I can't remember if these engines are the same physical size or not. Does anyone know? I'm wondering if I will have to modify the cross member when I am trying to drop the Chevy 261 in. I am using a later model (1948 - 1952/53) bellhousing with a SM420. It originally had the GMC 228 in the frame.
Last edited by Peggy M; 07/30/20249:02 PM. Reason: added full truck year to help with searches ;)
Daniel, IIRC - the length on the GMC 6 is about 3" longer than the Chevy 261. This previous conversation on comparing Chevy 261 and GMC 270 seems to confirm that. The GMC 228 shares the same external dimension as the 270 as far as I know. Others will be along to add further details soon I think.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
You don't have to make any permanent mods to the frame. Bolt a small piece of 1/4" steel plate to the front crossmember and drill it for the Chevy motor mount bolts. Quick. simple, and reversible if you happen to run across a GMC engine sometime in the future. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Once you get the Chevy engine in place you should consider a fan shroud. The Chevy fan will be 2-3 inches further away from the radiator than the GMC fan was. A second option would be a "spacer" for the fan and longer bolts.
Last edited by Bill Hanlon; 07/30/20248:19 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Thanks everyone for the input, I was afraid the dimensions were slightly different. I would really like to find a nice 228 or 248 that would drop in so I like the idea that Jerry has. The 228/248/256/270 would all drop in, right?
Jerry, could you elaborate more on the plate? I have plenty of material I'm just having a hard time visualizing how that would look.
Bill, I don't currently have the correct radiator for the truck. I have a big truck radiator that came with my 1940 GMC military truck that I am using the front clip off of. It is 3 or so inches thick vs whatever the original radiator was and it also includes a fan shroud. HOPEFULLY it will fit if I use the 261. If I end up going the 228 etc route, it may not and I may need to get an aftermarket radiator that is thinner. I could also always go the electric fan route but I would prefer to keep a more original look.
Daniel, Check out the Other Online Sources (OOS) forum. There are currently 3 different sale ads for GMC engines that folks have posted. 228 on up to 302's in the mix. You might also check out this ad from 1946chevypickup . He is offering to part out a 1958 GMC that looks to have an engine still in the bay. His location is much closer to yours. When I get a chance, I will poke around the web for something closer to your locale and will lets you know.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
Jerry, could you elaborate more on the plate? I have plenty of material I'm just having a hard time visualizing how that would look.
It's simply a piece of flat steel plate, about 1/4" thick, that's wide enough to be bolted to the original front motor mount holes and extend back far enough for the Chevy motor mount to rest on. Then bolt the Chevy mount to the extension plate. Maybe you could put a couple of flat bar angle braces down to the lip of the crossmember to keep the plate from sagging under the weight of the engine. "Shade Tree Mechanics 101!" Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
If south central Tennessee is within your travel radius I've got a complete, rebuildable GMC 228, fan to bellhousing, that's looking for a home. I scavenge up every 261 I can find. PM me! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
If this rig is going to get used as a truck I would advise against using only an electric fan. They don't pull enough air for truck duty regardless of what the catalogue says. I have one in addition to a 6-blade fan as shown on your military rig and I still see 230 deg.on a 95 degree day pulling a 7% grade in 3rd gear, even with a 4" radiator from a 2-ton.
1951 3800 1-ton "Earning its keep from the get-go" In the DITY Gallery 1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.
I figure I'll only be loafing around town. The furthest I plan on driving it is about an hour from the house. But that's good to know. The 5 blade fan I have in the picture is currently at the powdercoater as I planned on using it.
Last edited by Peggy M; 08/02/202412:06 AM. Reason: Remove quote - not necessary ;)
