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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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Is it a 34/36 or a 38/38? I up jetted my 34/36 and it ran awesome!!! Up to 45 MPH, lol. It always ran lean at WOT and seemed to have a bit of a ping at higher RPM's. To be honest, I never really figured it out, got it better, but not perfect.

If it is a 34/36, I'd say stop chasing your own tail on jet sizes and get a 38/38, world of difference. I oit that carb on and it ran 10 times better. I did have to reset the floats, though.
 

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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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I would start with checking the timing.
 
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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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Quick question. Is your vacuum advance hooked up to ported or intake manifold vacuum? It should be to manifold vacuum. Period. No debate. If it is to ported vacuum it is wrong.

Yes. You could have a worn distributor (I hate the word dizzy, it is not called that in the professional world, it is a redneck internet I don't know how one really works term. This is just unjustified rant from me but I have never called one that nor has any decent tech I have ever worked with. DO NOT EVER USE THAT TERM AROUND ME AGAIN. JK. People who call them that just sound dumb though. If you want to shorten the word call it a dist. :RANTOFF:)

The shaft bushings may be worn but that will generally be seen with a timing light at idle and the marks are not steady on the pointer. You will see it jump up and down rather than hold steady at 8 degrees. Another thing is the centrifical advance may be sticking or binding at times. With your vacuum advance disconnected you can rev your motor up to about 3000 RPMs gradually while watching the timing marks. It should smoothly advance up to somewhere around 30 degrees or so. It needs to be pretty smooth and consistent if you do it over and over again. The same is true for the vacuum advance. It should provide true and consistent movement when tested with timing light. That can be done at idle with a vacuum pump hooked to the vacuum advance.

One last thought and this is one can be tricky is carbon buildup in cylinders can hold in heat and stay cherry red and ignite fuel upon entry into the cylinder rather than waiting for the ignition to fire it. This condition is pretty rare and sometimes not really explained how it happened. I would have to type a book on my theories of how it can happen. But anyways, this just popped its head up in a situation that I know of a couple of weeks ago. A very dear friend and fellow tech that I have worked along side of and respect the hell out of, he is an amazing engine builder and hot rod kind of guy ran into this on a vintage Mach 1. The car pinged no matter what. It had been messed with and messed with with no resolution. John (my buddy) advised the customer that this was really the last and only problem that could be the issue. This prognosis was made some time ago. The customer was reluctant to pull the heads then, kept driving it like it was. He sold the car for a very high price but when he went to get it ready to ship it ran like absolute crap. It had misfires on two adjacent cylinders which and low compression on both which indicates a blown head gasket in between those two cylinders. John tore the heads off and sure enough the gasket was blown where it was suspected but he also found that those two cylinders had the hardest carbon deposits on them known to man. I was not a simple cleanup, the stuff had to actually be chipped at and broken up. I was in the combustion chambers on the heads but really caked up on the pistons. He did the cleanup and reinstalled the heads and miraculously the spark knock was fixed and the Mach 1 ran like it never had before for the customer. BTW, the spark knock is what caused the head gasket to blow. Detonation is a *****.

Sometimes you can cure this without a teardown. The product I believe in the most is GM top engine cleaner. If you heat up an engine and rev it up to maybe 2000 RPMs and pull it in through a vacuum source til the motor runs rough and then get it to stall out by basically flooding it with the top engine cleaner and let it heat soak. for a good while to break down the carbon in the cylinder. Crank it up a couple of hours or so later and it will smoke like all get out. Run some more TEC through it. change the oil and see how it goes.

Trans fluid can do the same when used the same but not as effective. Sometimes running water though can steam clean it. These are both used in somewhat the same method as described for the top engine cleaner.

Be fully aware. You are pouring liquid into a motor that does not combust. It can hydrolock an engine and bend or break connecting rods for instance if you are not on top of your game. Use at your own risk.

Others may mention seafoam or other products. I have never tried them.

Hopefully this helps.
 

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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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You can call them a dizzy. Everyone else does. My rants are not always serious. I gave you a JK and a wink in that paragraph.

It is hard to say if that port is manifold or not but it is easy enough to tell. If it is ported, it will probably cure your problem to move it to manifold vacuum. It should be manifold vacuum though. I know that there is internet info that goes both ways but running ported provides vacuum and thus timing at the wrong time and does not provide more timing when it is really needed.
 
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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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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?

Seriously. Do you still have an EGR and does it function?
 

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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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Have you verified if your vacuum advance is ported or manifold vacuum? You can tell it by putting your finger over the hose at idle or using a vacuum gauge.

Sometimes when I share theory and knowledge it sends people off the deep end. I tend to ramble and do not convey the simple parts of my message well.

Finding an advance timing light is a bonus, and arguably a necessity if you will continue to run carbs and distributors but many of them are becoming vintage and way to much money. There are other means.

Your EGR is blocked off for sure. Lets not reinvent the wheel. Many people have eliminated it with success. It can help with forgiveness for spark knock at cruising speeds though.

Another thought is Harmonic balancers can slip over the years. There is a hub that mounts to the crankshaft, then a rubber insulator, and then the outer wheel that has the timing mark. Inertia over time and rubber rot can make your timing marks fall backwards. It can be verified by checking true TDC of your engine. A dial indicator is best, but sticking a screwdriver in the spark plug hole and really paying close attention to when the piston goes up and then down and has the degree or two where it is at the top. Find that and see if your balancer mark points to zero.
 

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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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Another thought is Harmonic balancers can slip over the years. There is a hub that mounts to the crankshaft, then a rubber insulator, and then the outer wheel that has the timing mark. Inertia over time and rubber rot can make your timing marks fall backwards. It can be verified by checking true TDC of your engine. A dial indicator is best, but sticking a screwdriver in the spark plug hole and really paying close attention to when the piston goes up and then down and has the degree or two where it is at the top. Find that and see if your balancer mark points to zero.
I really would check the balancer marks at true TDC that is verified by piston movement. You said at one time your timing was set to 4 degrees and now it was back to 2 degrees.

If you decide to go the HEI route, you can find distributors that are adjustable as far as both the mechanical and vacuum so you can tailor its curve.

Have you verified that your vacuum port you are plugged into on the carb is manifold vacuum and not ported? Manifold vacuum will be 18" or so at idle, ported will be zero at idle and the signal will get stronger as the throttle is opened.
 

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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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If it is pulling full vacuum at idle, it is manifold vacuum. Carbs can and do offer both types of ports on them. With me not really being familiar with a Weber carb I just was not sure which way that port on yours is.

I really need to find a cheap Weber to take apart and study and become familiar with it. I am a Carb guy from way back and really understand them very well. They all have the same basic principles to operate but how it is executed from one brand to another can be very different.
 

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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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Look at this picture from an earlier post of yours. . To the lower left you have a vacuum line that goes into the intake manifold. It should be a rubber hose, then a check valve and a plastic vacuum line connected to it. What I would do is put a longer piece of rubber line with a tee between the intake port and the check valve and plug the distributor vacuum line to that tee. That way there is no doubt whatsoever that you have the correct vacuum signal to the distributor.
 
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