Motor timing 180* out?

I think I'm going to start a new thread on this as the "Timing 180* out" is no longer valid and may confuse potential posters.
 

greg92jeepxj said:
Hey mr. Turbogus ! Yeah , I'm not fond of the term " dizzy" in terms of a distributor either . Since your inspection of the distributor drive gear and cam drive gear yielded satisfactory , I cannot see how a distributor would have "walked" out of time on its own . I'm sure you will get the engine back to,preliminary timing TDC #1 compression stroke and set the rotor accordingly and give another twist of the key . Electronic ignition is funny that way when cylinders are crossed. But the only way an engine could even start 180 degrees out is if the distributor was advanced or retarded enough to start the sequence on the correct cylinder or closest to it. It would be like pulling the distributor and turning the rotor shaft 180 degrees back to,correct it. It amazes me you had the engine running well in this condition. Can we blame the engine builder ? Did they break the engine in to turn key customer delivery condition ? I know of no way other than incorrect install or if the hold down let the distributor hop,out while running . But for the gear to mesh exactly 180 degrees by jumping out of the engine isn't possible . So I'll just say I agree with you to replant the distributor as per standard install as we have be raised from pups and been doing since then and expect it to fire as we always have . This is very interest oping however . As a last note , it will also pay to make certain that valve timing is correct as per your last statement in your post. I would want to be sure too .
Click to expand...

You may have just explained an issue I have... I bought my '86 CJ7 4.2L about six months ago. It was running OK, but had original Carter BBL which needed rebuilding, so I just put a new Redline Weber on it. Regardless of the carb, it just never really ran great. So, after buying a timing light, tach, and vacuum guage I went about verifying everything was close to spec. The timing never really looked right. At first when running the best the timing mark was off the scale advanced... Somewhere at around the 12 o'clock position on dampener. So, I decided I would backup a little further to baseline. I chose not to take the valve cover off being a holiday, time of day, and no spare gasket.

This may not have been the best practice, but I aligned the mark on the dampener with the TDC mark on the scale. I confirmed that #1 piston was at the top. I wasn't sure if it was compression stroke. I then took the HEI cap off and was surprised... It looked to be 180* off. It will not run when I drop the distributer gear in what should be the correct position - to be understood as the contact pointing at the #1 cylinder terminal. This would tend to indicate that the dampener or the cam was 180* off. I will need to verify what stroke #1 was on, but could the cam be off and the firing order be shifted by 3?
 
Hello and welcome to jeepz.com
was wondering if you did try the distributor installed 180 degrees opposite of the way it was first installed . Although I don't like to guess , the only way to be absolutely sure the valve timing is correct is to remove the timing chain cover to observe the timing marks . Laborious as that is , it will certainly confirm if any misalignment has occurred , i.e. the chain has jumped timing . The good thing though is that you get to confirm valve timing and check for #1 piston TDC compression stroke . Then there will be no guessing there after . Jumping a tooth or two is always possible and always on our mind in these conditions . if we get into the engine this far , may as well swap out a chain and gear set . Not suggesting you do so but if mileage is high . It may have a worn timing set and setting initial timing would only be so good with excessive slack in valve timing and a bit of compression is lost due to late or early intake valve closing causing performance loss.
There is a short cut but I don't think much of it and requires a dial indicator .
You would remove the valve cover and verify valve opening and closing as the engine is turned manually to verify if the same or close amount of degrees is before and after TDC .
At best , this is only a best guess and have you close but if we are going to this length , I think it would be worth pulling the timing chain cover and just do it right . Besides , who's got a dial indicator ?
Simce the engines performance is in question , it would be worth the chain and gear install if you believe a total rebuild isn't needed at this time and compression would be expected to be good .
you question if possible for valve timing to be off by 3 degrees , if it jumped a tooth or so , it is very likely . I think at this point , it is worth , if you didn't mind , pulling the timing cover and verifying valve timing . Do be sure the no. 1 piston is in fact at TDC compression stroke by checking compression .
it should be , no doubt but why not be sure as long as going to this length . If you have compressed air and a spark plug adapter , just fill the cylinder with air as the cylinder holding air will verify both valves are closed .
 
As it turned out the primary issue was a stuck intake valve, since repaired, now it's on to find the CORRECT speedometer.
 

Hi... Thanks for quick response, but I'm thinking I may have not stated things quite right. I did not think timing was off by 3*, although some stretching may have occurred over the last 116K miles. For what it is worth I am 99% sure I'm the 3rd owner. First owner was a couple that had it until about a year ago at their beach house. Then sold to another, basically just to turn a profit. I had it checked out by a trusted mechanic to insure soundness and to identify any major obvious concerns - basically got a clean bill of health.

Back to your 3* comment, what I was wondering was if it was possible to have the plug wires correct, the timing being relatively correct (it runs OK at about 14 BBC using the timing light, and have the rotor 180* off? This to me indicates that it's firing order is then 6-2-4-1-5-3. Because the timing light is basically confirming the rotor is in sync with the timing mark (TDC minus about 14*) , then #1 piston must be at the top of the exhaust stroke at TDC alignment with scale and dampener mark... No?
 
I think I may have thought through as least some of this... The PO had marked the distributer cap for #1 and I used that cable for timing light. I did not verify that the cable actually went to #1. When I pulled off all the cables and put them back on the timing mark was on the scale and could actually be set. It still runs better being more advanced than spec, but at least everything makes a bit more sense! Now I need to dial-in the Weber... Carburetion was never my strong suit, and haven't been around it for a good number of years.

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I really advise confirming proper initial timing before carburetor adjustment .
you don't want to tune or be able to attempt with timing out . Too rich will build carbon and too lean will cause damage due to pre ignition .
Simce the engine dosen't have a lot of milage and it is believed the valve timing is on from the mechanics inspection , the engine should be in good health . It still should be confirmed that number 1 piston is at TDC compression stroke when distributor rotor is firing number 1 distributor terminal .
You want to get the engine to start and run at its normal and proper specs effort starting any tuning . Advance and retard of initial timing can then be set for best performance to go on to carburetor tuning . You do at least want a good base line for the carburetor idle mixture settings for a good starting point of initial timing setting or the engine will just run poorly .
14 degrees before TDC is extreme and suggests to timing is out as far as distributor placement .
it suggests to me that the distributor has to be set at this firing mark because of either the firing order of the spark plug wires may have been started from the wrong cap terminal in its rotation and distributor retarded to compensate or possibly the distributor was installed this way .
it has been said that a rotor can be in any position to start a firing order as long as the firing order is maintained . While this is true , it's always preferred to go by the book to avoid confusion for yourself or someone else in the future at tune up time or diagnostics .
If the distributor installed rotor start point is currently different and off from the book and ignition wires are off from that , then the advance or retard is adjusted to compensate resulting in such degrees difference to compensate.
Rather than try to figure what the previous owner or whom ever set distributor installed as it is and wires set in order as well , it would be best to start again to be in agreeance with the book so no question of proper setting .
A distributor should be installed so that rotor and number 1 terminal give approximately equally rotation advance or retard for equal access of either setting if needed . I prefer it that way and just feel it works right too. No need to worry about vacuum advance being turned toward engine block and needing more rotation and unobtainable for instance .
In your case , it does sound like the distributor install or just the firing order is off from where it should be just to get proper advance / retard . I'm only advising to start from scratch by the book since the confusion of firing order versus distributor install is causing problems now .
But yes , I see from your posts that you do see a less than book spec install and setting that it's most likely that is the case . But I will say , 14 degrees BTDC is extreme .
in tuning , it's advised 2 degree adjustments at a time made to initial timing for best performance and checked with dwell / tach and vacuum readings for best performance before carburetor setting are done . Finding the balance between initial timing and carburetor adjustment is essential . The Weber carburetor will make that more "fun" to obtain . Never tuned one but said to be a tricky carburetor to adjust and obtain best results with . Great when adjusted right .
 

From my last post , I stated that adjusting 2 degrees at a time from initial timing be made for best performance . This should only be done if the factory recommended timing setting could profit from such an adjustment . This is not a requirement . It is done by many to obtain best performance but be advised this affects cylinder pressure and cylinder temperature so we need to be careful to avoid extreme damage is possible . Engine knock is tell tale , so is engine temperature . That is why book stock specs are always advised . I agree with that too .
 
yes. /\ also a note. as your engine ages, those settings can drift a little because of chain stretch and gear wear so if you use a vacuum gage to set your time and carb, it will get you to perfect. google it, if you are not aware of how to use one
 

Hoping to get back at it this weekend. When I last worked on it I got it close, but I have a concern with vacuum advance. Currently, HEI is connected directly to the correct port on Weber, but could not detect vacuum there - if ported even rev'ing didn't help. The only other place I see to get vacuum from is a fitting on the exhaust manifold directly below carb. By the size of it I would say it's thermally activated (but it is not the pancake valve - whatever that was called... ERG, maybe) . It did have strong vacuum at operating temperature, but did not vary by RPM. I'm not sure that would be good source for distributor. PO removed most of vacuum lines.

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Perhaps posting a couple of photos of your 4.2 will help others discern where else you can draw straight vacuum from Sgt. Erik.

Former Sgt. myself USMC
 

Their are two ports you can use for vac advance, one is full time manifold vac, which would be any port under the carb throttle plate or on the manifold (draws vac at idle). The other is ported vac, which would be the port on your carb above the throttle plate (little or no vac at idle, but receives vac as throttle plate is opened). Most if not all AMC jeeps came with ported. If you are connected to ported now and get no vac when you rev it up, the diaphragm in your advance can may have ruptured, cheap and easily replaced at your local parts store. Easy to check, take the hose off of the can and suck on it, if you can suck in air it is ruptured, if not it is good. Let us know what you find. You can switch to full manifold vac if the carb port isn't pulling vac, but you will have to make a few changes in your settings
 
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The reason I was asking for pics is on account I've been looking at that 360 of mine in 'Black Betty' for more than a couple of years now and can't imagine the configuration of the 4.2 and where those port may be, not only that but I've been spending a lot of time trying to figure out the Vortec motor in my GMC. :p

Thanks for your service Sgt. Erik
 
Hi Turbogus,
As to your very last comment... You are more than welcome! I just set everything to spec with the exception of the high speed idle. It's sounding pretty sweet. I'm going to take around the country block once all the moisture gets off the glass! And, I took some pics, but I'm on my mobile and I do not see where you attach them???

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Just got back from my ride and was rather disappointed. While it sounded good at idle, an no load, out on the road I felt the performance was subpar. When I mashed the pedal it balked and had a bit of a pop out the tailpipe then started accelerating. I tried to climb a decent hill on a side road, and again when mashing the pedal I got the same response. And, it just didn't seem to have any real power going up the hill. It held speed, but that's about it. One thing I should mention is it is an automatic. (No comments, please... My wife insisted!) I think I can attach pictures here... I closed the app and went to mobile website. I guess I can only add one pic at a time!
 
Try this again! _20170121_145247%7E01.jpg

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