Spark Plugs

LuckyPenny

Petty Officer 1st Class
Joined
Feb 21, 2003
Messages
256
I know reference material is as hard to get as parts of older engines, but I have a short question. I have a 1977 Mercruiser 250 (350 CID (5.7L)) and would like to know what the proper spark plugs are. Currently it has R43T's installed. What reference I can find lists that plug for the 1990's version.<br /><br />What is the correct plug? also temp range (hot, midrange, cold)
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: Spark Plugs

luckypenny, my clymers books says MR43T's, gap, .035". don't know about yer heat range question. also, i think the M stands for Marine on that plug #. as for yer book you'll need. perhaps one of the marine techs can tell ya what book ya need. or i called mercruiser and they told me what i needed. and of course there's always clymers or seloc manuals. the info i gave you was out of the clymers. 64-85 sterndrive shop manual..... have fun man...... oh yeah, when ya find out what real mercruiser manual ya need. go check out ebay and score one there. i needed 2 manuals, got one for $25 and vol. 2 is on the way for $16...
 

Bondo

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Apr 17, 2002
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71,310
Re: Spark Plugs

The MR43T has been the Right Plug for a marine SBC Forever........<br /><br />R43Ts are the automotive Equalivant.....<br /><br />MR43Ts have an Alloy body......<br /><br />There's Also a MR43TS that's a projected-nose plug........<br />Some claim Better performance,... If Your engine has the pistom,+ valve Clearence to run them......
 

LuckyPenny

Petty Officer 1st Class
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Feb 21, 2003
Messages
256
Re: Spark Plugs

if the MR43T is the right plug, what is the next step colder? Hotter?
 

Bondo

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71,310
Re: Spark Plugs

MR44T.......<br />MR42T........<br /><br />Why ?? Are you burning Oil or something ???
 

LuckyPenny

Petty Officer 1st Class
Joined
Feb 21, 2003
Messages
256
Re: Spark Plugs

I do not think I am burning any oil the engine is running very well. I do run in very cold water then the winter and very warm in the summer with a RW cooling system
 

Bondo

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Re: Spark Plugs

MR43Ts are what you want...........
 

cuzner

Senior Chief Petty Officer
Joined
Feb 14, 2004
Messages
771
Re: Spark Plugs

I,ve got an old seloc manual, actualy gives 2 types... the one Bondo gives for ac plugs, and for a few v40k don't know the difference though, wanted to give this manual away to someone who could use it BUT didn't thimk the mods alowed that . anyone interested e-mail me at cuzner@gosfieldtel.com, I'll ship to ya. Its seloc mercruiser 1964 to 1992.<br /><br /> Jim
 

lakelivin

Lieutenant Junior Grade
Joined
Aug 19, 2004
Messages
1,172
Re: Spark Plugs

Originally posted by cuzner:<br /> I,ve got an old seloc manual, actualy gives 2 types... the one Bondo gives for ac plugs, and for a few v40k don't know the difference though, wanted to give this manual away to someone who could use it BUT didn't thimk the mods alowed that . anyone interested e-mail me at cuzner@gosfieldtel.com, I'll ship to ya. Its seloc mercruiser 1964 to 1992.<br /><br /> Jim
what i took away is that they wouldn't let you start a post to give it away, but don't mind you making the offer in an existing post. Had something to do about risk of a post being used by other resellers scanning headlines and using them to find places to 'spam' the site.
 

cuzner

Senior Chief Petty Officer
Joined
Feb 14, 2004
Messages
771
Re: Spark Plugs

Was'nt sure... and did,nt want to take the chance. And Ya thought some people might think I was trying to start a scam....guess its just the way of the world now-adays.<br /><br /><br /> Jim
 
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