I rebuild a lot of Pontiac Tripowers, but now someone has asked me to rebuild a '66 Olds Tri-carb setup. Can anyone on this board post some photos of setups with original fuel lines, linkage, etc.? Do they actually use copper lines for the front and rear carbs?

 

I found this, it belongs to a member of the ROP board, and yes its showing copper looking lines in this restoration.

 

Thank you, Don. It's the third photo I've seen with copper 5/16" lines to the end carbs and aluminum to the center from the fuel filter bowl.

 

Does anyone know if the GF48 glass fuel filter that has no drilled and tapped hole in the center of the housing is the same as the one that does? It appears that the Chevrolet ones don't have the 1/4" tapped hole. Is there enough stock to drill and tap a hole there on one without? The ones with the holes are a little pricey.

 

The fuel bowl is not a gf48 st all. The original was a gf 422, impossible to find, but a guy who sells the carb tags on Ebay sell a repo for $300.00 if I remember correctly, I have one, its very nice. An orginal if you find one will cost you $800.00 to $1200.00. Also the carbs fuel lines are available from him.

 

I got the fuel lines and linkage from a Pontiac supplier I know in Ohio. They are very well done. I have some original Olds linkage and fuel lines that someone had put on a '66 Pontiac Tripower I bought on eBay. Repros compare very favorably. This is the setup I'm building for someone with a '66 442.

Too bad about the fuel filter. The GF 48 looks exactly like the Olds unit, but there is no tapped hole for mounting on the topside. There must be a better way than $300.

If the repro L69 manifold happens, there will be a lot of Tri-carb 442's around. He has tried several times on eBay, but no one has yet met his reserve of over $400. Maybe he will decide not to go ahead with the project.

 

I see the recast L 69 manifold on Ebay all the time, if I could figure out how to post a picture or two I would of some substitutes that are close for the fuel bowl. A 62 starfire and early like 63 Caddy both without AC are what a lot of people use but they are not 3/8 inlet and outlet like the olds one is, they are 5/16 and then you have to get brass adapters to make them work. This is the guy that sells the fuel bowl, plus the clamps, bracket and other items.
402-564-8141 (days) for Mike
I found it one EBAY!

 

There is one for a 50's Chevrolet/Corvette application that does have 3/8" inlet and outlet. It does not have a tapped hole on top, though.

 

The threaded fuel bowl has a neck on it that is raised about an inch over the top of the fuel bowl. That is where the threads are and why the GF 48 won't work, it dosen't have that extra material.

 

The line from the fuel filter to the fuel block is steel, coated just like brake line. The curves on the copper lines in the photo are incorrect, but Mike Siedlik is now reproducing lines that are correct. Same for the bends in the line from the fuel pump to the filter--it was steel and straight with both the ends bent about 45 deg. Resto pieces Ii have seen were wrong until Siedlik began doing them.

 

The repop intake is horrible. Ports, not correct, not align well etc...

 

This thread is 12 years old...

 

This is the gospel. I just installed one and oh what a nightmare. DO NOT BUY!

 

And now this thread is 13 years old...

 

It is still helpful since PP is still selling this junk to unsuspecting buyers though. I can only wish my customer had seen this thread before spending $1000's on junk.

 

Their repo 3x2 carbs are no better. They use the smaller regular 2V carbs and make end carbs out of them. The problem is they are smaller,1-1/4 dia. venturi versus the 1-5/16 end carb dia. I am in the process of making some repo end carbs that are the correct size and will almost identical to the OEM carbs.

 

Unfortunatley he bought those too, he got the whole tri power chinese change over kit except the fuel bowl. That he got the wrong one so I had to drill and tap it plus machine a cap screw to fit inside to hold it as well as milling out the fuel passage to provide flow around the new bolt. I got the intake on and sealed after many hours of machining. Now I am having issues with the carbs. The front and center carbs have vacuum leaks in between the throttle plate and body, while the rear carb is leaking fuel from the top cover . So off they all come again for more work. Heck even the fuel lines that came with it leaked because the flares where not made correctly so I had to remake those.

 

Thank you everyone for your input and suggestions. I finally got it running right today. I had to reseal all three new carbs today. The front and center carb had air leaks between the carb bodies and throttle blades and the third was leaking fuel from the top cover. The permatex number 1 helped a lot although it was difficult to it from being seen. The car runs like a raped ape now and the owner should be very happy. Thank you again for your help.

 

Hello: Since you seem to have some knowledge on the olds tri power, would you happen to have handy, the GM part number for the venturis cluster in the center carb. i need a spare as I need to drill out the one I have, and I need a spare in case I screw it up.

Thx
John

 

I wish I could tell you but the carbs that where provided to me where already assembled. I can tell you the center carb was from a 74 chevy pickup according to the casting number on the carb body. So a venturi from that should work. It was a Rochester 2GC carb. Sorry I don't have the info you want. Good luck with it though.

Rob

 

Just curious,why are you drilling the cluster? Some of the later 2GC carbs have an extra vacuum channel and the cluster needs to match the carb. I can probably help you if you get into trouble.

 

When I first got the car, I had trouble getting the engine to idle properly. My 400 motor on my 65 was re-engineered out to 442 cubic inches, and the venturi cluster for the 66 2GC is designed for 400 CI. I saw a video by a gentleman who works on the Pontiac tri powers, and he indicated you need to open up these two tubes for a better idle. I believe the two outboard tubes on the venturi are .032 diameter. He indicated you might have to go out as much as .040 for a 455 motor.

So, I’m thinking that I need to open up those tubes.



Any thoughts would be appreciated.



Thx

John

 

You don't need to open those tubes. Stock will work fine. If you have an AL or AU intake, you might have a vacuum leak at the base of the center carb.

 

 

My idle issue was cause by vacuum leaks and I agree that is not a substantial increase in engine size the stock carb should work and you shouldn't have to modifiy it. My gaskets where wrong and it made a small leak that I couldn't see till I took it back apart and closely examined every thing. We also used a smoke machine to help and it identified another couple of leaks. This man knows his carbs listen to him and you will be rewarded.

 

If I had a vacuum leak, that should increase the RPM's which is not the issue. I managed to get it to idle by turning the idle mixture screws out. I think I'm near the end point. The biggest real issue left, is at low rpm's the engine lugs and I have to manage the clutch a bit. I think it's because the off idle mixture is to lean. It's hard to believe that an increase of 42 cubic inches would not cause some issues on a stock carb. I'm assuming everything is stock. I had these carbs regasketed two years ago, but I have new kits and I do have some small leaks. I don't like messing with carburetors particularly. Not my expertise, but thanks for all your inputs!!

 

Low speed engine surging is sometimes caused by the jetting being too lean. INHO the factory 63 center carb jets are too small. If the power valve isn't working,that makes it worse. I have used up to 66 jets in the center carbs and 71 jets versus the 68 jets in the end carbs. The richer mixture the cooler the engine will run. You can get it rich and is not good but I prefer richer versus leaner.

 

I haven't been in to carbs to see what the jetting is, but the engine runs perfect the way it is, not likely to change jets. But I will take your suggestions. I guess this fall, I will rebuild all the carbs and see what the jets are. So thanks for the jetting info.

 

I was responding to your complaint of the off idle low RPM lugging. This is the point where the jets are on their own without power valve help.My 66 with 3.23 gears @ low speed/RPM's never had that dreaded surging.

 

Well, the lugging might have something to do with the custom Isky cam in the engine. It's fairly aggressive. Thanks for all the responses.

 

Tri carb wondering... do you synchronize the carbs like on a motorcycle? I know on a bike if the carbs ate synced the power delivery is smoother and stronger.

 

That's something for a dyno shop to do. I'm just a garage mechanic. I have a friend that used to synchronize the 4 carburetors on his Suzuki bike. My motor runs strong and it dynoed at 469 hp, so I'm happy with the jetting. Thanks for your input.

 

i was just wondering out loud if it was a thing w tri carbs. Its actually really easy to do essentially just ensuring each carb has the same vacuum signal. Im always happy to spend 15 mins for free horsepower

 

I don't believe there is a vacuum port on the drones. Don't you need an anemometer or something like that?

 

Synching carbs is necessary when there are two or more carbs that open together .
Particularly that aforementioned motorcycle where each carb feeds a cylinder .
On a system with progressive linkage , syncronizing carbs is neither possible or necessary .
On a tri - carb system it is necessary to make sure that both end carbs reach full open at the same time .

 

Thank you Charlie. That makes sense to me. The drones are working fine.

 

I see, it is logical that the carbs feed all cylinders VS the bike where its 1 carb per cyl.

jmn there is a tool called a manometer that measures negative pressure differential, That possibly could be used idk for sure. For bikes there are two similar tools, one is a set of 2,3, or 4 vacuum guages the other tool is similar toa 4 channel manometer. After ensuring all carbs open all the way simply hook up the tool to the vacuum port on each carb and adjust the ( 1, 2, or 3) other carbs to match the non adjustable carb, the end result even on a good running bike is satisfying crisp throttle response.

 

This is 55 year old technology and the linkage is doing it's job. The seat of my pants tells me all is well. Thanks for your input.