Spark Plug Gap

[MrSony]

I went from stock .060 gap for HEI Buick 350s to .045 and it idles a bit smoother at lower rpm. I think I may have gotten 1 or 2 mpg out if it. Results may vary.

 

[DR HURST 84]

I went from stock .060 gap for HEI Buick 350s to .045 and it idles a bit smoother at lower rpm. I think I may have gotten 1 or 2 mpg out if it. Results may vary.

Thanks! I will do the same on mine.

 

[airboatgreg]

.045 is perfect

 

[DR HURST 84]

.045 is perfect

Thanks you! Will do.

 

[DR HURST 84]

.045 is perfect

Thank You!

 

[paul.m]

Yup like the guys above stated 045 is what GM eventually came back to after problems with rotor caps and terminal jumping after a few thousand miles the gap would open up even more ! you could go even 035 if you wanted , but 045 is the general consensus .

 

[DR HURST 84]

Yup like the guys above stated 045 is what GM eventually came back to after problems with rotor caps and terminal jumping after a few thousand miles the gap would open up even more ! you could go even 035 if you wanted , but 045 is the general consensus .

Thanks Paul!

 

[Max Headroom]

Way, way back in the day, probably before most of you were born, I had a very sharp mechanic tell me that the reason the gap was opened up to over .060 was to help the low compression motors with flame propagation in the open chamber POS heads. He also told me that this only became possible with the HEI 50k volt coils.

 

[pagrunt]

Way, way back in the day, probably before most of you were born, I had a very sharp mechanic tell me that the reason the gap was opened up to over .060 was to help the low compression motors with flame propagation in the open chamber POS heads. He also told me that this only became possible with the HEI 50k volt coils.

Wonder what .040-.030 woud do on my L48 (10.25) with stock chambers?

 

[69hurstolds]

Way, way back in the day, probably before most of you were born, I had a very sharp mechanic tell me that the reason the gap was opened up to over .060 was to help the low compression motors with flame propagation in the open chamber POS heads. He also told me that this only became possible with the HEI 50k volt coils.

It was due in part at least for leaner and leaner mixtures for emission concerns, as well as taking advantage of the high output coils. They soon realized that they were straining the stock system and were failing HEI parts left and right much sooner than normal. Thus, they backed off the canyon sized gap. I'm sure it was a compromise. I could see the think tank now. Some of the old goats wanting 35-40 gap and some of the newer engineers fighting for 070 or something. Probably found out that 060 was much easier on the system and still performed well enough for lean mixture burning.