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post #61 of 65 (permalink) Old 04-13-2019, 06:41 PM
 
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Ok, got it. Started a new discussion titled "Distributor Timing" to begin a fresh discussion and separate your situation from the original post.

https://www.gtoforum.com/f170/distri...tuning-134141/
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post #62 of 65 (permalink) Old 04-13-2019, 06:55 PM
 
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So cj if I had your distributor I would put a breastís bushing in it to limit the travel ad knock that 30 back to 24 or 26.

You would then set the base at 10 or 12 for 26 total. You would then add 10 degrees from a vacumn can for 46 to 48 light throttle cruise.

Once there if no pinging, you cab turn the base up 2 degrees and check if ok you can run 38 total with 22 or 24 degrees idle timing.

You say you must have 26 or more idle timing,...well really you should see it this way a very radical cam CAN take more timing at idle....

But there is not a Mandatory number....24 or 26 at idle is smooth on a hot cam,...20 degrees is smooth on most hot ones.....can you go more?

Maybe but it is a distinction without a difference usually. The total timing is the most important number,....if you want more at idle that you have to take it out of the centrifugal weights,....I have done them 18 centrifugal and 18 base =36....+10 vacumn.......

That is 28 at idle, a real hot cam can take it, but the difference in idle cooling from 24 to 28 is not really of concern. The concern is when guys have base idle at 6 or 8 or 10.......and use ported vac with no more advance at idle.....even at 16 degrees idle timing like you have you will be ok.....you can run it like that....

There is no absolute number, some engines even can take 40 degrees, but you have to be really tuned in, like racers and engine builders like PJ and BigD....they know what their car needs.....b feel and experience..

So donít get hung up on it must be 26 base etc,..the difference of a few degrees will not likely even be noticeable, as long at the total is right nd no knocking
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post #63 of 65 (permalink) Old 04-13-2019, 07:02 PM
 
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Brass bushing ...sorry typo

I missed that notice PJ I was tying the response,maybe it can be moved to the correct forum
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post #64 of 65 (permalink) Old 04-13-2019, 09:28 PM
 
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Originally Posted by Lemans guy View Post
Brass bushing ...sorry typo

I missed that notice PJ I was tying the response,maybe it can be moved to the correct forum
OK, got it done. Just did a simple copy/paste to switch it over. Corrected the typo - I won't even ask. LOL
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post #65 of 65 (permalink) Old 04-20-2019, 10:00 PM
 
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Recommendation to all seeing AFRs spiking lean on deceleration (and /or back firing) - check for exhaust leaks.....Ask me how I know .

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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