hey guys


just switched the primary jets in my 4160 to correct the super lean cruise problem i had . well i order 65 and 66 jets so when i pulled the the origonal ones out i was supprised to find that the jets was stamped with 65H. what the heck is the "H" for coudl that be why going up one jet took my cruise from off the gauge lean to very rich like maybe 12:1 ??? thanks for your help i have the other 65 jets that i ordered so i might just try those and see if they are in between

 

H means Holley... just their way of marking their jets. Rather than buying jets individually buy the entire box. In the end its MUCH cheaper. Is the new jets you got made by Holley? If so they'd also have "H" stamped on them. If they dont, that could be your problem. Various companies make jets that all look the same but they're most likely all different (even though the numbers are the same)

 

The "H" designation was a recent change in their numbering. They were supposed to be a little more accurate than the previous pieces. I guess higher precision.
The way the jets flow, change by at least 2 numbers. Changing by 1 number can really net less or no change at all.
An example is that if you pulled a 65 and it happened to flow on the high side of the scale, and you replaced with a 66 which may be on the low side, you really have no change.

 

'smknZ' what kind of gauge are you using?

Ron

 

its an autometer whit faced air/fuel gauge which i realize is not super accurate im just using it to get things in the proper "range" i also realize the farther from stoich i move the less acurate the gauge becomes but the the change form the 65h to the 66 made a huge difference and when i hold the 65 h up next to the new holley 65 jets that i have the 65h looks noticable smaller ?