Help with engine hesitating under acceleration SBC 350

[Lou6t4gto]

Hello, my first post on this website!

I have a 1979 Camaro with a 350. Edlebrock carb #1406, edlebrock intake and headers, stock internals. The issue is that the car will hesitate/sputter when im at a stop and give her gas. It really has a hard time getting to go and if i floor the gas pedal, I will hear a somewhat a loud click from the carb seeming like it shuts out for a second. When the car is in drive and im stopped, the engine sounds boggish, in and out trynna breathe or something. Ive had this issue for a while and nothing seems to work.

Things I checked
replaced spark plugs and wires
took off and cleaned carb
new accelertor pump
new electric fuel pump
adjusted mixture screws/idle screw
new distrubutor
played with different step up springs for carb

Side note: When already going any speed over 15 mph the accelration seems fine, its specifically when stopped when it has a hard time

Any advice is much appreciated, im a 24 yr old kid looking to learn as much as i can

I know someone must have brought it up, make sure the Electric fuel pump can only push 5-6 PSI (Regulator), or that will drown it in fuel .6 psi, no more.

 

[rocket dawg]

Ethanol gas on these older style cars makes them run leaner. Making a small problem much bigger. All the suggestions are educated guess's as we cant see or hear it run. But each suggestion is fairly simple to check. Remove valve covers and check for a lose rocker arm. Start the car and watch the rockers do there thing, if one is barely moving, your cam has seen better days. Not likely but possible is the timing chain skipped the gear. Could be as simple as dirty carb. You say to took off and cleaned carb, as in disassemble, soak, ( basically a rebuild)? I know very little about Edelbrock carbs, I ran Holley carbs but not any more. I went with a Holley Sniper EFI. A back fire is a lean condition or a timing issue. Long shot is a restrictive exhaust but that would show up more on higher rpms. Keep us posted, I'm curious on this one.

 

[FrostysZ28]

I might suggest finding a good tuner in your area. Where do you live?

Detroit area

 

[FrostysZ28]

Ethanol gas on these older style cars makes them run leaner. Making a small problem much bigger. All the suggestions are educated guess's as we cant see or hear it run. But each suggestion is fairly simple to check. Remove valve covers and check for a lose rocker arm. Start the car and watch the rockers do there thing, if one is barely moving, your cam has seen better days. Not likely but possible is the timing chain skipped the gear. Could be as simple as dirty carb. You say to took off and cleaned carb, as in disassemble, soak, ( basically a rebuild)? I know very little about Edelbrock carbs, I ran Holley carbs but not any more. I went with a Holley Sniper EFI. A back fire is a lean condition or a timing issue. Long shot is a restrictive exhaust but that would show up motr on higher rpms. Keep us posted, Im curious on this one.

yes i took videos before hand to make sure all pieces were correctly back. I cleaned every part in carb cleaner and scrubbed all the black gunk off. I also install a new accelrator pump that had a broken seal. slowly working on diagnosis. thanks for input

 

[FrostysZ28]

1st off...welcome to Nasty!! Really great that you are willing to go after and fix the issue, rather than passing it off to someone else. Lots of great folk on this board.

I agree with what most said already here. Sometimes it is one issue, sometimes it is multiple issues. That is what can get frustrating, especially for newer eyes.

You could go after the vacuum testing first. It is basically free, and pretty easy. Check the carb to manifold gasket first with the torch, or carb cleaner spray. Move onto one vacuum line at a time connected to your carb. Sometimes the Brake booster or PCV can be the cause as well. Any other smog related hoses and things need to be checked as well. If you have a vacuum advance, this one will throw off the way the car runs. (This will show you that timing adjustment will make a dramatic difference with where the carb settings need to be, especially at idle.) You could check this one with carb spray as well, so you don't have to go through this. Remember, a hose can have a tiny pin hole or small slice somewhere along it's rout, not just at the ends. (Hoses are cheap...hint, hint). If the hesitation happens while in park as well, you can also plug off the transmission vac line to test. One at a time here.

Next, I would double check your timing, (not mentioned where you are at). I won't comment on where you should be, as there are smarter than me guys here who can better help guide you. Let us know your idle timing, all in timing, with and without vac advance. (Don't be surprised if your car stalls out when you take off the vac. advance, you will most likely need to bump up the idle speed screw to keep it running). Also what RPM "all in" happens at would help as well. I would assume your cap and rotor are good, as you have a new distributor. If it's an old cap and rotor, that is pretty cheap as well. I would move onto carb adjustment only after these are squared away, or you'll be doing it all over again.

Your Eddy carb has a max pressure of 5.5, so 4 should work well. The only issue you may have with that is if you hold the throttle down for a long time, you may use the gas faster than you are filling the bowls. Normal street driving, you should be fine. Anything over 5.5, and you push fuel past the seat, flooding the carb out. A vacuum gage is your friend here for idle screw adjustment. It gives you something else to gage by other than the idle moving up or down. I tune for best vacuum. I would take the idle screws right out, spray the holes with carb cleaner before you start, just in case any junk got put in there after cleaning. You had mention that you cleaned the carb. Depending on your process, it is possible to make a carb worse, by not knowing where all of the tiny little orifices are. (Please don't take offence to this, just trying to cover bases). There is also a small screen on the inlet of the carb as well. Some people focus on the small carb parts, and don't take off the brass inlet barb...the screen is in there. Make sure the float height is set correctly as well. It is a pretty easy/basic carb to work with. On that carb there are three settings for the accelerator plunger to be at. There are different squirter sizes available as well. Tons of rods, springs, etc. to chose from. If you go down this rabbit hole, chart your findings for each combination. (You will thank yourself down the road for this one). These are finer adjustments, but can make a dramatic difference.

thank you for this thorough comment. Im taking a ton of notes with all these replies

 

[Sbcking]

did you find the root cause of your troubles?

 

[FrostysZ28]

did you find the root cause of your troubles?

I just pulled her out of hibernation, not too long after I initially posted I had the car stored away for the early winter and couldnt work on it (it was eating me inside out lol) I will get back soon with an update now that its nice