raroz28

Head/cam LT1 - has comp 306 and mods in sig.

I put in the drivers side plugs yesterday and i've gapped them all to .045.

Is it worth it to pull them out and regap them all to .035?? I decided to read on here about it today after I already did the work and it seems that is the popular gap.

Is it worth pulling them? The 2 plugs on that side closest to the firewall are hellacious to get to with the BBK headers I have.

Injuneer

Are these "conventional" (non-precious metal) plugs? What is the heat range compared to stock?

What is compression ratio? What is estimated flywheel HP?

There are two reasons to reduce the gap from stock- 1) conventional plugs will erode (over maybe 20,000 miles), opening up the gap. The precious metal plugs resist erosion, and can go 100,000 miles or more without the gap increasing (unless the platinum pucks fall off the electrodes, like they did with the stock factory plugs). 2) very high compression or a power adder requires higher voltage to fire the plug, so high compression or a power adder combined with the stock 0.050" gap may increase the required voltage beyond the capability of the ignition system.

For "normally aspirated" (no power adder, 10.8:1, 500HP at the flywheel) I run a one step colder than stock plug (Autolite 104 conventional), gapped at 0.045". For the 150-shot, I go 2 steps colder (Autolite 103), gapped at 0.035". With the full 300-shot, I use an ice cold Champion racing plug gapped to 0,030". I do have an ignition system using 8 LS1 coils, so its a bit more robust than the stock LT1 ignition.

raroz28

Thanks Fred. I actually read a few of your posts while I was researching more and between all that I read, I decided to pull the 4 that were in and regap to .035.

They're cheap old NGK TR55 v power plugs. The plugs that were in my car were all .065-.070 aside from 1, which was around .050.

Here are some of the symptoms I had that are now gone with the installation of new blue streak 8.5mm wires (30 shipped from jegs) and new NGK v power tr55's ($11 from advance for 8 of them with discount).

Terrible fumes
Engine vibration
Surging at low speeds (5-10 mph in first gear the car would buck like mad)
Ate cat. convertor
Car broke up terribly on the top end, misfiring and hiccuping
Terrible gas mileage
Dyno tuner said plugs were too hot when I had it on the dyno and he could only do one pull.

All but the last two (because it's too early to tell MPG) are cured. The car sounds and feels tight and my "right now" throttle response is back at really low speeds. If I punch it at 10mph it kicks the rear end out again, whereas before it felt strong but not that strong.

It feels like a new car. I am happy with the .035 so far. I probably would have noticed a big improvement with the .045 I had in there earlier today but based on what I read, most head/cam guys were running .035. I have no complaints yet.

Fatdog2

In other words unless you are blown or juiced,might leave them at .50.Info from previous posts,not from my experience.Hope this helps.Myo2.

bw_hunter

I run my TR6 plugs at 0.038" and have a better idle compared to the 0.050" recommended gap. It isn't really going to hurt anything at a tighter gap as these engines don't run super lean. So, the NEXT time you do the plugs, think about the tighter tolerance, you'll be fine until then....