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First drive in the Z, Backfiring and sputtering.


messenger

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My '70 240Z sat for about 8 years in a garage before I got it. It did much the same as yours.

1) The first thing I did was remove the plugs and put a little oil in the cylinders incase the rings were stuck. Then I turned the motor by hand. I guess you're past that now.

2) I removed the carbs and gave them a good cleaning. That helped but it wouldn't run for very long.

3) I drained and removed the tank and took it to a radiator shop to be cleaned out. I also changed out all the rubber fuel hoses.

4) The rubber brake hoses were rotten so I changed them out and purged the old brake fluid.

The old car now runs and stops just fine. However, I think it would benefit from a complete tune up.

I let my 17 year old son drive it today while I was in the passenger seat. He got a real kick out of it and so did I. :)

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Ok, heres the update. I've checked the compression seems to be about 160 across the board, that seems in check.

I have checked the points, they are clean and the gap is correct.

I ran the car out of a gallon of 93 octane. No luck the car ran exactly the same after all of this, no different at all.

The car is still suffering from a lumpy idle, almost if I had a cam. While reving the car its still missing and hesitating, If I had not run the compression check by the sound of the motor I would think the compression is down. When I rev the car to about 1500rpm and hold it there, it runs pretty rough.

Help Me!!!

Thanks again

-jared

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Yes, reading back over this thread, I'm pretty convinced the problem is somewhere in the dizzy, may even be the advance mechanism. If the plate mechanism fails then it gives symptoms similar to this.

Give the cap a try.

Hmmmm, I wonder where I've heard this before...... (reply #4).......

Enrique

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Oh, no worries there. I wasn't referring to your repeating something I wrote as much as that Messenger (the original poster) hasn't yet posted whether or not he has checked that part.

As we all know, there are many "minor" problems that can be erroneously interpreted as being something else, and then repairs attempted that can really bollix the whole car up.

So, Messenger, as Carl has posted, you need to get at least 1/4" inch of MOVEMENT (if not more, I'm not sure). If you are NOT getting that movement, then it is very possible that the plate has returned to it's proper position SOMEWHAT, but not necessarily to it's proper position, and your timing is off. That's what the advance plate does, it literally adjusts your timing under heavy acceleration to allow the car to rev up. If it doesn't, then you'll experience everything you've listed.

Voice of experience here. My car went from a joyful ride to a handicapped, coughing turtle in the middle of a ride. Took it to a specialist mechanic and although he also did a tune-up and valve adjust, he told me it was the advance plate that had gone out.

2¢

Enrique

P.S.: I must be out of touch, but what does MOM stand for (no wise cracks guys)?

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Ok, the inner workings of this distributor are very foreign to me. I have it all apart, i looked in the distributor no sign of any ball bearings in there. Anything else I should check in there while it is all apart. I have it all apart other than the cam and counter weights those are still in there.

How can I check the "vacuum capsule" as hayes reffers to it, for the neccasary 1/4" of movement? Just by pulling on the spring?

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Sorry to post again but I just made some progess. I have figured out whast going on here and roughly how the system works.

Im pretty sure something is screwy with the vacuum advance plate. It is very hard to move or twist it is very notchey, I don't think that a little bit of vaccum would be able to move it very easily it was probally jammed. Im going to give it a nice cleaning and lubing.

Now to figure out where to set it?

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