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Old 06-11-2014, 12:21 PM
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locking out ignition timing?

The engine I built for my v8 s10 project has a very aggressive cam, more aggressive than it should be, and I was wondering if I might benifit by locking out the ignition timing to a set advance?

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Old 06-11-2014, 12:36 PM
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Yes, the ignition timing needs to be addressed and many fellows have found that locking it out is the answer. You may be able to help yourself even more by coordinating the static compression ratio with the intake valve closing point so that you're producing max cylinder pressure for the fuel you will use.
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Old 06-11-2014, 01:14 PM
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I have an aftermarket gm hei distributor, I belive its made by accel, do they make a kit to lock out the mechanical advance? And how would I go about coordinating the static compression?
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Old 06-11-2014, 01:21 PM
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TI's implying you get a smaller cam.

you can lock out the distributor yourself with either set screws or welding- I weld mine.

What cam/compression are you running? you may NOT want locked timing depending on your combo.
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Old 06-11-2014, 01:24 PM
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The cam is a 303/313 duration and .487/.508 lift, and compression should be close to 10:1
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Old 06-11-2014, 01:53 PM
How fast is fast enough?
 
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Quote:
Originally Posted by twenglish1 View Post
The cam is a 303/313 duration and .487/.508 lift, and compression should be close to 10:1
what cam, adv duration number mean very little.

what engine?

What fuel?
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Old 06-11-2014, 03:01 PM
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I beilive its his 11.1 305 with 233/243@.050.... very close to that anyways.
Huge cam, small motor....
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Old 06-11-2014, 03:03 PM
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SBC 305 build question
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Old 06-11-2014, 03:15 PM
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Yeah that's it, I know I could have chosen a better cam but oh well I am determined to make the best of this and learn for the next build
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Old 06-11-2014, 03:22 PM
How fast is fast enough?
 
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if you really have 11:1 you'll want some mechanical advance. 24 initial and 34 total is where I'd start. If you have a high stall that may be inconsequential though.
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Old 06-11-2014, 03:33 PM
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I don't think its 11:1 probably 10:1 at the most, any way to estimate it with a cylinder pressure gauge?
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Old 06-11-2014, 03:39 PM
How fast is fast enough?
 
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Originally Posted by twenglish1 View Post
I don't think its 11:1 probably 10:1 at the most, any way to estimate it with a cylinder pressure gauge?
nope. Do you have a high stall and gearing?
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Old 06-11-2014, 04:45 PM
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Not yet but I will, what would you recommend?
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Old 06-11-2014, 06:56 PM
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i just removethe weights and springs and then bind the advmechanism locked fully advanced using two cable tie wraps.

Orient the knuckle down under so to rotor goes back on.

Do not buy less than a 10" 3500 stall. That stall will only see 3000 stall behind a 305. really needs a 8" race converter.

needs plenty gear too. 4.56++
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Old 06-11-2014, 07:11 PM
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you can limit the adv travel stop or simply
lock it. depending on where you add the machine screw.
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