Complete rookie, 350sbc, vortec 274, 1 5/8 headers, 600cfm vac sec. Elec choke

I fire it up smoked like crazy. For about 15min i put it in gear go down the road get it good and hot the smoke stops i still smell strong exhaust. Man told me im over thinking the problem. I was about to get a calibration kit (jets and all). He said "adjust choke". I jist went out. Tapped pedal set choke, fired it up. Seen that the choke was closed tight. Shut car off adjust the choke to as open as possible without going outside "adjustment mark boundaries" and fired it back up (no pressing the gas pedal) it fires right up after a few seconds the smoke ALL BUT BUT DISAPPEARED. There was faint traces of smoke until full temp 185 degrees. After that very very faint puffs every so often. I locked down the choke and smiled.....

Question: is there anything else i need to do? Should check? The smoke is embarrassing when i leave it parked and the car cools completely when im away from home. Other than that the car performs great. I read the HOLLEY TUNING PROCEDURE in the sticky. Im not that advanced but eager to learn....... Im thinking i need to go to a 650cfm when a friends dad put a 750 double pump on the motor i could never get it to run right. I guess it was just too big. So i went back to my little 600..... So far so good. But i feel theres more..... Help please....

update: i just thought about it. Do i need to drive this thing and burn the unburnt carbon out of this motor?

 

Making the choke work right isn't really "tuning" IMO; it's more akin to maintenance, even though it feels kinda like "tuning".

As a starting point, set it such that it just barely fully closes when the engine is completely cold and it's about 70° out. There should also be a vacuum-operated pulloff of some sort; adjust that so that when it fully operates, it cracks the blade open about ¼".

Make sure of course that the electric source works right. Ideally you'd wire it so that it only gets power when the alt is alternating, but that takes a bit of extra circuitry (a relay at least, for sure). But, be absolutely certain that it's getting full battery voltage when running.

Then do the stuff in the sticky. Which incidentally I didn't exactly "write" all at once; it's more like Mr. Boundless collected pieces of things that I had written repetitively all in one place. All the same, it works well for any Holley, even the cheeeeeeep "universal" ones like 1850 which I'm not at all a fan of.

Changing the size of the carb is irrelevant to the matter at hand. A 600 is probably adequate if you don't intend to run it over 6000 RPM or so anyway, especially if your intake has a relatively large plenum such as a Performer RPM. The reason the 750 never ran right probably had nothing whatsoever to do with its CFM capacity; more likely, it was either messed up somehow, or its calibration was for an engine so different from yours that it was a total mismatch.

No need to worry about the carbon; it'll take care of itself. A new set of plugs however would be VERY good idea.

 

63-65 degrees outside:

 

No; that's just too much fuel, period. Fuel bowl level too high probably. It was blasting out the burn-your-eyes smoke with the choke full open.

 

Check float level....... Check
ill see if i can knock that out tomorrow after the dentist. Anything else???? And thk u

 

Carb tuning has to be done in the correct order. Float level is the 1st step.

You don't say what you're doing for a fuel system. If you're like most people your FP is probably too high. Doesn't need to be more than 5 - 6 psi MAX. Doesn't even need to be that high if it stays above about 3 during sustained WOT operation. The lower it is, the easier it is for the carb to control the fuel level. Too low of course you'll eventually run into fuel starvation. All you need is whatever it takes to keep the fuel bowls full.

 

The car has an electric fuel pump it also has a fuel pressure regulator the fuel pressure is sitting somewhere around 5 lb of pressure

 

Is it a 3-port regulator, with return? Is that the fuel pressure while it's in the act of screwing up, or at some other time?

 

3 port.
in , out, return
5psi while running

 

80457-8

No sight screw

No adjust screw
looks like im going to have to take both the bowls off and adjust by bending the arm that holds the float until the float is parallel with the roof of the bowl. All while holding the bowl upside down. Ugh, ill give it a try tomorrow. Dentist really did a number on me i dont feel like it today

 

That's a fairly new carb; latest version of the Holley carb listing that I have is from 2018, and that list # was only up to -7 then; so it's no more than a couple of years old.

By far not my favorite type of Holley carb. Very similar to the 1850. Harder to work on, hates high fuel pressure because of the smaller float and less lever arm advantage, secondary metering plate instead of jets, just ... not a real friendly piece to work with. Butt hay it's what you've got, and it's capable of working better than what it is, so...

You say 5 psi. Is that WHILE IT'S IN THE ACT OF SCREWING UP? What happens if you lower it WHILE IT'S IN THE ACT OF SCREWING UP? Does that have any effect? Note that the concept of WHILE IT'S IN THE ACT OF SCREWING UP is critical to the troubleshooting effort: electric fuel pump systems are well and widely known for their pressure to taper off somewhat as things heat up for some reason, so if the pressure is too high when cold but then settles down to 5 psi after it gets warm, you might well be out of control (of the fuel level) at startup but then when the pressure goes down a bit it gains control back. Looking at your throttle bores, that would be particularly, on the secondary side... there's signs of fuel in places no fuel should be, as though it's been bubbling up out of the air bleeds. I don't see evidence of that on the primary side.

 

Sorry i been workin alot
i will try my best to check that tomorrow. Thank u