The Stovebolt Site Forums The Shop Area Engine Shop GMC 228/248 etc question

Long story short is I have a '49 GMC and have been looking into keeping the inline 6 and running it with a couple hot rod parts but am looking for some more information on it. Do the full pressure modifications work for the GMC's too? Any chance intakes/split exhaust and/or valve covers from 216 or 235's are interchangable? Do the notes found on inliners and a couple other places for T5 swaps also pertain to the GMC's. Thanks for any information you can give me. It's much appreciated. Thanks

Speed parts are available for the gmc engines, but they cost more than chebby parts. All the T5 stuff you read for the chebby crosses right over to gmc... only difference is gmc used a pilot bearing and chebby used a pilot bushing. If you are planning to hop up a gmc 6... a 270 or 302 is a better place to start. Gmc engines ran full oil pressure long before chebby motors. Gmc blocks were cast with a higher nickle content so they wear better. Hope this helps

Yes, the GMC is already full pressure, with insert bearings in both the rods and mains. There is a full oil filter flow modification for the block on the www.oldgmctrucks.com site. I wouldn't bother with it unless you are doing a complete hot tank and rebuild on the block.

The valve covers are not interchangable. The GMC engine is about 1.5" longer than the Chevy. You can get Fenton split manifolds for the exhaust, and there are some nice intakes available for the GMC that don't fit the Chevy, like the Howard Log manifold.

The only things that really interchange at all between the GMC and Chevy engines are the distributors, bellhousings, and some types of fuel pumps.

The GMC engines were the hot rodders engine of choice over the 235. California Bill and others built some pretty radical ones.

I've got a 302 out of a '55 dump truck that's going into my '50 half ton. Its pretty stout.

anybody running a 228/248/270, etc;? wonder what kind of driving you're doing? what kind of mileage u're getting? hows the reliablity? I enjy something different, but would really like to get this thing running driving again. Looks like I might be doing a 235 swap for now and saving the 228 til I can track down a dual intake and some spped parts

I had a 59 gmc 1/2 ton with a 270, 3 on the tree and 3.07 rear gear. I got about 16 mpg till they reformulated the California gas back in the 90s. Then it dropped to about 14 mpg. It was about that time I put a 4bbl intake onand a holley 390 cfm carb. Gas mileage stayed the same but that 270 was really starting to wake up. I didn't have any other mods to that engine like cam or split exhaust or HEI... just a stock Jimmy motor with an aftermarket 4BBl intake. That truck was mostly driven on the highway at about 70mph. If taking the backroads I imagine mileage may have been in the 19 mpg range, but let's face it... a 1959 gmc is not the most aerodynamic vehicle on the road.

My current project is a 1940 gmc with the original 228. That engine will be coming out soon to make room for a heated up 302. I don't think the 1940 driveline will hold up to well to 225 HP, so I am swapping out everything behind the engine.

Gearing and driving speed have a lot to do with fuel economy. Carb choice can affect economy as well. If you want to build a rocket well you can't get off the ground without burning some fuel.

have problem with 228 dizzy oil pump drivr. anybody up

Why did you drag up a 12 year post to ask a question not even related to the original post? Please start your own thread.