Popping and misfiring
 

I have a 351w with alum 351c heads. It has high compression. The motor was run with a single holley on alcohol and ran fine in my race car. The motor has sat for a while. I put it in my 57 with a new holley on pump gas and how it wants to pop and mis. Could it be the pump gas dose not have enough octane to keep from firing on compression? Thanks Guy

reply
 

not sure how you put Cleveland heads on a Windsor but ok
if your using the same plugs as were on alcohol they are to cold,
if its really high compression could be in detonation, check your plugs for proper firing color.

also if it sat a while depending on cam style could have broken valve spring from setting

try 110 octane fuel

Tell more... when does it pop, when does it miss - any other engine specs - carb specs. Timing correct? Does it pop through the carb or exhaust?

Recheck the timing to be sure it didn't move.

Agree w/33Willys77, need more detail- missing under load, w/o a load, etc.
Ford C heads on a W block = Clevor. Takes different intake and valve reliefs, attention to cooling system details. Can make a strong running Ford.

If the carb was setup for alcohol it will need to be resetup for gasoline

In his first post, he mentioned he put on a new holley - I am assuming it is a carb set up for gas. Just need to know more about his condition and when it happens.

Missed that

Is it possible that two ignition wires got crossed, possibly going to the wrong plug/cylinder. That will make a motor pop etc.