General Category > Quadrajet Carb Talk and Tips
HEI Distributor mechanical advance curve options
Cadman-iac:
More pictures.
One note here, most of these results were obtained at 3500 rpm, although I did run all of them up to 4000, and even some as far as 6300, which is what the blower motor I used runs at full power.
I noticed that a lot of these would begin to loose some of the advance at speeds above the 4000 rpm threshold, but it was only a small amount, usually around 2 to 3 degrees.
I also did these tests using the smallest springs I had, I think they were .023" in wire diameter with 4 coils per spring.
I did one test using a bigger set of springs, I think they were the biggest ones I have at .032" thick wire and 5 coils per spring. These had the advance coming in much slower and not maxing out until over 5000 rpm.
So what I'm going with in my truck at this time is the 402 center plate and the 139 weights with the small springs.
I need to test this combo in the truck just to verify that my distributor tester is actually yielding correct results. I'll be doing this tomorrow, and I'll report back with my findings then.
Rick
PS: The picture of the timing indicator showing the light took 6 or 7 tries to get a picture that caught it just right.
Cadman-iac:
Something else about these center plates, the 422 plate is out of a Cadillac distributor, which explains why it's got a really small amount of advance compared with the others. Not sure what the other plates are from.
Rick
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