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Hex0rz · 11-02-2008, 05:24 PM

My borther has a 400 small block chevy engine and we did a tune up on it. About a week later, it ran lke crap and we came to the conclusion that its a pinging noise when accel. in gear.

In park if you open the throttle up it does'nt ping. wtf? It blows blue smoke on deceleration and a little bit of black.

So, I think the carb. need to be cleaned up and whatnot. I'm thinking the tune caused the truck to blow its seals. Matter of fact we did a compression test and cylinder #3 had no compression. So we may have blown the rings too.

My question is:

1. Anyone know the compression ratio of a 400 SB Chevy?
2. What should the ignition timing be and is that with the advance hooked up?
3. What should the idle be in Park?

Before we adjusted timing it ran fine. The timing was adjusted to 8 degrees BTDC with advance disconnected. Although, for that whole week he did'nt have any pinging until about a week later all of the sudden on starup one morning.

I'm thinking the previous timing before adjustment was retarded so that it could run 87 octane? Could'nt you retard timing to allow for a lower octane gas? But if the compression ratio is high would'nt that pre-ignite the mixture?

I'm just trying to figure this one out as I want to clarify whether or not I ruined my borthers engine. Because to my knowledge he was using 87 octane gas for the 4 years hes had it. But all the sudden after that tune up his engine blows smoke and pings, etc.

Anyone clarify? Thanks...

11-02-2008, 05:24 PM	#1
Hex0rz Registered User Join Date: Jul 2008 Location: Washington Posts: 69	400 small block chevy My borther has a 400 small block chevy engine and we did a tune up on it. About a week later, it ran lke crap and we came to the conclusion that its a pinging noise when accel. in gear. In park if you open the throttle up it does'nt ping. wtf? It blows blue smoke on deceleration and a little bit of black. So, I think the carb. need to be cleaned up and whatnot. I'm thinking the tune caused the truck to blow its seals. Matter of fact we did a compression test and cylinder #3 had no compression. So we may have blown the rings too. My question is: 1. Anyone know the compression ratio of a 400 SB Chevy? 2. What should the ignition timing be and is that with the advance hooked up? 3. What should the idle be in Park? Before we adjusted timing it ran fine. The timing was adjusted to 8 degrees BTDC with advance disconnected. Although, for that whole week he did'nt have any pinging until about a week later all of the sudden on starup one morning. I'm thinking the previous timing before adjustment was retarded so that it could run 87 octane? Could'nt you retard timing to allow for a lower octane gas? But if the compression ratio is high would'nt that pre-ignite the mixture? I'm just trying to figure this one out as I want to clarify whether or not I ruined my borthers engine. Because to my knowledge he was using 87 octane gas for the 4 years hes had it. But all the sudden after that tune up his engine blows smoke and pings, etc. Anyone clarify? Thanks...