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Holley Jets
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Author:  Jeb [ Mon Feb 06, 2006 7:02 am ]
Post subject:  Holley Jets
The Holley 1945 on my car is running to lean. I know because my plugs are white instead of the usual tan. What jet does this thing have in it now? I know these things came from the factory running lean but I don't know just how lean. Do the jets that they sell in summitt racing for the Holley 4-barrels fit my 1 barrel? If so I will order a few and a jet changing tool. What would be a good jet to change too? I really don't care that much about mileage I just want more power. I am also going to be putting on a larger exhaust pretty soon so I think that will aggravate the lean condition even more.

How hard are they to change in a 1945? Gotta get my car tuned for the race in Valdosta
Author:  DusterIdiot [ Mon Feb 06, 2006 7:19 am ]
Post subject:  Ouch...
The 1974 Carb I tore apart a few years back had a different setup proceedure than the 1975+ 1945's...the '74 carb also had a #58 jet in it compared to the 611/612's in the 1976 Carbs...


So tear it down, check to see if the jet is a 58, go to the speed shop and order a 61 or pull it out of the primary block on a 600 cfm holley 4 barrel....

-D.Idiot
Author:  Jeb [ Mon Feb 06, 2006 7:37 am ]
Post subject: 
set up procedure? I thought you just screwed out the old one and screwed in the new one.

I have a bunch of junk carbs in the back of the shop. I'll see what i have got back there.

Can you order the jets from NAPA?
Author:  Jeb [ Mon Feb 06, 2006 8:20 am ]
Post subject: 
I checked the summit racing site and they have #62 jets. Too rich?

The last time I had this carburetor apart it had some drill marks on the main jet. I think somebody before me tried to solve the lean problem also. So how do I tell what size the current jet is if it has already been drilled out? Can I use a drill index to dtermine the size?
Author:  DusterIdiot [ Mon Feb 06, 2006 8:42 am ]
Post subject:  Yep...
The 1974 adjustment 'setup' makes the acc. pump shot a bit leaner, and the linkage is set from a different measuring point than the 1975+, the 1975+ proceedure is much better, not so much guess work.

#62 might be OK , you'll know when the plugs are black :wink:

If it's drilled out, you'll have to pull out a set of pins drills or an index and just 'feel away' to find out what the last guy was thinking.

Have you pulled open a few others in your pile 'o carbs, any 1975+ 1945 should have the jet you want.

My local NAPA won't order or carry any of that stuff, if I need 1 jet, I go to the local speed shop and pay the $5...

good luck,

-D.Idiot
Author:  Jeb [ Mon Feb 06, 2006 3:52 pm ]
Post subject: 
I tried to get the jet out of a junk carb this afternoon but the I mangled it with a screwdriver by accident. The fit is so tight that it is impossible to get a screwdriver to lin up properly with the jet (jet is surrrounded by metal which constantly kicks off the screwdriver. What special tool did the factory use. I tried a jet tool but the shroud that helps hold the jet on to the tool wouldnot fit between the jet and carb body.
Author:  mpgFanatic [ Fri Feb 10, 2006 5:31 pm ]
Post subject:  drilling jets = bad idea
Quote:
how do I tell what size the current jet is if it has already been drilled out? Can I use a drill index to dtermine the size?
You can determine the rough diameter, yes. But according to every book I've read on the subject, some of the flow is governed by subtle things such as approach and departure angles, so as soon as those get mangled by a drill, all bets are off at knowing what a true flow number is. I suppose you could get away with drilling a jet for a one-barrel, but if you needed to match flow between two different barrels, drilling the jets is generally considered a bad idea.

Never actually done jet flow measurements, myself.

- Erik
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