Carb Issues - PLEASE HELP

[1987_chevy_]

i just had my carb professionally tuned. once the engine warms up it ran good, The first morning i got it back after the tune i started it up and it idled at about 3-400 RPMS. I could let it warm up for 15 minutes and nothing changes. when i put it in drive the RPMs go down and it stalls. it is a 383 stroker with a quickfuel 650cfm mechanical advance. i adjusted the fast idle speed screw hoping it would increase the ideal speed. quickfuels recommendation is like 1500rpm - 2000rpm and mine idles at 3-500 RPMS on startup. i dont think that screw did much. maybe i need to turn it more? idk tho

when i also got it back i would be able to cruise in 3rd gear and slam the gas and it would throw me back. now when i give it gas in 3rd gear it slowy makes its way up to speed. kickdown cable issue??

Im a young kid building my first engine, and these carbs are really starting to frustrate me. help would be awesome. i just want it to run right, its been nothing but problems.

 

[gpmorgan]

What do you mean by mechanical advance? Mechanical secondaries or manual choke or ???

 

[crazy4offroad]

Make sure you're running a good fuel filter. If dirt gets under the needle and seat it will flood a lot and run really rich with black smoke. You can take a spark plug out and check it for black soot, if you have any it's running rich.

 

[crazy4offroad]

What do you mean by mechanical advance? Mechanical secondaries or manual choke or ???

He means mechanical secondaries. Looks like a Holley 4150 650 cfm.
https://www.summitracing.com/parts/...MIoae0wLmA1wIVxCSGCh2uAQp2EAQYASABEgJh7fD_BwE

 

[gpmorgan]

If it has no choke tower then that's probably what's causing the low idle on cold start up. After warm up it should idle around 750 to 850 rpms.

 

[1987_chevy_]

What do you mean by mechanical advance? Mechanical secondaries or manual choke or ???

mechanical secondaries, my bad

 

[1987_chevy_]

If it has no choke tower then that's probably what's causing the low idle on cold start up. After warm up it should idle around 750 to 850 rpms.

the problem is, it wont warm up, i literally let it idle for 10 minutes this morning and it stalled. i got it running on my way home from work and it stalled at almost every red light.

 

[gpmorgan]

The idle mixture screws may need to be turned out (counter clockwise) to stop it from stalling. Is this the 87 truck your working on? Did it have a tbi engine with a 700r4 originally?

 

[gpmorgan]

Has it got a performance cam. What size?

 

[1987_chevy_]

The idle mixture screws may need to be turned out (counter clockwise) to stop it from stalling. Is this the 87 truck your working on? Did it have a tbi engine with a 700r4 originally?

it was a TBI with a 700R4, i did a 383 stroker and th400 swap. yes it also has a performance cam in it. .460 lift, i don't know all the information on it right off hand tho.

 

[gpmorgan]

Try setting the idle mixture screws 1 1/2 turns out and see if it will idle in gear. If you adjust the idle screw to far out it will render the idle mixture screws useless but you should be able to get it to idle around 800 rpms without uncovering the idle transfer slots in the lower venturies. Holly has a lot of tuning info on YouTube that may help. You need to be familiar with it before getting crazy with turning screws. What kind of fuel supply do you have?

 

[1987_chevy_]

Try setting the idle mixture screws 1 1/2 turns out and see if it will idle in gear. If you adjust the idle screw to far out it will render the idle mixture screws useless but you should be able to get it to idle around 800 rpms without uncovering the idle transfer slots in the lower venturies. Holly has a lot of tuning info on YouTube that may help. You need to be familiar with it before getting crazy with turning screws. What kind of fuel supply do you have?

Yeah idk if I really wanna mess with all that? Or should I bring it back to the guys that Dyno tuned it originally? It ran good when I got it back! It just ran like completely crap the next morning I started it! What do you mean fuel supply? Like mechanical pump?

 

[gpmorgan]

Yeah. Is it a mechanical pump? If you have had someone tune it,, then yes, take it back and let him repunt.

 

[gpmorgan]

There's not to much to a holly style carb. You just need.to know how it works. Half the fun of hotrodding is working on them.lol.

 

[1987_chevy_]

There's not to much to a holly style carb. You just need.to know how it works. Half the fun of hotrodding is working on them.lol.

If you know what you're doing! This is a daily driver right now and I need it to run good lol! The only problem is idk if he's gonna charge me to make it run right again? If so, I don't have money to do it!