HELP 1986 4.3 4bbl swithing from tb4 to Delco Voyager

pickupmanbill

Recruit
Joined
Jul 25, 2016
Messages
3
problem was no spark so it was more cost effective to swap ignition. now i have it all in an get nothing but backfiring and wont start. please any help is appreciated.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Ayuh,..... Welcome Aboard,..... How did ya time the distributor when ya dropped it in,..??

My guess is, yer one crankshaft revolution off,....
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
I went the same direction for the same reason. Cheaper to switch than to fix the old Thunderbolt ignition. You must nail the recommended setting with the jumper installed and hooked to power. On my year 4.3l engine that was 2 BTDC. Hit that exactly and I bet you solve the backfiring.

One other possibility is that firing order on the wires being off will definitely backfire.

Rick
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Make sure the engine is at tdc and the rotor points to 1 when you install. It could be 180* out. Check your firing order.
 
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