[Radman]

I have been fighting flooding problems with the tri-power. I just pulled one of the needle valves and seats. For some reason the needle tip is a flat rubber, and it has a wear pattern on it. Looking at the pattern the hole in the seat is not centered. My guess is that the needle rotates and the pattern doesn't match the seat causing the flooding. The thread size for my seats is 5/16 thread. The biggest needle/seat I have found is a .120. Will that seat be able to feed a Rochester RG 2 with a set of .070 jets in it? Fuel pressure is set at 4 LBS with a return regulator.

[Option 382]

The 5/16 inch seat thread is correct for tri-pwr. The hole in the seat for the fuel flow is just under .120 inch. It sounds like your trying to mix and match parts with the needle and seat. You need to use the new needle that comes with your new seat and don't try mix thing up (if that is what your trying to do). You standard needle and seat should easily run your .70 jets. It sounds like the needle and seat you have is the new flat blunt style and not the original pointed style needle.

If you float is brass make sure you don't have a pin hole in it causing fuel to make your float drop. Also check your float level and drop as well. Trash in the fuel can cause these problems as well, maybe a new fuel filter is needed.

[Kenth]

Most, if not all, aftermarket carb kits contains wrong sized or/and wrong style inlet valves for the TriPower.

Be sure to use the correct style .086" sized inlet valves on the outer carbs, all years.
1965 and earlier center carbs uses a .101" inlet valve.
1966 center carbs uses a .119" inlet valve.

[Cliff R]

Same with Q-jets, almost all over the counter kits have the wrong needle/seat assembly in them. I haven't opened up a kit from any parts store in at least 15 years that didn't have some "old stock" needle/seat assembly in it that had WAY to small of an orifice size for any high performance application.....Cliff

[Radman]

No I am not trying to mix the needle and seat. I am ordering a replacement needle and seat for all of the carbs. Hopefully I do not get the flat rubber tip this time. The pictures are of the seat and needle from the rear carb. With this type of needle and seat, the car would run fine for a while. Then it would flood out sitting at a light, or just starting to move in traffic. The pattern on the flat rubber is not concentric on any carb, and off center in one of them. I hate intermittant issues.

[gtofreek]

I wonder if you are having a fuel boiling problem. Does it only flood out when hot? If so, the fuel is probably boiling, which in turn makes the float bounce around and let too much fuel in.

When the fuel is in the fuel line, it builds up heat, but because it's under pressure, it doesn't boil[or vapor lock]. Now, as soon as it enters the float bowl, it is no longer under pressure and it immediately starts to boil.

I don't like those flat needles and seats either.

[Option 382]

Radman, let us know if by going to the pointed needle and seat helps out your situation.

[Doug Hopkins]

Radman, For what it is worth. When I had my tri-power 2+2 I had to use Sta-Bil fuel stabilizer during winter storage or my 2+2 would do this in the spring.

[Dick Boneske]

I use the Tomco needle/seat assemblies for four years now. They are one-piece assemblies--I can post pictures if you don't know what they look like. They are Tomco part number 555.

They have been 100% reliable for the dozens of carbs I've restored during that time. With the "old style" needle seats (pointed and flat) like the one in the OP picture, leakage problems were fairly common--many times just like you describe.

I think all Pontiac carbs in the '60's used the pointed type needle, but had a brass tip, not rubber. I've not seen that type for many years now. They all use the rubber tip-some pointed, some flat like the one in the OP.

[Option 382]

Dick, Could you post picture(s) of the new 1 piece needle/seat?

[jotrout]

I was curious about this piece also and found it here.

http://www.ebay.com/itm/Tomco-555-Fu...-/150841536566

[Cliff R]

Those are also available for Q-jets, and the best way I know of to get a nose bleed when it bounces off the steering wheel at the top of first gear on a hard run when the bowl runs dry!

They may fair OK in tri-powers, but I would NOT use them in q-jets. I actually had a competitor recommend them to me, and sent one here for testing. He was buying them from Daytona Carburetors (nearly as I can remember) and building circle track q-jets.

His business soared quickly, then died out about as quickly as it started, been out of business now for close to 10 years. I suspected that his carburetors were having issues staying full as he found himself tuning them with considerably different jets and metering rods that I was having success with, but I never mentioned this to him.....FWIW......Cliff

[Radman]

I got the Tomco one peace needle/seat last night. This is not a scientific test but I tested them by blowing through them, and using finger pressure to shut the flow off. One of the original needles took a lot of force on the float to shut off when I was blowing through it. I shook it and tried again, that time it took less than half of the force to shut it off. The Tomco seat took much less force to shut the flow off. I am putting the Tomco units in now. And will let you know how they work. First I need to get some longer carburetor mounting studs. I am also adding the ¼ inch heat insulator pads, and can only get half of the nut on the stud at the moment. I did compare the floats from the Tri-Power with one from a Quadra-jet. The Tri-Power float may be a little over 1/3 the Quadra-jet float size. Bets are that that is part of the flooding issue with all of the new needle and seat sets sold today.
I also took a picture of the set. I just have not got it out of the camera and into the computer yet.

[Cliff R]

We use an electric fuel pump here and adjustable pressure regulator to do that sort of testing. What I see is that most float-needle/seat arrangements do pretty good with higher than "normal" fuel pressure on the bench.

It is still a "static" test, and really doesn't provide any useful information as to how well they are going to work when placed in service. One basically has to put the carb in service with the parts they are going to use, and do some driving, hard acceleration, rough roads, hard braking, etc, and see if you have any problems with fuel control in actual use......Cliff

[Radman]

OK, I got the needle/seat from Tomco installed today. I set the fuel pressure at 5 pounds with everything cold. Turned on the pump and no leaks. I adjusted the floats so that the fuel level is .6 to .7 inch below the gasket line on the bowl. I do not want fuel spitting out of the bowl vent when I hit the gas hard. I started the engine, and ran it until everything was warm under the hood. Infra-red said that the carb bowls were at 180 degrees after about 20 minutes of running in the garage. I did notice that the fuel pressure went way down. I adjusted it for 3 pounds when the regulator was hot. Shut the car off and went to do errands. When I came back the fuel regulator was down to 88.
At that temperature the gauge read 6 pounds. Again I did not have any leak. Now if it will just quit raining, I can get some road time in with the car.

[Dick Boneske]

I hope this solves your problem. The Tomco needle/seats surely work nicely for my Tripowers.

I understand what Cliff explained. A Quadrajet relies on ONE needle seat for the whole engine. Tripowers have 3X the flow capacity at the fuel inlets.

[Cliff R]

Correct. They are also several varieties of that part made, with different orifice sizes, at least for the q-jet. They must not flow quite as well as the conventional set-up, as the incoming fuel doesn't have as much room to get past the disk and it doesn't move away from the orifice as far as the conventional type. The design seems to be very good with high fuel pressures, but I couldn't tell you if it will hold up in this new fuel, which is very hard on rubber, neoprene or low quality Viton parts......Cliff

[tripwr1964]

Originally Posted by Radman

OK, I got the needle/seat from Tomco installed today. I set the fuel pressure at 5 pounds with everything cold. Turned on the pump and no leaks. I adjusted the floats so that the fuel level is .6 to .7 inch below the gasket line on the bowl. I do not want fuel spitting out of the bowl vent when I hit the gas hard. I started the engine, and ran it until everything was warm under the hood. Infra-red said that the carb bowls were at 180 degrees after about 20 minutes of running in the garage. I did notice that the fuel pressure went way down. I adjusted it for 3 pounds when the regulator was hot. Shut the car off and went to do errands. When I came back the fuel regulator was down to 88.
At that temperature the gauge read 6 pounds. Again I did not have any leak. Now if it will just quit raining, I can get some road time in with the car.

where is the source of these tomco 555's? do a search and i only see couple for sale on ebay. are there vendors who sell these?

[Radman]

I ordered them from GSI Engine Management Group out of St Louis 800-325-9972

[tripwr1964]

i ordered a set of 3x yesterday from GSI. Had them by noon today! $4.95 plus shipping.

what's the status on these radman? working ok?