Petronix Ignitor questions

[steveg]

re: 35 degrees = 35/360 of 19.625 = 1.91" (1-7/8"+)

I'm at work and most my brainpower is on other topics, but I don't think this allows for cam rotation being half crank rotation; i.e. every degree of cam is two degrees of crank (advance is measured in cam degrees). At any rate, almost 2 inches seems like a lot for measuring advance at the crank pulley. I may be wrong here, but ...

From Norm Nock's book, page 88:

 

[Jeepster]

That's very helpful thanks.
one thing that is confusing me-
the timing for a stock set up should be 12 degrees BTDC ( according to the previous post, I thought the manual said 15?)
following installation of electronic ignition the timing needs re setting but to what number?
Fitted the powerspark ignition tonight ( what a faff, the pos earth requires some modding of the wiring) and now the engines runs really rough. Plan to buy or borrow an adjustable strobe tomorrow to see if I can sort it out.

 

[Bob_Spidell]

From Norm Nock's book, page 88:
View attachment 33941

OK .. we're talking crankshaft degrees. It's dwell that's in cam degrees.

 

[steveg]

That's very helpful thanks.
one thing that is confusing me-
the timing for a stock set up should be 12 degrees BTDC ( according to the previous post, I thought the manual said 15?)
following installation of electronic ignition the timing needs re setting but to what number?
Fitted the powerspark ignition tonight ( what a faff, the pos earth requires some modding of the wiring) and now the engines runs really rough. Plan to buy or borrow an adjustable strobe tomorrow to see if I can sort it out.

From the manual, page 21:


I've used 35 degrees at 3000 rpm for a long time - seems to work well with the gas I buy.

The 12 degrees was per Norm Nock, not the manual. That screenshot was to illustrate that the dimensions involved were referring to crankshaft degrees, not distributor degrees.

The 6400 rpm's a laff, isn't it. :wink-new:

 

[DerekJ]

By coincidence, after starting this thread, I finally got around to installing the Powerspark yesterday. My car is negative ground and the installation was fairly simple. Before we installed it we checked the timing at 500 and then 3500 revs where it was 32 degrees. At 500 the mark was jumping all over the place, it was steadier at 3500. After installation of the Powerspark the mark was dead steady at 500 but for some reason wasn't advanced enough at 3500 and was spitting and running rough. We advanced it to 34% and the car is now running fantastically well. I took it to the local bypass and thrashed it through every gear right up to about 100mph and it never fluffed, pinked or missed a beat. I'm very pleased.

I believe that my distributor probably has a worn shaft and that was causing the mark to jump around with the points system but the Powerspark has cured that. Some PO has also messed about with the base plate, which seems to have a couple of welds in it. We didn't try to remove it and so we didn't play around with weights and springs to adjust the advance curve. At the end of the season I may consider a new distributor, and after finally caving in and going electronic I may go the whole way and install a 1-2-3.

Points to remember are that your timing light might be slightly off and each car's engine is slightly different so that a certain degree of advance might work for one car but not another so best not to get so hooked up on a specific number. Set it in the region then make minor adjustments and test it each time until you're happy with the setting for your car.

For UK members, buying the Powerspark over the Alden is a no brainer. It's the same product for less than half the price.

 

[Jeepster]

By coincidence, after starting this thread, I finally got around to installing the Powerspark yesterday. My car is negative ground and the installation was fairly simple. Before we installed it we checked the timing at 500 and then 3500 revs where it was 32 degrees. At 500 the mark was jumping all over the place, it was steadier at 3500. After installation of the Powerspark the mark was dead steady at 500 but for some reason wasn't advanced enough at 3500 and was spitting and running rough. We advanced it to 34% and the car is now running fantastically well. I took it to the local bypass and thrashed it through every gear right up to about 100mph and it never fluffed, pinked or missed a beat. I'm very pleased.

I believe that my distributor probably has a worn shaft and that was causing the mark to jump around with the points system but the Powerspark has cured that. Some PO has also messed about with the base plate, which seems to have a couple of welds in it. We didn't try to remove it and so we didn't play around with weights and springs to adjust the advance curve. At the end of the season I may consider a new distributor, and after finally caving in and going electronic I may go the whole way and install a 1-2-3.

Points to remember are that your timing light might be slightly off and each car's engine is slightly different so that a certain degree of advance might work for one car but not another so best not to get so hooked up on a specific number. Set it in the region then make minor adjustments and test it each time until you're happy with the setting for your car.

For UK members, buying the Powerspark over the Alden is a no brainer. It's the same product for less than half the price.

Sounds like a good move with your ignition.
the figures you mention ( 32 and 34), is that degrees BTDC for strobe timing or degrees on the pulley?