Hey all, So I've been running the linkage shown in the pic for about 18 years now. It's worked ok...except for a couple of times. A long time ago the center carb stuck open on me. The long aluminum lever on the center carb slipped on the shaft leaving the center carb open. It was a terrible engine shutdown. Fixed it by adding a cone pointed lock screw on the shaft. But last year it happened again, but this time the coat hanger looking rod that opens the outer carbs got stuck in that brass barrel on the front carb and the center carb stuck open. The brass barrel just decided not to rotate when it should have. That was the last straw. I never really liked this setup and would like to install a better quality and safer operating linkage. Can you guys point me to a better system and where they can be found?? I really like my tri-power, it runs great. I just want to rebuild them and upgrade the linkage. Thanks in advance.
My dad bought one of those setups for his 57 Olds super 88 with the J-2 tri-Power in the mid 60's but I don't think he ever installed it. I'm thinking that there have always with that particular setup linkage wise over the years.
I know you likely have return springs on at least the primary, but the secondaries also need their own as well. I do not see anything jumping out that would cause and over center issue but the link on the primary is pretty high up, you could move it down a few pegs and tighten up the gap on the locking collars to get about the same actuating times for the secondaries.
So because of those cheesy aftermarket linkages I made mine. Works great but it does require another return spring for the secondary carbs. It’s hard to see in the picture but the lower linkage is a brass tube with a slot milled in it. A rod slide in the brass tube and you install a roll pin. The slot length is critical as that determines when the secondary’s open as well as closing. The spring and roll pin pull them closed.
Yes I do have a double return spring on the primary (on the other side), and the small stock circular return springs on the secondaries. I will try your suggestion as lowering my primary/secondary actuation rod will bring it more parallel with the secondaries rod. Thanks for the tip here Nick!
Kevin Ardinger said: "So because of those cheesy aftermarket linkages I made mine. Works great but it does require another return spring for the secondary carbs. It’s hard to see in the picture but the lower linkage is a brass tube with a slot milled in it. A rod slide in the brass tube and you install a roll pin. The slot length is critical as that determines when the secondary’s open as well as closing. The spring and roll pin pull them closed." Your setup has both primary/secondary, and secondary rods running parallel to each other which eliminates the rotation of parts. I like this. Based on what I have seen online so far I may have to just think this out and build my own linkage. Thanks Kevin for sharing your setup with me it gives me an idea I can work with.[/quote]
Pontiac started selling OTC progressive linkage at least as early as 1957 for racing. From memory, the Olds carburetor spacing is identical to Pontiac. Most of the Pontiac stuff (maybe all) has been reproduced. I would suggest checking with some of the Pontiac vendors, Ames in particular. Jon.
Hello, Having raced our 1958 Impala with a 348 motor and three Rochester carbs, one can say the stock vacuum set up does the best for the motor set up for daily driving and when necessary, full power acceleration. But, the whole system runs on a rubber tube being connected at all times, so, if there is a crack in the rubber or it accidently falls off, now, you only have the center two barrel for power. But, comparing the progressive linkages available for most three 2 barrel applications, adjustment is definitely necessary at all times. As mentioned, return springs are also a check daily item. It may open when the pedal is pressed, but it may not open all of the outside carbs for full efficiency. Adjust, adjust, adjust is the key. The vacuum product took over all aspects of normal 2 barrel operation and then full power outside carbs when necessary. Despite all correct installation and constant precise adjustments, I did have the progressive linkage get stuck on a full acceleration run to show my friend the power and sound from my new muffler system. As a fast speeding Impala was heading for a “T” intersection, constant pulling on the pedal mechanism to shut down. Finally, turning off the motor/car was the last skidding stop before heading into the cross traffic… whew! No damage, other than pride and that #@$!^ progressive linkage. YUK! Jnaki Here is a story from a past post on the HAMB... I remember reading one of these types of flyers that was given to us by our dad's friend in Los Angeles. He was an expert mechanic, was well schooled and had surprising contacts in the industry from the very early days of Los Angeles hot rods and cruisers. When we still had the 58 Impala 348 280hp+ from 57 to 65 they gave us some good knowledge. They were very informative, as these flyers are supposed to be. After trial and error, we decided that the vacuum version was the best set up for our Impala. We tried the progressive linkage and liked the looks, but did not like the function, after many adjustments to all of the carbs. When the center carb was full open, the progressive linkage did not open the outside two carbs to full. When they were adjusted to full open, then the motor ran funny. The best was to run the center carb to full and hope that the outside two opened up. But, the back of our minds, it was not the best for daily street driving. At the drags, we set it for full center and full outside carbs with one push of the lever. But, remember, it was all out drags and no daily stop and go with normal traffic. All three two barrel carbs at once were not the best for comfortable daily street cruising to high school or at night to our Bixby Knolls hangouts. Now, with the vacuum, the center worked all of the time and when pushed to open to full throat, then the other two kicked in and opened to full throat. It was simple, felt great driving around to school, on dates, to the beach and even up into the mountains. Although in the mountains, those that knew, adjusted the carbs for better driving in high altitude environment vs. the ocean level driving. (and vice versa when we came down from 8000 feet to sea level…) So, the vacuum is/was the best for us. But, if you can’t set up a vacuum, then a progressive unit should work for you. You might be adjusting the Progressive link set up until you get it to where you like for comfortable driving. But, it did take many adjustments to get close to full power. Did I mention that progressive linkage stuck on one late night, foolish, full power acceleration away from my friends house? When we sold the Impala to another younger teenage friend, he knew about the vacuum verses the progressive linkage. So, he kept the stock vacuum unit, but had the progressive unit if he went back to the drags to race. Progressive was good for the drags, but, for us, not so good, on the street. YRMV
Thanks Jnaki! I never gave the vacuum system any consideration. I do have some documentation here similar to what you posted. I'll spend some time reviewing it. Thanks again and take care.
http://hotrodcarbs.com/store/rochester-tri-power-progressive-linkage-kits.html This is where I got the photos, you might call them and see if they will help with your questions. Also, a HAMB conversation with @hudson48 might yield some info as he is using the linkage shown above.
1965 Pontiac Catalina 389 ci. 338 HP Tri-Power option, automatic transmission. Vacuumfrom the base of the front carburetor goes through a one-way check valve to a T fitting, one leg to the vacuum reservoir, the other to the thermostatic switch. Once the engine is to temp, the switch opens letting vacuum to the Trico vacuum switch on the center carb. The accelerator pump linkage opens and closes the switch, allowing vacuum to the canister on the back carburetor which pulled the ends open. When closing, air is pulled from the top of the front carburetor through the open portion of the switch allowing the canister to relax. It's a slow process and nerve racking waiting for the power to shut down!
Beautiful! Absolutely beautiful! Too bad the folks that reproduced the tags didn't care about color. If you want to play with it, on that particular configuration only, the front tag is brass colored, the center black, and the rear burnt orange. Of course the originals were anodized aluminum, but paint will also look nice (top of tag only). I was always too frugal to buy the reproduction tags, and made my own. Usually, one can search the supermarket and find either a soft drink or a not so soft drink packaged in an anodized aluminum can of the correct color. How about posting a picture of the driver's side of the air cleaner showing the decal? Jon
Wow what a nice intake!!! Hey Joe thanks for the eye candy and how it works. Is that a factory stock setup???
It's as close as I could get it, dad purchased a new 1965 Catalina 9 passenger wagon with the 338HP tri-power engine, automatic and 3.23 rear axle, he won stock eliminator in '65 with it. This is the set off of it, I made new fuel lines and most of the vacuum lines, the originals were a little mangled from being on a lot of different cars we had. We think the 338HP engine is the only one to get a factory chrome air cleaner lid, it had painted valve covers. The 421's had chrome valve covers and three air cleaners. I have seen where less then 1300 engines were sold with this option. This also shows how much was involved in the vacuum systems, the mechanical ones were much cleaner looking. They were all vacuum from '57 to '64, even the manual transmissions, in '65 and '66 the mechanical linkage was offered on the manual transmission cars only.
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