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[email protected] JoeCool Performance
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Discussion Starter #1
Hey Guys

The time has come to start thinking about putting together some tune ups for my Double cross plate.

I have a 349 with about 12.5 to1 compression,ported AFR 205 heads,ported funnelweb intake with cloverleaf completely removed with a 850dp with annular boosters. The cam is 260 [email protected] .50 .672 lift on 109.

What I'm looking for is jet mapping for 175,250,and 350,(currently I have a super pro shot side outlet noid but a trashcan noid will possibly find its way on so I'd appreciate those as well) timing numbers that will get me a nice crisp clean tune,I would prefer somewhat of a higher fp tune but hell beggars can't be choosers so any help would be appreciated. I have looked at the jetting chart on the NOS website but I am unsure on timing numbers.Also at what shot would I have to go from a -9 to a -10 plug? Nothing will make me happier than to arrive at a tuneup that will light the candles lol. Thanks in advance

Joel
 

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Here's the tune-up that ran well for me using a 4150 NOS double cross plate. 78N/67F, 5.0 psi fuel, 900 psi bottle, 15 degree retard. I used a 10 to 11 jet spread on smaller shots too. I used a -9 plug on the smaller tune-ups and -10 on the one listed above. This was a 15:1 18 degree SBC.
 

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18 degrees but your combo is a good big different than mine was. My approach has always been to establish what timing it likes on motor-only and retard from that baseline.
 

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[email protected] JoeCool Performance
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Discussion Starter #5
That's usually how I do it but my box only goes up to 15 deg retard and on motor I run my timing high enough that the retard is not enough sometimes. On my last run with a bigshot plate on a .82n .73f tune I ran 22 deg.
 

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Same here. The 7531 step retards max at 15 degrees or 25 total. I just use step one and two combined when I need more than 15.
 
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