I have them on my shelf, which shoul;d I install. my motor and mods are below I am running a accel super coil and a MSD 6 AL box. Thanks

 

I don't know the heat range comparability of the NGK & rapidfire's there, so I can't compare.

What's the static CR, and cam duration? or DCR?
Either way, i'd put in the R43TS, and do a few good WOT runs. Then pull the plugs and inspect the heat line.
How to read Plugs

It seems everyone has a different view on plug reading, "read *there* to find the mixture, but not *there*... Other joe blow will tell you differently.. etc. Anyway, this is a good way to check the heat range.

 

Hey I really like that link to read plugs, Thanks!

 

It is the universal motor from goodwrench I think the comp is around 8.5, the rapidfires and the NGK plugs are there match for the R45TS plugs.

I changed the drivers side out and and put the 43 plugs in and the throttle reponse seems a little slugghis, I still have rapid fires on the pass side ( I got tired) I still have the old stlye rapid fires in the car ( the ones on the shelf are the new style) I like the old style but they do not make them any more.
I did notice the the ground strap does have pitting on them though. They have been in the car for about 7 years but have under 5000 miles.

I will take the 43 out and put somthing else in, the pass side is a pain that is why I want to know which to use before I change them. Thanks

 

oh geez, you'll want the R45TS' or else they'll be too cold and just carbon up.

 

I always go Delco r45ts is the ticket

 

Stock compression will want stock heat range generally. If you used nitrous, or had a much higher CR, then go to a lower heat range.
Most generic copper plugs will be the same between brands. I have no brand loyalty. I have used delco R42T, champion Rv8C, and autolite R144 back to back. They cross to be the same heat range, but different brands. No perf difference that I could tell, but the champion ones are silver colored (zinc plated perhaps), compared to a black oxide coating on the others.
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So if you're reading mixture, I prefer not to use a black oxide plugs, it just makes it harder. Hence, I like the champion plugs.

 

I have 4 R43TS in at teh moment and 4 rapid fires, the car seems more sluggish then when they where all rapid fire plugs, is this all in my head? thanks

 

Can't say on that. Rapidfires probably aren't giving you any performance upgrade, but the R43's are probably too cold as well.
Use the R45's now, c'mon.

 

MSD reccomends going down 2 heat ranges when using there box, all of the books say to use either the 45 or 43 stock so Do you guys think that the 43 are still to cold? the 45 will fit everywhere but teh #1 plug hole it hits the header.

P.S sonix in one post you say to use the 43 and then in another you say to use the 45 why? would I colder plug make it feel sluggish?

 

I read your mods, and it sounded like a pretty hot motor, so I suggested two ranges colder. Looking again, you haven't really done anything. Just bolt ons, and suspension stuff, no aftermarket heads or cam. Then you mentioned 8.5:1 SCR, which is the main factor in choosing plug heat ranges, so I changed my choice to the R45s. Stock CR, stock plug.

A colder plug will just carbon up, and give decreased performance over time. If you can't use a certain plug, they do have shorty plugs for headers.

But what "we" think you should use, and what YOUR motor wants, is always going to be different. You saw the link on reading heat range? Drive it WOT a few times and check for the heat line.

 

The 43 are stock on some motors, are they a plug that is to cold? will they foul out in a 100 miles, or more up in the thousands? I know these are ? that are hard to answer because there are lot of diffrent things that come in to play but in your experince? thanks

 

try them and see.

 

I put the NGKs in, I did notice that more of the porceline(spelling) at teh tip sticks out, where the metal Ont eh others cover more. Iput the ur4 in the ngk tech said that it was a hot plug and he said he recommended the ur5, but everything I read said the ur4 crossed over to a r45ts. Thanks