Hi, thanks in advance for any help given.
Holley carb has problem idling. It will idle at 900 RPM or so in neutral and then slowly creep up to about 1400 RPM,stay there for a bit, then slowly back down again, stay there a bit and back up etc. Sometimes it wants to die when it drops down.

About 470 cubic inches with automatic. Around 6 to 8 inches of vacuum at 900 RPM. Timing currently at 26*, but does the same regardless of initial timing. Tried another carb which is a 850 cfm and it idles rock steady with about 10 to 12 inches of vacuum with zero issues. I rebuilt the carb, and tried adjusting as best I could.

Holley HP List #80513
6.5 PV tried different ones and same issue
Jets Prim 79 Sec. 86
Air Bleeds Idle 75 High Speed 25
Squirters Prim. 31 Sec. 36
Secondary Idle transfer slot is "square"
All mixture screws 1 to 1 1/2 turns out

At this point I don't know what else to try. Am I overlooking something. Did something wrong or silly.
Help would be greatly appreciated.

Thanks
Onig

time to get in touch with member "thumperdart".
if not here, i think he does facebook.

Sounds like you have an internal vacuum leak with the 1000 cfm carb. Is the carb stud hole plugged?

X10

1000 cfm on 470 ci ??? Seem a bit large IMO but,

Keep it simple, IE: In order for it to gain RPM it has to be getting more air or the timing has to be advancing.

Try it with the throttle linkage and vacuum advance (if your using it) disconnected . It would also be a good thing to verify your timing mark is stationary while this is happening

Also make sure your secondary blades are not moving (Long shot).

Check the gasket and screws between the baseplate and main body. I've been bit by that more than once

If the above checks good I'll agree there appears to be a leak between the base of the carb / intake or internal to the carb. If using one of the soft paper gaskets you should be able to see the imprint of the baseplate on it.

that'll keep you busy for a bit keep us posted

never thought that hole would go straight through, but will check.

Just checked the air cleaner stud hole and it is blind.

No vacuum advance hooked up. Timing does not move.

Screws are tight, gaskets are new.

Base plate gasket does has imprint on it. It was new as well.

Hopefully he chimes in.
I don't do facebook.

onig

Don't hold your breathe, he does not come on here anymore

With that information I would go back to the carb.

1. what is the history on the carb??? New / used

2. Not sure if that carb has a 4 corner idle or not ? If it does try completely closing off the rear screws and adjust using only the fronts. See if it improves.
3. Repeat the process closing off the front and adjusting the rears. It may help isolate which side is having the problem.
4. Only other things I can think of are
1. the cork seals leaking around the mixture screws. 2. wrong metering block gaskets 3. Wrong base to main body gasket

5. Carefully dismantle in inspect it, the gaskets and all the mating surfaces.

I would use compressed air on all passages making sure they are clear.

Reassemble and try again.

or put the 850 on and shelve the 1000 ( a bit of humor )

Keep us posted

Well you have some sort of leak if the intake vacuum changes by that much when you change carbs. Keep looking.

If this thread is still "alive", I suggest the OP check out the original Holley calibration for an 80513. Going from memory, that tune above is waaay leaner than what it would have come with. It may "look" right because the traditional 850 that runs better might be jetted similar to what's described, but those two carbs have different boosters, different metering blocks, etc., and are intended for two different applications.

The factory jetting is 84/84, PV on both ends.

What are the cam specs?
Headers?
Mufflers on or not?

The .075 idle air bleeds seem pretty big to me for a race-type calibrated carb.

So I took it all apart again, checked all passages to make sure they were clear, blow them out with air. Put new gaskets on and put back to stock specs.
Still has problems.
Left the 850 on so we could drive and enjoy it.
Now looking at getting another 1000 cfm carb. The 850 makes it low on power compared to the 1000.

Thanks for all your help guys.

Onig