Carburetors - Gary's Musings

[Gary Lewis]

Interesting!  Good to know I wasn't alone.  I hated that carb!  As said, I came from a history of Carters and had no problems at all with the WCFB on the '58 W-engine, but the Holley on that brand new Bee was awful.

I wound up having my next door neighbor, the head of the massive machine shop at Conoco, have it put on the mill and a couple of passes taken on the primary face.  That made all the difference.  Of course by then I'd learned a few of the gotcha's on a Holley, like making sure you lube the o-rings on the transfer tube as you install the second bowl.  Oh, and if you use an aftermarket kit make sure that the one hole for the accelerator pump is on the correct side.  

[85lebaront2]

I learned to hate Carter built Quadrajets, Pontiac used them and whatever cheap alloy they were using on the older carbs, the ones with the inlet gasket on the outside face, the threads would come right out of them when you rebuilt them, I used to keep a stock of Tomco repair nuts, the problem was there was no way to get a filter in them and you'd better blow out the inlet area after installing one, it was a self threading deeper nut.

[Gary Lewis]

I probably have one of those repair kits as well.

And don’t forget the main well that leaked. They had rubber pieces that were supposed to seal that well, and they had o-ringed plugs with pointed tips that kept them in. And some coated them with JB Weld.  I tried all of those fixes and finally settled on tapping the hole and installing a SHCS with Loctite. Problem solved. Somewhere I have a little Cafe Vienna powdered coffee tin with a few of those other fixes in it as well as a tap and several SHCS.

[85lebaront2]

Gary, the SHCS were the solution to adjusting the mixture on a VV, you popped out the cup plugs (which needed to come out in order to replace the jet O rings) tapped the air horn and installed plugs. Guy I sold Preston to, had a setup someone made him to adjust the jets with the cup plugs out and the engine running. That is what I used on the one I ran on the 312 to tune the mixture.

[rbond]

Oh, my... what a fantastic thread... a LOT of great info here guys... thx.

And with that... I want to grab some carb advice, as I have more questions now than I did before... but the basic q is: Should I replace my 4180 with an Eddy and if so... which one???



Carbs have always been voodoo for me... as much as I've stared at them... and rebuilt a few... I admit I've never really figured out what all the bits and pieces do... I usually just carefully clean it, put in the new gaskets, jets, etc, and put it back the way I found it... and hope it all works correctly  which is what I did with this 4180... and I was thinking "as long as I set everything "close" to where it was upon disassembly... I should be ok". Now I'm not so sure.

Just in case anyone's interested... I finally turned the key on my loooong rebuild project (my F350 rustbucket) and low and behold... it started right up... (once I chose the tank that had fuel in it ) and it headed straight for 1800rpm and just stayed there. I've been futzing with it to try to get it to idle at temp... but even with the idle adjust screw all the way back... it won't go below 1000rpm. That doesn't seem right... I would think I should be able to shut the whole engine down by adjusting the idle out to it's max... no? It's also smelling very rich.

I'm starting to think that perhaps I've messed up the rebuild and should have it redone by someone who knows wtf they're doing. Based on this thread... I'm now thinking I should just replace the thing with something better.

The motor is pretty much a stock 460 except I'm sporting the Eddy Performer 460 manifold... and I have all the CA emissions to deal with. I'd like to strike a balance between fuel econ and power... and I'm certainly not planning on taking the beast to the track

Thoughts?

[85lebaront2]

Ok, couple of Holley items, first, are the secondary throttle plates closed? If they are stuck partially open then it will (a) not idle down and (b) run rich at the 1800 rpm level. Choke, is it opening fully? Same issue idle will be high and rich. If it is opening, make sure the fast idle cam isn't sticking. The vacuum throttle kicker (diaphragm on driver's side) may be holding the throttle open.

Final item, if you get the idle down and it is still rich, you probably have a blown power valve.

It you are in CA, be sure you can actually use an Edelbrock (Carter AFB to me) and still be legal.

[ArdWrknTrk]

If you just rebuilt the carb I'd assume you replaced the PV.

The PV is leaking if the truck is pig rich at idle and pops on trailing throttle.

Seems like you have a vacuum leak.
Check any lines and caps on the vacuum 'tree' where the brake booster attaches towards the rear of the intake manifold on the driver's side.

You can try spraying some carb cleaner or other hydrocarbon around the egr plate and intake manifold to see if the idle goes down.

That will point you in the direction.

[rbond]

85lebaront2 wrote

Ok, couple of Holley items, first, are the secondary throttle plates closed? If they are stuck partially open then it will (a) not idle down and (b) run rich at the 1800 rpm level. Choke, is it opening fully? Same issue idle will be high and rich. If it is opening, make sure the fast idle cam isn't sticking. The vacuum throttle kicker (diaphragm on driver's side) may be holding the throttle open.

Final item, if you get the idle down and it is still rich, you probably have a blown power valve.

It you are in CA, be sure you can actually use an Edelbrock (Carter AFB to me) and still be legal.

ok! thx, 85... I decided to take a closer look at the various points you made and checked the secondaries which seem to be closed fully... I did find that the fast idle adjust screw (a bitch to get to!) was holding the primary plates open ever so slightly. This while at OT... so the adjust screw should be sitting on the shortest "step" of the fast idle cam at that point... right?
Adjusting it down to the point where the plates are just at the fully closed position (used a light) and that allowed me to get the idle down and adjustable with the idle screw... and not smelling as rich. I still don't know my A/F ratio... but that's a separate project.

As for the PV... I installed a new one with my carb rebuild... so I'm hoping it's not blown already... I only have about a hour of "hot" time on the thing so far.

And you're correct re the Eddy and CA emissions... they're not compliant... so, no Eddy for me

thx for the feedback.

[rbond]

ArdWrknTrk wrote

If you just rebuilt the carb I'd assume you replaced the PV.

The PV is leaking if the truck is pig rich at idle and pops on trailing throttle.

Seems like you have a vacuum leak.
Check any lines and caps on the vacuum 'tree' where the brake booster attaches towards the rear of the intake manifold on the driver's side.

You can try spraying some carb cleaner or other hydrocarbon around the egr plate and intake manifold to see if the idle goes down.

That will point you in the direction.

Thx, ArdWrknTrk... yup... new PV... I did replace and pre-test ALL my vacuum lines, motors, valves, etc... so I'm hoping I don't have a leak... but since you brought it up... I DO in fact have a vacuum question that I'll post as a new thread...

Cheers!