- Joined
- May 7, 2012
- Messages
- 250
- Reaction score
- 3
- Location
- Near Houston, TX
- My Car
- 1971 Coupe. 302 2V - C4 trans
It seems to run fine at various timing settings as long as the RPMs are below 3-4K RPMs. Adjusting the timing a little at any RPMs below 4k doesn't make much difference.Ok, Did you do what I suggested?
If so what were the results when you drove it?
it misses at very high RPMs (5K RPMs) without load on the engine, so it is difficult to perform this test.Rev the engine until it misses then move the distributor in both directions and see if it smooths out.
Spark plugs are all in good shape. As I said they were all a nice tan color, and properly gapped. Compression tests were all nominal and generally consistent for all 8 cylinders.I mentioned it could be plug wires or weak points spring or bad advance or the electric choke . Try some other plug wires from another car and disconnect the choke as I suggested then post the results after you do these tests . You will likely not find the prob unless you simply start changing parts.
If your spark plugs are black they can cause the same prob.
This seems like the key issue. timing is off at the high end. So far, I can't find any malfunction in the mechanical or vac advance systems that are causing my timing to be off at the high end..Here's your numbers
800 10
1200 8
2000 16
3000 20
4000 22
5000 25
The numbers below are far more common unless the compression is extremely high.
650 .... 10
2000 .. 20
3000 .. 32
Understand. If you review my previous post, you can see the initial timing is about 10.Your stock distributor should provide a maximum of 10* vac advance and 21.5* centrifugal. So total should be 10* + 21.5* + initial Adv*. Tuning spec says 6* BTDC so the max you should see would be 37.5*. This is design but optimal for a motor is usually 34 to 36*.
Right now, I can't get the initial timing below about 10 due to vac advance module hitting the air conditioner bracket....
again: initial timing is 10deg at idle of about 800-850. 15 in-mg vacuum.What is your initial timing set at and your idle rpm?
I tried. I don't have any instructions for how to adjust this device, and it didn't seem to make much difference with the hex screw tightened down or loosened.When you replaced the vacuum adv did you adjust it to provide the correct adv?
I'm posting some pics of the distributor. I disassembled it tonight to inspect, clean. it looks fine to me. If anyone sees something in the pics out of whack, let me know - I don't see it.
very helpful thoughts here. I did this and when I look at the weights, they seem to be stamped with 13L (although the "3" is backwards???) implying 26 degs advance. I posted pics and I can't find any "rubber in the slot". Can you elaborate on this? this mechanism seems to move freely and the weights are free to move as designed. I can't find any problems looking at it. I noted that one of the weights is stamped with "62" and the other with "64". The springs holding each look a little different, but both seem to work fine.I suggest inspecting the breaker plate for mechanical binding or the small round plastic glides being damaged or missing (I'm assuming OEM distributor). If those are good, carefully remove the breaker plate and inspect the mechanical advance, checking for binding of the weights. Look to see what numbers are stamped on the advance limit stops. The one being used will have a stop pin covered with black "rubber" in the slot. If it is stamped 13L that means 26 degrees of mechanical advance at the crank, when it is all in. 15L means 30 degrees etc.. Just my thoughts on the matter.
Chuck
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