murphinator

iTrader: (2)

just did plugs in my 6 speed stock internals/bolt ons car as it was starting to miss a whisker up top and the plugs that came out were ngk tr55 gp's and the gaps were huge (.075-.080) I know these coils are powerful but I assume the plugs had worn to this wide of a gap rather than it being intentional , I have put 17k on the car since buying it and hadn't done plugs yet.

I went with a .060 gap on the new plugs but figured I would ask if people are getting away with larger gaps on the truck coils in normally aspirated uses , I was able to run .060 in my 3800SC cars which are coil packs not coil on plug with up to 13# boost and no blow out issues so I installed them at that but if that is tight for these coils I can re gap them.

Thanks in advance

dr_whigham

iTrader: (49)

I always run mine at .055 like they come out of the box (checking them all, of course)

On a H/C/I car it depends... Compression and whatnot. Anywhere from .045 to .035. On mine, at 11.7 I went with .040 I believe.

murphinator

iTrader: (2)

mine came out of the box at .045 (autolite 103's-had great luck with copper core autolites on other platforms)

stock LS1 gap is .060 so to be clearer I was asking if D585 heat sink truck coils on a stock internal , normally aspirated allowed more gap ?

I understand higher cylinder pressures require smaller gaps ( in some cases) , whenever I sprayed my supercharged 3800's I would shrink the gaps to .045 but was able to stay at .060 ( stock gap for SC3800 also) without spray at 13# of boost with no spark blowout issues and those have coil packs that share cylinders (3 coil packs/6 cylinders) so pretty comfortable that I was being conservative with strong coil on plug being able to at least be able to run stock gaps - do you have the truck coils DR Whigham?

BTW I did the plug wire swap up at my camp with no means to jack so got all 8 done from the top side - that back pass side one is a bitch , spent more time retrieving my ratchet lodged down between the primaries at the collector than the rest of the operation lol

Paul Bell

iTrader: (9)

I like .055 also.

LS1-450

iTrader: (33)

I'm .044", 12.1 SCR, 8.4 DCR, NGK TR6. For yours, add me to the .055" TR55 group.

dr_whigham

iTrader: (49)

I don't run truck coils bc quite frankly, I don't see the need. My LS1 coils make the fuel go boom just fine.

Rise of the Phoenix

iTrader: (27)

Same here. LS1 coils haven't let me down yet. I'd be willing to bet there are about 100 things that will fail before they do.

Paul Bell

iTrader: (9)

YEAHBUT without a doubt, my engine responded better when I made the change-with a tune for the dwell.

LS1-450

iTrader: (33)

Mine too, + the megasquirt comparison clearly shows better spark @ high RPM.
Nothing against guys who choose not to. It's simply something that we will always choose to do.

murphinator

iTrader: (2)

they were already on the car when I got it so I understand those with the point of view of why do the upgrade , my other 2 ls1 cars are on stock coils.

A lot of guys posting they are at .055 so I am comfy with my .060 decision on a mild bolt on car .005 is generally not going to make or break on a NA plug gap choice if the wires and spark source are in good working order and I did wires also plus my miss is now gone...

Thanks for the couple posts from guys with the truck coils , Paul Bell I recognize your screen name from my search before this post to try to find a gap answer before posting this truck coil specific gap question( the 25 page thread on truck coils/dyno gains) I will have to look at the file but knowing the guy I got the car from and his posts on HPT forums I bet he increased the dwell values to match the truck coils ability to survive increased dwell times without frying due to the heat sinks ( see Paul I did read through the whole thread lol)

I guess my mission for this thread is accomplished - it doesn't appear truck coil guys run super large gaps but rather my plugs had worn the gaps that much , pretty much what my assumption was but thank you all for verifying it.

Firebirdmuscle

iTrader: (16)

I have mine gapped at .045 and are doing just fine with the truck coils