If I remember correctly, that carb kit you got was for the original carb, right? If so, the power valve is correct.

Let me ask this: If you're sitting at idle in neutral, and you gun the gas and let off, does the exhaust show any black smoke? Does the engine just rev up like normal, and not stumble? And under load, the same thing, it just accelerates and acts normal? If so, the accelerator pump doesn't really need any modifications.

 

Folks, keep in mind the 500 cfm Holley list 4412 was designed and built as a race carburetor, not really meant for the street. Why Holley doesn't state this fact in the catalog, I don't know. Huge internal passages, big transfer slots, big jets and that 50cc REO squirter. Meant for iron head, iron manifold spec circle racing that do not allow carb mods past jetting and maybe removing the choke and choke horn. These are mall block V8s that turn upwards of 7500 rpm (yeah, it can be done).

What was on the F600/370V8 was a 350 cfm Holley that probably, based on my intarwebs snooping, had #62 jets and a 6.5 power valve. A bunch smaller, easier to tame.

Idle mix on that 500 would be easy - just adjust until it idles as smoothly as possible without loading up. Don't have the idle speed screw turned in too far, as this will expose the transfer slots, adding a butt-load of fuel. No Bueno for setting the idle mix.

Throttle tip-in is going to be the hardest to tweak. I would go down to the 30cc squirter and get the assortment of accel pump cams. Find one in the middle range (should be a chart with the kit) and check throttle response under load as well as statically.
Holley 20-12: Accelerator Pump Cam Assortment Includes 8 Different Cams | JEGS
There is a video tutorial on that page for you.

Okay, the main jets. Since you can't stick your truck on the dyno and test all day, that method is out. Yeah, revving it while stationary and looking for black smoke is somewhat valid, it's not that accurate, either. At any rate, you will be changing jets from experience. This new garbage gas we have to run makes plug color testing real hard.

Question to the OP; can you get "Farm Gas", the stuff with no alcohol in it? If so, you can set your jets by plug color testing. Get the engine warm, then take off down the road like a bat out of hell. Get into top gear, let it pull hard for 10 to 20 seconds, then cut the ignition and shove in the clutch. Let the engine quit turning as quick as possible as you stop. Pop the hood, pull a nice hot plug from either #1, #4, #5 or #8. Farthest from the carb. Try not to burn your paws while you're at this. In good light, look at the bidness end of the plug.

Black center electrode ceramic insulator means you're waaaay too rich. Go down a minimum of two jet sizes. Medium brown, try going down one jet size. Tan, where you can say it's tan, is good. If you have to guess if it's white or tan, maybe go up one jet size. White, or white with black specks, waaay too lean. Up two jet sizes minimum. BTW, those black specks are off of your pistons. Yeah.

See how this is complicated, to the point I can't just say put #XX jets in and go? I mean, the #73 jets might work but it will probably be too rich. I ran #68 jets and I think it was the brown cam in my sportsman Fox body T-bird. 9.0 to 1 351 windsor, early 351 heads, I think the manifold was about a '73 or so cast iron piece, Huge lumpy cam with cast iron exhaust, T&C Toploader 4 speed, anywhere from 4.11's to 6.00 gears, depending on the track. 3200 lbs with my fat butt in the seat. On real short bullrings, we ran the 350 cfm carb if it was allowed.

I guess I should say, I would recommend getting the blue bowl gaskets, if you don't already have one in place. Might not hurt to have a spare set (bowl and block).

You did say you wanted to be a Master Holley Carb Technician, right?

 

Hey thanks for all the great info... Unfortunately I got busy again and had to push project to side again but as soon as I finish job I'm doing should have time to get back at it .... And a holly carb technician I will be after this haha probably a good thing tho cuz gonna have truck for a while

 

is this the carb you were saying would work with the 370 ford engine?

 

That, my friend, is the best all around 2bbl ever made in my opinion. Used from little 255/260 small blocks all the way to 390 FE big blocks. Good price, as long as they don't gouge for shipping.

It will need a manual choke cable, if you don't already have one. Generally, just bolt it on, turn the idle mix screws in to gently bottom, then out two turns. Fire up, set idle speed, go. Choke might need a bit of adjustment, too but it's not daunting. It comes with good instructions and it is infinitely tunable. Should be good out of the box for you with the exception of trying some accel pump cam experimentation. You might need a bit more, a bit sooner for your heavy truck.

I've ran this on International SV series motors, 304, 345, 392. Ran like a champ on any of them. The 392 in my T-All needed the cam moved to the #2 screw position. That is explained in the instructions. Had one on a 260 in a shoebox '64 Falcon and a '69 390 in an F250. Very versatile.

 

Sweet gonna place order now and yeah it's free shipping so $322 is the full price you know if my 4412 carb is worth posting on Craigslist for sale cuz I don't need it and would like to get sumthing out of it besides all the waisted time on it haha if not I guess I'll jus let it dust bunny up sumwhere til I buy a race car that needs it haha (probably won't ever happen tho)

 

Yeah, put it up on CL and see what you can get for it.

 

So got the new carb like in 2 days from ordering it luckily I'm located near Kentucky where the holly manufacture/distributor is located so she came quick got it put on and wow she started up tuned the idles screws a bit to get it to run a bit better and Wah Lah she fires right up everytime now im amazed finally it appears things are panning out for me haha gonna be taking it for a test drive this weekend to see how she drive with new carb

 

Good to hear you're making progress now. Do post back and let us know how the test drive goes.

BTW, got any takers on that 500cfm Holley yet? LOL!

 

So got busy never ended up taking for drive but did move around in driveway but it was running good and starting everytime..... and all of sudden old man winter came and froze everything including my progress on truck cuz it won't start for nothing no choke no gas in carb jus cranks and cranks til battery looses juice any ideas I been checking things and its jus so cold out now I might have a brain freeze cuz its has gas at carb plugs are sparking engine cranks slightly weak but i jus figured its cuz it's so cold and I do religious anti freeze checks in everything I own so not frozen up. Just put 5 gal of fresh gas in to bring up to a quarter tank so should have good explosive fuel any ideas???

 

Last thing I did when it was running good i let it get to operating temp and changed oil and filter put a quart of the Lucas oil amendment and after I started up and ran good and next day same thing...... got cold didn't start for a week and she wouldn't start for nothing and been messing with it everytime I feel like freezing my butt off which I'm not gonna lie hasn't been to much but I did buy a compression tester the other day was gonna check that out cuz I'm lost in the ford truck world lol

 

So nvm that last post wasn't getting enough fuel to carb having issues with keeping aftermarket inline fuel pump primed (the in-tank pump was by passed with inline fuel pump not sure why) the inline fuel pump is about 12inches away from top of tank so there could only be 16inches or so of line to keep fuel in for pump to suck but pump is only 14in above bottom of tank where I assume the line sucks from and only 3 in higher then top of tank is this jus not gonna work without me pressuring the tank via rag and hose to get fuel to pump to fill carb......should I jus fix in-tank pump or is there other options with the inline pump????? Any input would be greatly appreciated..... and btw when I got the fuel to carb via priming, the truck ran great it was jus too cold out last time I was messing with it so patience were dried up haha

 

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   I've read this entire post and sounds like you've had a time I just went through a similar dilemma on one a friend bought and brought to me to start from scratch in a sense sounds like your real close I would start by verifying a few things this diagram was on passenger valve cover look up some of the abbreviations that helped me a lot in tracing out all of the lines also double check for a port at the back of the carb between egr valve it's a bigger one nothing was connected when I started on mine so huge vacuum leak these engines are bad for burning valves start by hooking up a vacuum gauge to manifold vacuum theres several ports just to the right of distributor you should have 14-20 with a fairly steady needle while running and advance line disconnected a fluttering needle could be a sign of valve not sealing or carb adjustment issue and throttle plate partially opened or a vacuum leak a cylinder leak down test would 100% confirm a valve issue but different can of worms for now your timing needs to be close before making any carb adjustments I would shoot for 8°for an initial start seems like you did from pics but with vacuum gauge connected you want to shoot for maximum vacuum adjust distributor advance unplugged engine running move each direction and see where you max out you may retard it just a touch from max you will have symptoms with to much advance like hard start clamp down where you feel is best then move to idle screws on the holly there should be one on each side of carb do the 1and 1/2 turns out from bottom just like any carb now all this adjusts is air flow at idle changes nothing for performance or open throttle symptom and each side controls each bank or half of engine once again monitor gauge and shoot for best vacuum I normally go in until audible motor load then begin to back out until it smooths out and best vacuum is achieved do this for each side then make minor adjustments to idle speed screw on linkage and set rpms now this part alot will argue about the factory hookup for advance is above the throttle plate on passenger side of carb with this port there will be no vacuum at idle because the throttle plate is blocking it off which is normal this was throwing you off when you were trying to check if the advance mechanism was good it's designed to allow advance at partial throttle for instance just cruising down the highway say 1/8 to 1/4 throttle supposed to be more efficient especially for highway driving now keep in mind at wide open throttle your gonna lose vacuum and the advance is doing nothing no matter which port your on I personally disagree with using the high port and switch to manifold vacuum where I said to connect gauge there you will have advance at idle so when you make your adjustments for timing and carb you can obtain a higher vacuum when adjusting initial timing and carb adjustment and even lower idle speed because when u connect advance it will bring rpms back up some with this high vacuum it will make for better low end response for instance taking off on a hill or loaded harder to kill engine but to each thier own experiment each way if you like now u mentioned there was an aftermarket fuel pump that could be causing some of your fuel issues with a carb u only need 5-9 lbs of fuel pressure there should be a regulator on your supply line near passenger rear of engine I would really recommend putting a gauge inline between regulator and carb and see what your at because if pressure is to high needle and seat won't close and you'll be overfilling bowl and having other issues also check your egr behind carb u can use a hand vacuum pump on diaphragm and physically watch the valve open and close when u release in situations where say u roll down a hill and your in gear letting engine hold back that's gonna be a situation of very high vacuum because your off throttle so plate is closed but your turning higher rpms creating more pull from piston thus higher vacuum that's a time erg will be really opening recirculating exhaust you'll wanna verify valve is opening and not plugged up with carbon I've seen them blocked off with a plate butif this is done you'll very likely experience popping or backfire in those downhill deceleration or holding back scenarios that's a situation where high port may be more beneficial or retarding timing some and as far the carb what u have looks to be the same as what was on this one as far as I know its original do some research on recommended cfm to cubic inch ratios the higher the cfm the more air flow someone recommended a 310?cfm Or so 2 brl that seems a little low but I probably wouldn't go bigger than 650 hope this helps