Getting fustrated with engine

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Austringer
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Getting fustrated with engine

Post by Austringer » Sun Dec 18, 2016 8:17 pm

Just rebuilt the carb and set the accelator pump at about .008 mils when sitting at high idle (choked). When starting from a dead stop, the engine just about dies on me unless I back off on the gas and short of nurse it past this massive dead spot. Once moving, no issue.

My compression is around 125-130 on all 4 cylinders and this is with choke and throttle plates wide open, engine turning over 4-5 times.

Time is set dead on mark and i get a rough idle unless I advance it about another 2-3 degrees, was worse before carb rebuild, next step is to take an new carb, swap out the accelerator pump and economizer assembly (the little rubber things) with the ones I put in this carb (for the new crappy gas situation) and try again. I set the idle at 625 and timed it at this speed. I'm also only getting about 14-15" of hg at idle off the special bolt for vacuum pressure. When 1500 plus rpm, getting a nice 18-19" hg.

Going to do a leak down test tomorrow to see how the rings and valves are. What should I expect as far as a percentage leak? Also going to change out the points to see if that makes a difference as well as set them to spec.

Other thing that is bothering me, getting a little bit more oil than I like in #3, (rear driver side). Spoke with Robert W and he said he has had the same experience.

Any suggestions on this would be most appreciated and this rough idle and flat spot is about to drive me up a wall and is making this vehicle not as fun to drive......
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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Austringer
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Re: Getting fustrated with engine

Post by Austringer » Sun Dec 18, 2016 8:19 pm

Thinking of pulling off the heads as well to check the cylinders, the engine was gone through 2-3 years ago and NOS cylinders put in, but I want to check for condition to be 100% sure, didn't see any silver dust in the engine oil when I changed it out.

I'm about ready to put new piston rings in (if the walls look good) and while I'm in there, check the rod bearings...

as you can tell, i'm a bit frustrated.
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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Bill H.
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Re: Getting fustrated with engine

Post by Bill H. » Mon Dec 19, 2016 5:05 am

Jason, where is your timing? Albeit your vacuum is there I'd suspect timing or electrical such as condenser breaking down.
Bill H.

"Each shall seek his own kind, in other words, a bird may love a fish but where would they build a home together?" Tevye, Fiddler on the Roof

1952 Dunbar Kapple M100
1953 Willys M38A1
1962 AMC M422A1
1965 Stevens M416B1 X 2
1967 Kaiser M715

2 Timothy 3:1-5

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Re: Getting fustrated with engine

Post by mspeters » Tue Dec 20, 2016 6:09 pm

in addition to isolating the ignition parts, including a coil swap, check the intake manifold for corroded through freeze plugs between exhaust and intake zones. You can inspect them with the carb off, or remove both exhaust heater pipes and shoot some carb cleaner through the exhaust section when it's running. Mine had 1/16" hole; the DPO could not find, they swapped to a Falcon carb, then gave up and pulled the whole engine. A tip-off could be needing full/max rich on the idle mix screw to obtain a stable idle. I can't get more than 16 inches vacuum at low idle.

Is the PCV valve replaced or clean ?

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Re: Getting fustrated with engine

Post by Austringer » Tue Jan 03, 2017 8:42 pm

An update on what I've done over the last few days, at least since my last post.

I pulled the cylinder heads off to check the cylinder walls and they look great, the guy told me they were new and I believe him.

I thoroughly cleaned the piston tops as they had some carbon build up, and did the same thing with the valves and combustion chamber on the heads.

Installed a complete new exhaust system from headers to the exhaust tip

Installed NOS carb with new accelerator pump and economizer valve thingy.

Pulled all the spark plugs and put them through the bead blaster (using crushed glass) to clean them up, set the gap to .030.

I pulled the distributor and installed a M151 electronic ign kit that I had extra since the lobes vs the flat spot are the same for the M151 and the Mite.\

Put everything back together cranked it up, set idle to ~650, confirmed timing was on the mark (~4 BTDC)

SAME darn PROBLEMS........

Still only getting 15 inhg of vacuum on the vacuum gauge

When I try to give it some throttle... it wants to die as the vacuum goes to pretty much zero and I have to back off on the throttle until it catches itself, gets some vacuum and then I can tease it into accelerating.


After this disappointment, I pulled the plugs again and conducted a leak down test on each cylinder at TDC, and the average for each cylinder was around 25% which is well in the green on the testing kits I have....

After doing this, well during, I remembered the PVC valve and the comment made earlier about making sure it was clean etc.

I removed the covers from the top of the engine to expose the pvc valve, then installed everything back minus the cover and left the little heater pipes off to test something that was mentioned earlier..

With the PVC valve removed, I started the engine and put my finger over the brass fitting to cut off any air getting in that way. With my finger on the brass fitting, still 15 PSI. I then reconnected the line to the pvc valve and sprayed starter fluid around the carb gaskets.. no effect... then around the intake manifold to cylinder head gaskets... no change.... then into the header area where the little pipes go in... no change.

I'm pretty much at my wits end with this thing and trying to figure out what the hell is wrong with the vacuum pressure and why it basically dies when I try to even slowly accelerate it. something is killing the ability to create a vacuum and I can't figure out what the hell is causing it.

Please help...

Thanks
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: Getting fustrated with engine

Post by Babadave » Thu Jan 05, 2017 6:54 am

I think mspeters may have already hit the nail on the head with your problem. manifold vacuum leak.
man.jpeg
man.jpeg (97.4 KiB) Viewed 3876 times
My engine actually ran with this manifold installed. :?:

Pull yours and check it VERY carefully ? Sometimes just spraying starter fluid won't locate the problem. Especially if the leak is between the heat riser plenum, and the manifold plenum.

Good luck !
"We've been looking for the enemy for some time now. We've finally found him. We're surrounded. That simplifies things."
Lewis Burwell "Chesty" Puller

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Austringer
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Re: Getting fustrated with engine

Post by Austringer » Thu Jan 05, 2017 7:10 am

Got it fixed last night, I did everything mentioned by the previous poster regarding the PVC valve, heat riser etc. I ended up abandoning the timing light and mark and timed it with my vacuum gauge and engine analyser (RPM). With modern gas (higher octane), i needed to advance the timing about 15 degrees to achieve max vacuume at approx 650 rpm. Once max vacuum was achieved, I backed off the vacuum around 1.5" and settled with 16" and she now purrs and the dying at acceleration has gone away 90% unless I basically go wide open from idle (which would kill vacuum in most engines). She starts right up and runs well. Adjusted the idle mixture as well until I had 650 rpm and maintained the steady 16" vacuum. Turns out the timing I needed on this one was about 15 deg BTDC. Also, no pings or pre-ign under acceleration and load (light and heavy).

Now it's fun to drive again. :-)
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

renovate7
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Re: Getting fustrated with engine

Post by renovate7 » Sat Apr 22, 2017 4:25 pm

I had a heck of a time setting the timing on my GMC inline 6 in my DUKW. Ended up timing it by ear with tach attached to number one wire. Turned the distributor till I got max rpm and backed it off a bit. Runs very well. It was designed for 73 octane fuel. Even using the formula of so many degrees change based on an increase in octane just didn't work. The ear is mightier than the timing light, some times.

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Re: Getting fustrated with engine

Post by Bill H. » Sat Apr 22, 2017 6:01 pm

Glad it's fixed bro! :wink:
Bill H.

"Each shall seek his own kind, in other words, a bird may love a fish but where would they build a home together?" Tevye, Fiddler on the Roof

1952 Dunbar Kapple M100
1953 Willys M38A1
1962 AMC M422A1
1965 Stevens M416B1 X 2
1967 Kaiser M715

2 Timothy 3:1-5

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Re: Getting fustrated with engine

Post by Zottelbock69 » Thu Jun 15, 2023 1:23 am

Hello everyone,

I got into the same situation. After the engine has been rebuilt from scratch, it is not possible to get it to run smoothly. I exchanged the carburetor, complete ignition including ignition coil, ignition cables and spark plugs but no change. Intake manifold was checked for cracks and holes. Ignition timing is set to the marking, 4° BTDC. Changing the timing makes also no change.

When I unplug the ignition cables individually, I notice that the front right cylinder #2 fires only a bit, the rear right #4 doesn't at all at idle, left side is OK. I checked with an endoscope to see if something was stuck in the right intake, but it's super clean. The heat riser valve opens and appears to be OK.

Compression is 130-132 on all 4 cylinders.

Any suggestions or ideas?

Many thanks in advance and nice greetings from Vienna,

Guido

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Re: Getting fustrated with engine

Post by mspeters » Thu Jun 15, 2023 4:28 pm

Good luck. May take more time to find the root cause.

- By chance, is there a new 1/8” NPT brass elbow on the passenger-side hollow valve cover bolt then running over to the distributor ? Try temporarily plugging it. The stock part has a very small orifice to bleed a small amount of vacuum, or else the right bank runs leaner than the left bank at idle.

- Is the PCV valve sealing to it’s pilot hole size @ idle vacuum.

- put a timing light on Cyl 2 & 4 ignition wires to verify consistent spark.

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Re: Getting fustrated with engine

Post by takpak » Sat Aug 05, 2023 7:45 pm

After I got my engine rebuilt, and rebuilt the carb, I couldn't get mine to run either. It wouldn't idle at all. After rebuilding the carb twice, at a fellow rebuilder's recommendation I sent it to Daytona Parts in Florida. They specialize in carb rebuilds, especially unique ones. Took six weeks, but when I got it back, it ran beautifully. The guy told me they have a special ultrasonic machine ($40,000) that they clean them in. He said the regular carb cleaner sometimes just won't do it all. It get in all the small orices/ports and really cleans them. I'm a believer now! I'm getting a few hours on it now, and the engine is starting to smooth out/break in as I run it. It starts really easy, generally don't even have to choke it. WAY easier than the GPW or the M-43.
Terry K.
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Re: Getting fustrated with engine

Post by Zottelbock69 » Thu Nov 16, 2023 4:20 pm

Hello everyone,

After a lot of back and forth I got the engine running, but it wasn't easy. Since only the right cylinders were affected, I thought it was a problem with the cylinder head. I removed this and found no problems, nor with the cylinders, which were in ideal condition. Then I dismantled the hydraulic lifters and they were also in perfect condition. All in all, the situation became even more unclear and I reassembled the engine. No difference from before, the right cylinders simply didn't run properly.

Then I removed the distributor and powered it with a drill and hooked it up to 24V, up to an equivalent of about 5000 rpm I had a 3/8" spark, which should be more than enough. It should, because as it turned out later, there was no spark left under compression (error 1:NOS ignition coil defective).

The next problem that was not visible was the new Prestolite ignition from an M151, here I set the air gap to 0.01" but the sensor was built quite crooked The sensitive part of the sensor was far too far from the trigger wheel. I was able to achieve this by regrinding the base of the sensor (error 2: sensor crooked).

The third problem was, that 4 new membranes and diaphragms that were supposed to withstand the ethanol in the gasoline had become completely leaky. Both membranes of the fuel pump, the diaphragm of the accelerator pump and the diaphragm of the economizer. (error3: not real ethanol resistant rubber)

From rebuilding the motor, which was running excellent at this time, until today, unfortunately, 5 years have passed in which the parts appear to have aged badly. But now everything is OK and I hope that this will help other guys.

Nice greetings from Vienna,

Guido


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