Distributor curve question

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Apr 3, 2011 | 04:14 PM

rustywheel68

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Distributor curve question

The vehicle- street-cruiser Galaxie 500, with a stock 390/auto.

I've been gearing up for a distributor recurve, and finally got into it this weekend. Before I took it apart, I took a baseline reading (using a tach and an assistant on the gas pedal). Its not the most accurate method, but its the best I've got.

Baseline:
Initial: 10 degrees
1000rpm - 10
1500rpm - 21
2000rpm - 26
2500rpm - 28
3000rpm - 30

Then, I took it apart. Its got stock-looking springs- one heavy, one light. The slots are "10L" and "15L". the arm is currently using the 10L slot, and there is a little rubber bushing around the arm, which i guess is limiting it to 8-9 degrees, instead of the full 10.

Since I was running 10 initial and its using the 10L slot, it appears that I'm all in at 3000 rpm, which was surprising, since its got a heavy spring.

So- I'm looking for advice on which way to go at this point.
I suppose I could leave everything alone, and just try to run 18 degrees initial...or I could switch to the 15L arm and then back off to 8 initial.

Thoughts? Should I even bother with changing the springs? I've got the Mr Gasket 925D on hand.

Thanks-

Apr 3, 2011 | 04:57 PM

Ziegelsteinfaust

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From: Chino Hills

For my mild cam/low compression D-Chamber or old school wedge chambers I like 14* initial, and 36* max total.

I would advance the timing, and try lighter springs. The experts say you want full advance by 2500 rpm, and some low compression motors can take it all by 2000 rpm.

Its a game and I would try a few combos to get what is right for you car. Atleast Ford put the dizzy up front. Right???

Apr 4, 2011 | 08:56 AM

krewat

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From: Long Island USA

I think that "10" is WITH the rubber bushing. It's supposed to be there.

As long as you have a "stock" cam, and you get enough vacuum at idle at 8 degrees to run the carb on the idle circuits, I'd go for the 15 slot and see what happens.

Apr 4, 2011 | 02:19 PM

Bear 45/70

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From: Union, Washington

Just bump you initial to 16° to 18°, that will give you a 36 to 38° total mechanic advance which will maximize your performance. This will also help mpg.

Apr 4, 2011 | 02:22 PM

krewat

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From: Long Island USA

At 16-18, he's running the hairy edge of the starter not turning the motor over fast enough when it's hot, is he not?

Apr 4, 2011 | 02:32 PM

Bear 45/70

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From: Union, Washington

Quote:

Originally Posted by Krewat

At 16-18, he's running the hairy edge of the starter not turning the motor over fast enough when it's hot, is he not?

I never had this issue with any of my 428s or 390s running 18° initial. I had to get in the 20°+ of initial to encounter kick back.

Apr 5, 2011 | 09:47 PM

rustywheel68

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I figured I'd start with the easiest option first- I've bumped the initial to 15. So far, so good. The car is happier, for sure. I'll drive it a bit, and may try to get it up to 16-18 over the weekend.

thanks-