[Dick Boneske]

I restored a set of carbs for a '66 Bonneville recently and sent them to the car owner. Note from the pictures that the carbs are correct '66 Tripower carbs. I set them on a '66 manifold I have on hand for the pictures.

The car owner bolted the carbs on and started the engine--all three carbs flooded (float bowls overflowed). Needless to say, he was quite upset and contacted me for a solution. I suggested some possible solutions to the problem such as dirt in the fuel lines lodging in the needle/seats. He had installed all new fuel lines from the tank forward and the setup included a new GF61P filter mounted on the front carb. He had also installed a new replacement fuel pump.

Without any clue as to the cause of the flooding, I suggested he send the carbs back to me. I disassembled each carb, confirming there was no dirt in any of the float bowls, needle/seats sealed properly, and both end carb brass floats were OK with no gas inside them. I removed the end carb throttle bodies to confirm that the throttle plates were still sealing well when closed (DAG 213 was applied during rebuild). I replaced the phenolic float in the center carb as a preventive measure as I 've seen them saturate with gas and allow flooding.

I've heard from a few other old car enthusiasts about replacement fuel pumps delivering too much pressure. These Rochester carbs can handle a maximum of about 6 psi before the bowls flood over. One of my friends put a gage on the fuel line with a stock replacement pump read 8 psi.

The best troubleshooting method, in my opinion, is to install a gage in the fuel line to measure pressure. I will send a fitting and gage to the car owner so he can see what the pump is delivering. An alternative would be to replace the pump, but knowing the pressure would be a more positive method of determining the cause. He asked about a regulator, but not many of us would want to contend with that under the hood of our old Pontiacs--unless it's a modified setup with electric pump, etc.

I'll keep you appraised of how we get this resolved.

[Dick Boneske]

I forgot to mention--the larger of the two check balls goes under the venturi cluster. The small ball goes in the accelerator pump well.

The hole in the accelerator pump well is just the right size to allow the large ball to drop partway in and stick. Sometimes, holding the fuel bowl upside down and banging it on a flat surface will dislodge the ball, but not often.

[Tom Vaught]

Don't know why some have had their pics posted up-side down lately.

Tom V.

[Kenth]

I guess AC cars with return line on fuel filter to the fuel tank can take slightly higher fuel pressure than w/o?
I´ve been using an electric fuel pump, dead end, Carter P4070 5psi, for at least 20 years on my 1966 Tripower GTO, never flooded or ran out of fuel at WOT since.
Correct factory style inlet valves, .086" for the end carbs and .119" for 1966 center carb is a must.

IMHO

[carbking]

Dick - have had LOTS of customers in the last few years, when calling about carburetor kits, mention flooding. We now always ask if they have replaced the pump recently BEFORE we sell them the carburetor kit.

Have had customers report WAY more than 8 psi from supposedly reputable American companies (but reboxed, off-shore junk!).

Jon.

[Dick Boneske]

Originally Posted by carbking

Dick - have had LOTS of customers in the last few years, when calling about carburetor kits, mention flooding. We now always ask if they have replaced the pump recently BEFORE we sell them the carburetor kit.

Have had customers report WAY more than 8 psi from supposedly reputable American companies (but reboxed, off-shore junk!).

Jon.

Jon,

Is there a source for fuel pumps that reliably produce output similar to original pumps--about 4 1/2 to 5 1/2 psi?

Or do you have a source for rebuild kits for these old pumps?

Thanks,
Dick

[mgarblik]

I agree Dick that all three carbs. flooding after your restoration of them would indicate fuel pressure is too high. Don't know what your set-up is at your shop but you could possibly bench test your work with a regulated wet test of the needle and seat using a low flash point solvent or diesel injector test fluid. Then when you ship them they could be "guaranteed leak free". I don't think this is the case with all three carbs flooding but I have had one or possibly 2 flood when the end user insists on wrapping the fuel line fittings with Teflon tape and then installing. Especially if they wrap it the wrong direction, little bits of the tape commonly stick the needles when it tears off. If a customer insists on sealing the nuts, I recommend only using a liquid pipe sealant with Teflon. As we know, if the lines are flared correctly and the fittings are in good condition, no sealer is necessary. Let us know what you find.

[Dick Boneske]

I am sending the carbs back with a gage and fittings to check pump pressure. As we're finding out, excess pressure is fairly common with today's aftermarket pumps.

I'll ask again--is there a reliable source of fuel pumps or rebuild kits that maintain the original 4 1/2 to 5 1/2 psi?

[bill ryder]

Hi Dick. Go to the 64-65 GTO forum and search Claude. I have posted him several times. As you will read, he has been in the fuel pump business all his life. "Bill"!

[Tom Vaught]

Thanks for the info Bill.
Great to have a Pontiac Fuel Pump Guy's name.

Same kind of deal as SUNTUNED does with Pontiac Distributors, I assume.

Merry Christmas to all of the Tri-Power Guys.

Tom V.

[1stgenbird]

I rebuilt the carbs on my 66 Tripower this summer to replace gaskets, accelerator pump, etc. Once i reinstalled them, the center carb began leaking gas from the top. I pulled it back off and found one of the check balls had fallen out as I put the carb together. Put the ball in and all was fine. I thought initially that it was too.much volume from the fuel pump, which I had recently replaced, so I bought a Mr. Gasket fuel pressure adjustment gauge but didn't end up using it.

[1stgenbird]

Originally Posted by 1stgenbird

I rebuilt the carbs on my 66 Tripower this summer to replace gaskets, accelerator pump, etc. Once i reinstalled them, the center carb began leaking gas from the top. I pulled it back off and found one of the check balls had fallen out as I put the carb together. Put the ball in and all was fine. I thought initially that it was too.much volume from the fuel pump, which I had recently replaced, so I bought a Mr. Gasket fuel pressure adjustment gauge but didn't end up using it.

I meant a Mr. Gasket fuel pressure regulator.

[carbking]

Dick - Then & Now Automotive is the premier supplier of quality rebuilding kits for older fuel pumps.

781-335-8860.

They are located in the Boston area.

They make the kits themselves.

Sorry for delay in answering. Extremely busy these days, don't hit the computer as often as I used to. Carburetor kit demand is the highest today since we started in business in 1974!

Jon.

[Old Man Taylor]

Jon - Do you think that has anything to do with the Ethanol in pump gas?

[carbking]

Originally Posted by Old Man Taylor

Jon - Do you think that has anything to do with the Ethanol in pump gas?

Jim - YES!

Jon

[Doug]

So, as to tripower carbs, has there been any direct side-by-side testing of float valve designs comparing the conventional tapered needle point style, the Daytona plunger style and the Grose style?

I found this article about the Grose style and noted that it suggests satisfactory operation in the 6-8 lb fuel pressure range.

http://merakgroup.com/weber-needle-s...sus-grose-jet/

[Tom Vaught]

If the float cannot maintain the fuel level in the bowl at the proper ENGINEERED fuel height then the calibration will be off across the performance band.

Carbs were designed by Rochester Engineers for 5-6 psi typically.

So you start screwing around with 6-8 psi and you really get the carb logic out of sync.

Tom V.