View Full Version : Spark Plug Suggestions...

08-10-2008, 08:47 PM

1994 Maristar, Indmar 350. What plugs do you like? Gap?


08-10-2008, 10:33 PM
Check with these people, http://www.skidim.com/ or your MC dealer or your NAPA dealer. Take a plug out and take it with you if you check locally.

08-10-2008, 10:56 PM
taking the plug would work...but there is no way for sure it is the correct plug, if someone else replaced it

08-10-2008, 11:13 PM
"What plugs do you like? Gap?"

What's wrong with using what it came with?

AC MR43TS. If the motor was replaced/repaired and it now has Vortec heads, this would change. I don't have my notes handy but I think the gap is .045"

08-11-2008, 08:31 AM
Yep, 0.045, MR43LTS...thanks for the Indmar link.

While I'm at it, I'm going to perform a compression check. What's a normal range for a completey stock, healthy, 250-hour TBI 350? I've done a few comp. tests on automotive 350's but never marine. I would guess they should be simliar.


08-11-2008, 10:26 AM
MR43LTS is only for LT-1 and motors with Vortec heads, which is what I meant by different. TBI before '98 use MR43TS, as I posted before. Do not use the MR 43LTS on the older TBI motors.

Compression is the same- run it to normal operating temperature, shut it off and remove the spark plugs, then test each cylinder.