James B

I am running R44LTS plugs in my VORTEC heads. I was wondering what the gap should be. On my 70s motor the plugs were gapped at .035. Should I do the same with these plugs?

Lon Wayne

Sounds correct but call A local parts shop they can tell you for sure.

bashcraft

What kind of ignition are you running? I always gapped my plugs at .035 when running points and .045 with an HEI.

James B

I set the plugs at .035 but I am running an HEI distributor. Maybe I should re gap them to .045

Hauq`

I don't know were I read it, but I gapped my plugs to .060. I have a new HEI "Proform"? unit. I've only ran it around a little and it seems to work fine. If I have trouble I will regap, but it's a pain because I have to take the headers off.

crazywelder

With an HEI you can run a wider gap. On a stock HEI, you should not exceed 0.040 or 0.045 inches of plug gap. A larger gap has the advantage of more complete burn of the air and fuel mixture, but it also takes more power to get a spark to jump a large gap, so the gap should be matched to the type of coil you have.

I'm not sure what type of coil/module combination Proform uses, but if you have a high performance coil and module such as MSD or DUI, you could run gap at 0.050 and possibly 0.055 but a stock system won't jump that gap efficiently and the large gap will cause a miss and/or premature coil failure since the coil has to work harder to jump the large gap.

GDaina

Non HEI or any other high capacity ignition systems, the plug gaps are .035, I 'm not sure what the gaps are with the HEI ignition

vetteguy75

I have a Mallory HEI system in my '75. I've been running AC Delco 44RT's, gapped at .060" since I can remember....no problems....

Busrydr

To throw a little more mystery in this post:

I have a 73 and have updated the ignition to an OEM 75 HEI and appropriate plug wires. If I look at AC Delco's website it states a 75 Vette plug gap should be .060 for the Platinum and standard plugs. But for the AC #10 Rapidfire plugs the gap is listed at .035. Oversight on AC Delco's parts or does that #10 plug not require the larger gap?

acr

I know this is an old post but since some one may use this in a search I'll add what I read/know.
GM recommends this plug for use in their 330HP 350 Crate motor, their recommended gap is .045. It has a longer reach, .715" than many other makes, usually .708", & apparently provides better ignition for iron Vortec heads.

Shawn Lillard

I know this is an old reply but I just found “shorty” plug socket at Summit. Life saver with not having to remove headers anymore.

Jebbysan

More than .045 is not recommended for the simple fact that it decreases the life of the strap and electrode. There is little to no gain going from .045 to say .060.......
I run my own MSD ignition at .040.

Jebby

MelWff

This thread is 13 years old

Mark G

Yes, a "Time-honored" topic I guess you could say. ha ha.. (or like a virus that won't go away)

71chimera

https://www.chevrolet.com/content/da...e-19367082.pdf

above's a GM 350/357 crate w/ iron GM vortecs & HEI
page 7
0.040" w/ acd R44LTS