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TeamRush Help

810 Views 12 Replies 3 Participants Last post by  Junk Yard Genius
Myself, like many others, have enjoyed your articles on the TFI upgrade. I converted mine about a week ago and it is truely
worth the cost. I still have a problem with a dead spot when I accelerate. It's not always present and other times it wants to almost
stall, pop, and then come alive again. It seems to happen around 1300 RPM and doesn't matter if the engine is hot or cold. I have
a rebuilt dist. I can't seem to figure it out. Any ideas? I have a 1980 cj7 304 and TF999.

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Does it 'pop' down through the exhaust, or up through the carb?
If it blows down through the pipes, it is almost always ignition,
If it blows up through the carb, it's almost always carb...

If it's a 'dead' spot in acceleration, it is probably the accelerator pump.
If it does it when you have steady throttle at that rpm, it may be carb or ignition...

Does it go away or climb over it if you pump the throttle pedal? (More Accelerator pump)
Does it go away if you let out of the throttle a little bit and hold RPM around 1300? (Accelerator pump)

Around 1300 rpm is where your carb is transferring from idle circuits to main jet circuits...
It's also where your centrifugal advance should be in movement...
It's also where the vacuum advance should really be topping out...

You may have enough engine now to uncover other problems.

Give info on engine/ size/ carb/ trans when you post next, and will slap this alligator's butt too!

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
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Thanks for answering. It pops up thru the carb. If you continue to accelerate it will go by it and catch again. The engine is a 304
with a 401 intake adapter plate and a 1406 edelbrock carb. tranny is 999. I had a ford 460 carb on it before and it did the same
thing. It seems to do it at the 1st to 2nd shift point. I remember when I set the timing it seemed to jump a little bit during accelertion.
Any help?

I forgot to answer your question. Yes you could discover Florida..........If Al Gore invented the internet did he also invent the JEEP?

No, Thank God. The Jeep was invented by Karl Probst in Butler, Pa. in 1940. He was a design engineer for Bantam./wwwthreads_images/icons/cool.gif
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Find and down load the original article on using a vacuum gauge I wrote if you don't already have a copy.
Hook a vacuum gauge to the cotton picking thing, and I think you might find the problem...

You said it did it with a different carb, and I know you upgraded the ignition recently, did you change the distributor during the ignition upgrade?
If so, did it do it with both distributors?
Have you looked into the possibility of the module being bad?

Here is what I'm thinking,... so keep in mind this is just thinking out loud....

If it's popping through the intake, the only way it could be the ignition is...
1. If the module malfunctioning around 1,300 rpm and firing the cylinders too soon...
That would still require an extraordinary set of circumstances to occur.
You might trade modules with someone and see if their jeep does it and yours stops doing it...

2. Check to make sure the centrifugal advance and vacuum advance are working as advertised. (Since it only happens at a specific rpm, I don't see how this could be affecting it.)

3. Verify the timing mark on the balancer. That is a long process, but worth the trouble to make sure your timing is correct. (again, this is a long shot)

4. Check the resistance on the distributor pick up coil. A break in the winding can cause some strange things... (another long shot)

5. Do you have a factory tach? I have seen the factory tachs do some strange stuff when they are going bad... (another long shot)

6. If all else fails, swap distributor, module and coil with someone, and see if it still does it.

A lot of work, but that would rule out the ignition system entirely...

The only way to make ignition 'Pop' back through the intake manifold is to fire one or more cylinders so early the intake valve is still open.

Bad cam timing, bad lifter or lifters, sticking valves, worn out valve guides, pitted or grooved valve seats, weak valve springs, bent or broken rocker arms and bent push rods can all make the symptoms you describe.

So can too lean of fuel mixture, vacuum leaks, leaking intake manifold, or raw fuel leaking into the intake tract.

Hang a vacuum gauge on that sucker, and verify your idle mixture.

Do a compression test with all the plugs out.

I'm betting if it's not idle mixture or bad accelerator pump, it's one or more cylinders is below 90 lbs, and you have very weak valve springs...

(Bad accelerator pump will cause exactly the symptoms you describe. But if you changed carbs, what are the chances of two carbs having the same problem....)

If that is the case, have a head job done, and get some new valve springs. Check the cam for lift, and check the lifters for wear and function.

Pay real close attention to the head gasket for anything that looks like a blow through between cylinders.

If you reinstall and still don't have any compression, time to go through the short block.

I'm also betting you have a cam timing problem. The AMC engines had a real problem with cam chains stretching so much the valve timing is screwed up.
They stretch so much they can actually jump a tooth on the crank gear...
Again, check the cam for lift. AMC cams like to round down the lump on the cam, and that WILL cause the problem you describe.
(can't call it a 'cam' anymore, you have to call it a 'round'..../wwwthreads_images/icons/wink.gif)

I tore down about 30, mostly factory assembled, AMC engines in the last six months, and they all had one thing in common, worn out cam Bering, flat cam lobes, and timing chains that could be worn by fat guys as belts.
Lots of front covers damaged by timing chains.
Lots of lifter faces worn through, especially on the even fire bank.

Lots of factory retarded cam timing for some reason.
I assume emissions control, but that is a guess.

Most all of them showed oil loss to the #7 & #8 rod bearings in a big way.
Most showed signs of pitiful valve spring pressure... Lots of chatter, slop, and bounced valve locks.

All had factory rear main seals leaking like a sieve...

Most had fuel pump drives, cam gears, and distributor gears worn out for lack of lubrication.

Just thinking out loud...
Let me know what you find please...

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
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My engine is fresh. I rebuilt it myself. I've got new pistons, crank, cam, double roller timing set, rebuilt dist( from autozone), the cam
timing gear was verible but I triple checked it to make sure it was in the correct position and even used the old chain and gear to
verify the position. I'm sure it's not the carb, I do have an extra duraspark module and I'll probably change that tomorrow. I am kind
of leaning towards thinking that it is a problem is with the distributor either with the weights hanging up or a bad pickup. This problem is
intermittent and other than that the engine really turns on. I did read (and copy) your article on vaccum. The vac seems to be good for
the cam I have in there. I'll let you know how I make out. Thanks a ton.

An intermittent problem with a distributor is hard to catch unless you have a distributor machine, and then it's tuff!
I wish you luck...

You might try pulling the vacuum advance line off of the distributor and plugging it...
And use a timing light to watch the timing mark as you rev it up to about 3K and let it back down...
It will tell you if anything is sticking...
If it's just hanging up around 1300, then try that several times and see what you get...
You may have to find a friend that will let you swap distributors, or try one from the parts store, but you may have to take it back, so make sure it's one that is friendly.
I'd also check the coil...

Let me know what you find please. I'm interested in this one... Aaron.

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
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You said to also check the coil. Which one?

Bye the way if you do discover Florida you would find that every other license plate is from New York. Do you think it's because
of the new neighbor in town (Hillary)?

One other question------ Does the duraspark module need to be grounded. I've got a glass body.

Check both the distributor pick up coil, and the ignition coil.

The Dura Spark Module is supposed to ground through the black wire that goes to the distributor, but I always splice into that wire and ground it manually.

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
Well today I replaced the duraspark unit with a used one I had . It ran really bad so I changed back to the original unit and guess
what. The thing runs perfect now, no more hesitation. All I can figure is must have been a bad connection. Thanks for your help.
Also, I did have an extra dist. but during my engine rebuild I decided I would turn it into a shaft for prelubing my engine. When I
hooked it up I couldn"t get much oil presure. Well to make a long story short I missed a oil galley plug. Saved my engine from
certain ruin.

Another benifit of pre lubing!

Glad to hear you found your problem. Ford had a real problem with the module connectors for some reason.
I always fill my connectors with dielectric grease to seal moisture out.

Just a thought.

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
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