A2 motorpool rebuild

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rickf
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Re: A2 motorpool rebuild

Unread post by rickf » March 21st, 2019, 9:23 pm

Those same bolts that hold the exhaust manifold also hold the intake manifold so if they were loose you are sure to have an intake manifold leak which will cause it to run lean and cause acceleration back fires and it can burn a valve if you push it. If this is a later A2 get yourself an exhaust gasket and intake manifold gasket set.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Husker
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Re: A2 motorpool rebuild

Unread post by Husker » March 21st, 2019, 10:12 pm

It was the 2 bolts that bolt the exhaust pipe to exhaust mainifold that where loose
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

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Re: A2 motorpool rebuild

Unread post by rickf » March 22nd, 2019, 9:55 am

Ok, Keep in mind they are only supposed to be tightened to something like 18 ft/lbs. It is pretty light. Otherwise the pipe will get deformed. I just went back and saw you reference to the oil pressure, 20-25lbs. is not really that low depending on what oil is being used and how hot the engine is. Does it come up if you rev it up? And are you sure the gauge you are using is good? 10 lbs. per thousand rpm is considered the universal standard for oil pressure that is needed. The 151 will generally run higher than that but you don't want too much pressure or you will blow the filter seal out.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Husker
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Re: A2 motorpool rebuild

Unread post by Husker » March 22nd, 2019, 10:41 am

It climbs when reving I have the idle set as low as possible so it should be ok the gauge is like a 40 dollar set of amazon brand new first use


I’m going to set the valves tonight and hook up the timing light again to see if I can get anything before I start messing with the idle mixture screw
My fear is I did something wrong assembling the engine during the rebuild and since this is the first time testing it I’m only just now noticing the issue

If it’s running to lean it should t be the gas system the lines are brand new pump is new civilian one I’m using 2 inline filters and the one next to the carb is always full.
The only obvious one is the carb to fuel line fitting isn’t original so that could be a choke point I have the original now got it yesterday I’ll install it as well
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

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rickf
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Re: A2 motorpool rebuild

Unread post by rickf » March 22nd, 2019, 4:59 pm

Running lean would be a carb adjustment. Or a vacuum leak.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Husker
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Re: A2 motorpool rebuild

Unread post by Husker » March 23rd, 2019, 7:34 pm

Did the carb tuning with the tach dwell and it helped a lot but still backfired
Then pulled my plugs and did another compression test got 95 in all cylinders
All plugs were black and the gap was to small. Cleaned and regaped them it ran a lot better. Tomorrow I’ll do the carb tune again and and see if it fixes my backfiring
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

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rickf
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Re: A2 motorpool rebuild

Unread post by rickf » March 23rd, 2019, 8:51 pm

That compression is a little low, Not bad and even across so I might suspect a valve adjustment. You say it was rebuilt? Are you sure the cam was put in on the right tooth?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Husker
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Re: A2 motorpool rebuild

Unread post by Husker » March 24th, 2019, 12:23 am

That’s what I am fearing
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

Husker
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Re: A2 motorpool rebuild

Unread post by Husker » March 24th, 2019, 12:31 pm

Is it possible I’m using the wrong plugs? Autolite AER3S
P/N 8668752

I don’t know if it would do anything
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

Hambone
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Re: A2 motorpool rebuild

Unread post by Hambone » March 24th, 2019, 12:54 pm

Husker wrote:Is it possible I’m using the wrong plugs? Autolite AER3S
P/N 8668752

I don’t know if it would do anything
Are those for the M715? Seems they had a longer reach?

Husker
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Re: A2 motorpool rebuild

Unread post by Husker » March 24th, 2019, 2:24 pm

Turns out my I only have 2 matching plugs..... 3 autolites only one is the model above the other 2 are aer3sa
Last one is a crown somthing plug

They all look the same and fit fine in the mutt and run ok at idle

Did the valves again not sure if I did the valves while running right but it idles so much better then it did
I did the carb adjustment and it’s set well but when accelerating around 2k rpm it starts to backfire from the carb

I looked at the timing again and it’s not advancing when accelerating so I’m gonna open the distributor and look at the advance weights
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

Hambone
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Re: A2 motorpool rebuild

Unread post by Hambone » March 24th, 2019, 3:02 pm

I've had a coil that would run fine on idle, backfire on acceleration.

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Re: A2 motorpool rebuild

Unread post by rickf » March 24th, 2019, 5:12 pm

Wait a minute! Didn't you say the distributor took a hit in the fall? I asked if you checked it out to see if the shaft got bent. Have you had the distributor out and given it a thorough going over?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Husker
Master Sergeant
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Posts: 374
Joined: August 26th, 2016, 1:52 pm
Location: Fairfax Virginia

Re: A2 motorpool rebuild

Unread post by Husker » March 24th, 2019, 5:19 pm

The advance weights were rusted in the closed position they are now loose and it runs great!
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

Husker
Master Sergeant
Master Sergeant
Posts: 374
Joined: August 26th, 2016, 1:52 pm
Location: Fairfax Virginia

Re: A2 motorpool rebuild

Unread post by Husker » March 24th, 2019, 5:21 pm

Yea I pulled the whole distributor out before reinstall but never looked under the module at the weights it’s spun freely
US Army Fort Belvoir

19XX M35 something. Sold......
1972 M151A2
1967 M416
On the hunt for an M1031

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