Rolling Idle

[Bootybandit]

Holley 4160 (which I now HATE). I rebuilt this because the accelerator pump was leaking and it sat for 5 years. Pump still leaks, I looked at the pump and the cover seemed to be a little warped. I determined this by setting it on a flat surface and it looks slightly bowed between the screw holes in the middle. I also noticed the pump diaphragm appeared really Poopy and is splitting SO.... I'm ordering a new Blue diaphragm and will use rtv. Is this a good idea? And... Could a leaky accelerator pump cause a rolling idle? I also plugged all the vac ports and still got a rolling idle. I need help or Im going to pull it of and beat it beyond repair and order an Edlebrock like my brother told me to do years ago.

[Gary Lewis]

I'm not a fan of Holley carbs either, so I understand your frustration.  But I have taken a file to the cover of the accelerator pump to make it flat.

However, I don't think you want to use RTV on a carb.  It hasn't worked for me and I don't think it will for you.  I'd get the cover flat and hope it'll seal against the new diaphragm.

Speaking of the diaphragm, could I get you to edit your post to change your comment about it?  We try to keep this forum family friendly, and that isn't.

As for the rolling idle, I think that is usually due to a very lean condition - so lean the engine almost dies but then comes back.  And I don't think the accelerator pump will do that.  But, I'll tag Bill, who used to run an ignition and carb shop, and I'll be he will know.

[Bootybandit]

Many thanks, I cleaned up my potty post I knew better.  Tomorrow I'll pull it again and shave it down in the mean time I'm shopping around for a 4106 I can rebuild.  Ebay has one for 125, used.  Have any thoughts on buying used?

[85lebaront2]

I used to put Holley pump covers on a large vice and use a big hammer on them to get them flat.

On the rolling idle, with the engine running try closing off most of the air horn (choke portion) with your hand, if the idle smooths out and seems steadier, you are too lean, so open the idle mixture some more. If it gets worse, then you are too rich and it may be a bad power valve (the main reason Gary doesn't like them).

[mat in tn]

2nd that. I was trying to imagine "rolling idle" and realized the falter and recover symptoms. very possible that its lean enough to "cycle" the power valve. typically, if it were a rich cond, it would not recover but load up and have a very rich exhaust. this when I would uncap a small vacuum line on the intake and see if it stalls or revs up. stall is lean. revs up is rich. 1/8" is about right size port to uncap.

[Gary Lewis]

The others explained about the rolling idle. As for the CarterEdelbrock, a 1406 is my favorite. And a good used one is fine. Easy to rebuild and no fabric holding fuel in to leak. I’m

[ArdWrknTrk]

Holley's have a built in power valve check ball since 1991.
Post the build date from the front of the air horn on the driver's side.
Does it smoke like a chimney and want to stall at idle? Does it clear it's throat as you get on it? Does it burble and pop on trailing throttle???
They are good reliable carbs that are easy to tune if you know how. (Certainly FAR easier than an SU or something)

My 0-08457-S worked fine, but I never overtightened the screws and always used the proper (blue) Teflon gaskets.
I gave it to George Maroudas, down there in Louisiana, and he hasn't reported their Ranchero has any problems...
If you crank the bolts you'll warp covers, bowls, base flange, and even the body.
Bill will tell you. He ran a carburetor shop (Preston) for quite some time!

I (think) I still have a 650 AVS sitting on the shelf in a barn, all wrapped up w/ a new accelerator pump installed.
Gary can argue, but I think the air valve secondary is a better carb than the aluminum four barrel.
650 might be a bit much for a Windsor, depending on what you have in it.  

[Gary Lewis]

No argument at all, the AVS is better than the AFB, and the 1406 is essentially an AFB.

As for being a bit much, that's the beauty of the AVS - you can easily adjust the opening point of the air valve.  So if it comes in too soon and the engine bogs just loosen the lock screw, tighten the adjustment screw a bit, tighten the lock screw, and now it won't.

[ArdWrknTrk]

I know how it works!  

But I don't know if it still exists (along with all my other tools & stuff)

I was really happy when George wanted the Holley for their last year Starsky & Hutch bordello-mobile.  😉

[Gary Lewis]

The "how it works" wasn't for your benefit.  

[85lebaront2]

While we are discussing carburetors, one of the best 4 barrels on a moderate size engine, is the Rochester Quadrajet. I say moderate size due to the small primary barrels, they only flow about 260 cfm meaning on a large engine, you are into the secondaries at moderate speeds.

This is why the older GM powered motorhomes are gas hogs. A friend tried disconnecting the secondary linkage and found that on level ground with no head wind, roughly 45 mph was all he could get. This is why a 454 powered motorhome makes a 460 Ford look like an economy engine.

If you have one on a lighter vehicle with a smaller engine where you can cruise on the primaries only, the Q-jet will give excellent fuel economy.

[ArdWrknTrk]

But you need a spread bore 351W manifold for that!

I'm not sure what your options are today, as far as finding one of those.

[85lebaront2]

Most aftermarket manifolds are multiple carburetor pattern ones.

[Gary Lewis]

It is possible to run a Q-Jet on a square bore intake.  I did it back in the 70's on my '72 F250 Camper Special w/a 390.  I used a spread-bore to square-bore adapter and hogged out the intake to match it.  There are some adapters still made for that today.

I do like the Q-Jet.  I have one sectioned so I can see the passages, which came in handy when my nephew called and couldn't get one to idle correctly on a big engine.  Many of them, including that one, had restrictions in the idle passages so you couldn't make the idle mix too rich.  But when you put a carb from a small engine on a big engine those restrictions have to be drilled out.

The one on my 390 worked out very well.

[ArdWrknTrk]

My Performer, I had to hog it out just to fit the 650 AVS.  🤷‍♂️

I know that Transdapt makes a 460 spread bore adapter, but that's another $60 I don't want to spend.

[Bootybandit]

"clear it's throat as you get on it" but after few moments will go back to the rolling idle then die.  I thought I had the air fuel mix correct with a vac gauge.  I started out with 1 1/2 turns went from 15 psi to 17 psi and that was it (is that normal?).  The passenger side screw screwed out more than the driver side.  I think this is the number you were looking for 80457-8  and under that 0602 Oh I forgot to mention plugging the 1/8" port causes to increase RPM.  And thank you all I'm learning a lot here already.

[ArdWrknTrk]

So it was made in June of 2002.
These have a check ball.
22 year old rubber diaphragm could easily be bad, though.

If you start it and look down the primary (front) bores, do you see it dribbling fuel out of the boosters?

[ArdWrknTrk]

What kind of heads do you have on this truck?

[Bootybandit]

the dribble is for sure the accelertor pump I'll look down the boar and see.  I have no idea about the heads I bought them refurbed and the sent them to a pro for a eval and installed.  

[ArdWrknTrk]

Well, you've got to fix the acc pump weight before you can diagnose anything else!

I didn't know that they were stock rebuilt heads.
We all have a variety of configurations from home porting, pro porting, aluminum performance heads to professionally ported Trick Flow heads like Gary's Dad's truck.

I just want to be clear on what I'm dealing with.
Sometimes, you can have all the best parts, but slapped together by Florida Man, like poor Vern.
So much money and good parts destroyed by imbicles.