Thread: Tri-Power Rebuild

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I’ve got some down time so I decided to pull out the Tri-Power I took off the 57 Plymouth and go thru it. It was a good working unit when I swapped it out for the Dual Quads but it did look like it’d been on a car that I’d been driving for 12 years.


T1 by M Patterson, on Flickr



T2 by M Patterson, on Flickr



It was a pretty straight forward rebuild and detail the carbs and intake.


T2 by M Patterson, on Flickr




The one thing I did change was to replace the rubber fuel lines with hard lines.


T1 by M Patterson, on Flickr



Over all I’m happy with it. Originally my thought was to put it up for sale and I still might but after looking at it for a while it hit me I do know where a couple of builder HEMIs are but even more interesting (for me anyway) I think I might know where there is a builder 331/354 Spitfire (Poly) motor .

I built a 354 Spitfire back in the 70s (ended up in an F20 Farmall for tractor pulls) so I kind of have a soft spot for them. As they were based on the Fire Power HEMI ….the short block is the same and to convert them to a hemi only requires changing the heads, pushrods and exhaust manifolds …..and possibly pistons depending on the CR you want to run. The Intake manifolds interchange between the Poly and HEMI !!

Their kind of an unusual looking engine which I guess is part of the appeal and they only made slightly less HP than the HEMI did.


spitfire by M Patterson, on Flickr


Of course if I build either another HEMI or a Poly I probably end up wanting to put it into something ….say a 55-56 Chrysler, Plymouth or Dodge…..not that I’ve looked for any on E Bay or Craigslist mind you



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A Poly motor would be way cool. Definitely rare with a capital R! I think I can say with confidence I've only ever seen 1. Way more Hemi's running around.

That turned out nice! Gotta love 3 deuces. To me at least, they scream hot rod (just like 2 fours).

I have had two sets on SBC's and I think they are the most street friendly multi-carb setup, too.

Very nice work Mike! I like the idea of the spit fire engine. That would be very unique. I doubt most people would even recognize it.

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That really looks great Mike, super nice work!

Thanks everybody. I've been playing with it a little more.


I always liked the way a Tri Power looked with 3 individual air cleaners. When I started messing with Tri-Powers 35 years ago I quickly found out that the little 4” air cleaners were way too restrictive for anything more than a relatively stock engine of around 325 CI or less. There was a reason that the factory Tri Power units mostly used a single large air cleaner rather than individual air cleaners. The exception being Pontiac and Oldsmobile which used at least a 5” air cleaner with low restriction filters.


I also figured out that when you hit the 350CI mark that most engines respond a lot better to a large base center carb rather than the small base carb most intakes are set up for. That being the case most of the Tri-Powers I’ve built over the years have been set up for a large base center Carb with its corresponding larger inlet throat.



The “go to” filter on my Tri Powers has generally been the oval 60s era Ford style. They are still reasonably priced, new filter are readily available, plus it’s easy to build a custom base for. They are also about the lowest profile filter you can fit under the hood (and this Tri-Power is TALL).


T3 by M Patterson, on Flickr


I came across some “dune buggy” air cleaners many years ago with offset inlets. By offsetting the 2 outboard air cleaners and centering the middle air cleaner I can get the three 5 1/2” air cleaners on the tri power. Of course the inlets were only 2” instead of the 2 5/8” and 3” inlets I needed for the Tri Power but modifying is the fun part.


AC 1 by M Patterson, on Flickr


If I actually end up running these air cleaners instead of the big oval one I’ll replace the filters with either paper ones or K&N filters.

+1 for the separate air cleaners, but I totally understand the long oval one, too.

When I first built my T-bucket, I had the Stellings and Hellings style helmet style air cleaners. Not only were they only 4" elements, but the helmet cover only had about 3/16" opening around the base for air. They looked great, but I might as well have stuck a sock in the carb. I wound up changing them out to some Obrien Truckers cleaners with an open element.

JMHO, I have found multiple carbs balance a little better through a single air clean. However, low profile air cleaners seldom supply enough air for multiple carbs on a healthy engine.
Your manifold and carbs do look nice!

"Helmet covers" I can't help it - I'm picturing WWI German helmets with the spikes. I'm sure it's been done.

"......"Helmet covers" I can't help it - I'm picturing WWI German helmets with the spikes. I'm sure it's been done......"

Oh yeah.

HAC by M Patterson, on Flickr

But no those aren't the ones Mike was talking about.



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The old Ford air cleaner elements bring back some memories, in my early days of circle burning we ran 2-2 barrels (2GC Rochesters) on methanol and used 2 of these elements and a home made base and top to get enough air in to feed the engine! The rules said you could have 4 barrels of carburation but we never could get the 4 barrel carbs of the day to work right on methanol, with extensive modifications, the trusty Rochesters were up to the job!

Now days you can buy (or at least could a year or so ago) an element that is twice the height as the stock one.

If you had the same difficulty finding any big jets for the Rochesters I've run into I'll bet you had a trusty set of drill bits for the jets to get enough methanol into the engine too.



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Originally Posted by Mike P

Now days you can buy (or at least could a year or so ago) an element that is twice the height as the stock one.

If you had the same difficulty finding any big jets for the Rochesters I've run into I'll bet you had a trusty set of drill bits for the jets to get enough methanol into the engine too.

If you had the same difficulty finding any big jets for the Rochesters I've run into I'll bet you had a trusty set of drill bits for the jets to get enough methanol into the engine too.

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Yup, a special set of drill bits that a machinist buddy of mine sent me. However later he sent me a tap that we'd drill out the threads where the Rochester jets screwed in and rethread them for Holley jets. Always liked to do a bit of radius work around the hole in the jets, too.