1960 Buick 401 Black Carburator

[Bill Stoneberg]

My 1960 Buick Electra with a 401 and a 4bbl Carter AFB  has been running poorly recently.Took a look at it this past weekend and it looks like exhaust is coming up through the carb. The throat is black like a tailpipe and sootty too.  I dont see any signs of soot on the manifold but my throttle return spring has a black coating on the bottom.  

I know there is exhaust gas going through the manifold, could that be escaping somehow ?

I have the steel plate and gasket on the carb.

 

[old-tank]

Sounds like it developed it's own EGR.  Plug the exhaust crossover under the carb in the manifold...it's only purpose was to help vaporize the fuel in cold weather.  Our fuel is already too volatile and we seldom drive in those conditions anyway.

[Beemon]

Are you backfiring? You mention loss of power, have you thrown a vacuum gauge on it yet? 

[avgwarhawk]

   The crossover on mine was clogged.   Some soot.  I cleaned up with carb cleaner and reinstalled with new gasket.    

 

[60FlatTop]

Check your choke heat tube, too. Perforations in the swedged pipe in the exhaust manifold can circulate sooty exhaust to the carb.

Bernie

[avgwarhawk]

15 hours ago, 60FlatTop said:

Check your choke heat tube, too. Perforations in the swedged pipe in the exhaust manifold can circulate sooty exhaust to the carb.

Bernie

 

 

Need to keep this info in my memory bank! 

[Bill Stoneberg]

My gasket was shot and the manifold looks like Chris'.  Ordered a rebuild kit and we will see if that will help. 

 

Anyone have a spare Carter AFB 2982 S laying around ?  My base is eaten up and I would like to replace it as opposed to having to do some work on this one.

 

That is what caused the gasket failure I imagine.

[avgwarhawk]

When I removed mine I was going to rebuild but after seeing the gasket and manifold I decided to clean up with carb cleaner.   I did so and reinstalled  Hesitation became minimal.  I then used K100 fuel treatment that really made all hesitation disappear.  The carb rebuild kit sits on the bench.

 

I think I'm becoming a case study in ethanol and older rubber products in carbs.   Runs fine on the original build.      

[Beemon]

Make sure you get the heat shield that goes under the carb, too. Its supposed to protect it from deteriorating. Heed Willie's words and plug the heat track. I daily mine in Seattle during the winter and have no issue with mine plugged.

[Smartin]

Carb cores run about $200 or more...then you have to rebuild them with no guarantee the core is any good.

[Joseph P. Indusi]

This problem can also occur on the straight eight engines.   I had to discard an intake manifold off of a 248 cubic inch straight eight from the late 1940's.   There is a plenum at the base of the manifold under the carburetor where exhaust gas circulates to heat the carburetor base to help warm the carburetor during startup in cold weather.   In this particular manifold the wall in the casting separating the exhaust plenum and the intake section had rusted through so exhaust gases could enter the intake manifold: as Willie says, it created it's own EGR system.  This could be very hard to diagnose as the cause of poor performance.

To test a manifold for this defect,  on a level table turn the manifold upside down so the carburetor opening is facing the table.   Now pour water into the exhaust plenum and see if water runs out of any of the four intake tubes or the carburetor opening.   If it does then the portion of the casting separating  the exhaust plenum from the intake section is defective.   The manifold could still be used by fabricating a steel plate to block off the exhaust plenum from the valve body (hot box).   However, there may be other defects in the casting given this defect.

Joe, BCA 33493

[Bob Engle]

There is a large core plug in the underside of the intake manifold.  If you have corrosion in the top exhaust areas, there is a good chance the underside core plug is rusted through also.

 

Bob Engle

Edited October 19, 2017 by Bob Engle
add photo (see edit history)

[Bill Stoneberg]

Last time I looked at my manifold it was good. I dont want to remove the AC compressor again to pull it off right now. Then I will to paint it and it just grows exponentially. 

I did take the carb apart and it was full of gummy varnish and the step up rods were coated. Accelorator pump had pretty much disolved or at least the plunger part had. Soaking in parts cleaner at the moment while waiting on the kit to come.

[Bill Stoneberg]

Spent a couple of hours with a paint can full of parts cleaner and a brush that turned into a plastic pan full of the same stuff. An AFB Carb does not fit into the can that the parts cleaner comes in.

 

Anyway before and after pictures below. Look at the varnish in the float bowl for example.

 

Edited October 20, 2017 by Bill Stoneberg (see edit history)

[old-tank]

So much for the increased detergent claims in premium gas.

[Beemon]

Huh, my WCFB looked the same when I first got it, but there was no indication of an exhaust leak at the base. How bad does your base look?

[Bill Stoneberg]

It had a bad case of cancer. I filled a good sized divot with JB Weld yesterday and have some more to go today.  It looks like it will hold. Biggest holes was about a 1/2 inch deep.

I forgot to get before pictures though.

[avgwarhawk]

My 4GC did not look sooty like yours in the pictures above.  Mine was more coated with grease and grime on the outside.  Inside appeared to be what we normally see on carbs with some mileage.   This was my carb before cleaning.   The soot on yours is a mystery. 

 

 

Edited October 20, 2017 by avgwarhawk (see edit history)

[NTX5467]

Modern fuel "detergents" are more about keeping the backside of the intake valves clean than carb float bowls.  But with Direct Injection, that's wasted.

 

NTX5467

[old-tank]

5 hours ago, NTX5467 said:

Modern fuel "detergents" are more about keeping the backside of the intake valves clean than carb float bowls.  But with Direct Injection, that's wasted.

 

NTX5467

Who knows if even that is working unless you disassemble.

[60FlatTop]

Deter and detergent are completely different words. The oil company advertising people overlooked that when the ads caught on.

 

Direct injection is getting a problem all its own. Fuel spray will carburize on valves. Using a decarbonizing chemical to remove the particle buildup on car with those integrated mini turbochargers (Ecotech) can put through pieces of carbon large enough to damage the high speed turbos. You need to watch out for that nice garage man who offers all those extra services.

Bernie

 

[RivNut]

On 10/19/2017 at 8:21 AM, Bob Engle said:

There is a large core plug in the underside of the intake manifold.  If you have corrosion in the top exhaust areas, there is a good chance the underside core plug is rusted through also.

 

Bob Engle

If / when you have a hole in this plug, you'll hear it sputtering like an exhaust leak.

[NTX5467]

With Direct Injection, NO fuel spray on the intake valve heads or other parts of the intake tract.  It used to be that any deposits needed mechanical removal, but I think there are some chemical kits to do that now.  Many YouTube videos on this subject, some which date back to the earlier EcoTech days.  Seems that some of the "looks" of the intake tracts and such we used to not worry about are now "issues" with DI.

 

It's a tricky mix to get the fuel to burn cleaner than ever, plus motor oils that will do similar when they get into the intake tract.  Cant just do it with fuel-only any more.  One of those "orchestrated dances" that must be "right", by observation.  In the earlier engines, there can be some benefits to these fuels/lubricants, but cleaning up an existing situation might be tricky for some.

 

In the mean time, I'm going to watch the squirrels chase acorns from the oak trees.  

 

Enjoy! 

 

NTX5467

Edited October 22, 2017 by NTX5467 (see edit history)

[Bill Stoneberg]

I spent a good portion of the last 2 evenings watching Baseball and filling in and sanding the hols in the base of the carb, I have the filled in and the base is flat now. There was on BIG hole on the leftand lots of little pinholes throughout. I took JB weld and ran a skim coat over the holes and then sanded off most of it.

 

 

[avgwarhawk]

Really something that the base developed pits and such.   Keep us updated with the repairs.  

[Bill Stoneberg]

That is what happen when you dont have the steel plate.  I got the carb kit today and will start putting it together tonight.

 

[avgwarhawk]

19 hours ago, Bill Stoneberg said:

That is what happen when you dont have the steel plate.  I got the carb kit today and will start putting it together tonight.

 

 

So you are saying the the EFE cross over on the intake that is under the carb should have a steel plate that prevents the hot gases from pitting the bottom of the carb?   Makes sense to me.  If I recall, when I pulled mine, there was no steel plate however the gasket had a steel sheet between the two pieces of gasket material.  Quite certain this was an original gasket.  The cross over was clogged as you can see in my picture.  I did clean up the valley but I left the holes plugged.  I did not see a reason for having them open adding more heat to an already bad situation with ethanol.    

[Bill Stoneberg]

Chris, on the AFB's (Aluminum Four Barrel) carb, the gas from the exhaust gas, and all its noxious components,will eat the Aluminum base of the carb.

They put the steel plate against the bottom of the carb so this doesn't happen. 

It is not supposed to be necessary for the Rochester. 

I had the same plate on my Riviera that had a AFB.

I plugged my manifold holes so this wont happen again.

[Smartin]

The Rochester base plates are cast iron, so the steel plate is not needed.

[NTX5467]

That heat track-style manifold (and related gaskets) were used by Chevy up until about 1969, on some applications.  The  sandwich gasket (steel core with gasket material bonded to it) is the way many baseplate gaskets were made back then.  Seems like the soft gasket was against the manifold, then the stainless steel plate, and then the carb.  Our '69 Chevy pickup had that set-up, with a QuadraJet spreadbord, as I recall.  Always wondered how well that flat stainless plate worked as a "gasket" against the bottom of the carb, but it apparently worked pretty well.

 

NTX5467

[avgwarhawk]

18 hours ago, Bill Stoneberg said:

Chris, on the AFB's (Aluminum Four Barrel) carb, the gas from the exhaust gas, and all its noxious components,will eat the Aluminum base of the carb.

They put the steel plate against the bottom of the carb so this doesn't happen. 

It is not supposed to be necessary for the Rochester. 

I had the same plate on my Riviera that had a AFB.

I plugged my manifold holes so this wont happen again.

 

Got it.  I have the Rochester.  Thanks for the info! 

[Bill Stoneberg]

Found what may have been causing some of my issues. The thermostatic valve assembly was broken allowing  additional air to  flow to an outlet below the scondaries.  This is normally supposed to be closed except when idling during hot conditions. Being broken, it was always open.

Luckily I have some parts and had an extra valve. 

[Bill Stoneberg]

Discovered something interesting while putting the float jets in... the jets don't sit straight up and down, they are tilted towards the inside.  

Only took me 20 minutes of wondering what was going on and why didn't this fit to figure it out.

[avgwarhawk]

Are the jets were they need to be now? 

[NTX5467]

"Float jets"??  =  "Needle and seat"?? 

 

AFB with metering rods that index with primary-side main jets in the floor of the float bowl?

 

Just curious.

NTX5467

[NTX5467]

For the record, here's the assembly sequence for the stainless steel "baffle" and the related soft gasket (possibly a composition gasket with a thin layer of metal inside).  The particular illustration is for a Pontiac OHC 6-cylinder, but the sequence is the same.  The other illustration is from an earlier '60s Chevy 327/300 V-8.  Wasn't aware of an intermediate spacer/insulator on those applications, though, as later QJets didn't have that one.  Third one is more Buick-specific.  The stainless steel item is termed "baffle".

 

NTX5467

Edited October 28, 2017 by NTX5467 (see edit history)

[Bill Stoneberg]

Success strikes again !  Got the carb put back on the car this morning and the car started right away.  I found it helps you if put the throttle return spring on.  But it ran and after doing some minor tuning we went for a drive.

Car drives like it has never driven before.  Good response,  not bogs, hesitation or backfiring.

Idle needs some work and I have to reset the choke, but for the most part I am happy.  It drives like my Riviera did.

I should have done this a long time ago instead of chasing imaginary ignition gremlins.

So now I have new points,. wires, cap and rotor along with coil PLUS a rebuilt carb.  Cant ask for more.

It is time to drive the car.

I can't say enough about the Carb Kings kits. Had everything I needed to make this work. I am very happy.

Edited October 29, 2017 by Bill Stoneberg (see edit history)

[60FlatTop]

Amazing, I think a lot of LS swaps have been done, or assumed necessary for just those reasons. Well, that and peer pressure.

 

The first question is "How did they get the premium money out of this car when it was on the showroom floor?"

 

Now you can:

Bernie

[KongaMan]

On 10/28/2017 at 1:01 PM, NTX5467 said:

 

This shows something I've long wondered about.  The aftermarket baffles I've seen look like this one, with one big hole in the middle rather than one hole per barrel (like the gasket).  Doesn't that create leakage between barrels?

[Beemon]

Yes it does, and would also create turbulence above the plenum.