Those marks are probably 2 degrees apart, not one. This is from the '78 FSM:

So for nine degrees advance you'd have to set it between marks 4 and 5. But from the picture I can't tell where zero is. If you want to do it right you should find TDC with a dial indicator and degree wheel.

 

You said the cover on it now is different than the original one. But you did not replace the damper - the other half of the marks. They work in unison with each other. Mixing and matching will give you false readings.

Those marks may be accurate, but probably are waaaaay off! Don't trust them anymore.

Since it's now passed smog OK, you don't need the marks until next time.

What I'd do is move the distributor a little one way or the other, test drive it, if it's better, keep going that way a little at a time. Eventually it will start getting worse again, then set it to where it runs the best. It just takes a little experimentation.

Then, after you find the best place, dirty up the mark on the damper so it's unreadable, then make a new bright white mark opposite the 9 hash, so it looks like the proper mark.
Next time it needs to be smogged the tech will use that mark without realizing that's your mark.

Or get the correct damper that goes with that timing cover.

 

Thanks guys for your help. I called my friend that help me fix the engine after it dropped. He had said that he compared the mark from the old cover to the one I have on now and the only difference is this cover starts at TDC while my original cover went a few notches below TDC. I had ordered new OEM cover but the casting on the cover was off and out of round. I guess they had a bad batch. With my head under the hood with the timing light, What's your guys method on keeping a constant high RPM? The book is saying that I need 1,600 rpm but I don't have a gauge under the hood?????

Carnell

 

I shove a piece of metal in between the idle screw and throttle....and then adjust....

Are you also disconnecting the vac advance on the dist when you do this?

Also....when you are adjusting the timing....try using a vacuum gauge as well....in 'most' cases, your vacuum will max out when the timing is right...or at least close. I use that method to get it close (since the dist is on the opposite side of the timing marks)....and then tweak it in with the light.

Man...I sure do like FI and solid state ignition systems.....

 

The marks on the covers may look the same, or similar. You've already noticed they are not the same! Notice how far apart those little hash marks are - representing 2 degrees each.
Now picture if those "almost similar" marks are not exactly in the same position on the cover. Even moved a half inch is a bunch of degrees.

I've run into that problem several times before - they "look" to be the same, but a side by side comparison with a scale will show the differences.

That's why buying aftermarket stuff is often wrong. They look the same, so the parts monkey ASSumes they are the same - then you have a problem.
Have a look at a Jeep dealers book - I think there were 6 "flavors" of covers for that engine, all with "similar but different" marks.

A wooden clothespin - take it apart - the taper on it works great for a throttle positioner. You can even grind it to a finer taper if needed.

 

I always use a vacuum gauge to time any carberated motor. The rubber in between the dampiner sleeves has been known to slip, this is true especially on SBC's.

At idle with the gauge hooked up to manifold vacuum SLOWLY advance the distributor until the highest reading is reached, usually accompanied by a stumble. Then slowly retard the timing until the gauge shows 1in.below the highest reading.
You should be between 18-20 inches of vacuum at this time.

Always works for me

 

I'm not sure what hose or hoses that goes to the manifold?? Can you point me in the right direction??

Thanks,

C

 

By looking at your picture (thanks for posting them) the rubber plug at the base of the carb. should have manifold vacuum. Manifold vacuum exists at idle, ported vacuum only happens when the throttle is opened.
Manifold vacuum is the one you want. Remove the plug at idle and see if you have vacuum if so hook into that.

Hope this helps and let us know the results.

 

I went home sick yesterday. I plan on trying to work on the timing tonight or tomorrow depending on how I feel. I'll let you guys know what comes of it.

Thanks again for your help,

Carnell

 

"IF" the distributor is connected straight to ported vacuum, then setting it with a vacuum gauge is valid - it works great.

But - in this case it's still hooked up the way Jeep had it as a smogger. Any other way it shouldn't have passed the visual inspection. If the shop that passed it did their job, it HAS to be hooked up factory original.

The distributor vacuum now - or should be - is hooked to manifold vacuum through 2 solenoid valves. The ECM determines when to allow vacuum to the distributor by switching on and off those solenoids - at op temp, in high gear, above a certain RPM etc., several criteria.

In this case the manifold vacuum is only used as a power source to operate the distributor diaphragm - much like manifold vacuum is sometimes used to operate heater controls, windshield wipers, headlight doors, even power brake boosters. It's just an easy source of energy.

Setting it by the vacuum method will most likely made it run terrible. But try it.

I haven't tried it, but that method may work if you rev it up to about 2500 RPM while you find the highest vacuum point (the solenoids should both be open then.) Then, once you've found that point, turn the distributor back about 3/8" - measured at the circumference of the dist.

By "back" I mean turn it in the same direction as the rotor turns - that lowers the advance a little.
Then try starting it again - if it "bucks" on starting, lower it a bit more at a time till it starts without "bucking" (trying to kick back) during cranking. Then test drive it. Let us know how it runs like that.

"IF" you get it to where it runs acceptable, then re-adjust the carb properly to get it to idle smoothly again. Obviously they had to get it super lean at idle to pass.

You can check the timing marks to see if they are accurate or not - simply find TDC by probing through a plug hole - to physically find TDC - then look to see where the damper mark is pointing on the cover. If it agrees - then no problem.
If it's showing wrong, you could re-mark it rather than getting the right cover/damper set.


IF - so many "IF's" - after you are certain the marks are accurate - then let us know - we can guide you through a very simple procedure to "wake up" quite a few more ponies hiding in your engine. More power, higher revs, AND better mileage! It takes 0 dollars and 5 minutes to do it. But next time it needs to be smogged you have to reverse the simple procedure back to stock - else the smog station won't (shouldn't) pass it.

Smog laws are not based on what works, has lower emissions, or runs better - they are based on political bribes!

Wait till you see what's next in smog laws!!!!!!!

 

I am really surprised that you have not tried the "vacuum timing method" in my book it is somewhat old school.

What I refer to is static timing, before the racers had mapping computers and the modern technologies it was one of the ways they used to set up a engine that was so modified that this was the only way to initially set it up,
as I was taught by my father.
If you add a cam, raised the compression or your balancer had slipped this was the way to do it.
even when of the smog crap came to be in the '80's it still worked for me.
He used to do the buck thing, dial the timing up until it kicked back when starting and then back it off a bit, UNTIL he /they learned how to do a static timing/ vacuum setup.

I don't agree with the fact that you feel that by using this method will make the engine run bad, until you have at least tried it?

My suggestion is that if you have some time do a comparison, set you timing using a timing light and compare it with a vacuum gauge... or vice versa, as I have done many times!!!

Leave all of the vacuum lines hooked up, try it!!!!

 

Timing by vacuum - done it many times - probably in the hundreds. And the "advance till just before it bucks" method too. BTW - That's my preferred method when in doubt or equipment isn't available. Once you learn them, it's surprising how accurate you can be with them.

Static timing? Terminology differences? "Seat of the pants timing?" Static timing is when you set the timing with the engine off. (Static - not moving.) It's a good basic start.

Vacuum timing requires the engine to be running so there is vacuum to measure.

But - remember in this case you are dealing with a smogged down engine. The advance no longer works smoothly like we've all been used to. It no longer follows what the engine needs for power and mileage. All that is forsaken to make it have low enough emissions so they could sell them.

The curve of the manifold vacuum is sorta reversed from the old curves we are used to. The "curve" itself isn't really used, the vacuum is only used as a power source to pull the diaphragm when the ECM and the temp switches allow it - if they even work anymore.

The stock procedure on these is to run it up to 1600 or thereabouts, then set it to 16 or so. What that's doing is setting the mechanical at about mid-way of it's total advance. It's just a different point than setting it at the bottom end of the RPM range. Then after letting it drop back to idle, the bottom end of the curve will be somewhere around 4-8, depending. That's "IF" the mechanical advance is still working correctly - Jeeps distributors are famous for having the weights stick.

Interesting - some older Mercedes set base timing at 5, some even 6,000 RPM. You have your head down near the fan and belts to see it at that speed! Scary!

Then you just "hope" the ECM and all the switching devices do their part when in gear.
When you drive one of these, you can feel the solenoids kicking in and out as you accelerate.

As far as I remember, there never was a Chevy set like that, midway.

As you no doubt know, timing is very important to an engine. The engineers when having to make it conform have to do lots of things to "get it to comply" rather than worry about performance.
If they never got it to "comply" - it would be a mute issue - no more Jeeps!

It's easy to see how much that affected performance. Those engines configured that way barely can rev beyond 2500. Yes, you can get them up to 3000 if you wait a loooong time, but there's no power up there. That little 6 is more than capable of 5000 or more.

Since I no longer have a chassis dyno to actually plot the ideal curve for these engines and tailor the distributor to what the engine needs, I have to drop down to the next best suggestions. (Yes, every engine is slightly different.)

I believe in doing the total, not just partial.

Here's what I often do - even though I'm no longer in business, I get requests all the time. You can differ if you like.

1. Disconnect the vacuum line at the distributor and plug it off.

2. Find the fitting on the carb that provides the vacuum to the EGR (some go through a solenoid, some a temp switch, some go directly.) Run a hose from that port ON THE CARB directly to the vacuum diaphragm on the distributor. (If there's another vacuum hose on the port running to the evap cannister, tee that in to it.)

3. Disconnect and plug the vacuum line to the EGR Valve at the EGR Valve.

4. Set the timing at idle to about 8 degrees.


What you've just done is threefold. Now the distributor will advance slowly, keeping up with the engine's requirement for power and efficiency. It's now using PORTED vacuum.

And the EGR is no longer operable.

And, you've set the timing at the bottom end of the curve.

What you'll find is it'll idle better (once the carb is adjusted properly). And it'll feel much "snappier" when accelerating, and at cruise speed you'll actually have power enough to pass someone!
It will rev up much higher than before too.

Cost - nothing.
Time - 5 minutes.
Try it - you'll love it!

And - adjusting for the highest vacuum then retarding a tad will work like you expect it to! Or you can use the "advance till it bucks and back down a scosh."

I have to admit - I sold my last shop a few years ago, I just do this sort of thing for fun now - keeps me out of trouble.
It's been awhile since I've done one of these - the last one was almost 2 weeks ago.


Naturally I must put in a disclaimer - this is for off road use only. Next time it has to pass smog tests, it must be in the original configuration to pass. Take and save notes as to what you changed so it's easy to put it back -- in case you drive it in the street again.

 

Success!!!!! I think

Thanks again for all the posts.

I reset the timing, fast idle, curb idle, blaa blaa blaa. I made several runs on the freeway and she seems to be running good. Rich I didn't try the trick. Jeepdawg offered me some help a awhile back on some electrical issues that I'm still having and when I go see him, we can make the carb changes. I did hook up a vac gauge and at idle got no reading. If i revved the engine, the gauge came alive but only then.

Thanks agian for all the help. Now just need to get my gauge lights working!!!

Carnell

 

Sounds like you found the ported vacuum, remember it, that's the one you'll need for the conversion.
Ported vacuum is weak or 0 at idle, gets stronger as you increase the R's, but under full punch it goes away again.

The vacuum you want for the gauge is manifold vacuum - it'll be strong at idle, and strong at high cruise speed. Should be in the range of 16" or more. It will drop as you accelerate hard, but bounce back up once you stabilize the R's.

That's the one to use if you try the vacuum method of setting timing. The port should be right at the carb's base - or you should be able to find it on a Tee somewhere along the intake manifold - as I remember, there's one a couple of inches behind the carb.

Determining and getting the timing advance correct - near perfect - for the application and intended use is a complicated precision operation. Each vehicle with all the major and subtle differences in exhausts, intakes, compression, valve timing, etc., makes it an interesting science.

Ha Ha -- There is no such thing as a "generic engine." So that means there is no "generic specs" that fits everything. That's why I got the big bucks to custom tune them. What works for one doesn't mean it works for another.
The best we can do - especially over the internet with no equipment - is try to do the best we can.
Fortunately in this case, close does count.

Glad it's coming together for you.

If you really want to wake up lots more ponies in it, consider going to a GM HEI and an MC2100 (or fuel injection.)

But here again, smog becomes an issue. Even though it runs much better and creates less pollution, the smog nazis (politicians) have not been bribed enough to approve it.

 

Whats the MC2100??

I thought I saw something in 4wd parts catalog that after market fuel injection had a smog waver???

Carnell

 

Many of the aftermarket FI systems qualify for a smog exemption. Check with your local smog station to see which ones qualify. Some claim it, but not all are legal in all states.
You get what you pay for!

MC2100 - That's a common Ford carb - much cheaper than FI, but not quite as good. They work very well for off road purposes.
There's lots of info on it here - do a search.

 

I thought I saw something in 4wd parts catalog that after market fuel injection had a smog waver???

Yes, both Howell (TBI, about $1100) and MOPAR (SMPI, about $2500) are California CARB approved. Also, you could swap in a 4.0L from a YJ. That is a lot more involved as you need to start swaping electroncis, fuel pumps, and exhaust parts from the donor. Then you'd have to have it approved at a CARB station.

 

MC2100 looks like a good and cheap option. I would like to do the FI but I but I would like a lift, tires and some goodies.......



Carnell

 

But with the MC2100, you can't leaglly drive it on the highway.... Everything else will come, but first, make the Jeep reliable.

 

Good point and I didn't know that it wouldn't smog with the MC2100. Welcome to CA.....