Well Iv seen with around 400 hp and MSD ignition 35-40? was leaning towards 35..

these are NGK TR55

 

My very qualified tuner prefers and recommends between .030 to .035 for plug gaps. I had mine at .035 and now he wants me to go down to .030 on my next set.

 

ya I was thinking .35 for now and next set .30 and if i notice a bad/good diff go back or not

 

whats ur ignition

i got a 6AL, MSD wires, MSD Coil and MSD Pro Opti so i know im juicin it alittle more then stock

 

OEM opti unit with MSD cap and rotor, MSD "Blaster" coil, and Taylor Thundervolt wires w/ tr55 plugs.

 

from what I hear any kind of after market box raises the gap about .5 because they juice it that much more like i said i was leaning toward .35 maybe

 

Stock coil puts out more in the higher Rs than the MSD ones

 

yea I would do .035 unless you are forced induction or nitrous

 

This dude says .050 unless you're running FI or NOS. Then you go .035

https://ls1tech.com/forums/showpost....21&postcount=1

 

hmm i sent him a msg

 

Mine are set at .050" and I dont have N2O.

What is the reason you guys are going to .035" when OE spec is .050"?

 

...yea, and then higher compression and rpms is supposed to make the cap go down again. Those rules are way back from standard SBC days, and the LT1 behaves a bit different.

The OEM specs arent always geared towards max power - hence the very modest timing and running pig rich from the factory. In most N/A high performance LT1s, especially in the higher rpms, you get more power and smoother response from a smaller gap in the .030-.035 range. The bigger stock gap tends to "wash out" under high compression and high rpms.

Then again, what credentials does my tuner have - besides being a personal friend of Ed Wright and working as a Chevrolet engineer since before most of us were born, and tuning hundreds and hundreds of TPIs and LT1s in the process .

I gained 35 to the wheels over a professional mail order tune with him.