carb jet size
 

H I I have a 94 carb on a 255 merc stock engine and feel it's running to rich. I'd like to know the proper size jets. I think 54's are in there. Thanks Jim T.

Re: carb jet size
 

I found Holley#51 jet size to perform well on my 51 Merc. #54 seems a bit large.

Re: carb jet size
 

I would make sure the power valve isn't leaking or ruptured before you start changing main jets. Over the years Holley 94 jet sizes varied from about #50 to #57 depending on the year and if car or truck.
The main discharge nozzle bars were changed over the years. Three different styles that I can think of.

Sal

Re: carb jet size
 

What model 94 do you have?

Re: carb jet size
 

flatjack9 It's a 8BA.

Re: carb jet size
 

Yes I did find it loose a while ago and tightened It. I will check it out again. Who has the best rebuild parts or kit ?

Re: carb jet size
 

You found it loose?... It has a gasket that must seal properly or you'll run rich. Before you buy a new power valve, remove the old one and test it: It should hold suction to your tongue. The gasket surface should be flat, not a radius as the new ones are. If good, check the gasket and reinstall. If bad, Daytona Parts.com is one source for the correct power valve. I'm not sure which vacuum # to get for an 8BA, someone else should post that value.

Re: carb jet size
 

They are generally 7.5

Re: carb jet size
 

Where do you find the number?

Re: carb jet size
 

Number is stamped on the power valve.
#51 jets came with my 239 cu. in. 8BA Holley 94 2 barrel carb.
Worked fine.

Changed to a 390 Holley. That also came with #51 jets. Works fine.

Re: carb jet size
 

The Walker # 15302B carb kit works well. I've used many of them. It has the correct power valve that seals well too.
Available through O'Reilly's auto parts and on EBAY. Made in the USA.
Also, Dayona carburetor in Florida has good kits and power valves.

If the power valve in your carb is wet with fuel on the vacuum side, it's ruptured.

Sal

Re: carb jet size
 

Walker Products 15302B Carburetor Kit
https://www.oreillyauto.com/detail/c...it/wlk0/15302b

https://i0.wp.com/mercurycarburetor....pg?w=790&ssl=1

Re: carb jet size
 

Also, I've seen a lot of OLD power valves where the diaphragm is dried up and hard . . . yet still doesn't leak. You should be able to easily actuate the power valve with your finger and with suction. If it doesn't easily move - replace it.