Best carb?

[Lattimer]

I know this is probably right up there with which oil is best, but I need some input on choosing a carb.

My truck has a 327, will soon be a 4-speed manual. Has and Edelbrock Torquer II and an Edelbrock 1406 carb (electric choke).

It runs great under normal driving, runs great at WOT. No stalling. Hesitates sometimes when the 4-barrels open, but not too bad.

Problem is that no matter what I adjust/clean/change, I can not achieve a consistent idle. Start the truck, warm it up, idles at 800. Drive 20 feet, idles at 1200. Drive 20 miles, idles at 600. Shut it off, start up again, idles at 1200.

I've been through the idle mixture procedure using both rpm and vacuum, and while I have leaned it out a lot at idle from where the PO had it, and increased idle vac to almost 29", I just can't get it to idle at a consistent speed. Can't locate a vacuum leak anywhere. Everything except the carb has been replaced in the 3 months I've had the truck.

I am very close to giving up on this POS and putting it on Craigslist. I considered pulling it apart and rebuilding it, but the last carb I tried that on never ran again (it was on a motorcycle). I don't know of anybody local I would trust to work on it, and FWIW I really like new stuff anyways.....LOL.


So, who prefers what carb, and why? I believe a rebuilt Q-jet is not an option with my manifold. Another Edelbrock seems like a poor choice.
I was looking at Holley, Demon, and Quickfuel on Summit and Jegs. Is one better than another? Downsides to any?

I'm really a newbie to carbs. This is the first non-motorcycle or lawnmower carb I have ever worked on. I'm slightly under 40, so its been fuel injection my whole life.....LOL

I've been reading a lot, but that doesn't always correlate to real world. Any advice is appreciated!

[chiefcfd]

That sounds like an electric choke problem. I have that same carb. I don't however have the choke hooked up. I experience hard cold starts after sitting for several days but the idle is awsome.

[jhwkns]

http://www.jegs.com/p/Holley/Holley-...43849/10002/-1 You'll never go back.

[Billett]

I've been having problems with my 1406 as well. Idle is inconsistent like yours and mine also has a terrible off idle stumble. Every time I start to roll off from a light or stop sign it wants to die on me.

[Lattimer]

Originally Posted by chiefcfd

That sounds like an electric choke problem. I have that same carb. I don't however have the choke hooked up. I experience hard cold starts after sitting for several days but the idle is awsome.

It cold starts in about half a crank after sitting 2 weeks.

Choke seems to work fine, pulls open as the truck warms up and stays there, at least with me watching it in the driveway.

[jhwkns]

Low RPM, and idle issues plague those Edelbrock carbs. You won't know how well your truck can run 'til you try something different.

[Lattimer]

Originally Posted by jhwkns

http://www.jegs.com/p/Holley/Holley-...43849/10002/-1 You'll never go back.

390 cfm seems small for this engine. If you run the cfm calculation jegs has on their site, it comes up just under 600. I definitely don't want to decrease power. Are you running that carb?

[Lattimer]

Originally Posted by Billett

I've been having problems with my 1406 as well. Idle is inconsistent like yours and mine also has a terrible off idle stumble. Every time I start to roll off from a light or stop sign it wants to die on me.

I don't have a stumble. Just can't make it idle decent.

[Lattimer]

Originally Posted by jhwkns

Low RPM, and idle issues plague those Edelbrock carbs. You won't know how well your truck can run 'til you try something different.

That's where I am headed, just don't know what the something different should be.

[jhwkns]

Originally Posted by Lattimer

390 cfm seems small for this engine. If you run the cfm calculation jegs has on their site, it comes up just under 600. I definitely don't want to decrease power. Are you running that carb?

Yes, I wouldn't recommend it if I didn't. They work great, and it's plenty big for a 327.

Do a search on 390 Holley, and you'll find a bunch of posts that'll back me up. Performance, and economy.

[jjhare]

I have had good luck with this demon.

http://www.jegs.com/i/Demon+Carburet.../1900/10002/-1

[Lattimer]

Originally Posted by jhwkns

Yes, I wouldn't recommend it if I didn't. They work great, and it's plenty big for a 327.

Do a search on 390 Holley, and you'll find a bunch of posts that'll back me up. Performance, and economy.

Most of what I see on a search references 6 cylinders and a couple of 283s. Holley website carb finder recommends a 570 street avenger.

[Gene]

Originally Posted by jhwkns

http://www.jegs.com/p/Holley/Holley-...43849/10002/-1 You'll never go back.

I've ran Holleys before. I will never go back

[jhwkns]

Lattimer, are you running a fuel pressure regulator with the 1405. If not it might help your idle issues.

Are you planning running over 400hp/7,000rpm? If you are, then you might need a 600cfm carb. If not, then don't dismiss my advice. Contrary to popular belief, you don't need a really big carburetor to go fast.

[Lattimer]

Originally Posted by jhwkns

Lattimer, are you running a fuel pressure regulator with the 1405. If not it might help your idle issues.

Are you planning running over 400hp/7,000rpm? If you are, then you might need a 600cfm carb. If not, then don't dismiss my advice. Contrary to popular belief, you don't need a really big carburetor to go fast.

don't take me the wrong way, I'm not dismissing it. Your advice is just contrary to what I have always been told and what I am reading.

I think eventually this engine will be about 350 hp when I am done. It might be a little under 300 now (complete guess).

What engine are you running?

[Lattimer]

Originally Posted by jhwkns

Lattimer, are you running a fuel pressure regulator with the 1405. If not it might help your idle issues.

Are you planning running over 400hp/7,000rpm? If you are, then you might need a 600cfm carb. If not, then don't dismiss my advice. Contrary to popular belief, you don't need a really big carburetor to go fast.

oh, and no, I don't have a regulator.

[jhwkns]

Originally Posted by Lattimer

don't take me the wrong way, I'm not dismissing it. Your advice is just contrary to what I have always been told and what I am reading.

I think eventually this engine will be about 350 hp when I am done. It might be a little under 300 now (complete guess).

What engine are you running?

I'm running a 305, but wouldn't hesitate one bit to use one on a 327.
Here's a good article, with dyno numbers to back it up. keep in mind the the test engine was a High performance 383. The numbers on a mildly built 327 would favor the smaller engine. If you check the torque measurements, you'll be surprised.
carburetor shootout

Originally Posted by Lattimer

oh, and no, I don't have a regulator.

Excessive fuel pressure will push fuel past the needle and seat, and will cause rough, and inconsistent idle. I believe they recommend less than 3psi.

[Lattimer]

Originally Posted by jhwkns

I'm running a 305, but wouldn't hesitate one bit to use one on a 327.
Here's a good article, with dyno numbers to back it up. keep in mind the the test engine was a High performance 383. The numbers on a mildly built 327 would favor the smaller engine. If you check the torque measurements, you'll be surprised.
carburetor shootout


Excessive fuel pressure will push fuel past the needle and seat, and will cause rough, and inconsistent idle. I believe they recommend less than 3psi.

since you said that, I did a little hunting. Ordered a regulator from Jegs. Id love it if that solves my problem. New carb is not in the budget right now anyways, I'm at least a couple months away from buying one. Already bought too much stuff this month.

[jhwkns]

Originally Posted by Lattimer

since you said that, I did a little hunting. Ordered a regulator from Jegs. Id love it if that solves my problem. New carb is not in the budget right now anyways, I'm at least a couple months away from buying one. Already bought too much stuff this month.

Cool, I hope it fixes it for you. Those Edelbrock carb's aren't bad. I've had them before. After getting the jetting right you can get great performance from them. They're super reliable, and easy to work on, but getting them to idle perfectly is a problem. Buy the jet kit, and get your HEI re-curved for your application. Do some studying. There's a lot of info out there if you look around.

You asked "what is best?" I like Holley's. A Barry Grant 500 would be my second choice. The BG is also much less expensive.

[Lattimer]

Originally Posted by jhwkns

Cool, I hope it fixes it for you. Those Edelbrock carb's aren't bad. I've had them before. After getting the jetting right you can get great performance from them. They're super reliable, and easy to work on, but getting them to idle perfectly is a problem. Buy the jet kit, and get your HEI re-curved for your application. Do some studying. There's a lot of info out there if you look around.

You asked "what is best?" I like Holley's. A Barry Grant 500 would be my second choice. The BG is also much less expensive.

as much as I can tell mine is jetted right or close to right. Runs great except for idle and a slight hesitation sometimes if you jam the throttle too fast. Plugs are light tan color. I get about 12 mpg with 3.73 rear and a heavy foot. If I can get a consistent idle speed I will be perfectly happy.

[smoknbarrels]

I have seen this before... what shape are the throttle return springs in? guys usually stretch them out when they have the carb on and off several times, thus not allowing the primaries to fully return to close, so it gives it varying degrees of high idle.

next time its idling high, jump out and give the throttle a little extra push closed right on the carb... I bet 2 cents its not returning all the way back to idle.

[Lattimer]

Originally Posted by smoknbarrels

I have seen this before... what shape are the throttle return springs in? guys usually stretch them out when they have the carb on and off several times, thus not allowing the primaries to fully return to close, so it gives it varying degrees of high idle.

next time its idling high, jump out and give the throttle a little extra push closed right on the carb... I bet 2 cents its not returning all the way back to idle.

return spring and throttle linkage is all new. I have a dual spring (small one inside a bigger one). If I push on the linkage I will get maybe a 50 rpm drop, so it can close a little tighter. but when it idles high I still only get the slight drop if I push on it. Told home grown throttle linkage that was on the truck used to hang up and stick the throttle open, so I replaced it with one I built with heim joints.

[smoknbarrels]

good thing i only bet .2 cents. perhaps the carb is just simply worn.. do any of the shafts have play in them? have you ever seen a rebuild kit for an edelbrock? I hope your day job is watch making!
just get a holley 600, they are cheap and common, easy to set and easy to fix.
how are you checking for vac leaks? you using a gauge? or spraying with WD-40 around carb or something?

[Lattimer]

Originally Posted by smoknbarrels

good thing i only bet .2 cents. perhaps the carb is just simply worn.. do any of the shafts have play in them? have you ever seen a rebuild kit for an edelbrock? I hope your day job is watch making!
just get a holley 600, they are cheap and common, easy to set and easy to fix.
how are you checking for vac leaks? you using a gauge? or spraying with WD-40 around carb or something?

I was spraying wd 40 and listening for any changes. Manifold is new, all the gaskets are new, and all the vacuum caps are new. I have been tuning with the vacuum gauge to set the idle mixture. What I read was max out the vacuum at the correct idle speed and back off 1/8 turn.

I haven't been able to compare this carb. to a new one. It doesn't seem excessively loose to me, but it could be tighter. I'm used to clearances being a couple mills withthe stuff I work on (mechanical engineer), not sure what its supposed to be on this carb.

I think I would buy new rather than rebuild this one.

[Divine 59]

Hesitation during the transition between primary and secondary circuits indicate the secondaries are opening too quickly.

Most people will disagree, but I run a Q-jet on my 71 Cutlass. I sent it out to a really good carb rebuilder. It came back in fantastic shape. Only adjustment I had to make was the high idle. Deano asked me questions about my engine set up and built the carb to my specific engine. I have not touched it in over six years.

On the street a Q-jet is my carb preference. Economy if you keep you foot out of it and performance when needed when those big secondaries crack open.

Think about this....GM spent $$$ in research and development on the Q-jet. It was designed to be the best carb choice for a GM engine. Holleys are good, but I give the nod to "Q".