Ive been gathering information on here trying to figure which spark plug is the correct one to use in my 5.7 vortec block in my 88 gta. Im running tahoe vortec plugs for now (dont remember which I bought from the store)

Im looking to use Delco plugs but I will post alternate manufacturers parts for reference.

Delco:
R45LTS
R44LTS6
R44LTS
R44LT
R43LTS
R42LTS
CR43TS
41-993s (Platinum Plated) IRIDIUM
#8's

I believe these are marine spark plugs but a few guys suggested them for different reasons

MR43LTS
MR43

Threads said LT plugs are incorrect and dont go into the combustion chamber out the threads and to stick with LTS

I found these on rockauto have them in my cart now copper plugs: R44LTS6

also found the 41-993s on rockauto

Champion:

RS14YC6 stk no. 13 mid heat range
RS14YC gapped at .045
RS12YC stk no. 401
RS10YC
RS9YC stk no. 304 colder

Thread said wouldnt use RS14 plugs in performance setup

NGK:

BKR8EIX or 2668
TR-55's iridium?
TR5

Autolite:
605
604

ZEX #82070-8

Im not saying any of the things im going to post are ACCURATE just what ive gathered

the plugs have to be 3/4 reach plug and extra long thread taper seated (LTS I believe)

Guys were saying not to use platinum because it will cause detonation and to use copper because its a better conductor. In a few threads they mentioned the platinum melting into the cylinder sounds horrible.

Ive been gapping the plugs at 0.35 I believe what the stock motor called for, never crossed my mind this would need to be altered as well. This is where I think I need your input guys majority of the threads said to gap the plug to 0.60 and most plugs come pre-gapped at 0.60 however a few guys mentioned gapping the plug to 0.45

last stupid research point I came across guys were saying 96 or 97 tahoe plugs and as far as I know theyre the same thing 96 was just the first year of the vortec

Any input or thoughts are highly appreciated thanks for your help guy

 

ttt

 

NGK TR55 or old delco numbers FR3LS, FR4LS, FR5LS
Edit: (TR55 not TR5 like I had)

 

whats the difference between the 3 delco ones?

 

What's wrong with the plugs you have now? Have you taken them out and read them?

 

Just to make sure we're understanding you, is this just a Vortec block? or complete with L31 Vortec heads?

For Vortec heads, numbers off the top of my head for all-around performance are:
1. Autolite 104's
2. NGK TR55's

Gap of .045" +/- .005" is good

 

Heat range

 

I think I may have used platinum and the guys that helped me tune my motor said they arent the correct plugs for my setup but they would work for now. I tried contacting them but theyve havent responded and im trying to get the car running right

 

I ordered my block from ATK it has vortec heads. Im a bit confused by +/- .005 I understand the .045 part

 

could you explain heat range to me? I would probably be driving the car everyday if the usage matters

 

http://lmgtfy.com/?q=sparkplug+heat+range

 

.045" +/- .005" means a gap anywhere between .040" and .050" will be just fine. Shoot for .045".
Those two plugs I mentioned (104 and TR55) are the correct heat range for everyday driving and will tolerate all the high performance use your engine is capable of naturally aspirated.

 

thanks man

 

thanks. you mean 604?

 

No, Autolite 104. Copper core. It's common as nails, all auto parts stores around me carry them.
I use that plug in my daily driver Vortec pickup as well as in my 540 hp LT1 ImpalaSS roadracing and dragracing.

 

I have 41 993. Plug smelt like fuel a bit and looked kinda fouled. Ill be switching to copper plug R44LTS6. Still not sure what to gap plug to. .35 .45 or .60 . Hopefully the car will start with fresh plugs

 

Gap them to .045"