Edelbrock 600 adjustment

[butch27]

I,m running an Edelbrock 600 cfm  carb on a 302 Ford. I can't get the air/fuel screws do do anything! I,ve run them all the way in and the car still runs- can't get any adjustment..Any ideas?? Thanks

[enjenjo]

Best guess is a vacuum leak. At least that's what I usually find.

[wayne petty]

ok... a little more info is kinda needed...


is the engine idling to fast??

is the choke all the way open??

is there any fuel pouring over the boosters...

do you have any compressed air... and cans of carb cleaner spray??/ brake cleaner???

when i run into these problems...  i take out the idle mixture screws... lightly blow compressed air into the holes where the idle mixture screws were...   spray some carb cleaner into it also... blow that out....

it is possible that the  air bleeds on the top of the primary booster assys have gotten clogged....   so .. any vacuum is pulling straight fuel .. not calibrated fuel...

where is the throttle set at??   can you  back off on the idle speed screw on the throttle lever...

edelbrock has trouble shooting manuals for all of their carbs...

there may be some OEM carters that have a slightly different metering system for the idle... where the screws adjust the air bleeds...

i know that early 70's holley applications are that way... the idle mixture screws are not adjusting the idle mixture.. they are limiting the idle air bleed...  so turning them in makes the carb richer at idle..

carb number if you please....   front foot of the carb...  1234 5

[GPster]

One odd-ball suggestion. The linkage is not holding the throttle open is it? Maybe you're not running on the idle circuit. GPster

[chimp koose]

could be a ruptured power valve. Any good backfires lately?

[wayne petty]

its a shame that the newer edelbrock AFB and AVS carbs don't have the idle speed screw like this 4171 S from a 66 cad with ac and AIR injection..

it would work so much better as the idle speed is totally controlled by the idle air bypass screw in the middle... leaving the primary throttle blades in the proper position ... they used this feature on dual quad carbs also.. but with a big HEX so you could adjust the idle speed with a wrench...


some of the demon carbs have an idle speed adjustment right down the center of the carb under the filter hold down stud...  its actually a bypass so you can set the primary throttle lever properly and not have to drill holes in the throttle blades to keep it on the idle circuits...

i wonder how much difference there is.. as edelbrock has the PCV passages right at the front...

and a funny.. one day i got a call about a fellow installed an edelbrock afb/avs... and it was flooding so bad.. and the accelerator pump seemed to be totally dry...   he in his wisdom had hooked the fuel line from the pump right to the PCV nipple...

[taxpyer]

Silly thought but,,,,,,,,,,,,Had a motor that I couldn't adjust my idle. :?  I was told once by a fellow that a malfunctioning PCV valve is akin to a huge vacume leak, ,,,,,,,,, cleaned out the EGR base and everything was wonderful.  I could adjust my idle like crazy. Valve should be pulled closed at an idle. Just a thought.

[Mikej]

Throttle plates open to far. Idle passage plugged. Or what Frank said.

[butch27]

Thanks guys --I,m on it today. They all sound like good things to check. It's a new carb.

[enjenjo]

the one I usually miss is the PCV port on the back side of the carb.

[lofat46]

I had a similar issue and it was a combination of things on 1460 600 cfm carb.  First I was running too much fuel pressure (no more than 4-41/2 pounds Edelbrock told me) which blew out the needles and seats but it took a couple years.  Second was what someone had as an earlier suggestion, the idle circuits were clogged with small bits of the 4 inch rubber fuel line that had started to deteriorate.  Replace the line, removed the mixture screws and blew air into them until the air started coming out the vent tubes.  Haven't had a problem since.

[butch27]

I did the take them out and carb sprayed then a little air.  Now adjustable .

[29abone]

:? I had a similar problem when I installed a used Carter Comp series AFB and a modified stock manifold on my 312 ci y block.  There were several problems.  It wouldn't idle below 900 rpm.  The P.O. had removed the choke rod on the lt side and used it to replace the accelerator link.  It was too short and held the throttle open.  I made two new links.

Then I decided to check the floats.  They were up-side down and adjusted wrong.

Reinstalled the carb and fired it up.  Still wouldn't idle down.  Checked for vacum leaks, but couldn't find any.  I pulled the carb again and looked in the manifold.  I had removed the material between the front and rear bores and done some minor porting.  When I did this I ground through in one spot and epoxied an aluminum patch over it. The patch blew off and probably went into the cylinder.  I started taking the heads off to check thins out, when I had a minor health problem and I haven't gotten back to work on it yet.  Might need another 57 Ford 312 manifold if anyone has one.

Going to be a busy winter.

[Carnut]

I have a couple three of these Carter/Edelbrock ABF's that got to where they wouldn't idle, so I just replaced them with new Carbs because I'm no longer in the carb cleaning and rebuilding business.

I'm gonna feel real stupid if all I had to do was remove the idle screws and squirt in carb cleaner and the blow them out.

I don't even like thinking about this.

heh, heh, guess I'll find out the next time I have a poor idling carb.

[wayne petty]

the air bleeds are constantly pulling air in as the engine operates...

any dirt that gets past the air filter gasket or the air filter may settle on top of the carb and get pulled into the air bleeds...


i have run into several versions of the air cleaner mounting gasket..

Felpro/Air Cleaner Mounting Gasket
Part Number:  60032
depending upon what they throw across the counter...