The one thing I remember about the GMC V-12 when I was much younger and was a parts runner at a heavy duty truck shop is when they set the timing on those engines the backfire was deafening
I only got to see a Seagrave V12 run once only at night, and it was pulling a long 6% grade headed back to station. The fire blowing out of the pipes was simply amazing as was the sound! It was only going about 15 MPH though...
We had a Murphy 852CT power house on an 855 Cedar Rapids Commander rock crusher. That engine sounded like a locomotive when it started. It would start at -20F without external heat by holding that governor till the oil pressure caught up to it. Just an amazing engine.
Oh boy! Not me ducking my head to the right when the camera gets close to that fan, as though the stupid thing could actually get me lol Listening to ALL of these beauties purr is music to my ears, but I must say even as an avid Ford lover, that GMC is hypnotic!
I took photos of a Fully Restored Cab over Single Axle GMC truck in the Toll Road in IN or OH last November I-80 at a rest stop with a V-12 in it. My FAther had a 67 Chevy Tandem axle truck with a V-6 401.. It ran very smooth a bit low on power and liked gas very much .. very low compression ration . It would wind up to about 4,000 RPM's if you really wanted to push it .. a 5 speed tans with a 4 speed auxilary .. You could split a lot of gears and do a lot of shifting.
The Seagrave and the Murphy are real magic. The GMC, I hated working on those things. Gas hogs, no power, hard to work on. They were snuggled into snub nosed trucks with half of the engine buried under the cab with horrible access. But it is nice to see one running again. Cheers
I am just two trips around the sun under three score and only worked on a few of the GMC 702 12 cylinder (twin 351 GMC V6 engines) one was in a ‘62 GMC Crackerbox two more were stationary mounted engines one of which was attached to a water pump another to generator and the last was in a 38 foot wooden Bay built Dead-Rise fishing boat. Personally I found there power/torque output was equally to or exceeded the horsepower of most diesels engines of the day and not that bad to work on except for the front couple of cylinder on the GMC Crackerbox truck. The truck got about 5 miles a gallon loaded which was about average with other engines of the day doing the same work and the old man who owned the the truck, boat, and stationary equipment has told me that the reason he got the GMC Truck with the gas V12 back in 62 that some of the routes he ran there were no filling stations that had diesel fuel for sale. When I first started working on these dinosaurs the old boy had retired from driving except for harvest time and ran a charter boat the rest of the year. The boat he owned he had built in 1968 and he put a freshly rebuilt 702 V12 in it because of the reliability of the one he had in his truck. He said a friend of his had a the duplicate to his boat except it had 8V-71 and both boats used within a few gallons of fuel per day of fishing. One of the things that I was impressed with the GMC 702 V12’s was just how many hours they could run with just minor maintenance/service done to them. On a side note the GMC “COE” model truck’s pretty much were a pain in the butt to work on regardless of what engine was in them the same way the early 70’s thru about 2000 rear wheel drive vans were to work on. Myself I have not worked on one of these monstrosity in over 20 years I still have a sentimental soft spot for them but understand that today they are obsolete curiosities that are fun to put in custom show car/truck builds and on display so people can see and hear engines from the past run for people to see and appreciate history
@@gullreefclub I had the smaller "brother" to the 702... I had a 305 V-6 in an old GMC half ton.... I loved that engine (except at fueling time) ... It ran flaw free all the time and I guarantee you could NEVER overheat that engine.... I went to palomar mountain with a friend and I pulled a larger camp trailer.... We pulled those hills and it never missed a beat.... what a great truck and what a great engine... They are all pretty much in the junk yard now or... in another use.... (cast parts for a ocean going troller) .... Thanks for the memories...
I had a GMC 478M v6 in my boom truck excellent motor. GM tried to make them toroflow diesel but they were not so good . In high school I had a 1/2 ton shortened 1965 GMC with a 305v6 worn out but ran . Detroit also married 871 and 671 into 16v71 etc . Worked on generator sets with them .
Yes the valve / seat assembly can be removed without removing the cylinder head. The Auburn V12 that was later enlarged & built by LaFrance has a similar layout.
You don't want to run it too slow, the oil pressure will drop dangerously low. That is one of the smoothest running V-12 engines I have ever encountered too. I'm curious why it was discontinued.
I have a 1947 ME4 on my sawmill. She has a bad valve in the cylinder head. Otherwise all there. I could use some help locating some parts if possible. Thanks in advance.
AZTrout If you can find out what size the valves are and the length and the diameter of the valve stem you may be able to use a similar valve from a different engine.
@@brucethomas3100 Thanks guys. Found the valves. Rear valve was destroyed. No further damages. Brick shit house. Put it back together last weekend. Good for another 76 years.
The one thing I remember about the GMC V-12 when I was much younger and was a parts runner at a heavy duty truck shop is when they set the timing on those engines the backfire was deafening
As a previous owner of a 1963 Gmc with the 305V6, I always appreciate a twofer for V12. Onward!
I only got to see a Seagrave V12 run once only at night, and it was pulling a long 6% grade headed back to station. The fire blowing out of the pipes was simply amazing as was the sound! It was only going about 15 MPH though...
We had a Murphy 852CT power house on an 855 Cedar Rapids Commander rock crusher. That engine sounded like a locomotive when it started. It would start at -20F without external heat by holding that governor till the oil pressure caught up to it. Just an amazing engine.
OUTSTANDING ! Just need a Hall-Scott !
Oh boy! Not me ducking my head to the right when the camera gets close to that fan, as though the stupid thing could actually get me lol
Listening to ALL of these beauties purr is music to my ears, but I must say even as an avid Ford lover, that GMC is hypnotic!
I took photos of a Fully Restored Cab over Single Axle GMC truck in the Toll Road in IN or OH last November I-80 at a rest stop with a V-12 in it. My FAther had a 67 Chevy Tandem axle truck with a V-6 401.. It ran very smooth a bit low on power and liked gas very much .. very low compression ration . It would wind up to about 4,000 RPM's if you really wanted to push it .. a 5 speed tans with a 4 speed auxilary .. You could split a lot of gears and do a lot of shifting.
The Seagrave and the Murphy are real magic.
The GMC, I hated working on those things. Gas hogs, no power, hard to work on. They were snuggled into snub nosed trucks with half of the engine buried under the cab with horrible access.
But it is nice to see one running again.
Cheers
I am just two trips around the sun under three score and only worked on a few of the GMC 702 12 cylinder (twin 351 GMC V6 engines) one was in a ‘62 GMC Crackerbox two more were stationary mounted engines one of which was attached to a water pump another to generator and the last was in a 38 foot wooden Bay built Dead-Rise fishing boat. Personally I found there power/torque output was equally to or exceeded the horsepower of most diesels engines of the day and not that bad to work on except for the front couple of cylinder on the GMC Crackerbox truck. The truck got about 5 miles a gallon loaded which was about average with other engines of the day doing the same work and the old man who owned the the truck, boat, and stationary equipment has told me that the reason he got the GMC Truck with the gas V12 back in 62 that some of the routes he ran there were no filling stations that had diesel fuel for sale. When I first started working on these dinosaurs the old boy had retired from driving except for harvest time and ran a charter boat the rest of the year. The boat he owned he had built in 1968 and he put a freshly rebuilt 702 V12 in it because of the reliability of the one he had in his truck. He said a friend of his had a the duplicate to his boat except it had 8V-71 and both boats used within a few gallons of fuel per day of fishing. One of the things that I was impressed with the GMC 702 V12’s was just how many hours they could run with just minor maintenance/service done to them. On a side note the GMC “COE” model truck’s pretty much were a pain in the butt to work on regardless of what engine was in them the same way the early 70’s thru about 2000 rear wheel drive vans were to work on. Myself I have not worked on one of these monstrosity in over 20 years I still have a sentimental soft spot for them but understand that today they are obsolete curiosities that are fun to put in custom show car/truck builds and on display so people can see and hear engines from the past run for people to see and appreciate history
@@gullreefclub I had the smaller "brother" to the 702... I had a 305 V-6 in an old GMC half ton.... I loved that engine (except at fueling time) ... It ran flaw free all the time and I guarantee you could NEVER overheat that engine.... I went to palomar mountain with a friend and I pulled a larger camp trailer.... We pulled those hills and it never missed a beat.... what a great truck and what a great engine... They are all pretty much in the junk yard now or... in another use.... (cast parts for a ocean going troller) .... Thanks for the memories...
I had a GMC 478M v6 in my boom truck excellent motor.
GM tried to make them toroflow diesel but they were not so good .
In high school I had a 1/2 ton shortened 1965 GMC with a 305v6 worn out but ran .
Detroit also married 871 and 671 into 16v71 etc .
Worked on generator sets with them .
Cool. We have stationary engines in the UK but not that big!
I have a few of your engines, UK versions. Ruston Hornsby, have 2.
Wow, what an awesome engine
They are all awesome and run flawlessly,but the GMC wins my heart
I have a 6 Cylinder M-22 I think it is Murphy Diesel in my crane.. 1103 Cubic Inches runs 1,200 RPMS wide open .
Nice collection. Thanks for sharing
The Seagrave had an odd valve layout, halfway between an OHV and a flathead.
Yes the valve / seat assembly can be removed without removing the cylinder head. The Auburn V12 that was later enlarged & built by LaFrance has a similar layout.
Sweet engine , murphy
Sounds so sweet. Immediately makes me think of compression release & pony motor.
What? I'm giving my age away??
You don't want to run it too slow, the oil pressure will drop dangerously low. That is one of the smoothest running V-12 engines I have ever encountered too. I'm curious why it was discontinued.
My four cylinder Perkins Diesel in a Massey Ferguson 230 can idle down to 250 RPMs
GMC V-12 is actually 701.59cu/in
I have a 1947 ME4 on my sawmill. She has a bad valve in the cylinder head. Otherwise all there. I could use some help locating some parts if possible. Thanks in advance.
This not my engine. Find a machinist who can make you one
AZTrout
If you can find out what size the valves are and the length and the diameter of the valve stem you may be able to use a similar valve from a different engine.
@@brucethomas3100 Thanks guys. Found the valves. Rear valve was destroyed. No further damages. Brick shit house. Put it back together last weekend. Good for another 76 years.
I didn't know Murphy made a water cooled diesel, only ones I've seen are air cooled.
Welp, heres proof. Thanks for watching and comment
Diesel? Spark plugs?
Three different engines being talked about. 1 diesel and 2 gas engines
Esse é um motor a gasolina, não a diesel.
¿Cómo sabes que no es diésel?
como você acha que isso não é diesel
@@boa721well it have spark plugs
@@ismaelduarte888there are 3 engines in this video.. 1st one is a diesel, other 2 are gas. Dont be an ass
The output of those GMC V12s seems pretty disappointing given the size of them.
Their from the 30s... they had massive torque, what do you expect? Dragster hp??
@@boa721 Actually they are from the 60's but remember they are truck engines built for big torque / long life at low RPM & peak HP is at only 2400RPM
They were horrible gas hogs.
Sounds like the GMC has some fouled plugs .. check the points and dwell
That was interesting where do you find all these motors what a great hobby. Some people might say why i would say why not