73 grancoupe
Member
Has anyone ever used the old offenhauser tri power setups. I think they look good and alot cheaper than a Mopar six pack.
Tri power setup
- Thread starter 73 grancoupe
- Start date
I think if you ask enough people familiar with any of the six pack set ups that you will learn that they are hard to tune and even harder to stay tuned. Yes, they look cool but IMHO you would be better off with a single 4bbl carb. If you have to have multiple carbs, go with two 4bbl carbs.
73 grancoupe
Member
It's just crossed my mind a few times about how cool it would look!
stubs300
Senior Member
Tri power? That's a Pontiac thing, I don't think it will work on a Mopar!
Ironwolf
Senior Member
I myself like this set up !!!!
From my friends you have genuine 440 6bbl cars, the main issue is the power valve in the center carb blowing out whenever the car might pop-back when starting. Newer Holleys are supposed to have the anti-blowout "fix", but I'm not sure how well they might work.
When the 3x2 Mopar set-up came online, it was dead in the middle of the earlier exhaust emissions calibration era. Higher idle speeds, solenoids for this or that, all of which were more troublesome to deal with than even a stock Holley 4160-type carb. Much more involved to change the power valve in that center carb than on a single 4bbl carb, by a long shot!
A side issue is that when the Offy manifold was designed, the designs went more by "looks" than actual flow tests, which would mean the factory Edlebrock manifold would be superior in all respects.
The secondary carbs were run by vacuum diaphrams, as I recall, so you didn't get too much carburetion at lower rpms (where it would bog the motor). These might be a "maintenance issue", too, as would the power valve in the center carb.
One of our club members has a '70 Cuda 440+6 with a 3.23 axle ratio. It was turned correctly and "right". Highway mpg was about 15-16mpg at 65mph cruise. It was his only car back then, so it saw regular use. It was as reliable as any other Chrysler 440 was, for that matter. But most usually had 3.55-3.91 rear gears, which negatively affected the mpg and highway cruising.
I do concur, they look neat but you HAVE to know how they work and how to work on them, for best results. There were many "fixes" that didn't work too well, back then, so "stock is best" as the general baseline rule . . . then tweak from there. A good and reliable electronic ignition system might help, too, with the starting issue.
The "visuals" are there, but a normal 4bbl on an Edelbrock dual plane can work just as well, if not better. The modern Mopar Perf single 4bbl 426 HEMI manifold and carb puts out more power than the older 2x4bbl set-ups did, back then. A single 4bbl is so much better with respect to the air flow patterns than ANY multi-carb manifold, by observation.
Back when the 3x2bbl systems were popular, the 2bbls probably flowed about 200cfm at the most and most 4bbls were about 450cfm, max. Only way to get more airflow into the motor was multiple carbs. Better manifold designs and improved airflow carbs basically obsoleted the multi-carb set-ups back then, except on inline motors. Getting airflow OUT of the motor tended to negate any max affects of the multi-carb set-ups, too.
Your money, your desires, etc.
CBODY67
When the 3x2 Mopar set-up came online, it was dead in the middle of the earlier exhaust emissions calibration era. Higher idle speeds, solenoids for this or that, all of which were more troublesome to deal with than even a stock Holley 4160-type carb. Much more involved to change the power valve in that center carb than on a single 4bbl carb, by a long shot!
A side issue is that when the Offy manifold was designed, the designs went more by "looks" than actual flow tests, which would mean the factory Edlebrock manifold would be superior in all respects.
The secondary carbs were run by vacuum diaphrams, as I recall, so you didn't get too much carburetion at lower rpms (where it would bog the motor). These might be a "maintenance issue", too, as would the power valve in the center carb.
One of our club members has a '70 Cuda 440+6 with a 3.23 axle ratio. It was turned correctly and "right". Highway mpg was about 15-16mpg at 65mph cruise. It was his only car back then, so it saw regular use. It was as reliable as any other Chrysler 440 was, for that matter. But most usually had 3.55-3.91 rear gears, which negatively affected the mpg and highway cruising.
I do concur, they look neat but you HAVE to know how they work and how to work on them, for best results. There were many "fixes" that didn't work too well, back then, so "stock is best" as the general baseline rule . . . then tweak from there. A good and reliable electronic ignition system might help, too, with the starting issue.
The "visuals" are there, but a normal 4bbl on an Edelbrock dual plane can work just as well, if not better. The modern Mopar Perf single 4bbl 426 HEMI manifold and carb puts out more power than the older 2x4bbl set-ups did, back then. A single 4bbl is so much better with respect to the air flow patterns than ANY multi-carb manifold, by observation.
Back when the 3x2bbl systems were popular, the 2bbls probably flowed about 200cfm at the most and most 4bbls were about 450cfm, max. Only way to get more airflow into the motor was multiple carbs. Better manifold designs and improved airflow carbs basically obsoleted the multi-carb set-ups back then, except on inline motors. Getting airflow OUT of the motor tended to negate any max affects of the multi-carb set-ups, too.
Your money, your desires, etc.
CBODY67
If you look carefully at a lot of the classic hot rod cars that were driven on the street, you will find that while everything looks functional, a lot them have the two end carbs blocked off. There is a good reason for that, the older Offy tri-power manifolds had a design issue with getting balanced fuel flow to all cylinders. We had a 383 with this set up (3 Holleys ) and it would almost always be drowning the four inboard cylinders with fuel while the four outboard cylinders (1-2-7-8) would be running too lean. This is why a lot of the older 3x2 setups ran like crap most of the time. We junked the Offy setup in favor of a T-6 single plane setup and found with a 750 Holley dual pumper we gained about 15hp and got rid all the troublesome tuning issues and we got balanced fuel distribution and a lot less pinging and burned valves on the outboard cylinders. I agree that the Offy 3x2's looked neat, but they just were not very functional.
Dave
73 grancoupe
Member
I seen a few offy intake setups on eBay for a 440 I thought they looked good wasn't sure how good they worked. The twin 4 barrel set up sure does look good.
commando1
Old Man with a Hat
I'll be honest. I don't know anything about them.
I never wanted to because all my memories of them were being with guys that had them and trying to tune them leaving their driveway and trying to tune them when they got to the local hangout. Gawdamn they were annoying. Soured me for life. My 4 carb Honda 750 was as bad as it got for me. And I was doing the same thing. After every round trip.
I never wanted to because all my memories of them were being with guys that had them and trying to tune them leaving their driveway and trying to tune them when they got to the local hangout. Gawdamn they were annoying. Soured me for life. My 4 carb Honda 750 was as bad as it got for me. And I was doing the same thing. After every round trip.
Last edited:
65Fury440
Senior Member
I have been eyeing the old CB 750s just to beat around town on.
My good friend had a 73 that I grew fond of.
I thought I read somewhere, a company was making brand new CB 750 repops? looked but can't find the info.
1974 Honda CB750Four, Norcross GA - - Cycletrader.com
65Fury440
Senior Member
BTW Stan, you're cool for an old guy!
Part of what used to happen with the older 3x2 setups was they had a solid linkage rod between the two end carbs. Good in theory, in practice, what happened though was that rod would expand and contract enough with a warm vs cold engine and ambient temp changes to move the end carb butterflies a few thousands of an inch, just enough to get air flow and mess up the mixture settings that you had just spent hours getting "just right". Changes in humidity as the day went from dawn to dusk also messed it up.
Dave
commando1
Old Man with a Hat
BTW Stan, you're cool for an old guy!
Fwiw, it absolutely kills me that 750s are expensive collectables. Common as tin cans back then. The m/c version of the 57 Chevy owned by every dull working man and beater fleet.
Last edited:
Seems like some of the carbs had genuine idle circuits in them and others didn't?
Some of those mechanical linkages were better than others, from what I've read. Some were "default movement" in orientation and others were "progressive", which allegedly worked better with smoother transitions into the end carbs opening.
CBODY67
Holley made carbs with an idle circuit delete as it used to be called, that was a throttle plate with no metering screws. Not too many folks used them because there was an issue with an over lean condition if the butterflies were not completely closed on the linkage setup or on jamming the throttle wide open. (Carb went from zero flow to max flow and usually the accelerator pump was Just a tad slow to compensate) The carbs with the idle circuit had an over rich condition if the linkage did not close the butterflies completely. Kinda damned if you do, damned if you don't situation.
Most of the "progressive linkage' of that era (Pre '70) used a fixed rod between the two end carbs and an adjustable slider on the center carb to preset when the two end carbs kicked in. Later on, somebody developed a linkage with a slider for each of the end carbs so that the rigid linkage did not force one carb or the other slightly open if the temp changed or the linkage was not properly set. Still tough to set up as both end carbs needed to open at the same rate for peak performance. (Used to have to cycle the throttle several times and use a feeler gauge to check the free play over and over)
Dave
Dave
Everyone is taking apples and you may be posting about oranges.
The Offy setup was Stromberg 97, Holley 94, or Rochester 2G carbs with a mechanical linkage. Nothing like the six barrel/six pack OEM Mopar setups.
I'd stay away from it myself. This was 50's tech. Old carbs that you aren't going to get parts for etc. Performance will be most likely dismal at best.
IMHO, the appearance would only look "right" in a nostalgic custom or hot rod. Not a C body.
commando1
Old Man with a Hat
Damn hard for me to keep abreast of modern hot rodding now because it evolved at a pace that was basically too expensive for me. But I overheard a few guys convincingly explain that there are 4 barrels today that outperform any dual quads of the sixties or any 6bbl (in any configuration. 6x1 or 3x2. I don't care) setup.
73 grancoupe
Member
And that's why I'm here!
Similar threads
