47-59 GMC Engines - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**cff** · 03-10-2021, 10:22 PM

I have a 51 GMC half ton pickup with a 228 cu in engine. I would like to put in a 270 or 302 GMC engine. Will either of these two engines bolt right in without any mods?

Bimus · 03-10-2021, 10:55 PM

I have a GMC 270 and a military 302 out where I can get pictures I know the exhaust is larger .

**mr48chev** · 03-11-2021, 01:12 AM

Outside dimensions are the same. just as any change there may be some linkage issues on the carb but none that you can't get past.

No matter what size those GMC engines are they are a bit spendy to build.

Bimus · 03-11-2021, 12:22 PM

Both engines are military the 270 is out of a 42 and the 302 [Green ] from a mid 50's it has motor mounts at the front on the sides and I don't know if the military 302 where drilled for a pilot bearing in the end of the crank. trouble with pictures I will try later today

Bimus · 03-11-2021, 09:31 PM

still can't post pictures because security token is missing ?

**cff** · 03-11-2021, 11:01 PM

As long as they are physically the same size and bolt up the same, I would be happy. I don't have a 270 or 302 but I was gonna try to find one or the other. I do have a 292 but I don't think it will bolt right in will it? Anyone know what I have to do to make the 292 bolt in easily? Will the bellhousing bolt up? Thanks, Ron

**mr48chev** · 03-11-2021, 11:05 PM

Upload one at a time. meaning choose one file and upload it, then choose the next file and upload it and repeat until you get them uploaded. I have the same issue and either my computer or my network or both is too slow and it times out if I try to do more than one or two. After you get them uploaded they will post.

You may also have an issue if you are trying to post very high resolution photos. I often shoot at 16 meg so my sunset or mountain photos can be blown up to poster size and forget that when I run out back to take a shot of something for show and tell on here.

mick53 · 03-11-2021, 11:06 PM

I think the 292 bell housing is the same as the SBC. Keep in mind the 292 has staggered engine mounts. I don't know GMC engines but the 292 is about 3" longer than the 235 I think.

Bimus · 03-12-2021, 01:34 AM

Thank you one at a time worked

Bimus · 03-12-2021, 01:43 AM

I have few 235 in pickups and some in the shed and can measure and fit parts if needed '

MtGMC · 03-12-2021, 02:52 PM

Civilian GMC 248/270/302 engines all fit the same bell housing and the “horseshoe” front motor mount and will bolt right in. Military versions of the 270/302 have very different front mounts.
The 270 is not too hard to find, but it will definitely cost more than a SBC rebuild. However, it will definitely be different from the crowd. There are performance upgrades available.

mick53 · 03-12-2021, 05:22 PM

I have a junk GMC engine in the pile with a 3 speed I have been trying to give away for years. Nobody seems to want it. I think it must not be one people want.

**mr48chev** · 03-12-2021, 11:31 PM

Quote:

Originally Posted by cff

As long as they are physically the same size and bolt up the same, I would be happy. I don't have a 270 or 302 but I was gonna try to find one or the other. I do have a 292 but I don't think it will bolt right in will it? Anyone know what I have to do to make the 292 bolt in easily? Will the bellhousing bolt up? Thanks, Ron

You need a cast iron V8 bellhousing from a 55 to early 70's truck. You also need a 168 tooth V8 flywheel

The water pump gets real close to the radiator on a Chevy but You might have enough room on the GMC As long as your radiator has the GMC mounting bracket positions and not Chevy.

The Mount pads are staggered side to side on a 292.
Passenger side mount is in front of the fuel pump on a 292

Passenger side mount is behind the fuel pump on 194/250

I bought what was probably the last pair of 292 mounts that Chassis engineering Inc sold before they sold out to Heidts. They didn't have the deal made with Heidts when I bought mine and they were selling pieces for pennies on the dollar.

I went out and dug my mounts out of the garage and took some photos. They wouldn't be that hard to duplicate if a person was a good fabricator.

I'll have to make the pieces that weld to the frame to use the Ford Flathead style biscuit mounts with when I get to that point.

mick53 · 03-13-2021, 10:38 AM

Here are mine.

**mr48chev** · 03-13-2021, 11:02 PM

Thanks for posting those Mick, I've got them saved for my reference file.

**cff** · 03-14-2021, 09:14 PM

Yeah Thanks. Good info

03-10-2021, 10:22 PM	#1
cff Active Member Join Date: Feb 2014 Location: langley BC Posts: 161	GMC Engines I have a 51 GMC half ton pickup with a 228 cu in engine. I would like to put in a 270 or 302 GMC engine. Will either of these two engines bolt right in without any mods?

03-10-2021, 10:55 PM	#2
Bimus Registered User Join Date: Dec 2018 Location: Farmington NM Posts: 112	Re: GMC Engines I have a GMC 270 and a military 302 out where I can get pictures I know the exhaust is larger .

03-11-2021, 01:12 AM	#3
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,718	Re: GMC Engines Outside dimensions are the same. just as any change there may be some linkage issues on the carb but none that you can't get past. No matter what size those GMC engines are they are a bit spendy to build. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

03-11-2021, 12:22 PM	#4
Bimus Registered User Join Date: Dec 2018 Location: Farmington NM Posts: 112	Re: GMC Engines Both engines are military the 270 is out of a 42 and the 302 [Green ] from a mid 50's it has motor mounts at the front on the sides and I don't know if the military 302 where drilled for a pilot bearing in the end of the crank. trouble with pictures I will try later today

03-11-2021, 09:31 PM	#5
Bimus Registered User Join Date: Dec 2018 Location: Farmington NM Posts: 112	Re: GMC Engines still can't post pictures because security token is missing ?

03-11-2021, 11:01 PM	#6
cff Active Member Join Date: Feb 2014 Location: langley BC Posts: 161	Re: GMC Engines As long as they are physically the same size and bolt up the same, I would be happy. I don't have a 270 or 302 but I was gonna try to find one or the other. I do have a 292 but I don't think it will bolt right in will it? Anyone know what I have to do to make the 292 bolt in easily? Will the bellhousing bolt up? Thanks, Ron

03-11-2021, 11:05 PM	#7
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,718	Re: GMC Engines Upload one at a time. meaning choose one file and upload it, then choose the next file and upload it and repeat until you get them uploaded. I have the same issue and either my computer or my network or both is too slow and it times out if I try to do more than one or two. After you get them uploaded they will post. You may also have an issue if you are trying to post very high resolution photos. I often shoot at 16 meg so my sunset or mountain photos can be blown up to poster size and forget that when I run out back to take a shot of something for show and tell on here. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

03-11-2021, 11:06 PM	#8
mick53 Registered User Join Date: Oct 2018 Location: Warsaw IN Posts: 897	Re: GMC Engines I think the 292 bell housing is the same as the SBC. Keep in mind the 292 has staggered engine mounts. I don't know GMC engines but the 292 is about 3" longer than the 235 I think.

03-12-2021, 01:34 AM	#9
Bimus Registered User Join Date: Dec 2018 Location: Farmington NM Posts: 112	Re: GMC Engines Thank you one at a time worked Attached Images Last edited by Rickysnickers; 03-12-2021 at 09:39 AM. Reason: flipped pics

03-12-2021, 01:43 AM	#10
Bimus Registered User Join Date: Dec 2018 Location: Farmington NM Posts: 112	Re: GMC Engines I have few 235 in pickups and some in the shed and can measure and fit parts if needed ' Attached Images Last edited by Rickysnickers; 03-12-2021 at 09:38 AM. Reason: flipped pics

03-12-2021, 02:52 PM	#11
MtGMC Registered User Join Date: Apr 2017 Location: Montana City, MT Posts: 10	Re: GMC Engines Civilian GMC 248/270/302 engines all fit the same bell housing and the “horseshoe” front motor mount and will bolt right in. Military versions of the 270/302 have very different front mounts. The 270 is not too hard to find, but it will definitely cost more than a SBC rebuild. However, it will definitely be different from the crowd. There are performance upgrades available.

03-12-2021, 05:22 PM	#12
mick53 Registered User Join Date: Oct 2018 Location: Warsaw IN Posts: 897	Re: GMC Engines I have a junk GMC engine in the pile with a 3 speed I have been trying to give away for years. Nobody seems to want it. I think it must not be one people want.

03-13-2021, 10:38 AM	#14
mick53 Registered User Join Date: Oct 2018 Location: Warsaw IN Posts: 897	Re: GMC Engines Here are mine. Attached Images

03-13-2021, 11:02 PM	#15
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,718	Re: GMC Engines Thanks for posting those Mick, I've got them saved for my reference file. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

03-14-2021, 09:14 PM	#16
cff Active Member Join Date: Feb 2014 Location: langley BC Posts: 161	Re: GMC Engines Yeah Thanks. Good info



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