The Stovebolt Site Forums The Shop Area Engine Shop GMC engine help

Dear fellows:

I've started to work on my 49 1/2 ton engine. It's working perfectly (I was really lucky when I bought the truck) but since I'm sort of restoring it to its hayday glory, I've come up with some issues. I'll be bothering you quite often so please, be gentle. I'll appreciate any help.

First I would like to know exactly what motor is it. Motor number says A228####, but block casting 2324002. I have the shop manuals for 47-54 and 55-59. On the first, it says that the A means oversize measurements on some items (bore, crankshaft, etc.) and the following the CID. So it should be a 228, but on a lot of places I have seen that the casting number belong to a '55 248. What confuses me more, is that the shop manual for 47-54 tells that those model years can carry the following motors: 228-248-270, and the 55-59 270-302-347. If this is true, the motor is a 54 or the made 248 on 55 also? Is there a difference in engine between 55 1st and 55 2nd?

The later will help me choose the proper carb. Mine has a Rochester adapted. I have researched and found GMC uses Zenith, but I want to know which might be the appropriate. I still have more questions, but don't want to overwhelm anybody.

Yours

Chinito

GMC last manufactured the 228 in the US in 1953. in 1954 and 1955, the 248 was the smallest engine made and 56 and later, the 270 was the smallest engine. In Texas and many other states, vehicles were titled by the engine number. It was common when a replacement engine was installed, that the original engine was ground off and the original number stamped on it to match the title. Factory engine numbers were evenly spaced. If someone restamped it, the numbers are usually a little crooked. A228 would be a correct engine number for a 49 1/2 ton.

I also have a '55 date code engine with casting #2324002. It came from a '55 or '56 Blue Chip (same series as task force Chevy). It is stamped 248. That casting number isn't listed on the Inliner's list. And as you stated, Blue Chips weren't supposed to have 248s. My theory is these are replacement engines. Replacement engines came with no serial number because vehicles were titled by engine number. The common practice was for the mechanic to stamp the engine number from the old engine onto the replacement engine. I have no idea if mine is really a 248.

Charlie, the factory short blocks came with the first 3 numbers denoting the displacement already stamped and the mechanic finished it out. However, if a used engine was installed, the boss was ground smooth and numbers were stamped on. If you look at the numbers and the first 3 look professional, it could be a factory short block. If they all look professional, its probably the original engine. If they all look like I did it, its probably a used engine and can be anything. The only way of knowing for sure then is like they used to do at the old Double Eagle strip in San Antonio..Make you pull a head. Maybe you have a 270, beings it runs so good. But a good 248 is a big improvement over a 228.

Well, the truck was sort of assembled from different year parts, the frame and cab are original 49 but bed is 55 2nd and the differential is yet to be identified, since I'm still not working on it. So the engine could be anything. The truck is in Guatemala and I'm pretty sure it was originally sold here. American car dealers here historically have never been good (neither japanese cars for that matter), in having spare parts, much less spare engines. I think the guy took a motor he found and put it in the truck. As far as the motor number the A looks crooked, the 228 sort of good and the rest, well, like a doctor's prescription. I'm really not counting on it being the original. Basically the question is if the block forging number is enough to determine the CID of the motor, or like Crenwelge said, I'll need to pop it open to be completely sure. The head stamping are: a 55 on the left and a CFP next to it, then a 117 on the center and the 2194819 on the right with a AF below it. I've read that somo 228's and 248's share the 2194819 head, so, correct me if I'm wrong, I think this will not help determining the CID. By the way, above th 2324002 block stamping, it has GMC-7.

Guys: Did someone figure the above? I just want to buy the appropriate carb for that engine. Since my truck came with a Rochester, not a Zenith.

Thanks