I just purchased my 76 vette.... it has a quadra-jet that is not in too good of shape. Idles poorly... Lots of bogging, hesitating etc. I have an Edelbrock C362S triple duece intake and 3 rochester 2's I bought from a friend of a friend converting to Dual quads on his dragger. It has the progressive linkage and air filters etc... Now I have never used tri-power before but have heard they can be a nightmare to set up, and keep them adjusted. My vette is more or less my saturday night special, and don't plan on driving it ALOT, but I love the look of the three dueces on an engine. My big question is... Is the performance from 3 dueces worth the setup and adjusting? Are they as good or better than a good after market intake and holley? A big "saying" I've been hearing from some some-what knowledgable friends is..."all show, no go". Any tri-power users out there? :confused:

Thanks for any suggestions or advice.
Loren

 

Loren, Before you go changing manifolds and carbs Pull the Q jet off and send it to Lars in Colorado. He will rebuild it BETTER than new and he can also tell you what to do with the distributor. As Lars says, most carbie problems are acutally distributor problems.
I believe the search function is still off line but if you page Lars with another post he will chime in.
Lars is THE Carb and Distributor guru.
His work will amaze you. There are many testaments to the Lars-brettor here on the forum.
:cheers:

 

No question it would be better performance-wise to get the Rochester performing right. That Edelbrock 3x2 is a poser set up. Certainly not intended for performance. They are not hard to set up, which was your question. But if you must have a 3x2 on a smallblock, pony up the $2k+ when the Barry Grant sixshooter comes out. More similar in design and performance to the 340 SixPack:

 

Tri power carbs are not a nightmare to setup , and the performance will certainly satisfy your needs . Unfortunately the use of multiple carburetion has become somewhat of a black art and negative comments tend to come from people that do not run them and have never done so . Perhaps some members running multiples will add their own comments !

gman :thumbs:

 

then you must be a black arts magician G :)

 

Mine works great, and I've never had to touch it after initial setup/tune!
I really haven't been able to find the upper end of the power band with this, redline comes too fast!

And you're right, the "WoW!" factor opening the hood is great!

Paul

 

Exactly right. I'd tie the Quadrajunk to a rope and drag it before making any mods to it. It simply ISN'T a performance carb. Ever wonder WHY Chevy (and every other make) used Holleys on their hot performance engines?
Three deuces are NOT all that difficult to set up. As long as you have a nice stiff rear end gear, they can be very nice for street use. The progressive linkage may be a problem though. Popping all three carbs open at once will probably be too big a gulp of air for a smallblock. Vacuum linkage for the two outer carbs would be a lot more effective and easier to live with.
Multiple carbs always scare the uninitiated. They think that you have to adjust ALL THREE carbs. You DON'T! The only adjusting is done to the center carb. The two outer carbs are just "cores" with no air and gas adjustments.
So adjusting deuces is like adjusting one single Rochester 2 barrel. Hardly an overwhelming task for most backyard mechanics. :D
I ran a 1970 Dodge Super Bee with a 383 Magnum and the six pack setup for years, and it was the best-performing induction setup I've ever driven. Too bad the factory rat motor tri-power setup for the Vette is so "low rise". It would make a LOT of power with a better manifold design.

Dep


[Modified by DJ Dep, 7:49 AM 4/7/2004]

 

Dep , you can adjust the mechanical progressive linkages so they will perform just fine with no bog at all . Multiple carbs rule !!!!!!!!!! yeah

gman :smash:

 

It takes one to know one TT ,,,,,,,,,,,,,,,,,,,,,,,,,,,

gman

 

Tri power carbs are not a nightmare to setup , and the performance will certainly satisfy your needs . Unfortunately the use of multiple carburetion has become somewhat of a black art and negative comments tend to come from people that do not run them and have never done so . Perhaps some members running multiples will add their own comments !

Right on the money.

A few points though....
I don't know if the Roch 2V's can be set up with vacuum control diaphragms You may have to stick with mechanical linkage on those. Check with the old 1958 Chevy 348 tripower gurus.... maybe they (rochester 2V's) had vacuum diaphragms... I don't remember. It's been a long time since I worked on one of those.... probably 1960.

Progressive mechanical linkage means that the two outside carbs do not open immediately when the center carb starts to open , but then play "catch up" so that they are fully open at the same time the center carb is fully open.
This should be adjustable if you have a good quality progressive linakge setup

My first (high school) car was a Ford 292 with an Offy intake & 3 deuces.. I designed & built the progressive linkage for that because it was not available commercially.

2nd point... Some tripower setups do have idle mixture screws on the outside carbs.,.... such as the factory Ford big block tripower on the 1962 Tbird. The outside carbs (Holleys) have metering blocks just like the center carbs and were adjustable. Holley made a special "D" shaped adapter for their multiple carb synchronizing tool specifically for this reason.

My BB Chevy tripower (which I am reinstalling sometime over the next few weeks) has non-original replacement throttle bodies on the outside carbs with idle mixture screws in them.

PS... I currently have a Holley 4175 800cfm spreadbore on the car, and when the trips are set up properly, they walk all over it. I bought the 4175 brand new and it's in perfect condition.




[Modified by Tom454, 4:32 PM 4/7/2004]

 

If you are gonna run tripower Holleys, then go with the Mopar versions. Only adjustments made are to center carb. KISS principle :D
I said progressive linkage MAY cause problems. Sometimes it works great, other times it bogs big time.
Vacuum-operated tripower came standard on the Pontiacs of the early 60's.
Ugly-as-poopie dashpots, but better than bogging. The front and rear carbs snapped open like an extra passing gear on my Super Bee. Never failed to impress the people I rode with or raced ;)

Dep

 

I ran a 1970 Dodge Super Bee with a 383 Magnum and the six pack setup for years, and it was the best-performing induction setup I've ever driven. Too bad the factory rat motor tri-power setup for the Vette is so "low rise". It would make a LOT of power with a better manifold design.

I don't know of any factory 383 Sixpacks but, I had a 440 Sixpack Mopar and they are fine in stock shape but can be a "mother" to tune on a modified motor (speaking from expirience.) The 1967 Tri-power IS a high rise design and I would pick a single 4bbl over 3X2bbls any time with our modern manifolds. Tri-powers came about in the 50's because of the limited flow potential of most carbs in that era. Give me a good dual plane manifold and a nice 4bbl any day!


[Modified by DJ Dep, 7:49 AM 4/7/2004][/QUOTE]

 

Yawn...well some folks like to be DIFFERENT. Tri-power gives you economy AND performance in one package. You run on the center 2bbl carb and the front and back ones ONLY open when needed. Mine wasn't a factory 383 six pack. Edelbrock made a duplicate manifold for the 383 that used the 440 carb setup. Still worked great.

Dep

 

Yup, another Tri-power user :seeya

 

Sorry George ,,,, no tri power here ! I run four dcoe webers on a moon crossram . They are no problem to tune ,,,,,,,,,,,,,,


Geo aka gman :seeya

 

Have to agree with The Depster, I wouldn't change the trips on mine for all the tea in China...have tremendous throttle response, I can adjust the secondary openings in a heartbeat, based on my driving habits....

 

Tom454,

I would be very interested to hear more about your modification with idle adjustments in secondaries. I've got a factory 435 tri-power setup that I have long toyed with the idea of installing on my 69.

Chuck

 

It is really good to see other multiple carb fans here besides my self !

geo :seeya

PS ,,, it's kinda hard to keep off the pedals with multiples

 

wow! thats alot of replies..... but i still can't say i know what i'm going to do.... still getting alot of both sides. well actually i think i'll just put it on, set it up, and see if i like it. in the end i guess thats all any of us can do....(experiment) thanks for all the info... i'll let you all know what happens. maybe i'll end up with a performer and holley in the end. it'll be fun to learn and play anyway.

Loren :cheers:

 

Once more time for the record...

I have a 4175 Holley spreadbore 800 cfm w/1968 Vette aluminum low rise on my 454 right now, and the 1968/69 GM 900 cfm tripower/1968 aluminum low rise manifold makes the 4175 feel like a VW bus. GM went to the low rise 1968/69 due to hood clearance issues... they had no choice. It was either low rise, or no trips. I'm glad they picked the trips.

It's all in the mechanics ability to fully understand and tune an engine.

Chuck... I contacted Holley a few years ago to determine where the throttle bodies came from, but they had no clue. I can give you the casting numbers if you would like. The secondary throttle discs also have the usual 1/8" hole drilled in them for "racing".
I have two complete GM TriPower setups and I can compare the modified set to the original part-for-part.

Another forum member had his GM BB trips modified to use metering blocks on all three instead of just the center carb (so he claimed, I did not see it). This is similar to the 1962 Ford setup. But... I think he had to use short bowls (Ford ?) to get it to fit.

Pontiac 389 GTO fans..... I don't remember.... did they have vacuum secondaries??