Re: [Amc-list] Performance 195.6! ignition timing.

[Tom Jennings <tomj@xxxxxxx>]

Welp, I am armpit deep in it now. Mostly good.

I did road tests to check my timing increase assumptions. For 
standardization I filled the gas tank, warmed it up, etc. Test was 0 - 
61.6mph (3000 rpm in 3rd, tach is on the dash...) from a dead stop with 
OD locked out.

Did a test with stock timing (10BTDC) and my crazy 25BTDC.

Did three runs each.

Umm, no real difference! 15.6 seconds plus minus. More runs, more 
consistency (that's a consolation I guess). No pinging at all. Was WOT 
except during shifting. I shifted about 3400 rpm and 4000 rpm, the 
latter to overcome the huge 2 - 3 ratio gap.

I take this to mean: 36 degrees total WOT timing is not too much for 
this engine. Stock is 22! Maybe I would have seen some improvement with 
slightly less than 36 degrees advance, but it at least wasn't 
crazy-high, and if I make the distributor do 22 - 25 degrees centrifugal 
advance, I can go plus minus 5 static for adjustment range.


15 seconds to 60mph is long enough that you read a newspaper between 
shifts, so I got to watch the tach. Full advance comes in around 1800 - 
2000 (I measured earlier), so out of that 15.6 seconds, it only spent 
probably 5 - 8 seconds over 2000 rpm (where it really pulls (it's all 
relative :-)). So any improvement from timing wouldn't probably be THAT 
noticable, but I think if iI ruined timing, deterioration WOULD have been.

I also found I can't really do more than 20 or so degrees mechanical 
without the weights hitting the can, so I will drill incrementally and 
check.


I also found that the vacuum advance unit itself limits vac adv, but 
it's easy to file a small lump down and get another 2 - 3 degrees from 
it. I did that on a junk part so I can test it separately, later (one 
thing at a time...)



It's much more fun doing my own performance hacking than buying parts 
and bolting them in! Plus it appeals to Rambler Mentality...
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