What is good compression on an F-134

ndnile

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#1
I have a recently acquired an M170 (M38a1 variant) with this engine and would like to get an idea of where it is at health wise.
Compression going from #1->#4 cyl is 100, 100, 105, 115.

Surfing the web, I've found a pretty wide range of numbers for what an F-134 should be. One reference said 90-110lbs, another simply 135lbs. Perhaps the variation is due to the high and low altitude civilian heads and whatever the military used. There is a lot I want to do to and with this jeep. I'm just wanting to get an idea of how far out a rebuild is so I know where and when to focus energy and $$.

Thanks, Doug
 

MMCMESWS

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#2
I have a recently acquired an M170 (M38a1 variant) with this engine and would like to get an idea of where it is at health wise.
Compression going from #1->#4 cyl is 100, 100, 105, 115.

Surfing the web, I've found a pretty wide range of numbers for what an F-134 should be. One reference said 90-110lbs, another simply 135lbs. Perhaps the variation is due to the high and low altitude civilian heads and whatever the military used. There is a lot I want to do to and with this jeep. I'm just wanting to get an idea of how far out a rebuild is so I know where and when to focus energy and $$.

Thanks, Doug
 

diggerG

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#4
Those are pretty safe numbers. Compression #s are variable. Was the engine warm or cold? plenty of oil? adjusted valves yes or no? Some people squirt a little oil in the cylinders first. Does it smoke or rap? Oil pressure ok? lose anti freeze? If your answers are no then worry about other issues. Throwing away those 9" brakes is a good start. They aren't worth spending $$$ on.
diggerG
 
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ndnile

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#5
John, thanks for the #'s. Greg, I think the engine was cold. Did not squirt oil. I know I should've. No smoke. I'm not sure what a "rap" is. Haven't adjusted valves yet. I think the valve train is noisy, so that is on the short list (at least I hope that's the noise, and I think it is). Oil pressure was real good. Haven't driven it enough to monitor anti-freeze level, but the fluid is green and the oil is black.

I'm positive I will be adding an OD and pondering a webber carb and headers for a few extra ponies, so couldn't agree more on the brakes.

Thanks, Doug
 

MMCMESWS

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#6
Those are pretty safe numbers. Compression #s are variable. Was the engine warm or cold? plenty of oil? adjusted valves yes or no? Some people squirt a little oil in the cylinders first. Does it smoke or rap? Oil pressure ok? lose anti freeze? If your answers are no then worry about other issues. Throwing away those 9" brakes is a good start. They aren't worth spending $$$ on.
diggerG
One thing you should do is get a Service Manual. You can get one at Kaiser Willys www.KAISERWILLYS.com Ph - 1-888-648-4923. The pressure should be uniform between cylinders, within 10 psi. Also how good is your battery and starter? Any problems there will give you a bad reading. And a stupid question, I have to ask. Did you take all the spark plugs out? A person who was referred to me had low compression. So I asked him first-off, did you take all the plugs out? Ah no, why? He was afraid of getting the plug wires mixed up, hey we all do that. The service manual has a good set of instructions on checking compression and problems. If you are going to try this again I would suggest that you take your "old girl" out for a spin and get her warmed up and oil circulated. One other thing. I put a Pertronix ignition system in mine and changed out the carburetor to a Solex. I installed a Solex because you can adjust the low speed jet with the engine running, which comes in handy when operating at high altitudes, we got up to 12,400 ft in Colorado. We have two 46 CJ2A's. I have had one since 1971, the other one we have had for two years. The newest one the the wife found, yes the wife found it! Oh its so pretty you have to go see it. So we bought it. A lot work was done on it, most of it wrong. But it sure looked pretty! Besides beating around California, we have been to Moab and Colorado with it. And we are going again this year. If you get in a group of old Willys guys and you have a problem there is always someone who can help.

Happy 4 Wheeling
John
 

ndnile

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#7
Hi John, Thanks for your knowledge. All plugs were out. Throttle WOT. Starter may have dragged a little, but not horribly so.

WRT Pertonix: At first I was going to tell you this wasn't an option because the jeep still had its original 24volt system, but then I did my due diligence to confirm what I was going to say was true. I was pleasantly surprised to find they do offer a 24volt variant. Yep, that is now on my list as well.

Solex: Right now I'm leaning towards a weber 32/36 DGV. A progressive 2bbl makes sense to me. Aside from cost, there might be some linkage fabbing that gives me pause. I had a very positive experience with a Weber carb in my youth. It really perked up the rig I had.

2nd CJ2A: On one hand I would say congrats on the CJ2a find, but I think the real find was your wife. WRT your first CJ2a, my buddy just barely has you beat. His first car was a 46 CJ2a that he got in 69 which he still has and wheels in. It was on the Vintage 4X4 run with me (listed in the events section). It is the one with the hard cab on it next to my USMC Willys MB.

Wheeling: Sounds like you have life dialed in. I've only done the local areas and other than snow, nothing really technical. Would love to do MOAB sometime and I constantly pester the wife about moving to Colorado.
 

MMCMESWS

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#8
Hi John, Thanks for your knowledge. All plugs were out. Throttle WOT. Starter may have dragged a little, but not horribly so.

WRT Pertonix: At first I was going to tell you this wasn't an option because the jeep still had its original 24volt system, but then I did my due diligence to confirm what I was going to say was true. I was pleasantly surprised to find they do offer a 24volt variant. Yep, that is now on my list as well.

Solex: Right now I'm leaning towards a weber 32/36 DGV. A progressive 2bbl makes sense to me. Aside from cost, there might be some linkage fabbing that gives me pause. I had a very positive experience with a Weber carb in my youth. It really perked up the rig I had.

2nd CJ2A: On one hand I would say congrats on the CJ2a find, but I think the real find was your wife. WRT your first CJ2a, my buddy just barely has you beat. His first car was a 46 CJ2a that he got in 69 which he still has and wheels in. It was on the Vintage 4X4 run with me (listed in the events section). It is the one with the hard cab on it next to my USMC Willys MB.

Wheeling: Sounds like you have life dialed in. I've only done the local areas and other than snow, nothing really technical. Would love to do MOAB sometime and I constantly pester the wife about moving to Colorado.
I wish I had known about your run earlier this month. Are you going to be in Plymouth in April?
John
 

ndnile

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#9
I wish I had known about your run earlier this month. Are you going to be in Plymouth in April?
John
I will be at Plymouth most of the week. I’ll PM you my site # tonight when I get home.
 
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#10
I did a quickie compression check on my '46 CJ2A - L134 last year with plugs out, engine cold and throttle plate closed, and using a push-in type tester.
I cranked the engine over 5-times watching the needle bounce between strokes. I got consistent 125 for all 4-cylinders.
My guess is, depending on pistons and how much material has been machined off of the block deck and head could increase or decrease average pressure from the spec. I would check valve clearances and run it for awhile.
 
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#12
Leanard, I believe 125 PSI across the board is really good for an L-134. Congrats!
yeah, who would have thought right !
And I was so thrilled ( it must have just been carbon build-up ) hahahaha
Hey, I understand carbon can increase compression. Another way is to install a turbo. _ _ _ thinkin out loud.

So Doug, did you take it out and blow-out the Cob-webbs yet !

What are some of your favorite northern California jeep trails Doug ? Have you been up to the top of Prospect Peak ? off of I-80 near Eagle Lakes.
Broke a front driveline way up Prospect, and we were looking for the Sierra Trek / 4-dice Creek trail, which we did find, but the creek was too deep to forge off-season. I haven't yet traversed the north side of the creek portion of the trail leading to Meadow Lake.

For those of us up here in northern California, the Rubicon trail is hard to beat but taxing on equipment.
I have a favorite called the Pelligreen Jeep Trail which runs along the north side of Mill Creek in Tehama County, elev approx. 1800 ft.
And, I haven't 4-wheeled much since 2001, my last trip in and out of the Rubicon. _ _ _ I've been slacking. hahahaha
 

ndnile

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#13
yeah, who would have thought right !
And I was so thrilled ( it must have just been carbon build-up ) hahahaha
Hey, I understand carbon can increase compression. Another way is to install a turbo. _ _ _ thinkin out loud.

So Doug, did you take it out and blow-out the Cob-webbs yet !

What are some of your favorite northern California jeep trails Doug ? Have you been up to the top of Prospect Peak ? off of I-80 near Eagle Lakes.
Broke a front driveline way up Prospect, and we were looking for the Sierra Trek / 4-dice Creek trail, which we did find, but the creek was too deep to forge off-season. I haven't yet traversed the north side of the creek portion of the trail leading to Meadow Lake.

For those of us up here in northern California, the Rubicon trail is hard to beat but taxing on equipment.
I have a favorite called the Pelligreen Jeep Trail which runs along the north side of Mill Creek in Tehama County, elev approx. 1800 ft.
And, I haven't 4-wheeled much since 2001, my last trip in and out of the Rubicon. _ _ _ I've been slacking. hahahaha
I haven't gotten this M170 on the road yet. Waiting for a buddy to get back from vacation who has one of those 90 degree angle drills. I broke off two studs when I removed the exhaust manifold to adjust the exhaust valves. Of course one of them had to be the rear-most stud. Not sure I can even drill it out with his angled drill. Might have to pull the motor out a ways. Simple things seldom work out simple for me.

Been wrenching on a 43 GPW that fell into my lap. Today I hope to get the cleaned out fuel tank and re-cored radiator reinstalled. Brakes will likely be another day.

As for trails, I've only done back roads really. My rigs are stock open diffs with NDT tires. To-date other than snow, I have not done anything that would challenge them. Most MV owners don't take their rigs off the pavement, doing mostly parades. Every June I go with a group of fellow MV owners who are not afraid to get dirt on their tires for about 4 days of back road fun. Last few years have been around the Truckee area because one of the guys knows the area down to most every stump and ditch. Last year we doodled around and off of Henness Pass Road which runs from Hwy49 and Verdi NV. Real pretty area. Mostly for our Truckee friend, we wanted to branch out to another area, but the Mendocino fires put the kebash on our plan-A and the heavy snow this year has stopped us from scouting another area we are considering. No firm plan yet on where we are going. Might hit you up on your Mill Creek trail, though it's a bit low in elevation for us.
 

54 wagon ken

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#14
I haven't gotten this M170 on the road yet. Waiting for a buddy to get back from vacation who has one of those 90 degree angle drills. I broke off two studs when I removed the exhaust manifold to adjust the exhaust valves. Of course one of them had to be the rear-most stud. Not sure I can even drill it out with his angled drill. Might have to pull the motor out a ways. Simple things seldom work out simple for me.

Been wrenching on a 43 GPW that fell into my lap. Today I hope to get the cleaned out fuel tank and re-cored radiator reinstalled. Brakes will likely be another day.

As for trails, I've only done back roads really. My rigs are stock open diffs with NDT tires. To-date other than snow, I have not done anything that would challenge them. Most MV owners don't take their rigs off the pavement, doing mostly parades. Every June I go with a group of fellow MV owners who are not afraid to get dirt on their tires for about 4 days of back road fun. Last few years have been around the Truckee area because one of the guys knows the area down to most every stump and ditch. Last year we doodled around and off of Henness Pass Road which runs from Hwy49 and Verdi NV. Real pretty area. Mostly for our Truckee friend, we wanted to branch out to another area, but the Mendocino fires put the kebash on our plan-A and the heavy snow this year has stopped us from scouting another area we are considering. No firm plan yet on where we are going. Might hit you up on your Mill Creek trail, though it's a bit low in elevation for us.
Hey Doug ,
Really like that Verdi Nevada spot ! One of my possible “retirement areas “ . Thinking I could work part time at Cabelas and save me a fortune with the employee discount haha. Let me know if your 90 degree drill doesn’t work out . I’ve got a Makita 90 that’s pretty small . Be glad to loan it to ya :cool:
 
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