Swapping the old engine.

Hello everyone! I have a 1954 gmc 350 2 ton pickup hi/low rear I'm wanting to know what the easiest engine swap would be?? Not 100% what the current engine/trans are that's in it now so any info would be greatly appreciated!!

 

Welcome, and how about some pictures of the engine bay? What does the rear end look like, closed drive? Cell phone pictures are fine. Email the pictures to me if you are having trouble posting and I will post them for you. I sent you my email in a "conversation". Click on the icon that looks like an envelope in the upper right part of the screen

Charlie Stephens

 

probably a 270 ci straight six. With an SM420 transmission. But that's just a guess.

Easiest swap might be to put a Chevy v8 in it, with the manual transmission bellhousing from a 50s V8 truck. But it might not get you what you want. We don't know what you want.

 

Pictures would help, but I agree with Squirrel, it is probably a GMC 270 if it has an original engine. It may have a 5 speed trans, some of the big trucks had the extra gear. If you figure out it is a GMC six, if you scrape off the crud by the distributor machined pad, there will be a stamped number indicating the cubic inch.

 

Attached are the pictures of Matt's engine compartment:
Charlie Stephens

 

if you care what engine it has, look here for the stamped number. They use the displacement as the beginning of the engine number, which makes it easy.

 

I think that 2spd rear axle will be uncomfortable as its ratios is low and lower...

 

This should help you decode what you have there. But be careful what you wish for, that is a lot of old truck. They were not known for performance.
http://www.oldgmctrucks.com/page0010.html

 

The cubic inch is stamped on the pad by the distributor,,

Woops, just saw the above post,,,

 

my guess is a 302, Ill take that boat anchor off your hands........

 

not very likely that it's a 302, unfortunately.

 

Probably not a 302 but the little brother to it, I think squirrel nailed it with the 270
302 was mainly in the bigger trucks and buses military stuff etc.

Sbc with a manual or and auto would be the easiest.

Need to check what ratio rear you have, as these trucks were meant to work on the farm and had granny low stump pulling rear axle ratios.

Any pics of the whole truck?

 

Thank you to everyone for all the info. I was interested in what current motor is so I can get a few parts for it if I can un-seize it... Just to move it around the yard. Still debating the swap the preferred option would be a 12 valve drivetrain but may look into other options.

 

So if my trans is still good I could just swap bellhousing?

 

yes, I think so. I plan to do something like that with my 58 GMC 370

 

And would the vaccum system for the 2 speed rear still work with the v8 swap?

 

sure, why not? you just need to connect it to a threaded hole in the intake manifold, most SBC intakes have that hole, behind the carb.

 

Ok you could have any engine from a 228 ,248 ,270 or 302. Beings its a 54 the v8 bellhousing will bolt to your crossmember. I would swap bellhousing and re place with a later 63 up six. My choice would be a 250. Get the front engine mount from a bread van for the late six and it will be almost a bolt in. Use the original clutch fork and linkage. If you want more speed swap for bigger 10.00 -20 rear tires.

 

Thank you for all the info I can see asking YOU more questions in the future haha!! But I will get the numbers tonight off engine.

 

I put a later 250 engine in a 54. the trans bolted up to the 63 truck bell and it bolted to the 54 crossmember. A 53 crossmember is different. I fabbed mounts to front mount the 250 six. Used the stock radiator but converted to a alternator and did away with the stomp pedal starter. If you go V8 yyou have dist firewall clearance issues and exhaust manifold steering sector issues.

 

Matt, you mentioned the 12 valve so I guess diesel is an option under consideration. Have you thought about say an old Detroit Diesel 4-53 or 4-71?

 

Yes diesel is def an option and i havent done much research on the detroits only looking at the 12 valve because of it being 90% mechanical. But will check them out now thanks!!!

 

the first gen 12 is referred to as a "one wire", but it can be no wire by using a cable shut-off instead of the shut-off solenoid. We aren't supposed to talk of modern engines, but in that case of the 12 swaps, many of these old big trucks can then be used as "much more useful" vintage trucks ....power/torque & mileage.

 

I'm really wanting to do a clean ride/rat rod style like this picture I found on Pinterest.

 

You had better tread carefully, rat rods are not appreciated on this site.

Charlie Stephens

 

The trouble with those Detroits is they are 2 cycle and don't make torque at low RPM. You gotta keep the RPM above 1800 at all times. I drove trucks that had the 238 HP 6-71 and constantly shifting the old 10 speed Roadranger gets old real fast. the short stroke 53 series are weaker than the 71 series.

 

Not to ruffle feathers, But isnt there a hot rod section on this site? If I'm starting with something thats a little too far gone to fully restore why not make it cool just like the hot rod guys do?

 

That is OK but not what you are referring to in your post #24. And that truck does not look traditional!