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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: eventhorizon66 on December 05, 2007, 03:43:08 pm

Title: Spark plug heat range
Post by: eventhorizon66 on December 05, 2007, 03:43:08 pm

I was helping (observing while drinking a beer ;D) a buddy swap out plugs the other day when I noticed that three of the AC R45TS plugs were a little shorter and also looked like they had less center electrode exposed than the longer ones.  Sure enough the shorter plugs have exactly 0.008" less center electrode protrusion from the insulator tip (measured with a feeler gauge).  Is this enough to affect the heat range?  This doesn't appear to be production variance, because all the long ones are exactly the same and all the short ones are the same.  He's just as inexperienced as me and decided to hold off until one of us got an answer.

Title: Re: Spark plug heat range
Post by: Captkaos on December 05, 2007, 04:01:55 pm

If they are shorter, they aren't the same heat range, they are colder like R43TS. Where they marked R45TS? Where they new?  I would get some new ones that are the same.

Title: Re: Spark plug heat range
Post by: VileZambonie on December 05, 2007, 04:02:06 pm

Are you sure alll of the plugs are the same part #?  ??? They should all be the same unless you have an r45tsx maybe?

Title: Re: Spark plug heat range
Post by: ccz145a on December 05, 2007, 04:52:55 pm

Makes you wonder if a couple of cylinders burning oddly, though. And the previous owner "compensated" them with a different plug.

Title: Re: Spark plug heat range
Post by: eventhorizon66 on December 05, 2007, 07:18:31 pm

I failed to mention that the plugs I'm referring to are the brand new plugs, all of them marked "R45TS".  None of them have an "X" at the end. I had my friend send me a pic, see for yourself.  Am I missing something?  If they are not the same plugs which ones should he go with, the short ones or the long?

R45TS plugs (http://i208.photobucket.com/albums/bb247/1985C10/R45TS.jpg)

Title: Re: Spark plug heat range
Post by: VileZambonie on December 05, 2007, 08:15:31 pm

The reach on those plugs are the same. The one on the left has a longer insulator and jacket. There are several versions of the R45TS

R45TS, R45TSX, R45TS8, CR45TS, etc... It is possible they were also boxed wrong. What is the year make and model of his truck?

Title: Re: Spark plug heat range
Post by: eventhorizon66 on December 05, 2007, 08:50:24 pm

It was the length of the insulator I was concerned about, not the reach.

If they were R45TSX or R45TS8 or whatever, wouldn't that be printed on the insulator?  Should I tell him to go back to AZ (probably the source of the problem) and match to the longer ones or to the shorter ones?  Isn't the shorter plug going to be the hotter one?  Should you err on the side of hot or cold?  I'm thinking cold (stick with the longer ones).

Its an '79 C10 350.

All this trouble over spark plugs ::)

Title: Re: Spark plug heat range
Post by: VileZambonie on December 06, 2007, 04:53:42 am

They were probably boxed just boxed wrong. Your friend should be running an R44T and return those plugs.

Title: Re: Spark plug heat range
Post by: eventhorizon66 on December 06, 2007, 11:55:38 am

Thanks for the help, Vile.  I'll let him know.