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Discussion Starter #1
I have a Holley 3310-2 that I had converted into a 4150. I recently put a Proform non-choke body on because I didn't want a choke and Holley didn't offer one for the vacuum carbs. I had 72 primary jets and 78 secondary before the body swap. I now have 72 primary and 79 secondary. The 79 was the largest I had, more on order from Jegs. The car is a 450HP 390 FE engine, car weighs 3440 without me. I took it for a drive today with the newly modified carb and after its warmed up it has a hesitation on acceleration with a very faint popping out the exhaust. It seems like it may be starving a bit for fuel but I'm no carb expert so I'm looking for advice. I understand that the bleeds may be larger on the Proform but I've never dealt with them before so before I screw things up I thought I'd ask here. I do have a 4 corner Holley HP that I run at the track and did on the street but it really burns rich on the street and fouls plugs. It runs nice at the track with the HP. I'd like to get the vacuum 750 working good on the street and it will save a few gallons when cruising.

Thanks!
 

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I'm confused - what 4150? Vac secondary or mechanical? Dual metering blocks and stuff? Have you done the initial setup of the pump arm clearance (preload), pump cam, shooter size, initial idle mixture tune, etc.? If not, do that first and see where it's at.

David
 

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Discussion Starter #3
I'm confused - what 4150? Vac secondary or mechanical? Dual metering blocks and stuff? Have you done the initial setup of the pump arm clearance (preload), pump cam, shooter size, initial idle mixture tune, etc.? If not, do that first and see where it's at.

David
My mistake, I thought it was a "given" that a 3310 is a 750 Vacuum secondary Holley.

I had run the car sucessfully prior to the body change. I have he same accelerator cam in place, have set the idle with a vacuum gauge. The shooter is the one with the Proform and the arm clearance is .015. The Proform body is supposed to take a 750 CFM up to a 830 CFM so I'm trying to figure out where to go from here. The new body has larger and replaceable air bleeds. So it seems as though I have more air flowing through but not the fuel to match? I guess I'll experiment with jets and cams first as I do not have a air bleed kit yet.

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OK, we know what a 3310 is - I just didn't know what form of 4150 it was modded to. Holley has 600cfm VS and 850cfm DP and calls both of them 4150 family.
Is it MS now and with DP and both metering blocks? If DP, is the secondary pump set up 'as usual' for that style? Your new primary shooters - are they different than the 3310 or same? You have a custom setup, and I'm just trying to gather what you have to work with, and what has changed.

David
 

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Discussion Starter #5
OK, we know what a 3310 is - I just didn't know what form of 4150 it was modded to. Holley has 600cfm VS and 850cfm DP and calls both of them 4150 family.
Is it MS now and with DP and both metering blocks? If DP, is the secondary pump set up 'as usual' for that style? Your new primary shooters - are they different than the 3310 or same? You have a custom setup, and I'm just trying to gather what you have to work with, and what has changed.

David
I should have explained my mods better. I took a stock 3310 and bought Holley's 4150 conversion kit with a secondary metering block with replaceable jets. No idle screws and no provisions (drilled or tapped) for a power valve. I have jet extensions and notched float. The accelerator pump cam is the one that came on the new 3310. The squirter on the Proform body had no number designation on it so I put in a Holley 25 to get things going. I did not have time to take it out and test (rains came). I have a 25, 28 & 31 squirter to play with. My new jets arrived today. A kit from 80 to 90 so I have them to play with as well. I had loaned my buddy my box of cams so I'll get them back and play with them if needed. I'll have to figure out which to try first?

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OK, I got it. The first thing I'd do is verify your throttle blades are properly on your transfer slots. T-slot settings are crucial to all the other idle and accel settings. As you've tuned the idle speed and mix already, you can check your T-slots to make sure they still have reasonable exposure. If your primaries have more than .030 slot exposure, bump the secondary blades .010 and close the primaries the same amount. Re-tune idle. Test.

Still a lean spot? Nail it from dead idle and feel/listen for when the flattening happens. If it's instant, check that you have preload on your pump arm for instant shot. If so, try the .031 shooters. If it responds for just a moment and then flattens, back off to .030 or .029 and try again. Post-up what it's doing if you're still having issues by that point.

David
 

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just info ... converting into a 4150 ment it was a 4160 . no DP were 4160

3310's were first made as 780 cfm 4150's then holley changed rating to 750 cfm and 4160's

all are V/S
 

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Discussion Starter #8
With it raining I have no time to run the car. I had some time tonight to look closely at the carb. The squirter size is 25. Here are the (Proform) bleed sizes:

Primary
Idle, main, main, idle
75 36 36 75

Secondary
Idle, main, main, idle
45 36 36 45

I put some 84 rear jets in but still rain so no testing. It looks like a white pump cam in the 1 position.

Maybe on the weekend I'll get some time to run it.

Thanks,
 
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