Correct spark plugs

[Darol Wester]

I have a 22 ft. 1978 Cruiser with a 350 Chevy/Mercruiser outdrive setup. Every time I go in to buy plugs, they recommend a different set. ACDelco R45TS, Autolite 25, Autolite 145 etc. This boat is roughly 5500 lbs. It has distributor with points and a Rochester Quadrajet carb. The engine was new 5 years ago. If you need more info, let me know. What would you put in it?

 

[Wanshot]

Re: Correct spark plugs

I own a Chevy 350 newer however the plugs you listed are the correct plugs for GM 350. I have ran both ACDelco R45TS, Autolite 25 and IMHO the 25's seem to take the heat a bit better. I run them in my truck as well. gapped @.035 . I hope this helps...

 

[LAC_STS]

Re: Correct spark plugs

Look at my previous posts. I have a thread recently about it with the same engine.

Apparently autolite 25's are a ford plug. Plus mine were rusted after just 2 months.

I used the NGK BR6FS. There is an AC Delco equivalent. You'll have to look at my thread for the number. I'm on my iPhone so it's a pita.

 

[LAC_STS]

Re: Correct spark plugs

The 25's that were in my engine when I bought it wee only used for 2 months (about 50 hours) and they were rusted pretty bad for 2 months. Plus one of them had 3 cracks all the way down the porcelain.

Use a marine plug that won't rust.

 

[wire2]

Re: Correct spark plugs

The NGK BR6FS were OE in my '84 5.7, the current ones are at least 5 years old, run great, no rust. (although rust on the metal body of an unplated plug is only cosmetic. It just looks bad)

 

[Aloysius]

Re: Correct spark plugs

I really like Autolites, but have had problems with them rusting in a marine environment. ONLY for the rusting reason would I consider a marine plug with a rust resistant base.

I've got autolites in my boat engines now, but I wiped the metal with silicone to see if that stops the rust.

 

[gbeltran]

Re: Correct spark plugs

I think I would be using AC plugs either MR44T or MR43T. If you have been using the R45TS and don't have any signs of detonation go with the MR44T.