Customs 1965 Impala plugs hit pistons

Just put 661 heads on to wake up my 283. Gap closed on plugs. Old heads have washer seat, new have tapered. So I went with plugs for a 305 h.o. Who else had this problem?

 

Some plugs are designed with a projected tip that fits farther in to the chamber.You may need to go to a non projected tip.

 

R45T plugs instead of R45TS might fix the problem. Those are AC numbers, which may or may not make any sense to you. But they make sense to the folks who built the engines you're dealing with

 

I didn’t use resistor plugs back when I did that. AC 44’s were the plugs I used. When I went to Rochester FI I had to use C43’s (C was for commercial) which were the equivalent to 42’s to get to run right.

 

Thank goodness, I couldn't see anyone reporting on what spark plug they ran afterward. So I was worried it wasn't going to work after the fact.

 

Means something to me now, I only run ac delco in gm

 

To elaborate what Squirrel said, a quick lesson in AC spark plugs and what the letters and numbers mean.
The "R" denotes a resistor plug. The numbers, heat range, the smaller the number gets the colder it is. Only spark plug I think is the reverse is true is NGK but there could be others today. The "T" designates a tapered (non gasket) seat and the "S" is extended tip. When it has an "X" (for example R45TSX, R45TX) that designates an extended gap, if memory is correct as it's been a long time since I ran into that situation the gap has to be .060 for that designation. When you go to the auto parts store ask them to pull a R45T and a R45TS and compare the difference of how far the tip extends from the body of the spark plug.

 

So I went with R44T and no clearance issues... Its running, but its very loud. Would those 305 heads make the exhaust that much louder, I need quieter mufflers.

 

Can't say on the "loud" part, maybe it is just happy because it can breath better.

 

It also stumbles cant hande snapping the throttle... before or after all these modifications.

 

What are the quietest muffler people have used... I just wanna cruise in it.

 

This is typically not enough initial ignition timing, or not enough accelerator pump shot from the carburetor if timing is good.

What is your initial timing set at, and what carb are you using??

 

When you installed the intake gaskets did you block off the heat riser passages? That can change the exhaust note somewhat, using the crossover passage can dampen some of the exhaust note.

 

Timing...first thing to double check.

 

Summit K1104 Cam, Holley Contender Intake, 650 4 Barrel, 661 heads, stock manifolds but dual exhaust. "That had already been added" Crane L933 rockers.
Timing advance 0 degrees.