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350 Vortec Fouling Plugs

1064 Views 11 Replies 5 Participants Last post by  Aaron
Guys need some help. Recently acquired a sbc 088 Vortec engine with unknown cam. It had been sitting for about a year and the carb was in need of a rebuild but ran decent. Long story short I’ve replaced everything that bolts to the long block. It ran decent for a few miles and then the plugs turned black and sooty. I’ve verified timing with a tdc tool as the balancer mark was off. Now when I blip the throttle it want to sputter back thru the carb and shoot the occasional flame. I verified timing again and then pulled the plugs and noticed how black they are. Need some advice. Specs below.

350 Vortec with 1.54 pistons (so I assume they are .045 in the hole and horrible quench unless previous owner milled the block more.

unknown cam but it’s mild as the Vortec springs appear stock.

Quickfuel 650-q carb (stock and the accelerator pump shoots good as soon as I give it throttle)
Accel HEI distributor
Summit wires
Ran TR55 plugs gapped at .045 but just purchased some 3926 to try a hotter plug.
edelbrock rpm intake
Hv oil pump (60 at idle)
6.5 psi fuel and floats are in the center of sight glass.

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Autolite 3926 is not for a Vortec head.
Vortec head takes .708" reach tapered seat plug....the 3926 is .750" reach gasket seat plug, typically used in aluminum heads. Not interchangeable.

Autolite 605 is the stock Vortec application plug.
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