i'm lookin to be skooled . can anyone tell me how to identify the big 302 GMC inline 6s from the rest? what applications and years did they come in and are there other sizes of the same motor? i want to know all that the HAMB can tell me about these motors. i have a friend lookin to build one for a Bonneville car. plus the boys and i have a 50 Chevy truck we're building as a club project that we intend to use to haul all kinds of stuff, including a car trailer from time to time. i have a hunch that a mildly built Jimmy 6 with dual carbs and slit exhaust would be the cats *** for our period shop truck. maybe run it through a modern OD automatic trans or a heavy duty 5 speed manual. anyway. any and all info is appreciated. thanks boys and girls...
Have a look on OLDGMCTRUCKS.COM they have a lot of info on there and also have a message board. They have always been helpful when i have asked questions about my 1952 GMC 228 straight 6.
they DO have alot of info..in fact that's where i have been since i saw your post...BUT, in the technical stuff section, which lists the engine specs (which i am ***uming is most important for you), the links to the 302 are broken. i was looking for an email addy for the web creator, or a phone, something...but couldn't find...sorry, all the other sites i looked at were ****...
http://www.oldgmctrucks.com/Photos/GMC_Numbers.htm try that link if that doesn't work try posting on their me***ge board they really know there stuff but be patient there turn about on posts isn't as quick as this board. Daisyduke
Hey, go check out Tom Langdon, in Utica, MI, @ http://www.stoveboltengineco.com/index1.htm He has a stroked 302 that's pushing around 320" cubes. He is a retired GM driveline engineer, and an old drag racer ( there is a picture of his "Holeshot 6" g***er in the book "G***er Wars"). All of the GMC's, from 228" to 302", had the same external block dimensions, just different bore & stroke combos, plus some differences in the heads. Early small displacement versions used knuckle type pistions with heads to match. Later 302"s used flat or slightly dished pistons with very little combustion area in the head. Look behind the distributor on the p***enger side, there is a small machined pad with the engine code stamped in it; the first three digits are the displacement: 228, 236, 248, 256, 270, 302. There is a rare early '50's 270H, with a nearly hemi shaped combustion chamber and large ports, but I've never seen one. The best head would be from a 302" ('52 - '59); the only blocks worth building for performance are the 270 & 302. Not that the smaller ones are ****py; it would just be cheaper to build a 235" or 261" Chevy. Look on the Inliners site for lists of engine code #'s, they will help in I.D.ing an engine. BTW, about 50% of the 302" production went into military vehicles like 2 1/2 ton 6x6's. This is part of why GMC's got so popular right after WWII, there were surplus 270's to be had for cheap, and were a snug fit to replace a tired 216". Give the Jimmy an overbore up to 292" cubes, and most of the flatheads couldn't match them for displacement, or torque! Now, Get Inline! *****6
I was leaning toward an inline 6 but I think ****o wants to go with a small block. Maybe a 283 or 327 with a manual ******.I was thinking maybe a 2 or 3 carb set up with rams horn manifolds. I am just happy to have a project to work on. Maybe a Nailhead would look nice between the frame rails of that old truck. Did ****o give you the details of my ideas for the front end? chad
Daisy is right OldGMCTrucks.com is the place for information about big Jimmy motors. Rob English is the expert over there. If you join the forum and post your question under the technical topic you'll get a good answer. I want to say that a 302 will have two parallel bars cast in the block, but I can't claim to actually know.
Too late. We have one in the modified, two spares in my nephews garage and I just found another in a shed a mile from home that is a complete mint runner and cost me $20. Then I have this sitting in the shed waiting to go on one of them.
Sorry, all the black ones are spoken for. GMC's. I have a mate that lives locally with a 6x6 GMC truck. Another local guy is building a modified with one. Another friend is fitting one to a '38 Chev coupe. Another guy is talking of fitting one to his '54 Chev custom. Then last wekend we went to a car show with the modified got talking to a couple more rodders that were building cars using a GMC motor. People are starting to wake up to them.
Hey there Alfster, I'm the one fitting the 270 to the 54 custom. Been searching Trademe looking for a 371 for my one too. looks like we need to talk
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