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Huh Went to the track today these are the times I ran.
first run time run: 60' 2.142; 330' 5.401; 1/8 mi 9.054@81.04; 1000' 11.664; 1/4 mi 13.878@101.65.
second run time: 60' 2.106; 330' 5.929; 1/8 mi 8.985@81.08; 1000'
11.590; 1/4 mi 13.801@101.85
third run elimination: 60' 20.069; 330' 23.995; 1/8 mi 27.036@80.72; 1000' 29.649; 1/4 mi 31.859@101.82
The last run went to wot from the light it sounded like a rifle shot when it backfired thru the carb. The car died but restarted right up.
Checked the plugs and they looked alright(like light chocolate milk).
The car ran good all day both driving to and from the track.
I am at a lose on where to go from here. Hope to have this figured out by saturday. They are having a powered by ford day.
Hope someone can steer me in the right direction.

drive it like you stole it
Man! You really need to grab another carb and try to narrow this down. Starting with the carb is my recommendation. That way If it still does it we can look at timing, broken valve spring or wore down cam lobes. Just MHO

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Just cruising along minding our own business when BAM!!! The LAWS show up.
My backfires through carb have always been the result of a bad plug or ignition wire.

73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

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This is beginning to sound like a valve train issue to me.

Valve float?

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
3rd run, car's hot. Mixture leans out. Not enough accelerator pump, POP.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
yup you need more pump shot. when he car is hot the mix is lean.
My car would backfire through the carb if the timing was delayed too much.
Set the timing at 6 per factory spec and it would backfire, set to 10 no backfire.


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Hello Coilwire,

My take on this is your distributor is not in the right stop with relationship to TDC. Pull your plugs out, insert TDC indicator with whistle on the end to locate the TDC while rotating the engine. The backfiring through the carb is the timing of the intake valves not closing all the way during the combustion cycle. Just a thought.

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