Spark Plug Choise

[mikey]

Not my strong area

Running Mowtown (Chevy) 415 cu in with Alloy heads and 9.8 to1 CR.

Any recommendations on plug choise. I like NGK, but I realise there are a number of good comparable makes. I am guessing with the set up that I will probably have to go one stage colder than normal.

Looking forward to your help

Mike.

[Ron61]

Mikey,

I don't know which plug would be best for your engine, but so far as how you plan to drive it will help determin the heat range. If it is going to be mostly street use, I woud stay with the called for heat range as the colder ranges tend to foul quicker in stop and go traffic. I can get away with two rangers colder when I was racing, but went back to the standard heat range for the street. Also if you are using an aftermarket ignition, Jacobs, MSD, etc, you will need to gap the plugs wider than normal to gain the optimum power.

Ron

[mikey]

Yeh
Im running an MSD 6AL. They suggest around 50 thou, but the plu guys say stay within 8 thou of standard, so I'll try find a plug that is gapped around 42 thou from the box and gap up.
Cherrs for your reply
Mike.

[Ron61]

Mikey,

I use a Jacobs Pro Street and they say the same thing. I played with mine some and found I get the best results around with a gap around .047 - .049. Stock gap on my plugs is .035.

Ron