kairles

iTrader: (2)

I have a stock LB9 with a procharger kit running about 7-10psi. Is the stock plug and gap ok or should I go with a colder plug? smaller gap?

Reputation7

iTrader: (3)

ngk tr6

gapped at .028

calebzman

iTrader: (3)

With my setup, I run plugs that are 2 heat ranges colder than stock. 1-2 is recommended, so I went with the safer option. At first I gapped them between .028-.030 and it ran really bad. So, I bought the same set of plugs and gapped them .038-.040, and it was a whole new engine. I could finally tune it with some consistency. I think the smaller gap is more for people with drag cars that run high boost, so they are not blowing out the spark in the upper rpms. I run mine up to 6k at 10psi with no problems. At your level, you'd be fine starting off with a gap of .040 to .045.

8T9 BANDIT

any other opinions, i too am putting a procharger p1-sc on my lb9.

Reputation7

iTrader: (3)

ill stick with the .28 ngk tr6's.

Batass

It also has to do with how good you ignition setup is. If its stock, bring the gap down, if its aftermarket, I imagine you could run stock gap.

I have all msd stuff and .040 gap. I've taken it to 6k rpms and 10psi, motor ran clean. When I up the boost a little here shortly, extend rpms to 7k, and run meth injection, I think I'll close the gap up to .035.

It'd be interesting to see how power you could gain by running right on the edge. If only I had a dyno.......

kairles

iTrader: (2)

after talking with some locals and searching a couple forums I've decided to go 2 steps colder gapped at .030(stock ignition).

whats with the TR6's, do they fit in the stock heads or do you have aftermarket heads? the stock replacement NGK is a UR4 so I went with a UR6

83 Crossfire TA

iTrader: (2)

Here’s an original thought… how about trying it and using what the car likes? 2 ranges colder can be just right if the car is driven hard a lot, but in many cases will foul quickly and misfire at idle/low speed unless other changes have been made. A smaller gap will help fire the plug but will also result in more misfires and can cause the plug to run hotter. Secondly, if you look up the stock plug for t he TPI engines, you’ll notice that they changed heat ranges over the years as well as between the 305 and the 350, without a significant change in the engines, so what “stock heat range” is will depend on what you started with and what you’re looking up.

If you’re really still running a stock ignition you should probably do something about that first.

As far as TR6’s, they’re one heat range cooler than the stock replacement TR55’s used in LT1’s and LS1’s, and a popular plug for those running a power adder, and I will tell you that it will cause misfires in an LT1 car that is driven around at low speed most of the time, again, what is right depends on use and the individual car. They aren’t right for any of the stock heads a LB9 got…

Zdaddy

HIT THE NAIL ON THE HEAD! Every set up has the potential to be different! I'm running 16-17 lbs of boost and only one heat range colder w/ a gap of .035.... As a rule of thumb, one range colder on stock set up is safe... Gapping a plug down to nothing is making up for an inadequacy. I prefer the NGK Iridiums.