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[daredevil]

Initially starting my motor. how much advance would you start out with for base timing? 500 cube indy head 600 lift solid roller street motor 10.5 to 1 on 93 octane. I,m thinking about 8* with centrifugal adding 24* more. any opinions?

 

[Meep-Meep]

I think ultimately your advance will depend on how efficient your chamber is. A fast burn chamber (I.E. good quench and a flat top piston) shouldn't need much. That said I'd be willing to follow your thoughts if it were my motor.

 

[daredevil]

Talked to my motor guru and he said by the cam card it will need about 18 and 18 . Suprised the hell outta me. Glad I have intelligent people to turn to. I would have never guessed it needed that much.

 

[Meep-Meep]

18 and 18 is still 36 total, which is right about what a MoPar engine wants. Bottom line is you will be the one with your hand on the distributor and it won't hurt to start out like you said. You might be at 18 deg 20 secs after it starts once you get a feel for what it wants. If you were running real 100 octane race gas then I wouldn't be concerned.

I used to run 15 deg initial on my 383 (36 total) and it was fine but I didn't start it like that. It was only after some initial tuning that I figured out what it wanted. I think that's because the cam bled off enough cylinder pressure that it allowed (required) that much initial. You cam is pretty big so you are likely to fall in that same category. Some race engines run nearly full advance (36 deg) right up front with the last 2 deg or so coming over a few thousand RPM to keep the weights from bouncing.

 

[daredevil]

Youre spot on as he said thats where i should start but we may need to lock it out and bring up the initial. Sounds like this things gonna be a beast.

 

[dantrap]

I never had any luck with the 93 Octane even with aluminum heads. 36 total on race fuel worked good for my setup, which is similar to yours except mine is 12.5 to 1 comp. My timing is locked also, but i use an MSD timing control module for start up( it pulls 20 deg out) and also for pulling timing out when I spray nitrous. I am think about going to a digital 7 setup that i can play with the timing a little more, like adding a slew rate for off the line power reduction. I have to do a little more home work, but I think there is one in my future.

 

[daredevil]

thats an option i may look at too. thats a lot of compression for trying pump gas. mine should work fine. we built it specifaccly for 93 octane. if it needs more i may try jetting for ethanol. Its a street car so I dont want to run race fuel. Mileage is gonna suck already.



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[Meep-Meep]

At least you have 93 octane. The swill they peddle out here is 91.

If you have to go alky that could be a good excuse to put a blower on it :tongueflap:

Then maybe you can get some "go green" grant money for alternative fuel research :grin:

 

[dantrap]

Hey Daredevil, I will tell you we made a bit more power on 106 octane E-85 (summer blend)vs. 110 vp race fuel on a recent dyno run with an EZ Indy 512. With the cold air up here we ran out of jets at 106s, but did not have the time to make more changes. You cant beat $2.29 E-85 vs. $9.00 a Gal VP. They say you use about 25% more E85 but its still cheaper. This mill is going into 70 Ebody that is a limited use street car, but will run in the mid 6s on the 1/8. Let us know if you change over and how you make out. Good luck!