I bought a tri-power intake that uses Rochester carbs. Does any one know if I can use regular 2 barrel carbs as end carbs. What modifications would i have to make to use them?

What you need to keep in mind is the outboard carbs with the tri-power didn't have chokes on them. Since they operated on vacuum there was no linkage to bother with. If you don't already have the carbs, why not ante up and get the genuine Holley re-issue? Sure, they're a few buck$$$, but if you want to play you've got to pay when it comes to tri-power. There really weren't that many made ('67-'69 Corvettes only). Too bad!

As an aside, what I don't understand is that if the outboard carbs are vacuum operated, then why do they close when you release the throttle? You only have a linkage to the center carb. Wouldn't the outboard carbs operate on their own and stay wide open? How does that work?

My guess is he has a old small block set up
I am setting up a 68 B/B Tripower now I would think possibly they rely on the springs in the vacuum diaphrams Mike

Thanks for the info. I have to tell you guys the truth. This set up is actualy for an old pontiac GTO that originaly used rodchesters.

I had an old hot rod that showed using standard 2gv or 2gb (cant remember which) on an edelbrock tripower intake. If your intake used rochester carbs, then these carbs may work for you also. The 2gv is smaller and I usually see them on 307s and the 2gb on 350s/400 small blocks.

------------------
70 chevelle ss396 conv
66 chevelle ss396 hdp/conv
55 chevy prostreet

The first thing you need is a Chevy manifold...FRED

What closes the end carbs on a tri-power with vacuum end carbs? Just like on a Holley 4bbl with vacuum secondaries, there is a linkage to the end carbs with a slot arrangement on the end carbs that doesn't allow the end carbs to open any farther than the primary. It also is supposed to close the end carbs when the primary closes. This relies on the throttle return spring on the primary to close all three. You must have a moderately stiff return spring on the primary, or sometimes the secondary diaphrams will try to keep all three open when you lift. This is from experience at 118 mph. von

Elmarco, I'm setting up a Chevy tri as we speak with the aid of a carb pro. The pontiac uses a mechanical progressive linkage in some years. That's the only way to fly. The vacuum outboards are difficult to tune and will not perform as well as a direct linkage. The Poncho linkage is freaky and has a rod on the pass side inling the outboards. Do yourself a favor and buy the Edelbrock progressive linkage kit. $20 well spent unless it's an original resto job your after.

Yes you can use aftermarket 2 bbls but, you'll notice the Holley 2300 have a 4 bbl air cleaner boss. This must be milled into a half moon. The vaccum port on the back side must be plugged as well. The 50 cc accel pumps must be switched to 30 cc unless you have a HUGE monster mill that needs 150 cc of pump shot. This type of setup, when properly tuned is totally awesome and will outrun a 4 bbl IMO. Plus you might just get better cruise mpg since you'll be running on the center carb only. When you nail it, you'll have 1125 cfm at your disposal ( with the Holleys). Pretty cool. And no it will not dog and it is not too big no matter what anybody tells you. I know from personal experience. Although you may not notice any difference between 3/4 throttle and WOT if your mill is less than 500 HP.

The one bene of the Poncho setup is that you don;t have to spend $450 on a friggin air cleaner! The damn Vette boys have priced the Chev tripower parts outta site. Email me for any specifics. I'll tell you that the carb pro is quite secretive about what he does inside the carbs, but you get the jist of the general layout.

[This message has been edited by Gene Chas (edited 12-03-99).]

elmarco, there is a great BB for Pontiac Q&A, at www.classicalpontiac.com. The people who post there are Pontiac fanatics and know the engines and cars as well as those here who know Chevelles and other Chevy models.

One there is Todd, ask in the Q&A section by posting a question and asking for his opinion, he'll respond, he is a good guy. Others there are just as knowledgeable too.

Pontiac never used a set of Holley wide base carbs on any of their trips setups, only 2GC Rochesters, standard design for the center carb, special design for the ends. There isn't room enough to use the Holleys on any Pontiac trips manifold, even with adapters, (manifold is too short to fit the Holleys).

Distributor clearance is also an issue, must use a stock size distributor to clear manifold/rear carb, and the HEI requires way too much grinding to clear. There are a few solutions to this problem, drop-in modules, custom small HEI, aftermarket distributors. Ask the CP Q&A people, they have answers.

My experience with GM Pontiac trips is that the end carbs are more different than most realize. They do not have chokes, don't have conventional idle adjustment, because they don't idle off the end carbs (throttle plates must be totally closed for the engine to idle and respond properly, and work as the secondaries do on a four bbl carb), and some of the diff Pontiac setups don't use accelerator pumps on the end carbs. Idle was always off center carb only. A properly set up single four barrel will outperform a trips setup, but there is just something about multi-carbs, ain't there!!!

[This message has been edited by 65Z16 (edited 12-03-99).]

Gene, let me know when you start running three 650 annular discharge carbs on your 541 c/i ZL1 engine (yup, aluminum second design ZL1 engine from my old AA/FA program, set up for street use). The one I just finished for myself sits nicely into my '65 Chevelle 2 dr wagon.

It will be a nice quasi-clone parked next to my all original Z16. Even more fun driving this ol' grocery-getter.

[This message has been edited by 65Z16 (edited 12-03-99).]

Aw Z16, don;t I wish. I've been trolling for 3 of the 500 cfm ( 375) 82011's annulars. I've heard they come in 650 form as well. They're very trick, but I can't find em. If I can't by end of the month I'll have to settle for the 2300s. I like the way those aluminum bodies look, better than the silver whatever finish on the 2300.

Umm, be careful what you say. I know for a fact that the tri ran much better on my little 427 than did the single 4. But the fella kept the setup for his 509 so I have to duplicate it. The added bonus is that the low end was much better, more responsive, with the tri intake than the open plenum L88.

BTW, these work great on the mountain motors don;t they! His 509 just sings with the tri.

OK I'm really jealous. If you know of any 500 cfm annulars around, machined or not, please, please let me know. Thnx.

Gene, I was referring to the Pontiac/Rochester trips, not the Chevrolet/Holley setups.

I had to carefully weld and machine the base pads on the Chevy trips manifold to get the area big enounh to seal the 650s, and then bored the holes to fit the baseplates after I pinned the bases to the manifold to keep them in full mounting adjustment. I linked the front and rear butterfly sets with both an equalizer rod for the throttle shafts and a hose link for the vacuum diaphragms, so they would open same-same.

I have only had the engine running on the dyno so far, but it is serious stout, and nice to have a big block that weighs the same as a small-block engine. It's in the new wagon, but it will be a couple of months before it gets on the road.

I can't wait to go crusing in it.

Z16, with the smaller 500 annulars, the air cleaner boss must be machined to the half moon and the rear vaccum port must be removed and plug. Other than that, I milled out the center carb bores to be the same size as the outboards on the mani. They fit, but tight. The water outlet is a problem.

Well the real problem is that I can;t find any 82011 500 cfm annulars right now!!!! I'd hate to got with the standard 2300's. At leat with the annulars, you can pop the tops off to change your jetting rather than removing all 3 carbs to pop the fuel bowls off. I've placed wanted ads in Hemmings, called every speed shop that advertisies and most carb shops. Talk about a needle in a haystack! Most people don;t know what the hell I'm talking about.

Yup. I had to machine the carb tops for the air filter. I also made a curved pipe from the center carb to the PCV valve. I made a set of drop-on, pin indexed 5/8 in. plates to move the carbs up, with a custom three carb heat shield, and used a Corvette water outlet. Not a lot of clearance, but it all fits.

Since it is in a 65 Chevelle, and not a Corvette, I got a little more hood clearance to play with. I just got the front sheet metal on yesterday, and everything clears the hood with about 3/4 of an inch to spare.

Z16, well you got me thinking about the carbs again yesterday and during my lunch hour I called on a few ads from Hemmings. No go. Then I called the same small shop that said they could get them for me this summer ( @ $265 a pop!) and now even my last ditch stop says no go. Bummed. No 0-82011 annulars for my 67 Chevelle. Bummed. I'll have to go with the stock 2300 Holleys. Snooze, you lose, the saying goes. But I just couldn't dump the $800 while my full tilt restification was in progress. DAMN!

My intake has a vacuum port just below the center carb on the pass side for PVC.

Wally says that his friend that races stock class with a tripower found 1" spacers add some power.

I assume you're using the stock cleaner with a K&N element.

My carb guy said I probably wouldn;t "feel" the difference with the annulars anyway. But http://www.chevelles.com/forum/frown.gif

But if you have any ideas on whom to call, please email me. Thnx a mill.



[This message has been edited by Gene Chas (edited 12-06-99).]

A lot of outlaw dirt track racers use the 500 annular carbs, might try to find some and chat them up.

My next aluminum adventure will be a ZL-1 based 511 c/i, second design ZL-1 headed tri-power setup, for the street. A little different.

It will have a set of 650 carb bodies and throttle plates. Ever seen a three-barrel Holley carb? The 650s will be gutted of all fuel systems, and the two bytterflys will be gone. In their place will be a single throttle plate in each oval throttle bore. Since the manifold won't have wet flow problems, it can be used as the dual plane it is, with an open at the top setup, like cutting the divider down in a four barrel manifold. I'll use spacers to lift the carb (throttle) bodies and clear the manifold, not cut the manifold. They'll remain progressive, as stock (special triple driver circuits in the brain, fuel primary, fuel secondaries, propane-simple.

These will be mounted on a GM Winters 435 horse manifold, with a dual port nozzle per port EFI system. One nozzle will supply gasoline, the other will supply propane for extra fuel enrichment for detonation control with the 11.50:1 c/r and hydraulic roller cam.

Like I said, I do a lot of this kind of stuff. Keeps me off the streets at rush hour.

Z16 either you're totally BS'ing me or you're a flippin genuis. I did ask a Holley rep about three TBI's on a tripower and how to synchronize them, but I noticed the castings are a little large.

So from what you say, if I scrap the tri idea since all I have is the mani now, and decide to go with an EFI-converted Hilborn/Crower setup, you could probably piece that togehter in a few short nights!!!

All kidding aside, I figured the roundy round boys used them, but I'll go with the the less expensive 2300's. Finding three annulars may take years. Should've paid the long dollar. He who hesitates is lost.

Not for nothing and you are way more advanced than I , but why hyd roller why not soild? Seem more reliable and tunable IMO?

ZL1! My LT wish item. Not in an 'elle though. All glass '55 box or 61 Vette ( nonstock frame obviuosly). Can I come visit some time??? At least I can live vicariously.

You've got way too many fun projects going on! Best of luck with all of them. See ya 'round.



[This message has been edited by Gene Chas (edited 12-08-99).]

Gene, I used to be a Holley tech rep. I also used to run a AA/FA, using lots of ZL1 engines. I've had new ZL1 complete engines hoarded away still in the crates, for years. I've got enough to last for a few decades.

We used to buy these engines from Paramount Chevrolet, for the service manager's price, new in the crate, second design ZL1 (the one with the nice C exhaust ports and the little bump in the port floor), for $1495.00 + tax (early 70s). A crate ZL1 second design engine came from carb (the right 850 cfm carb), to pan, distributor (magnetic impulse type), water pump and balancer, flywheel, etc. It was one of the most complete crate engines GM ever offered.

I used to take the new cranks, rod/piston sets, cams, timing chains, valves, just about everything except the block and heads, and set them aside. I ran 541 and 570 c/i, before the NHRA came out with the 500 c/i size limit. I still have all those stock new parts stored away, just for special projects. Think what they are worth now......think what they'll be worth in five more years. Insane, isn't it.

Why a hydraulic roller? Solid roller lifters need rev kits to work properly in BBC engines, as the roller can end up bouncing off the cam during high speed operation. The hydraulic cam allows for keeping the lifter and valve train pre-loaded, stopping the roller bouncing. Also, I want to drive the car, not work on it setting the valves. I know, I know, setting the valves on a ZL1 is akin to going to adjustent heaven, but I'm getting lazier in my old age. Plus, the new hydraulic roller cam sets rev just as well as the older solid profiles.

You'd not like my private shop, lots of early historical aluminum engine pieces, even some special Mopar hemi stuff, you'd just end up starting a riot or something, then have a nervous breakdown. Gruesome suff.

You can make the 2300 carb bodies into throttle bodies. No need to butcher up TBI bodies that won't fit anyway. Just cut away everything that doesn't look like a throttle body.

I'm looking to end of year 2000 for all four of my 65 Chevelle projects to be done. These 4 projects will be clones in the Z16 layout. There's one hard top, one convertible, one two door wagon, and one panel wagon. My real Z16 has been done and pristine for about 10 years now.

We are all only as limited as we make ourselves. If we can think it, it can be done, we just have to work at it.

Z16, please forgive my internet-based skeptisism, no disrespect intended. Vestiges of a tour in intelligence.

You had insight in buying those ZL1's. My L88 began as a crate ass'y bought in 1971. I picked it up ( sans heads ) for $550 in 1977. SOunds like I got ripped since the zl1's wouldn;t have been all that much more ( complete).

Question for you: I keep thinking I should at least try a 850 ( or 950 HP ) on top of the L88 before I go to the TRi. Now I have a 750. The performance differential between the single 4 and tri I mentioned earlier also used a 750 double. The motor really woke up with the tri. Maybe becuase it was under carbed with a 750? BTW, the compression has ben reduced to 10.85:1 and the cam is a Crane mechanical with same lift, shorter duration than the L88 stocker. Do you think a bigger 4 should be run before the tri is assembled? I can't just do both simultaneously ( $$). Been searching for a used 850 to doll up and run to no avail.

Oh, and as regards your last statement, couldn;t have said it better myself.

Thnx in advance for any insight you may have.

OK, what do you need to know about Pontiac Tri Powers? I have had just about all the different type Pontiac Tri Powers. I have both a 65 and 66 Tri Power set up. Vacumm operated tri powers can be converted to mechanical linkage. Pontiac, Cadilac, Olds and Chevy used the same carbs until 1959, the 57-59 carbs are all small bore carbs, Chevy used the small bore end carbs until 1961 on the 348. I have a 348 Tri Power setup, the linkage is set up just about the same as a Pontiac. Pontiac used a small center carb until 1965, in 1966 Pontiac went to the bigger center carb. The 1966 Tri Power flows about 888 cfm and the 65 Tri Power is about 100 cfm less. If you have a 65 or earlier tri power try to get a big car air cleaner, they flow more air. 65 and 66 Pontiac Tri Powers will bolt to any 65-72 V8 heads without modifications. On a Pontiac engine a Tri Power will out perform a 4bbl.

Gene, the ZL1 and L88 engines came with the 780 cfm Holleys. Before the ZL1s were released by the dealers, the carbs were changed to an 850 double pumper. I seem to remember the L88s still had the 780s on them.

I also remember there were three separate design revisions on the L88 heads, 1st series, square exhaust port, rev. 2, round port, like 1st series ZL1, and 3rd ser. like "C" port sec. ZL1. The third series worked good. First series were used on trips 435 h/p 427 L88s (very rare, only a handful of 435/427s were built with the L88 head option).

I also seem to remember the third series L88 cam was either real close or same as ZLI 2nd design.

I might rummage around my info from the options and specs and see if I remember correctly. It has been a long time since I used anything STOCK L88 or ZL1. I have lots of L88 stuff, too.

It wasn't really insight that made me buy every ZL1 and L88 part on the planet, just the un-ending need for spare modifiable parts for the AA/Fuel Altered engines. Nitro and blowers take a heavy toll on all kinds of parts. Gotta have lots of spares.

Z16, thanks. BTW I always thought I had 1st gen heads, but they have the round exhaust, so to your reference they're 2nd gen.

My question didn't mean stock apps. Simply, in your opinion would an L88 make more power with a single 4 ( stock open plunum mani w/850) or a progressive linkage tripower ( w/ the 2300s like I'm planning)? I've asked the queston before but I would appreciate your insight.

[This message has been edited by Gene Chas (edited 12-10-99).]

You have more latitude with a single four barrell manifold as far as spacers and baseplate height over the trips. Also, the single four intakes have much better transitions in the runners and flow is better into the individual runner entrys than the trips manifold has.

With careful massaging, spacers and a better set of carbs (three massaged 500s), the trips would paralell the single four for strip performance. On the street, the trips would be superior.

Still, all depends on the particular comp ratio, cam, exhaust, etc. My statements are geared at both intakes used on the same engine package.

I have not ever seen the need for any carb smaller than 850 cfm on any L88 or ZL1, in fact, the best carb I have ever used on either engine was the 950 and 1050 three barrell carbs, they flat get it for a single four setup.

Years ago, on most aftermarket dual-plane intake manifolds, everybody used to wonder what the small groove was in the divider on the secondary side. It was so a three barrell's oval secondary plate would clear the divider. I'd like seeing a three barrell Dominator or Demon carb, I think it would work super.

Wow Z16 want to get rid of a set of aluminum heads? They would look great on my convertible.

------------------
'69 RS SS 396 375hp L78 Convertible, M22, 3.31 posi, deluxe interior, gauges, rosewood wheel, AM-FM,fold down seat, SS wheels

65Z16 thnx for ur opinion. I felt the tri would give more mid range for sure and maybe better mpg for highway cruise if I can figure out the sweet spot.

Chris I know a guy in Webster NY with a shop full and a basement full. Probably 75 pair all told. They ain;t cheap bud.

Just curious, about how much would a set of aluminum heads run?

------------------
'69 RS SS 396 375hp L78 Convertible, M22, 3.31 posi, deluxe interior, gauges, rosewood wheel, AM-FM,fold down seat, SS wheels

[This message has been edited by Chris396 (edited 12-11-99).]

65 Z16 I am setting up (or attempting to)set up a A Tripower manifold. It is a early 68 oval port I was wondering if there is a book that covers this specifically. It has a 4055 -1 center it is on the car and is running and driving but it still has problems. It seems to have a intermittent vaccuum leak that I can not isolate also I was wondering if you have ever played with these . This is probably Childs play to you but this pretty much my first shot at multiple carbs Thanks in advance Mike

Chris, I hate to quote another wares but figure 1G and then the machine work to freshen up. As usual, new aftermarket set of alums are very competitive and probably better heads.

Mike, I wish I could help with your carb prob. BTW, did you pull the whole enchilada apart and check flatness of the castings?

Step 2 buy a 2300 ( 3 is better ), have a bud at a machine shop mill the air horn, etc. Good luck. I really want to see your trips running right.

Curiousity is just knawing on me so I think I'm going to buy a stagger jetted 850, all set up for an L88 open plenum just to establish a baseline before I go to the tri next year. Crazy? Yeah, but I don;t think I'll lose much $$$ doing it. And you don;t learn by not doing so...

I am going to run it a few more miles tonight I want to break in the eng I just ordereed the rest of the original stuff choke coil etc . I have a few Ideas to check its running just not a 100% Thanks Gene Mike