Fuel injected 350 backfires

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06-12-2005, 08:02 AM
MOjeeper

Fuel injected 350 backfires

Hello I am new to this forum, from what I can tell you all can probably help me with this problem. I have a chevy 350 it is a fresh rebuild less that 3hrs of running. It has a holley intake dual plain, holley projection 950tdi,mallery distributer,flat top pistons, steal roller rockers(1.5) headers and single exahust. The problem is the timing light says that the timing is 48degrees advanced at idle (850rpm) it does not pop through the exahust then but if you rev to approx 2000- 3500 it will back fire and pop through the exauhast. I have not really tried to road test for fear that the engine would incurre damage from being advance so much. the commpression is approximatly 11to1. I am running 93 octain gas.
I have just recently tore it down to the timing chain and checked it and it is set just per the instructions in otherareas on the forum. I am really confused and if I spend much more time in the shop my wife and kids are going to find a new dad. Please help if you can.

MOJEEPER
06-12-2005, 08:22 AM
lt1s10

first off MOjeeper if the cam gears was off a tooth it wouldnt be running as good as it is. so you need to move on from there. the ? is why have you got so much timing at 800 rpm. your base timing need to be a lot lower than that. dont the holley projection 950tdi give you a way to set the base timing?
06-12-2005, 08:47 AM
urotu

That's what I'm thinkin' too, 48* at idle is way too advanced. You need to back off the timing and try again.
06-12-2005, 09:44 AM
MOjeeper

My ignition is seperate from the ecm on the fuel ingetction. It is not computer controled. \

MOJEEPER
06-12-2005, 09:47 AM
lt1s10

then why not set the base timing around 10 degrees and see what happens?
06-12-2005, 10:01 AM
MOjeeper

I will give it a try and get back to ya

Thanks MOJEEPER
06-12-2005, 02:30 PM
MOjeeper

Well that got it, sorta. it turned out that I had one plug wire off on the cap and the timing stabbed wrong. Thanks a bunch I know it may not seem like much but when you are lost and frustrated little things help.

Thanks
MOJEEPER
06-12-2005, 04:10 PM
lt1s10

Quote:

Originally posted by MOjeeper
Well that got it, sorta. it turned out that I had one plug wire off on the cap and the timing stabbed wrong. Thanks a bunch I know it may not seem like much but when you are lost and frustrated little things help.

Thanks
MOJEEPER

as long as you got it fixed. :D