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Author Topic:   Ignition timing
r19v
Dirt Roller

Total posts: 19
posted October 07, 2001 10:46 PM
How much total ignition timing advance do most of you use on a sbc on alcohol?

WILDphil
Dirt Full Roller

Total posts: 32
posted October 07, 2001 10:58 PM
I try to run mine around 36-40 degrees.

smayo964
Dirt Forum Racer

Total posts: 90
posted October 07, 2001 11:04 PM
Most of the builders and people I've discussed with run in the range of 34-35 degrees. Some run as high as 37. Per some tech publications, once you get above 34 your upsetting balance between ignition timing cam timing. In addition, you'll have more difficulty starting a stalled hot engine. Everybody seems to have their own preferences due to how each builds their own equipment. Hope that gives you some ideas.

r19v
Dirt Roller

Total posts: 19
posted October 08, 2001 09:23 PM
I thank both you guys for your replys. The reason I asked this question was that I read on a website, about alcohol as a racing fuel that to use 40 degrees plus timing advance and a minimum of 14:1 compression ratio. We are running 36 degrees advance and a 12.5:1 compression ratio. Is 14:1 a common compression ration to run with alcohol? Thanks

sdhnc29
Dirt Freak

Total posts: 467
posted October 08, 2001 10:16 PM
Yes , 14:1 is very common . In fact , most of our alky engines are at 15.5:1 . Alcohol is an extremely slow burning fuel , thus , these engines thrive on compression . On average , a 23deg. engine likes to see 36deg. of timing . But you should run your engine on a chassis dyno or engine dyno to be sure . Piston dome , and combustion chamber design will greatly influence your ignition timing . On a dyno , you can see the affects of ignition timing , and find the exact place that your engine likes to run best . Hope this helps !

r19v
Dirt Roller

Total posts: 19
posted October 08, 2001 11:21 PM
sdhnc, thanks for your reply and the sharing of your knowledge. Roger

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