Fox Popping Through Intake/exhaust

[Demustangs]

90 roller motor 4 barrel Holley 650 DP, e303 cam ,gt40 heads , dual valve spring upgrade, stock bottom end ,plugs are some rich some lean continuous popping under light acceleration pops at all driving conditions won't when new plugs are in though 13 degree initial ignition timing

 

[Mustang5L5]

Run the codes. Lean and/or vacuum leak most likely through the intake gaskets

 

[Demustangs]

Run the codes. Lean and/or vacuum leak most likely through the intake gaskets

 

[Demustangs]

4 barrel Holley 650

 

[mikestang63]

timing is off
vacuum leak
car running lean
valve springs floating
valves not adjusted properly

 

[Demustangs]

timing is off
vacuum leak
car running lean
valve springs floating
valves not adjusted properly

I checked all valves for bad adjustments all good checked push rods for any play that's ok too btw

 

[Demustangs]

I checked all valves for bad adjustments all good checked push rods for any play that's ok too btw

Now when I change plugs it runs perfect launches hard etc until like an hour of drive time url start popping uncontrollably