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jrmz28 08-24-2004 02:00 PM

total advance problems
Good day. My problem seems to be that if i advance my timing past 32 deg total i get detonation.I am running 355 sbc,10.5-1 compression,1.94-1.5 58cc heads.My base timing is 12 deg i also run no vacuum advance.Any thoughts that may help would be great thank you.

lluciano77 08-24-2004 02:03 PM

What is your cam duration @.050"?

Lobe Sep.?

What RPM is it detonating at?

jrmz28 08-24-2004 02:12 PM

total timing
My duration is 246 at 50,lobe sep 110,rpm? do not no took the car to drag strip this week end .Try ed 35 deg checked plugs after run showed detonation.

lluciano77 08-24-2004 02:49 PM

So is it safe to assume that it is not in the 2,500 RPM to 3,500 RPM range? That is where most detonation happens. Your cam should be able to bleed enough pressure to eliminate problems in this area.

On high compression engines, above 5,000 RPMs the pressure can build up again and cause detonation. That can't be fixed with more duration.

Try and pinpoint where the detonation is occuring. Have a friend with a trained ear ride with you.

Slant3 08-24-2004 03:53 PM

1 Attachment(s)
Thats exactly when mine begins to detonate.(wot at 3000 rpm)
check the plugs and they looked fine(only that they smell and have some fuel on them) .If I just steadly increase rpm it does'nt detonate. Only When I crush the pedal.
515 lift----246 at .050----108 lobe sep.---10:1 comp.

lluciano77 08-24-2004 03:55 PM

Your plugs look fine from that picture.

You need a magnifying glass to check the plugs for detonation. Look for aluminum balls.

Try having your advance come in sooner. Use the lightest springs.

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