grind4it

First off I would like to say that I searhed the forums for information. The issue I am coming up with is a wide range of information. I would like to try and narrow it down to something that will work well in my car.

I am building a 1985 C4 corvette with a LS1 and 4L60E. My LS1/4L60E came by way of a wrecked 2001 Z28. The car will be NA.

Here is the hardware:

Stock bottom
Milled 243 Heads with lightweight valves (out of a 2002 Z06)
The factory LS1 rocker arms (off my LS1)
Factory length rods
GM LS7 lifters
factory head gaskets
TSP Torquer V2 cam
LS1 Double roller timing set
Ported LS6 oil pump

LS6 intake
180* Thermostat
Full length headers
Full flow mufflers (no cats)
3500 stall torque converter

Does anyone have a spark plug and gap reccomendation?

Thanks,
Mark

allthrotle

iTrader: (2)

I gap mine at 50 on my h/c car.

grind4it

What type and brand of spark plug do you prefer?

grind4it

Come on anyone? I'm dying here. What about the "Iridium"? Platinum? I need some idea of what to buy.

allthrotle

iTrader: (2)

Im running standard ngk tr-6 v-power plugs. stock #4177 Im running a little bit colder of a plug because my tune is on the aggressive side.

grind4it

I am still a little upside down on the gap. The manual i have for the LS1 is calling out 60, Allthrotle is coming in at 50 and the parts store where i bought the plugs (thanks allthrotle) is telling me I need to gap the ngk tr-6 vpower plugs that allthrotle recommeded at 35.
So, anyone want to chime in on this?
Thanks,

rob69zombie

iTrader: (7)

I tried stock gap (60) with my new NGK TR-5's and it would barely idle. I closed them to 50 and it was a lot better. My friend that works at Advanced Auto pulled up the plugs in the computer and they had a Service Bulletin Announcement that said gap them to 40. We did and it runs perfect. My vote is for 40!

LS6427

iTrader: (2)

Forget what GM says, forget what NGK says and forget what parts store guys tell you.

If you gap them anywhere from .045-.055 it will work on any N/A pump gas LSx engine from bone stock to 700 RWHP. There will be zero difference in performance between that range or even a larger range. Its just not that important with an N/A pump gas engine.

I've tried gaps from .040-.060 on my 427ci and there is absolutely zero difference all through the rpm range. NOTHING.


.

01ssreda4

iTrader: (96)

i gapped my tr-55s at .060 and .055 with no problems.

Sigforty

That is what I used until I broke the 450 rwhp range.

grind4it

What do you gap at now that you are over 45 RWHP?

grind4it

450 rwhp

01ssreda4

iTrader: (96)

let me clarify my post above. I gapped .060 with full exhaust. When i added a cam i went with .055. No difference, it runs perfect.

81 Camaroman

Tr6 #4177 .55 gap

Sigforty

Well, I am running Tr8 plugs with a .035 gap due to nitrous. Once I broke 450 rwhp though I went from Tr55 plugs to Tr6 plugs with the same .055 gap. I only closed the gap for nitrous, but once I got to a certain rwhp level I noticed the engine prefered a slightly colder plug.

eamador11

NGK TR55s gap = .050
346 H/C