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Quadrajet Carb Talk and Tips / Re: HEI Distributor mechanical advance curve options
« Last post by Cadman-iac on Today at 08:34:24 PM » Ok, just a bit of background info here, after doing all of my testing using the angle protractor to determine what the centrifugal advance each combo of plate/weight I've got on hand will yield.
Remember i mentioned that the actual engine testing results were not the same as what I got on the bench.
But comparing my bench results with the list that Kenth just posted, the differences are very slight.
For 1 example I've tried on the engine, Kenth shows that with a 370 center plate and number 139 weights, he got an advance of 25°.
On my bench test, using the same plate and weights, I got an advance of 26°, which is just 1° off.
However, on the engine, this exact same setup yielded only 20°, even when run up to as high as 4000rpm, falling short by 5 or 6° depending upon who's results you use.
What gives? I realize that the springs can have an effect on both the rate of advance as well as the total available advance, I think. Is this correct?
The next question, where would you get new springs that are not Chinesium garbage?
I have multiple sets of springs, and there are differences such as the number of coils and the diameter of the wire itself. I'll try using the smallest ones I've got to see how it affects the total available advance. This may be what I've been overlooking in the past. Any ideas?
Rick
Remember i mentioned that the actual engine testing results were not the same as what I got on the bench.
But comparing my bench results with the list that Kenth just posted, the differences are very slight.
For 1 example I've tried on the engine, Kenth shows that with a 370 center plate and number 139 weights, he got an advance of 25°.
On my bench test, using the same plate and weights, I got an advance of 26°, which is just 1° off.
However, on the engine, this exact same setup yielded only 20°, even when run up to as high as 4000rpm, falling short by 5 or 6° depending upon who's results you use.
What gives? I realize that the springs can have an effect on both the rate of advance as well as the total available advance, I think. Is this correct?
The next question, where would you get new springs that are not Chinesium garbage?
I have multiple sets of springs, and there are differences such as the number of coils and the diameter of the wire itself. I'll try using the smallest ones I've got to see how it affects the total available advance. This may be what I've been overlooking in the past. Any ideas?
Rick

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