Holley 94 adjustable main jets... anyone tried them?

johnh7

johnh7

Senior Member
Has anyone tried the adjustable main jet sold by Vintage Speed? My 38 pickup is running rich so I went online to find new jets to lean it out when I found this product. It seems like an idea that was missed way back when. I have ordered a set to try them out.
This is what they post about them online:
JET-MAIN-ADJUSTABLE Adjustable Main Jets for Holley 94 Carbs Adjustable main jets to fit the Holley 94's -2100's-ECG's- and the other 3 bolt Holley carbs. Finally an answer to the constant battle of changing jet sizes to compensate for altitude or to get that perfect tune-up. Get your plug color just right. A simple turn of the nut clockwise will lean your high speed mixture and likewise a counter clockwise turn will richen the mixture. If you’re already running rich just install the adj. jets and turn down the fuel using the main jets you already have installed. If you need to increase the fuel go to a larger main jet and regulate from there. Main jets are not included but I have all sizes listed in catalog. These are sold by the pair.
This is the link to their web site if you are interested: http://vintagespeed.com/
 
Here is what they look like.
 

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Your motor is probably running rich from one or more of a myriad of reasons. None of which will be the jets.

Fuel pressure. Bad needle valve. Porous float. poorly sealing body to base (gasket or warpage) ruptured power valve. Wrong power valve. wrong power valve gasket.

Oh yes, I have encountered all of these.

If you have 51 jets or near, it won't be running rich because of the jets, it will be because of one of the above reasons, or even something I have missed out.

Mart.
 
The 94 is a fine example of the elegance of simplicity. Adjustable jets are about as useless as putting horseshoes on a camel, and 10 times more complicated.
 
I toy with adjustable main jets like these some years ago they did work up to a point but tended to give inconsistent flow through the range that a main jet normally works at
the length of the needle taper seams to be the important part IMO
 
I think you'll find there hard to set up, you cain't set then at idle and mean anything, you'll have go out on the road, stop and play with them, drive some more, get out check plugs, drive some more ect. I know I'd never get them right. I know, install a long cable on them so you can adjust while your driving, like a Model A. Walt
 
I have had adjustable jets on several single carb cars with both Stromberg and Ford carbs. I set them with and exhaust anilizer. They have worked for a number of years.
You can also adjust them by the color and carbon on the plugs. Check every 8 or 10 miles, clean and make small adjustments. Remember to check which jet delivers fuel to what cylinders. Different manifolds deliver to different cylinders. Once set they are vary rarely changed. G.M.
 
Adjustable jets have been around for a long time.....I first realized they existed perhaps 50 years ago. Back then, I wondered how you set a baseline and how do you know what the incremental turn is? My only solution was to find a friend with a relatively skinny butt so, when he was laying on the hood turning the jets, you could still see around his butt to keep the car on the road.
 
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