Team Camaro Tech banner

Replacement/Aftermarket Carb?

8K views 27 replies 12 participants last post by  1968RallySport 
#1 ·
I have a '69 w/ a 302 and a Holley 4346 carb and the OE intake manifold for a 302. I'm thinking about putting the original carb on the shelf - any recommendations for a replacement carb if I go aftermarket? I'm just doing street driving - do I need 750 CFM or am I better off to go with 650 CFM?

Thanks!
 
#3 · (Edited)
I'd agree that there may not be a good reason to shelve what you have. However, for general street purposes you'd prbly be better off in the 650 cfm realm for improved thottle response.

As for Quick Fuel - I recently replaced my 670 Holley Avenger with a Quick Fuel 680 Vac Sec. HR series. At first I was very impressed with all the added features, aluminum parts, etc. but has been extremely finicky to dial this carb in. I've never experienced such a battle with getting a carb dialed in properly for all aspects of fuel delivery. After about 2 months of experimenting (here and there as I can on wknds) and calling Quick Fuel techs who I've found will advise contradictory to each other (which is fine and typical in the industry but providing 100% opposite solutions for a basic questions, make me wonder and have since moved on to other sources cause I feel like I'm rolling the dice with reps on their ph. lines).

I've recently discovered that the linkage that activates the pump arm is chinsy and bends quite easily compared to a Holley. A few other basic linkage/parts are inferior as well when comparing side by side.

It will idle fine most of the time and intermittently changes idle speed by as muich as 200 rpm on me (I have no vaccum leaks, ignition issues or other problems). The choke does not operate consistently/reliably either so disconnected it. Cooler temps. drastically impact fuel to point of running fine at 75 deg. ambient and barely running decent enough to drive at 45 deg. ambient. I have a wideband so can pay close attention to how it's delivering fuel as well. Never seen that w/Holley's or Edelbrocks. Now that I've lived with this carb for a couple months, I would have paid more $ for a Holley of equivalent features cause I've never had issues with numerous Holleys (or Edelbrocks) over the years. The seconday plate was not adjusted properly from the factory (a very important essential of basic out of box functionality) and wasn't until recently that a tech pointed me in that direction as the possible cause of my tip in lean issues that still refuse to go away. It has some nice features and price is good compared to Holley but it's not quite the value that I thought it would be. I may have gotten a dud. I will say that under full throttle pedal mashing, it is doing well but I feel like I've lost significant ground when comes to reliable street manners. So I'm now thinking about putting this new one on the shelf cause the speed shop won't take it back.
 
#5 ·
Had lots of good luck with Holly double pumpers. Plus you can still run your stock fuel lines.
 
#6 ·
I'm thinking about shelving the Holley b/c I'm having a terrible time trying to get an electric choke to fit on the 4346 carb body. Maybe I'm over-complicating but I the conversion kit i bought (Holley part number 45-224) is an MF'er to get installed. Anyone else run into this problem?
 
#7 ·
You can not install an electric choke conversion kit on a 4346, nor any other Holley designed for an OEM divorced choke system, the required mounting bosses are not present on those main bodies. You can only install the electric choke on a carb that was originally designed for either an electric, thermal (hot air tube) or manual hand choke.

Eric
 
#12 ·
Good news: I'm not an idiot b/c I couldn't get the choke installed

Bad news: I'm an idiot for not knowing it couldn't be installed in the first place
Good news-bad news. the story of my life.:yes:
At the strip 4 or 5 years ago I said to my car club buddy out of frustration that I just want to get into the twelves. I had to dial in at 13 something. Then I got back to the pits and he said 'the good news is you turned a 12.45, the bad news is you turned a 12.45. Oh well, that's race'n.:)
 
#11 ·
Any 600 to 650 cfm Holly or Edelbrock carb will work fine. I suggest electric choke & vacuum secondary. Stay away fron the Edelbrock endurashine finish...it flakes off when exposed to gas or antifreeze. Some drop style air cleaners won't fit properly over the Edelbrock electric choke housing.
 
#13 ·
Thanks to all for the help and advice... I'm looking to go with a choke b/c the car is hell to start. There's no choke right now - when I manually choke (with a piece of cardboard or whatever is lying around), she starts right up. Maybe I'm missing something but it seems like a choke is in order - no?
 
#14 ·
Pump the accelerator a couple times before turning the engine over. Once it starts keep it running by using the accelerator pedal. In a few minutes it will be warmed up enough to drive. I have never needed/used a choke on mine in 30 years.
Currently running a 302, M22 & 4:10 12-bolt posi :D
 
#16 ·
Next time you go to start it, try this. Remove your air cleaner. Look down the carburator and manually work the accelerator. You should see fuel squirting out of both discharge nozzles on the primary side. Let us know what you see.
 
#18 ·
Crank the engine over until it starts. If it doesn't start. Pump the accelerator a couple more times. Crank the engine over again. As long as you have a spark, fuel and compression, it will start. You should be able to get the engine started and keep it running by pumping the accelerator until the engine is warmed up. Should only take a few minutes. No need for a choke.
 
#19 ·
Start from scratch. Check the float levels, fuel pressure etc. I do not have a choke on mine and like said before pump the gas a few times and go. Maybe you are flooding it? When I pump the gas I just pump it gently a few times while cranking it, going to the floor will squirt both primary and secondary pump.
 
#20 ·
OK - taking the advise and trying to start over before going with a new carb. Float levels look good. Both squirters are working well. Followed the instructions on the rich/lean screw - put it all the way in and backed it off half a turn. Once I do get the car started and warmed up, it will turn over pretty easily afterward - its just getting it started for the first time when I drive it.

I'm a rookie at fuel pumps and fuel pressure - are those the next two rocks to turn over? What should I be looking for?
 
#24 ·
I'm running no choke... When I get in, I typically pump it to the floor twice then try to start it. Inevitably, I have to keep pumping while the engine is cranking in order to get it to fire. This usually results in me flooding the carb - then I start over. After about 5 minutes, I can usually get it running. After I get the engine warmed up, I can turn it off/on with no issues - even if there are a few hours in between.
 
#27 ·
May have a fuel pressure leak down where after sitting..the fuel pressure is at zero...and has to pressurize the carburetor. Put a fuel pressure gauge before the carburetor and see what is going n. Check lines for pressure leaks etc. I run a Holley 650 Dual Feed-Double Pumper without a choke here in the North East and pump twice, start---dies,pump twice again and fires right up and I play with the gas pedal then hold the RPM to warm up. That is no matter how cold it is....even at 0 degrees Fahrenheit ! BTW..I don't drive the car except out of the garage at any temp below 45 degrees.

Kev
 
#25 · (Edited)
Pull a couple of spark plugs and see what they look like. are they black, wet, light gray? If your ignition system is working properly the procedure we are having you try does work :beers: Many of us do not use chokes.
Bear with me here. All a choke does is choke-off the air which makes your mixture rich. You can do the same thing using your accelerator pump. You have found out what is too much fuel, because you flooded the engine. Try pumping the accelerator a little less.
 
#26 ·
If you are set on running a choke,why not just install the original style hot air choke spring in the intake manifold well and connect the choke rod to the carburetor? If you have a factory 302 intake and carb,the choke kits are about $25 from any of the online suppliers.The installation of a choke might not solve your problem.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top