13660B Well Tube, Any Experts on Carb.. UPDATE 19 JUL FIXED!

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13660B Well Tube, Any Experts on Carb.. UPDATE 19 JUL FIXED!

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13660B Well Tube, Any Experts on Carb.. UPDATE 19 JUL FIXED!

Postby rstel01 » July 8th, 2018, 7:50 am

Hi all,

I've been very busy on a "rolling resto"/ "refresh" of a wonderful 1972 A2 I purchased through here a few months ago. It's been great, the amount of NOS parts available, ease of working on it. Really just having fun. going back to the last time I drove one in the 1980's when my only care in the world was a 3 weekend payday :)
Image

However, I am having a downright evil time chasing a Carb/Driveability problem during the motor refresh that has driven me crazy.

As I started expanding the range of drives from the house, I started picking up a hesitation/stumble and just general poor running. Prompting a refresh and indepth of the motor overall (plus it had a very annoying exhaust leak)

Thus far:
Coil has been replaced with a sourced (1989) NOS unit
Cap Replaced
Fuel Filter both on intank sleeve and carb intake
All cracked/frayed vac lines (to dis advance and coil cooling) replaced
PCV replaced
Intake Gaskets replaced, trueness of head and manifold verified, NOS gaskets and Copper Hi-Temp sealant. All vac leaks addressed
Exhaust manifold replaced with NOS unit, sealed with copper hi-temp (I learned the lesson with the gaskets on the earlier head and inducing vac leaks).
Timing verified
Valve clearance verified at 15 thou (oddly they were all spot on)
Wires are backordered at the moment but, no issue with a secondary ignition miss
Absolutely nothing indicative of base motor issue, it is a very solid powertrain
I have no ability to actually read fuel delivery pressure but, I am having no starvation issues and with a fuel line removed from the carb, no issue with filling a glass bottle during crranking

Now to the carb, which is driving me mad and I hope some of you have experience in the 13660B

Even during my increasing shakedowns, I was always having to "play" with the original carb idle A/F mixture and Idle and it was only getting progressively worse. The best way to explain it poor driveability. I attempted an overhaul (hey, it's a simple side draft and I've done enough Amal's and SU's in my day). I made the carb issue 10X worse, I angered it somewhere in one of the passages, or jets. No big deal, I'm beaten, drop back ten and punt.

I procured a new "flow tested" rebuilt 13660 from my supplier (my new crack dealer :D ).

I put it on and grrrrr, it doesn't run at all (unless on ether and only briefly). Ok, back to square 1.

Well the fuel valve was seized in the seat... ok things happen. Off comes the Carb, free the seat, back on. Starts right up but, dumping fuel in the body. Off comes the carb, measuring the float setting vs the TM, the float is off. reset the float. Ok runs now but, surging, stumbling at idle.

Try setting the A/F mixture and idle setting, but no real effect. Watching it down the bore while running, just a real ugly atomization pattern through the jet. It will get a somewhat "good" spray, fall off, stumble, then pick back up, but again very "splotchy", then a somewhat good spray, then the cycle repeats.

Ok carb off again, let's remeasure.

Well I found IAW the TM (9-2320-218-20-1) that the Main Well tube dimension is WRONG
Image

The TM calls out 42.67mm for this dimension with an allowable variance of .127mm. It's guidance if this dimension is wrong is to replace Carb.

For sanity, I checked my original and spot on:
Image

I contacted my supplier and he old me that it's ok and if there were problems with this that it would have had issues when they flow tested.

I'm not discounting my supplier and think they are wonderful to deal with but, I think they are wrong. In your expertise of workings with this carb, is the dimension for the well tube critical? I believe that it must be fully down and fully immersed into that lower area of the bowl.

Again sanity check, put old carb on and it idles ok (but, is crap everywhere else).

Any input regarding he well tube or other thoughts would be appreciated.

I'm at the point, where I'm getting ready to call this a $300 wasted experiment and try to get a NOS one.

Thanks in advance
Last edited by rstel01 on July 19th, 2018, 6:32 pm, edited 1 time in total.
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Re: 13660B Well Tube, Any Experts on Carb

Postby Fil Bonica » July 8th, 2018, 9:40 am

Contact our resident carb guru Rick Faunce.
He can probably talk you through it or rework it for you at his place.

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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 8th, 2018, 6:48 pm

Sorry for the late reply, crashed my truck yesterday and have been preoccupied trying to get it straightened out. That tube is pre-formed, it is 5/16 inner diameter where you are measuring and 3/16 where it presses into the carb and it seats instantly so there is no adjustment. the part sticking up in the venturi is MUCH ore important than what you are measuring. It should be a tapered cut with the taper facing the throat of the carb, I have sen these ripped off by people pulling out the venturi or getting in there to clean out the venturi and then you will have very little or no mid range or top end. he fact that you are having the same problem with two carbs is interesting considering you checked all the other things that need to be checked. Look in there and let me know if that section sticking up in the venturi is in it's proper place and condition.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: 13660B Well Tube, Any Experts on Carb

Postby rstel01 » July 9th, 2018, 5:49 am

rickf wrote:Sorry for the late reply, crashed my truck yesterday and have been preoccupied trying to get it straightened out. That tube is pre-formed, it is 5/16 inner diameter where you are measuring and 3/16 where it presses into the carb and it seats instantly so there is no adjustment. the part sticking up in the venturi is MUCH ore important than what you are measuring. It should be a tapered cut with the taper facing the throat of the carb, I have sen these ripped off by people pulling out the venturi or getting in there to clean out the venturi and then you will have very little or no mid range or top end. he fact that you are having the same problem with two carbs is interesting considering you checked all the other things that need to be checked. Look in there and let me know if that section sticking up in the venturi is in it's proper place and condition.


Rick,

Thank you so much for the reply and your valued input. The portion of the well tube in the body is oriented with the cut towards the butterfly, so it is correct.

Out of frustration, I took the "new" carb off (for the 30th time :D ) and set up a "frankencarb" out of the two. Essentially putting the bowl on the original body. Oddly enough, I can get a solid idle without the continual surge at about 95% "there" or so.

However, on the road and under load it will not return to idle rapidly. As in when shifting, the idle will stay almost at the same RPM range from when it was under load/you have throttle open. It takes a second or two to return to idle.

At this point I'm going to regroup and go back over the basics again

I've got a correct timing adapter coming, instead of relying on a static from TDC and the jury-rigged adapter I made from a regular wire.
My combination (low pressure fuel and vac) gauge is missing, so I've got a new one coming as I really need to know exact how many in Hg it is at idle and what PSI is being delivered. (Adult son doing a modern 5.0 conversion to a older Fox body Mustang has been carrying out raiding parties in my box).

Also going to go and do a cylinder leakage and base compression.

Ironically about 2 decades ago, before closing my box and departing for the much better Railroad Rolling Stock manufacturing carnival I supposedly knew what the heck I was doing!

Image

I'm having fun but, this driveability and carb issue is beating my butt...

Hmmmm.. there has to be a way to convert to mid 80's GM style TBI with a simple OBD1 processor and feedback loop.. next project :D

Thanks again
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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 9th, 2018, 7:18 am

You have not lost the idle tube from the bowl have you? A hanging idle would be unmetered gas or stuck throttle plate
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: 13660B Well Tube, Any Experts on Carb

Postby rstel01 » July 15th, 2018, 3:21 pm

It goes back again to the carburation.

After going through every source of a vac leak (prob 15th time I've done this), replace plugs, fuel (even added a 3rd new filter that is clear so I can watch it).

I again went "franken-carb" route but, the other way. using the new body from the fresh rebuilt carb of my supplier and the lower bowl section from my original. Pretty much musical carb parts by now.

Surprise, it runs. Playing with A/F set and idle again but, multiple road tests and we even took it out to dinner last night. It drives beautifully on road, great power no issues. But, still unacceptable in idle quality. 1/4 choke or so makes it manageable, but still a slightly "surgy" idle.

I think it is just a $295 waste of money on this rebuilt carb from the supplier. I'm just going to procure a new one.

The only oddity I have is regarding the timing, in conjunction to the light.

Image

Now that I have the correct adapter I can shoot correctly with the light. However, it is almost estimated 15% off where it should be. If I bring it to where the mark should be with the pointer, (essentially maxed towards firewall), it is so far advanced, it has intake misfires and exhaust manifold will glow.

Put it back where it was (roughly 2 fingers between oil filter) runs beautifully with no timing issues. Must be something with the light, I'll figure that issue out later
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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 15th, 2018, 3:51 pm

Have you removed the plate in the distributor to be sure the advance springs are not broken and are advancing and returning as they should? The timing issue looks like an advance timing light that is stuck on advance, or retard. Are you sure you were using #1 plug wire? I have seen many cases where some owner down the line replaced the oil pump or the distributor intermediate drive and got the timing 180 degrees off so they moved the wires around as a fix. Be sure that the advance in the distributor is advancing as you rev it and smoothly coming back as it slows down. Even if the light is wrong as long as it is consistent you should be able to see that.

Just curios, If you are using an advance light are you setting it to zero? That is where you need to set it since the timing mark is already at 6 degrees.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: 13660B Well Tube, Any Experts on Carb

Postby rstel01 » July 15th, 2018, 3:57 pm

rickf wrote:Have you removed the plate in the distributor to be sure the advance springs are not broken and are advancing and returning as they should? The timing issue looks like an advance timing light that is stuck on advance, or retard. Are you sure you were using #1 plug wire? I have seen many cases where some owner down the line replaced the oil pump or the distributor intermediate drive and got the timing 180 degrees off so they moved the wires around as a fix. Be sure that the advance in the distributor is advancing as you rev it and smoothly coming back as it slows down. Even if the light is wrong as long as it is consistent you should be able to see that.


Motion in the throttle shows the mark is advancing or retarding dependent on RPM under the light. Yes, firing order is correct pursuant to the data plate on drivers side of block and corresponding to the distributor. I accidentally had 2 and 3 swapped during one of the many times times it was apart and back together and while it ran, the intake firestorm was interesting. It is on No1 (closest to fan)

I sure it is something with the light for some reason, it might be an advance light. My fancy one died and never really replaced it with one of equal quality. It's just a cheapy I have currently
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Re: 13660B Well Tube, Any Experts on Carb

Postby rstel01 » July 15th, 2018, 4:22 pm

Maybe this will help

First one when first got "new" carb

https://www.youtube.com/watch?v=WIAl_BsvUX0

where I'm currently at with "Frankencarb"

https://www.youtube.com/watch?v=zFz3ntVUoOE
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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 15th, 2018, 4:28 pm

I went back to your first post and you say this is all after a motor refresh. Is it possible that you got the cam in a tooth off? Timing is critical on these engines and just a couple degrees off will sound like a carburetor issue. What you are describing with the timing light almost sounds like the cam is one tooth advanced. Have you checked idle vacuum?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 15th, 2018, 4:32 pm

I just listened to your videos and it sounds like you have NO idle circuit so I will ask again, did you lose the idle jet out of the carb bowl? If that jet is there then I would lean towards the valve timing being off since it is obviously hunting in the upper range of the carb and not in the idle circuit. I am guessing you have the idle speed screw cranked in pretty far.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 15th, 2018, 4:35 pm

What is the extra vacuum line on top of the fitting on the intake that the PCV is hooked to?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: 13660B Well Tube, Any Experts on Carb

Postby rstel01 » July 15th, 2018, 4:39 pm

rickf wrote:I just listened to your videos and it sounds like you have NO idle circuit so I will ask again, did you lose the idle jet out of the carb bowl? If that jet is there then I would lean towards the valve timing being off since it is obviously hunting in the upper range of the carb and not in the idle circuit. I am guessing you have the idle speed screw cranked in pretty far.


No the idle jet is in the bowl.

Realize the first video is with a brand new (rebuilt) carb out of the box from a major M151 parts supplier. That are "flow tested" (the same one where the inlet valve was stuck and wouldn't initially run).

The second video is where I am today, with a hybrid of my original carb (bowl portion) and the brand new (rebuilt) body.

Where I am today from the point of view of driveability is excellent, great power, no issues except for surging idle issues (intermittent btw). It'll be fine for a while, then start a low idle roll, overshoot its idle, settle down, then start to stumble and repeat '
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Re: 13660B Well Tube, Any Experts on Carb

Postby rstel01 » July 15th, 2018, 4:40 pm

rickf wrote:What is the extra vacuum line on top of the fitting on the intake that the PCV is hooked to?


runs to a fitting on the passenger side of the block, seemingly a passage to the oil pan

Image
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Re: 13660B Well Tube, Any Experts on Carb

Postby rickf » July 15th, 2018, 5:17 pm

Alright, There is your problem! That line is supposed to be a vent line that goes THROUGH the factory fitting and into the fitting on top of the carburetor. The only fitting that utilizes manifold vacuum there is the PCV. And by the way, I am also a rebuilder of these carbs and have 45 years of rebuilding carburetor experience. I know who you are talking and I will say no more about that!

Anyway, Take that line from the crankcase off of the fitting on the manifold and block the port on the fitting and see how it runs.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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