Plugs For Rebuilt 1963 75hp

[yorab]

I've read on some previous posts that the 1963 75hp V4 can use a J4C or a J6C plug. The J6C plug should be used when continuous low-speed operation is expected. Is this correct?

Which one should I go with for a freshly rebuilt motor? Should I go with one type of plug in the beginning and switch to the other after the initial break-in period?

 

[Chris1956]

Re: Plugs For Rebuilt 1963 75hp

Stick with the J4J until (or if) you get foulding problems. The J6J is a fall-back plug if you have fouling issues.

 

[yorab]

Re: Plugs For Rebuilt 1963 75hp

I'm anticipating some fouling since I must run an oil-heavy mixture during break-in. Should I run that hotter J6C plug to account for that?

 

[Chris1956]

Re: Plugs For Rebuilt 1963 75hp

I wouldn't run the J6J unless you have a problem. Eventhough those motors run a 24::1 gas oil mix, I have never had one foul a plug

 

[yorab]

Re: Plugs For Rebuilt 1963 75hp

Okay, I just picked up some J4C and I'll use them. If I find a problem, I'll post back here.