Right plug

[ericcarr2000]

I am in the process of reporting my 1990 sundancer. I know the casting number from the heads are 3917215. Can anyone help me out to find the correct spark plug for it?

 

[tlt383]

Those heads cross to 68-69 closed chamber big block heads, pretty desirable in the auto world, anyway, stock was AC Delco R43. If you have a pretty high compression motor and want to run a cooler plug, an R42XLS would work.

 

[alldodge]

I am in the process of reporting my 1990 sundancer. I know the casting number from the heads are 3917215. Can anyone help me out to find the correct spark plug for it?

That casting number are for 396 and 427 not a 454/7.4

 

[Bondo]

Ayuh,..... AC Delco, MR42T,.....

The M is marine, which is an alloy body,....

The XLS are much longer plugs for the Vortec heads,....

 

[ericcarr2000]

I tried the r42t plug and the threads aren't long enough.