A2 Engine in a A1

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Vanguard6
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A2 Engine in a A1

Post by Vanguard6 » Mon Sep 15, 2014 6:27 pm

What are the challenges in putting a M151A2 motor in a M151A1. Thanks
Vanguard6
USMC Vet
MVPA 11608
1952 USMC M38A1
1966 M103A3 w/bomb hoist
1967 USMC M151A1
1965 M416
1969 M416B1
1968 M101A1
1978 S280 shelter and M720 Transporting Dolly
1992 M101A2
T-3 Bantam Civilian Trailer
Chemical Corps Hand Cart


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W. Winget
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Re: A2 Engine in a A1

Post by W. Winget » Tue Sep 16, 2014 5:52 am

Your wiring harness is set up for a divorced regulator on the A1, you'll have to either splice two wires, or replace the harness for the A2 altenator to work VS the A1 Generator, or keep the Generator and regulator on you vehicle and merely swap engines.

The fuel tank should be changed from the A1 to the A2 style, as the in tank fuel pump is now redundant, and the A2 used a fuel pump on the engine. (you can keep all the A1 components and mount them on the engine if wanted though)

The A1 had vaccum wipers, you'll need to replace the windshield with an A2 electric setup (and add a wire to your harness) or come up with a vacuum port to drive your wipers (possibly use an AMC car fuel/vacuum pump instead of the fuel pump only on the A2) (again swapping the parts from the old A1 engine will solve this)

The A2 fuel pump pushes fuel past the filter in the carburetor keeping the bowl full, while pushing overflow to the A2 tank, if you do not have the overflow line to the tank (return line) then you can end up flooding the carb. (seen this on some systems, not all) (again if your just changing engine cores, keep all the old components and forget about it)

Engine/transmission mounting and connections/linkages are the same.

Starter is the same (seen a very early one with lever engagement though, but I doubt you have one of those Hens teeth.)

Thats from memory.
V/R W Winget
Looking for 1918 Standard B 'Liberty' truck parts

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Re: A2 Engine in a A1

Post by SV2IPW » Tue Sep 16, 2014 7:26 am

You must add a oil pressure switch in front of the oil filter ...this switch is for the emergency cut off of the electrical fuel pump of the M151A1.

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W. Winget
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Re: A2 Engine in a A1

Post by W. Winget » Tue Sep 16, 2014 9:09 am

I'm fairly sure the oil pressure kill switch was removed from the A2 engines. something about not wanting the engine to save itself VS. the driver and riders during a critical moment in getting away from a sticky situation.
If not, a bypass to the wiring harness should work.
A2 should only have the pressure switch that does not kill the engine I think.
V/R W. Winget

One simple question, What are you trying to do? put in a long block (A2) where the old engine has died, or swap out the whole system without the existing A1 parts? That should drive "what" mods have to be made.
WAW

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Austringer
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Re: A2 Engine in a A1

Post by Austringer » Tue Sep 16, 2014 9:42 am

I just did they s swap with a crate A2 engine power pack that I needed to put in an A1 that had some major engine issues.

What I had to do.

1. Remove a2 fuel pump and puta1 vac pump in its place.
2. Swap the correct engine mounts.
3. Swap the crank and water pump pullies.
4. Redo the correct vac and vent tubing system.
5. Swap the correct bell housing.
6. Remove alternator and put 25 amp gen
7. Swap top radiator mount/engine lift bracket.
8. Add the last w pressure cut off switch and vent line.

I think that is all. Not too hard, just get most of the parts from your a1 engine.
Jason Green
Atlanta, Ga

STILL NOT associated with the Georgia MVPA 15 years and counting as long as that one guy is president of the club....

1963 Willys M151 (under resto)
1969 M706E1
1983 M106A2

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Re: A2 Engine in a A1

Post by Rickf » Wed Sep 17, 2014 5:08 am

I would like to add a couple things here. You can keep your old tank, the A2 pump will pull through the ball valves of the A1 electric with no resistance if you decide to go with the A2 pump. Then you can always go back if you want. The return line on the carb was only there to keep fuel flowing to prevent vapor lock in extremely hot environments. The motor I built for the cross country convoy had no issues at all in the deserts of the western US without that line hooked up. The A2 fuel pump puts out 3-5 lbs. of pressure and that is all, it will not flood out the carb if the carb is set up right.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
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Vanguard6
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Re: A2 Engine in a A1

Post by Vanguard6 » Wed Sep 17, 2014 6:15 pm

Thanks to all who have added to this post they were very helpful.
Vanguard6
USMC Vet
MVPA 11608
1952 USMC M38A1
1966 M103A3 w/bomb hoist
1967 USMC M151A1
1965 M416
1969 M416B1
1968 M101A1
1978 S280 shelter and M720 Transporting Dolly
1992 M101A2
T-3 Bantam Civilian Trailer
Chemical Corps Hand Cart


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