding them tight against the cylinder walls was carbon and sludge packed behind them. In that case, you'll need to pull the engine and rebuild it- - - -but it's going th be much cleaner than it was before, easier to work on. Win- - - -Win!
Jerry

The valves and inside cover is clean with no sludge buildup, which I'm thinking due to the clean oil was probably rebuilt or re-ringed. Will try to get it running, just need a few things including time.