Detonation ?
Thread Starter
Team Owner
Joined: Apr 2001
Posts: 22,267
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From: Dallas TX
Detonation ?
Lately i've been noticing a metallic rattling noise around 3500-4000. There is a very obvious point where it starts. Is it detonation? It only does it in Drive, not in park/neutral. I have pulled timing for my 383, but i guess I need to do more? I'm going to go get some 104 octane today and see if it goes away.
Thoughts?
Thoughts?
Thread Starter
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Re: Detonation ? (gkull)
LT1 heads worked over a little. GM HOT cam. 11.55:1 CR. Automatic. It will do it either cruise or WOT. The reason i know the noise kicks in at a very distinctive point is because i can leave it in a lower gear and give it just enough gas to get to around 3500 and it makes the noise. At first I thought it was something to do with the transmission until someone mentioned detontation can sound like that at higher rpms.
[Modified by Glock'94, 11:57 AM 7/17/2002]
[Modified by Glock'94, 11:57 AM 7/17/2002]
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Detonation ? (Glock'94)
I don't know what your ignition consists of. But light throttle ping at cruise is caused by to much additional vacuum advance. WOT rattle is just way to much total timing.
In my 383 with 10.84 C/R I had the distibuter recourved to bring in the advance slower (not all in till 3200 rpm) and I lowered the total mechanical advance so I could run a higher intial advance to help smooth out the idle.
I'd pull timing out till you can run on pump gas without boosters.
In my 383 with 10.84 C/R I had the distibuter recourved to bring in the advance slower (not all in till 3200 rpm) and I lowered the total mechanical advance so I could run a higher intial advance to help smooth out the idle.
I'd pull timing out till you can run on pump gas without boosters.
Melting Slicks
Joined: Apr 2001
Posts: 2,114
Likes: 220
From: Ca.
Re: Detonation ? (Glock'94)
When you scan it-how much knock retard is it pulling out? Actually I ended up with max timing (max load and rpm) in the 20's.....
Also what's your mat? If you can feed it cooler air that will help a lot!
Also what's your mat? If you can feed it cooler air that will help a lot!
