1969 Thunderbird installing new carburetor

[OneAmongOthers]

So I went out and picked up a Holley 750 carb for my tbird and I am just wondering what goes into installing it. It’s my first time ever installing a carbuertor so any help with what needs to be done would be appreciated.

Carbuertor I purchased
https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-80459SA

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[cjbird]

So I went out and picked up a Holley 750 carb for my tbird and I am just wondering what goes into installing it. It’s my first time ever installing a carbuertor so any help with what needs to be done would be appreciated.

Carbuertor I purchased
https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-80459SA

Looks like good carburator, not sure about your cruise attachments but hopefully will work without much trouble if any. Without having someone read the plugs before and after you never know if jetting is just right, but doubt it will cause any trouble for street use. I was told by a few engine builders that they tend to be set up closer for chevy engines, any holleys I ever used were for circle track and needed to jetted and modified properly for my engines. I sent one 750 double pumper back east to be modified and the builder said it was a must to know if it was a ford or chevy application. All that being said I have used a few out of the box holly's like your and the were an improvement over the stock carb. Good luck, hope it helps!

 

[OneAmongOthers]

Hey thanks for the heads up! Cruise control was long disconnected so that should be an issue. Actually now he car has a Holley on it. Though I am not sure what Holley it even is. Previous owner didn’t either. I think it’s either a 600 or 650. Though this is the reason I am switching it. At least now I KNOW exactly what I got over the guessing game currently.

 

[cjbird]

Hey thanks for the heads up! Cruise control was long disconnected so that should be an issue. Actually now he car has a Holley on it. Though I am not sure what Holley it even is. Previous owner didn’t either. I think it’s either a 600 or 650. Though this is the reason I am switching it. At least now I KNOW exactly what I got over the guessing game currently.

Something else I'll throw in here, just an FYI,,, I have a 1978 Tbird, 351M 2 barrel of course, I rebuilt the carb, it had sat many years I suspect, anyway got it all back together and it seemed to have a noticeable stumble off idle when cold only. I moved choke adjustment all over, accelerator pump adjustment also, I had checked timing when I first started in and was about 10 degrees btdc, although the timing marks were rusty and covered with many miles if the power steering fluid, dirt, etc because the seal leaked. I thought ok for then as I hadn't done the carb yet or checked other things. After all was done, still the stumble when cold, when warmed up to operating temp it was fine. Well, then I thought, did I disconnect the vacuum advance when I timed it??? checked it again, with vacuum disconnected to distributor and it read close to 0 tdc, timing calls for 12 btdc, I set it at 14 and it's a new car! of course it runs stronger, etc. I spent alot of time looking for something that was right in front of me,,, oh well
Maybe this will help someone else.
John G

 

[DEVIL DOG 62]

Replace the gasket underneath, hook up the throttle linkage, hook up your vacuum hoses. they should be pretty close to where you take the old ones off.
The way I've always tuned in the jets of my carbs is start with 1 jet. Turn it in clock wise until the engine starts to shake then back it out until it smooths out. Do the same to the other one. Saves you tons of cash instead of taking it in somewhere and paying them to do it.

 

[cjbird]

That's right DEVIL DOG 62, that will adjust your idle mixture. those will have nothing to do with acceleration, but it's good to lean down the idle, uses less gas too at idle! Make sure engine is warmed up and choke is open before adjusting idle mixture.

 

[DEVIL DOG 62]

That's right DEVIL DOG 62, that will adjust your idle mixture. those will have nothing to do with acceleration, but it's good to lean down the idle, uses less gas too at idle! Make sure engine is warmed up and choke is open before adjusting idle mixture.

What other adjustments can you do to a carburetor to get better acceleration? You have two jets to adjust and the choke nothing else unless you're taking it apart and reporting the jets or something. I'm waiting to hear about carburetor adjustments to improve acceleration. Good Acceleration depends on a lot of things. Good Carb, Good plugs & wires, Good points & condenser, Good distributor & cap, Good coil, Good timing, Good mechanic doing all of these will get you good acceleration

 

[DEVIL DOG 62]

I forgot about adjusting the float level also. That's part of good acceleration

 

[cjbird]

I forgot about adjusting the float level also. That's part of good acceleration

Right Devil Dog 62, the idle adjustment is quite different from the 2 main jets, on a 2 barrel carb, 4100 series 4 barrel has 4 jets, and a 4350 4 barrel has 2 jets, I've not seen a 4350.
If the float level was too low you might run out of gas under full throttle. The accelerator pump throws fuel down the carb on takeoff/acceleration or if idling and testing with air cleaner off you can see the fuel go down the carb. When the engine rpm increases the engine will be loosing vacuum and the the power valve will open supplying more fuel. Thats about it, my carb had set for along time, I'm sure the fuel dried up and it needed to be cleaned and all passages needed cleaned and blown out with air, new float, power valve and accelerator pump, that's standard on most rebuild kits.
Well,thats the way I think it works anyway!
Good luck
John G

 

[DEVIL DOG 62]

Right Devil Dog 62, the idle adjustment is quite different from the 2 main jets, on a 2 barrel carb, 4100 series 4 barrel has 4 jets, and a 4350 4 barrel has 2 jets, I've not seen a 4350.
If the float level was too low you might run out of gas under full throttle. The accelerator pump throws fuel down the carb on takeoff/acceleration or if idling and testing with air cleaner off you can see the fuel go down the carb. When the engine rpm increases the engine will be loosing vacuum and the the power valve will open supplying more fuel. Thats about it, my carb had set for along time, I'm sure the fuel dried up and it needed to be cleaned and all passages needed cleaned and blown out with air, new float, power valve and accelerator pump, that's standard on most rebuild kits.
Well,thats the way I think it works anyway!
Good luck
John G

AMEN

 

[OneAmongOthers]

Hmm seems like a lot of work getting it set up. Hopefully I can get her running after all this. I just ordered an edelbrock intake for her as well so no more of that raggity ass intake currently on the car with all sorts of ports for emissions and crap. darn those late 70’s engines and that emission crap.

 

[cjbird]

your right OneAmongOthers, but it should go good with new carb. ALL the smog stuff fell off my car before I got it,,,, 😉it just added to the confusion when trying to set it up anyway. Just do basics, air, fuel,spark,should work fine. If you have time check carb basis's on youtube take a look, sometimes they make sense !
Just have to tell a story, I bought a 1957 ford 2 door hardtop a few years ago,, well maybe 20 years ago. I got it on my car trailer,, barely, and brought it home. well, took wife for first BIG RIDE! Drove about 3 miles, all seemed ok so decided to really step on the 57 from a stop, it took off ok, shifted into 2nd gear and it was like I turned the key off,,, coasted to a stop at a wide spot and it would not start. I looked at my wife and said "ain't cruzin fun" I got out, thinking air, fuel, spark, had air, had fuel, but no spark! it had points and they had closed up,(Guess that's why it was a chore just getting it on the trailer) I opened up the point gap a little and she said "take me home" which is just what I did of course!
Moral of the story,, air, fuel, spark,, getting in the right order is sometime hardest.
Have a good day!
John G

 

[OneAmongOthers]

Points was already removed off the car and I installed a modern electronic ignition system. Wasn’t going to even bother dealing with points.

 

[64ZCODE]

Get the throttle linkage set up correctly so you're getting WOT when the accelerator pedal is pushed all the way to the floor, which means your secondaries will be opening up correctly as well. Procedure: disconnect the throttle linkage from the throttle plate on the side of the carb; turn the throttle plate until the carb is at WOT and make a register mark on the throttle plate and the side of the carb; re-attach the throttle linkage where you think it should be on the throttle plate; have someone press the accelerator pedal to the floor and see if the throttle plate register mark lines up with the register mark on the carb, i.e. the carb is at WOT. Note Holley throttle plates have several holes including one that is too big in diameter for the throttle linkage, however Holley makes an adapter. Before you do the preceding, check to make sure the accelerator pedal has the required clearance from the tip of the pedal to the floorboard, sometimes carpet can be bunched up so that the pedal never reaches the full extent of it's travel.

For acceleration, 1) ensure the accelerator pump is properly adjusted, and note you can swap in larger or smaller accelerator jets which will affect the amount of gas delivered during the accelerator pump operation, 2) the Holley carbs have power valves (opens under specified vacuum conditions and dumps gas down the throat of the carb). Getting the correct power valve can eliminate flat spots in the power curve. Power valves are numbered and generally the number of the valve should be half of the manifold vacuum at idle, for example if the manifold vacuum at idle is 17 inches of mercury, then the initial power valve should be 8.5.

 

[OneAmongOthers]

Get the throttle linkage set up correctly so you're getting WOT when the accelerator pedal is pushed all the way to the floor, which means your secondaries will be opening up correctly as well. Procedure: disconnect the throttle linkage from the throttle plate on the side of the carb; turn the throttle plate until the carb is at WOT and make a register mark on the throttle plate and the side of the carb; re-attach the throttle linkage where you think it should be on the throttle plate; have someone press the accelerator pedal to the floor and see if the throttle plate register mark lines up with the register mark on the carb, i.e. the carb is at WOT. Note Holley throttle plates have several holes including one that is too big in diameter for the throttle linkage, however Holley makes an adapter. Before you do the preceding, check to make sure the accelerator pedal has the required clearance from the tip of the pedal to the floorboard, sometimes carpet can be bunched up so that the pedal never reaches the full extent of it's travel.

For acceleration, 1) ensure the accelerator pump is properly adjusted, and note you can swap in larger or smaller accelerator jets which will affect the amount of gas delivered during the accelerator pump operation, 2) the Holley carbs have power valves (opens under specified vacuum conditions and dumps gas down the throat of the carb). Getting the correct power valve can eliminate flat spots in the power curve. Power valves are numbered and generally the number of the valve should be half of the manifold vacuum at idle, for example if the manifold vacuum at idle is 17 inches of mercury, then the initial power valve should be 8.5.

Hey thanks for the info! I am in the process of installing the stuff, but I ran into a snag with the intake. it seems the Edelbrock intake is... different? The gaskets look like they are good, but its missing the center hole. (Fel-Pro gaskets, the Edelbrock ones are the same pretty much), and the rear passages in the intake are missing. Was this for something else and not a coolant passage? I know I got the right intake as this was the one listed for a 429/460 engine so what am I looking at?