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Discussion Starter · #1 · (Edited)
Well I'm trying to narrow my pinging problem which occurs around 55mph and 60mph. I disassembled the carb to make sure there wasn't any foreign particles, corrosion going on. Before I acquired this 1988 Jeep Wrangler with 4.2l engine and automatic. One of the PO's had replaced some of the jets and what I found was quite a difference from the paperwork I have from Redline. It has been nuttered from the looks of the twisted pr of wires to the dist.
From what I wrote down here is my findings Some seem extreme to me.
primary Main Jet 1.40mm, Secondary main jet 2.20mm, primary Air corrector jet 1.70mm and secondary air corrector jet 1.60mm I believe these two were backwords before reassembling. Primary idle jet .75mm, secondary idle jet .60mm. I had to adjust the float as it was not level but was allowing more gas in the bowl. At the same time I have added a fuel reg set at 3.5lbs. I've done a lot of trial and error with the timing but just want to make sure if it could be the carb or not. It has an original dist and idles great, vacuum around 20hg.
I plan on replacing the dist with a HEI soon. PO says the engine was rebuilt about 25,000 miles ago. Runs great till you go up a hill, I'm at sea level along the coast. Hope I gave enough info. thanks for any help
 

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Discussion Starter · #3 ·
Thanks gehlsurf, The one thing I forgot to put in my post that it is a 32/36 weber.
What you said, that makes a lot of sense with a larger weber. I was also considering a Ford 2barrel I've heard others are usings, don't know what it would take to mount it.
I'm stuck between the problem being a timing issue or a lean mixture at that speed range. The larger carb should deliver more fuel in that range.
Also I've tested for vacuum leaks, changed the plugs to Champion. Plugs look to be normal.
 

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Discussion Starter · #5 ·
For the last test drive I set the the timing to 8 degrees BTDC. Strangely it was quite advanced. I was getting ping at slower speeds under load. I stopped and retarded the timing. This helped out and cleared up the speeds up to 55mph. when I got back and hooked up the timing light and it was set back to 4 degrees BTDCf, that's where I found the timing the first time I put the timing light on the engine. I do remove the vacuum line and plug it when timing. In the mix I'm concerned about what the Dizzy is actually doing. I believe it's the original and worn out could be part of
the problem.
 

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Discussion Starter · #7 ·
Thanks Boojo, Dist it will be. I'm going to say the vac advance is hooked to the ported. It will show up in the picture attached. The orange tubing is to the Dist. I'll get into a lengthy history of the said Jeep but time is short right now.
I will run the engine up and watch the advance curve both vacuum and centrifical, good idea. I was definately concerned if the springs were working correctly. When i'm using the timing light I don't see any fluxuation of the timing so the bushing should be ok. I'll be back later
 

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Discussion Starter · #9 ·
That's ok, I usually call it a dist for short. The one thing I did notice was once you hook it back up the vacuum sucks the advance quite a bit if not most of the way. You can't a reading because it's way past the markings.
I did change the thermostat, From the gauge the temp was showing 160 degrees at most. The new thermo is a 195 degree and that now shows 212 degrees. Can't figure the difference would go up that high. I figured the old thermo was sticking so I replaced it. I haven't checked the cylinder pressures because I figure they should be good seeing that she runs smooth at idle and there is no variance with the needle on the vacuum gauge. question would be, when I give it full throttle most of the ping goes away so i assume it is dropping the vacuum pressure thus retarding the timing or giving it more fuel compensating for the lean mixture. I'm a bit uneducated on the air correction jets. I see no different sizes to change them or if that would make any difference.
 

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Discussion Starter · #11 · (Edited)
QUOTE="Boojo35, post: 41445628, member: 122380"]
If you are running a factory gauge I would not take the readings as gospel.

Yes. The vacuum advance being plugged in at idle should pull your advance way up off the scale. Somebody on the forum keeps mentioning that the "newer" timing lights or something like that are evil basically speaking of a light that you can dial back degrees. I have both kinds of timing lights. Taking away my dial advance timing light which was claimed to be evil would be like removing my right nut. I would not function well after that. When that timing mark moves past the markings by a long shot, I can dial it and bring it back to a mark and read the amount of degrees I brought it back. These lights are an absolute must for anybody that really knows how to curve a distributor and tailor it to a specific engine.

I have never worked on one of these Weber carbs. Sorry. I cannot answer specific questions about them.

A light bulb turned on though looking back at your OP. The 4.2L has an EGR valve. Do you still have an EGR valve and does it function? Forget all the EGR myths that the net brings. You are recirculating a free source of inert gasses to fill the combustion chambers at times when max combustion is not needed to motivate you down the road.. Inert gasses do not need additional fuel added to them vs non EGR so you can get the same power with less fuel. It takes a book to explain EGR operation, benefits, and even power losses. There are tons of myths and misunderstandings. But if a spark curve is set up to utilize EGR then eliminating it can cause issues. EGR does reduce cylinder temperatures and reduce pinging. Crazy. Hot exhaust gasses can cool cylinders. Who woulda thunk?

Boojo
To be honest I’m not sure but I doubt it. Taking up this YJ is something I haven’t got into for probably 40 yrs. I do understand what you are saying about the EGR and it makes a lot of sense . I will look into it and see what I would need to hook it up.
I do have an old timing light and I’ve never heard of one that reverses the advance so you can read it, sounds like a new tool. Thanks, a lot of food to chew on[/QUOTE]
 

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Discussion Starter · #12 ·
Here's a pic of what's left of my EGR valve. I also believe all the supporting parts are all taken off the engine. I think the EGR idea is to much of a job to undue by now. let me know if I'm wrong on this.

I did look at the adjustable timing lights. New light is in the plans.



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Discussion Starter · #14 ·
Ok Boojo

I'm getting some different ideas out of this conversation. Reverting back 6-8 months ago I was working on the vacuum lines particularly the front axle 4wd actuator to be specific. The short is the unit was all rusted inside and non functional. I went the easier way and replaced it with a mechanical actuator.
In the process of correcting vacuum leaks I eventually decided to check the timing. If my memory is correct I pulled the vacuum advance off the carb plugged it and used my timing light to find it was set at aprx 4 deg BTDC. I finally realized that the distributor was actually not plugged into the carb port, it was plugged at the upper arrow and this in not a port but just a brass pin sticking out of the carb. The lower arrow points to what I am calling the ported vacuum port. This at the time was capped off. All that said, the PO did not have any vacuum hooked up to the dist, timing was at 4-5 deg BTDC and I don't believe there was any ping at the upper speeds I have now.
My conclusion now seems to be that either the dist is not functioning correct or your example said would refer to something is not lining up, timing chain, H balancer basically in that area of the timing.
I will get back with more info if I can work in the cold today (it's -3 deg outside today). I think the timing is 4-5 degrees now so All I would have to do is disconnect and plug the vacuum line to the dist. I think that would put everything back to where it was when I acquired the YJ.
Thanks for this thought provoking conversation, I think it's narrowing things down to get the engine where it should be.
To clarify, the upper arrow is pointing to a post that the dist vacuum line was plugged into ( no vacuum to dist)
The lower port was orinally capped off but in the pic this is where I am getting vacuum to the dist now.
thanks again for your time!!
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Discussion Starter · #15 ·
Ok, Did a test drive this afternoon. Disconnected the vacuum advance and plugged the port. Idle was low but that was to be expected. Had no pinging but power was not there. Got home and checked the timing and it was at 2 deg BTDC so I advanced it to 7 deg BTDC and to another drive. This time I had much more pep and could actually gain speed while climbing the hills. Ran much better with more pep and no pinging.
With this now I'm thinking there is something wrong with the Dist and it's vacuum advance . The plan was to buy a HEI dist, 8mm plug wires and give it direct voltage from the battery run by relay run by the keyed power.
On a side not I had just replaced the spark plugs with the correct plugs RFN14LY. The PO had NGK BKR5E , I tried to cross reference them and they don't show up as a plug for the 4.2l engine, another weird occurance in this venture. Any comments or advice are welcome
 

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Discussion Starter · #17 ·
Boojo,
the port I had the distributor hooked to is coming off the carb and not the manifold below . When I put my vacuum gauge on it it is pulling a vacuum at idle. If this is the wrong place to connect the dist I have no idea where else to hook it in.
As far as the timing, I had retarded the timing on the fly before running it up the hill to see if it would stop the pinging. So 4 deg was a close guess. When the weather warms up I will definitely check TDC on #1 I’m with you on something not functioning correctly or being aligned incorrectly
 

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Discussion Starter · #19 ·
I found a diagram of the Weber carb and ports. I've been using the port shown as the correct port for the dist. On the other hand I have read that if the throttle plate is open a certain amount, vacuum will be present where at idle this port should be zero vac. Some say it should be zero till 1000 rpm's. What I've read is that my carb is a knock off and not an original Weber carb made in Spain. Some Identification is the choke cover is black vs white there is no raised lettering on the body saying both Weber and Spain. They say these are made of inferior metal and places like the throttle plate shaft will wear and at the shaft it will leak. I'm ruling this out as I did a vacuum check of the carb area with carb cleaner to see if I got a rise in RPM's. No change for me so I figure that was one problem to check off the list.
CRT HEI distributor and wires should be ordered today. I think there is more than I want to deal with in my original Dist, warn out.
Any comments and experiences on knock offs vs the Real Weber carb's?

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Discussion Starter · #21 ·
Product Font Rectangle Parallel Diagram

This is a vacuum diagram for the Weber carb or basically what I have except I do not have the CTO valve and EGR valve. If you remove those lines from the diagram that is exactly how I had mine setup. Right now I just disconnected the Dist line and capped it. I'm a bit confused about putting a Tee and check valve in the line?
I think there is a spring unhooked inside the Dist. because after timing and reattaching the vac line to the Dist you can watch the vac advance seemingly all the way advanced. HEI is scheduled to arrive today. If I get all the instructions read and I can borrow my neighbors heated garage I might have it in this weekend. Check compression, Balancer alignment and timing chain slack. But that's a long list because I have to replace a hydraulic line on my plow today and a few more chores.
 

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Discussion Starter · #23 · (Edited)
Well I wasn't thinking of that vacuum port because I haven't heard of using it for dist use. So yes that part was a bit confusing. Good explanation! I see where your going.
I did get the HEIl dist and plan on installing is soon, doing several tests and checks before so I know everything is within tolerances.
As for the Weber carb comments, I might have confused you. I wasn't complaining that it was a bad unit, I was looking for comments on personal experience of the knock off carb's performance over time. I don't have enough time with my carb nor know exactly what has been done to it because it's not in it's original state.
i do have a vacuum gauge,. I haven't put it on that port that I can remember but when I hooked the dist line back on I could see the advance arm of the dist move (my thought) more than it should. I also have used the vacuum gauge to set the timing. connected to manifold port I was getting 20hg of vacuum setting the idle. It still pinged between 55-60mph. That's what made me question whether the carb was properly jetted.
 

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Discussion Starter · #24 · (Edited)
BooJo, Thanks for your time. You have been teaching an old dog some new tricks. I've always done the mechanical work on our vehicles. Getting this YJ has been a challenge as it's not in it's original condition pertaining to the engine. Never really had to understand the details of how carburetion, ignition are working together. Besides timing an engine and being done with it I'm now challenged to understand how these things are functioning together during the course of idle through acceleration. My pre concept was that timing was a constant increase as RPM's increased and not variable vacuum conditions. And then add carburetion to the mix.
Seeing that all modifications to my YJ were done by PO's I don't know what all has been done. i'm challenged to figure out what has been done and what needs to be done to get it running correctly through out the spectrum. Just waiting for time and weather to get in a warm garage!
 

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Discussion Starter · #26 ·
Wait until we get started on how vacuum is really a pressure differential and how it all effects fuel delivery also. LOL.

This is kind of random but yet this thread was leading me down the path of trying to figure out how to explain a few things about vacuum and I stumbled into a writing by MOTOR that states that ported vacuum can never exceed intake vacuum.

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I will just drop this link here to prove that ported vacuum CAN exceed intake vacuum. There are things known as venturies and what they can do is cool.
Boojo, did you copy the wrong link, it not MOTOR? or is this an example? I do have a couple of old MOTOR manuals from the 70's on the shelf. If I get a change maybe I'll if there is anything interesting write ups in them.
Yes, this is getting interesting because fuel delivery is moving to the top of my list.
I did do a quick check with my new timing ligt and found that at idle the port on the carb is pulling around 18 degree's. I should have wrote it down but ot was cold and I had something else to do.
 

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Discussion Starter · #28 ·
I had a feeling the link was an example. That keeps me on track with lean mixture as a contender. There can stitl be some area in the carb restricting the fuel delivery. I don't know if there is an adjustable linkage between the primary and secondary or if it is a solid linkage. Wrong size jets causing a lack of fuel as the throttle opens while vacuum decreases.
I did get a chance to pull down the MOTOR's manual. They have a troubleshooting section. Pre-ignition, ping causes were described as timing, lean mixture, carbon deposits, exhaust valve adjustment, the air/fuel mixture being to warm, lack of coolant circulation etc. Nothng really stood out. I do put some of these things lower on the list because the engine was rebuilt 25,000 miles ago and it idles very smoothly. There was one think they said that sticks out is that it can be only one area and not across the whole engine, one valve, spark plug etc.
Another thing is the ignition module, does it still have the ability to change anything after being Nuttered? With the new HEI dist it can be totally eliminated. Just throwing out some thoughts here.
 

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Discussion Starter · #29 ·
Just a little update
As I had talked about installing a HEI Distributor and do some checking. I went through the compression check. All but one were even within a pound or 2. The third cylinder had a significant drop but still within the tolerances. Added a little oil to the cylinder and it was up to the rest of the cylinders. I didn't go any further seeing numbers were within tolerance.
Next was to check for any slack in the timing chain, I found that to be in good condition.
Last was to install the new dist. labeled everything and set up TDC for number one cylinder. marked position of the rotor and then pulled the old dist out. Installed the new HEI , regapped the plugs and installed the new SP wires 8mm. I removed the ignition module and found the heavy power wire, I believe it was yellow. This is what the directions said to use as a power source as it is key on power. run a wire to the dist and hooked up the tach wire. Set the timing accordingly and she started right up. So far I've done a little idle adjustment and set the timing.
Now for the results. I've been driving the Jeep for the last couple of weeks now. What a difference it has made. There is more power and to my amazement the ping is all gone. I have yet to fine tune the engine with my vacuum gauge yet and the weather is to cold to worry ATT.
I just disassembled the old dist and don't see visually anything that might have been the problem. The PO had just replaced the dist cap, rotor amd plug wires. I'm going to guess that the problem was either in the dist electrical or the ignition module was having problems or the combination of all including the coil.
Problem solved, time to move on to some more cosmetic details, solve a water leak. Always something to do! Thanks for all info and suggestions given.
 

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Discussion Starter · #31 ·
Thanks for the update. We love success stoTy

I wonder if the nutter bypass had been totally done. The ignition module did have the ability to change timing electronically. It had to in order to make a knock sensor work in the system. I will not even try to explain how it did it but lots of guys praise their results when changing over to an HEI.

I was thinking the same thing, I was leary of most everything one of the PO had done. I never did fully read the instructions for the Nutter bypass I assumed it was done correctly once I saw the twisted pair of wires. Oh well, water under the bridge. We’ll see how things go from here. I’m still not sure about my topic of this thread, Weber carb jets
 
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