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Unread 12-08-2013, 08:26 AM   #16
Truckon09
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Check to see if you have burnt valve. Hold a thin piece of paper up to the exhaust pipe and see if it try's to suck it in. I just got done rebuilding my engine at 190,000 miles, it had a burnt valve and the timing chain almost wore a hole through the cover.

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Unread 12-08-2013, 04:52 PM   #17
Wrenchtosser
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Quote:
Originally Posted by Truckon09 View Post
Check to see if you have burnt valve. Hold a thin piece of paper up to the exhaust pipe and see if it try's to suck it in. I just got done rebuilding my engine at 190,000 miles, it had a burnt valve and the timing chain almost wore a hole through the cover.
I'm starting to think what Im experiencing is related to something like a burnt valve. Ill try the paper trick...thanks for the suggestion!
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Unread 12-26-2013, 09:57 PM   #18
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UPDATE: Well, it's not a jumped timing chain, it's not a burnt valve and it's not a bent push rod. And as far as I can tell, I haven't made any mistakes on the Nutter Bypass or the carb install.

I even took it in to a very reputable garage! They spent numerous hours, tried a number of things (including different vacuum sources for the distributor advance), re-checked everything I did, made some idle enrichment screw adjustments...but very little improvement.

Basically, this thing just runs like ****. To make matters worse, I can't seem to get the guy I bought the carb kit from to respond to may emails.

There were suggestions to do further distributor mods, but I need to get this thing smooth with no roughness and missing before I go on to those kinds of mods or Im just going to be introducing more variables to the problem.

Please guys - I'm at my wits end here! Anyone have this experience in the past?

Again, the symptoms:

Occasionally rough idle, erratic miss
poor acceleration, heavy off-idle hesitation, especially in 1st and 2nd gear
Bucking and surging at highway speed
Terrible gas mileage due to rough running

Thanks in advance for anything you can throw my way to help figure this one out!
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Unread 12-26-2013, 10:12 PM   #19
dancytron
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I read the whole thread. Have you tried to do a regular tuneup yet? Pulled the spark plugs and looked at them?

I agree, you don't need to think about doing any timing mods to the distributor until you figure out the problem.

You can do a tuneup with better Ford parts if you haven't. http://www.jeepforum.com/forum/f8/i-...nitive-669495/ Also ground the ICM (black wire running from ICM to distributor) and the head.
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Unread 12-26-2013, 10:13 PM   #20
pete1991YJ
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Float level and accellerator pump come to mind, assuming that everything else is good -- tight vacuum and timing, etc. I'm real suspicious of your vacuum numbers tho, it seems real low. Checked for leaks around the manifold?
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Unread 12-27-2013, 01:46 AM   #21
Wrenchtosser
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Quote:
Originally Posted by dancytron View Post
I read the whole thread. Have you tried to do a regular tuneup yet? Pulled the spark plugs and looked at them?

I agree, you don't need to think about doing any timing mods to the distributor until you figure out the problem.

You can do a tuneup with better Ford parts if you haven't. http://www.jeepforum.com/forum/f8/i-...nitive-669495/ Also ground the ICM (black wire running from ICM to distributor) and the head.
Thanks for taking the time to read the thread and offer your help, I appreciate it a great deal.

The tune up parts are relatively fresh, as are the plugs, but honestly I haven't taken a plug reading. Ill do this and do another update.

The Team Rush upgrade is on the list of to-dos, and the grounding idea sounds like a good one. Im wondering if this isnt a ground issue...I had something like this on a Samurai and it turned out to be a ground problem.


Quote:
Originally Posted by pete1991YJ View Post
Float level and accellerator pump come to mind, assuming that everything else is good -- tight vacuum and timing, etc. I'm real suspicious of your vacuum numbers tho, it seems real low. Checked for leaks around the manifold?
I suspect my vacuum gauge isnt real accurate, however the mechanic I took it to checked everything out with a vacuum gauge and checked for leaks too. Everything was ok, they said.

Good question about float levels and accelerator pumps. I have to check with the guy who built the carb to see if it voids a warranty or something if I open it up, but that seems like where I may need to look next. Good suggestion.
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Unread 12-27-2013, 06:29 AM   #22
Old4X
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Put the original carb back on it and see what it does
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Unread 12-27-2013, 10:39 AM   #23
zeus87gn
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Old4X knows what he's talking about - I just went thru this issue a few months back

If you haven't investigated the dist issue yet, you need to
The fcty dist for our 4.2s only came with a few degrees of mechanical advance - 6 or 7 degrees - due to the computer that you have now removed from the system
If you still have this setup in the dist, you aren't getting your full spark and fuel burn
The correct setup is 15 to 18 deg of mechanical advance, manifold vacuum, base timing adjusted around 8deg give or take a couple for elevation isues and the carb tuned to suit
If you look thru the spy hole in the dist under the rotor, you can see the numbers on the weights - turn the engine with a wrench to see them
If they are 6 or 7, you need to change (modify, etc) the dist

I solved the problem on my 87 by replacing the dist with a rebuild for an 83 CJ - didn't feel like taking the old one apart
I'm not getting 22mpg, but it runs all too good

I'll take a stab here at your low vacuum readings - your engine is carboned up - you have low compression due to carbon on the valves
Fix the dist issue, hook up to manifold vacuum, make needed adjustments and run it for a few tanks of gas
You will need to make more adjustments along the way, but it will come around as it cleans itself out

HTH
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Unread 12-27-2013, 12:34 PM   #24
dancytron
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I have no doubt that Old4x is right that changing the distributor mechanical advance will give more performance and better gas mileage. He is right about everything else.


But, it isn't the cause of the kinds of problems this guy is having. Something else is badly broken and he needs to figure out what it is and fix it before he worries about changing anything else.

FWIW, I still have the original distributor (and carb) on mine, nuttered and it idles well and runs smoothly.

My guess is ignition related, like bad plugs, distributor cap or plug wires.
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Unread 12-27-2013, 03:43 PM   #25
Old4X
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Low vac at idle causes with engine that passes compression check:

vac leak
retarded ignition
non firing spark plugs.
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Unread 12-27-2013, 04:00 PM   #26
zeus87gn
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Had to go back and read some more

Quote:
Originally Posted by Old4X View Post
You said you checked well for vacuum leaks. Did you check torque on the intake manifold bolts in the head? They tend to work loose.
^^this^^ needs to be verified - 27ftlb
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Unread 12-27-2013, 05:14 PM   #27
jay-h
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Quote:
Originally Posted by dancytron View Post
I have no doubt that Old4x is right that changing the distributor mechanical advance will give more performance and better gas mileage. He is right about everything else.


But, it isn't the cause of the kinds of problems this guy is having. Something else is badly broken and he needs to figure out what it is and fix it before he worries about changing anything else.

FWIW, I still have the original distributor (and carb) on mine, nuttered and it idles well and runs smoothly.

My guess is ignition related, like bad plugs, distributor cap or plug wires.
No the amount of advance will not cause these problems but misfiring etc could be a bad distributor, loose bearings, shot pickup, or a bad spark module.

[BTW unless I'm terribly wrong, the stock computer adjusts the timing by RETARDING the spark, not advancing it. It gets the signal from the distributor and delays passing it to the spark module by a calculated amount. I don't think it can pass it to the spark module BEFORE the distributor triggers]
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Unread 12-27-2013, 06:12 PM   #28
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One other observation (not necessarily specifically referring to the original poster). People sometimes turn to nuttering when the Jeep is running like crap and are disappointed. If your system is in reasonably good shape, the Carter will run ok. Maybe not great but ok. If it is not running, or running very badly, nuttering is unlikely to help. You've got to fix whatever is wrong first.
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Unread 12-27-2013, 07:31 PM   #29
Old4X
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Quote:
Originally Posted by jay-h View Post
[BTW unless I'm terribly wrong, the stock computer adjusts the timing by RETARDING the spark, not advancing it. It gets the signal from the distributor and delays passing it to the spark module by a calculated amount. I don't think it can pass it to the spark module BEFORE the distributor triggers]
The computer does, in fact, advance the timing. Look up "phasing" on 258 and 4.2 distributors. Some of the smog distributors have to have their reluctors redrilled to correct phasing that is too far out and triggering to early once the computer is removed.

This can be checked with a timing light and a spare distributor cap that has a 1" hole drilled inboard of the #1 terminal. You use a timing light to show the phasing relative to the terminal.

eta: with the phasing of the reluctor, the computer can advance up to the max allowable by the reluctor passing the pickup which is above normally needed advance, but Jay is right saying the computer mostly retards the timing.

You still have to modify the advance plate or swap to a pre smog dizzy to get the full, needed advance that the computer allowed.
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