simpson36

Here are a series of bored TBs for crossfire. All of these bored Throttle bodoes have functioning balance ports and sealed stainless ball bearing shafts. The 2.125" set (second from right) were successfully installed and pre-balanced on a ported crossfire manifold on a mildly modified 350. Results were smooth idle, no off-idle stumble and strong pull to redline.

The MOATB (Mother Of All Throttle Bodies) on the far right is now completed. See next post for details.

simpson36

Here it is. Crossfire 2.375" MOATB ready for install. Temorarily installed on a crossfire balancing rig for testing. In the close up shot, you can see the balance port just above the throttle plate. 2.375 is the very largest possible size for a crossfire TB and it still easily pulls 6" on a water manometer for proper balancing balancing. The pair of these should flow over 1,000 CFM.

This set is going on a new 406 cu.in. small block with all forged internals in an '84 Vette. The engine is 4.155" bore x 3.75" stroke with 6" rods with an Offenhauser cross ram manifold.

I will be making adapters fo mount the MOATBs on the Offy dual quad lid, a custom linkage and custom fuel system for this setup. Targets are 500HP and 6,500 RPM redline. Lots more pictures to follow as we go thru this project, starting with build details and photos on the making of the Mother Of All Throttle Bodies! Stay tuned:

simpson36

First Mock up:

simpson36

Here is the final mock-up with some finished pieces.

85irocz355tpi

holy smokes batman! I have never seen cross fire look so good. Keep us posted. Interested in the final product.

robertfrank

iTrader: (27)

IIRC the lower intake needs to be modified as well if you run larger TB's. From what I have read in the past the lower intake is a HUGE restriction unless ported. I hear that when ported it can have some great gains.

BronYrAur

iTrader: (1)

Those look great, I'm impressed. You've had some really good posts lately ie the throttle body rebuild how-to. Cool project

Ronny

iTrader: (1)

Robert: He is using the Offy Manifold!

simpson36

Robert,

I don' want to hijack my own thread, but I think you must be talking about the crossfire maifold.

You can suck a medium sized dog thru the offy . .


Crossfire is great for people who enjoy root canals and getting poked in the eye with a sharp stick

OK seriously though, the Crossfire can be a good street manifold with a good port. I've done quite a few.
What I do a little different is to cut out the entire EGR including 'the hump' and them plate over the holes for smooth flow.


I do the initial port cuts on a mill using a template I made for that purpose and them just blend back by hand. The red circles are were you need to go in deep and get rid of the bad flashing, typical mostly on the '84 versions.

I add a deflector under the lid to help direct the 5/7hits to opposite TBs.



Maybe I shoud do a thread on porting the crossfire. It's actually an interesting topic.

simpson36

Oops! Sorry did it twice.

robertfrank

iTrader: (27)

Yeah the regular crossfire manifold is what I was talking about. I have seen pics of it and it ridiculously small.

simpson36

Here are a couple more views of the final mock-up.

Refinements left to do:

While both IACs can be plugged in, the front one cannot be removed without taking the fuel rail off. I think I can adjust the supply enough to allow the IAC to come out without taking any fuel lines apart. There is a potential slight interference between the feed line to the rear TB and the throtle cable (not shown in mock-up). There is a potential clearance issue between a tall valve cover and the feed line to the front TB.

I'm using a new bending too and a new flaring tool and I think I can modify the flaring tool to get a closer bend-to-flare distance. One of two results: one) - I ruin my new flaring tool, or two) - I can improve a couple of less-than-optmal spots in the design.

The owner is doing his own throttle and TV brackets, but I still have to mock up something to check clearances on the fuel system. I dragged out these two original crossfire brackets from my BIG TB project and slapped them on the Offy and was surprised to see that they are almost a perfect fit! The throttle bracket can even use one of the Offy lid bolts (maybe)!

The owner is still going to do his own thing with the brackets, but for my purposes, I can mount the original brackets with aluminum plates bolted along the edge of the Offy, as represented by the white poster board in the mock-up. The plates will be blasted with the blaster set on 'abuse' to get a somewhat cast aluminum appearance to hopefully blend in with the Offy. TB adapters will be done the same way. If they don't blend well, maybe I'll go the other way and polish them instead . . a little more Bling never hurts.

The front bracket mount was a freebee because it doubles as the 'Y' block mount which I had to make anyway. The mount for the TV bracket in the back will be significantly smaller than shown on the mock up. It is big now because I need to slide the bracket around to get the proper relationship with the TB and the TB is not locked down yet. The final mount will follow the countours of the bracket and be all but unnoticeable.

By using the original brackets, and having the fuel tie-ins close to the stock steel fuel line locations, this setup almost becomes a bolt on! I would not have imagined that at the beginning.

All you need are the TBs, the TB adapter plates, the linkage and the bracket mounts and you are ready to rock with an Offenhauser CrossRam. Unbelievable!

Ronny

iTrader: (1)

Do you feel the top plate will seal better than the stocker?

Can the top plate be removed with the TBI's and parallel plumb in place?

IOW's do the TBI units interfere with the top lig bolts in place?

simpson36

Good questions, thanks.

This IS the stock top plate for an Offenhauser CrossRAM manifold. This manifold is still in production, and can be purchased new from Summitracing for a reasonable cost.

http://store.summitracing.com/partde...5&autoview=sku

An original CrossRAM, if you could find one, would cost you thousands.

All I have is the owner's lid. We coordinate with each other to get needed measurements. He will be doing the install, the fuel line tie-ins and the air cleaner design and fabrication.

I will deliver the top plate with the TB's mounted, torqued down and pre-balanced. Injector pods will be crossfire with GM 90lb injectors. They will be raised up on aluminum spacers.

The fuel system is not completely finalized yet. I would like to build in a nitrous option and the owner said something about having a water injection setup, so the door is still open on the fuel system. The ability for the fuel system to be pre-installed on the lid is not one of my design ctiteria, but it does appear that it would be entirely possible. I don't know how wise it would be to ship that way.

Nothing will interfere with the stock lid hold down bolts and I am forbidden from drilling any holes in the manifold.

simpson36

Some progress.

Right now I am just making the mock ups into real parts.

This is the adapter plate to mount the TBs. Linkage arm extends below the base, so I had to make a clearance cut. Typical of the little surprises you get.




Next up make real versions of fuel system pieces 'Y' bloc and rail:




With a few more of these pieces, I can start the final assembly . . that's a fun part of the project.

simpson36

Progess on the setup has progressed.

Here are the last couple of parts that I fabbed to mount the 'Y' block, fuel rail, and throttle cable bracket:



Goes together like this:





And the completed assembly looks like this.
Both the supply and retun lines were moved down significantly. I've been thru the wrench clearance checks and stuff like that.
The system is maintainable and even the IAC motor can be changed out now without pulling the fuel system apart.
Clearance issues with the valve cover and throttle cable have been resolved.




There are a few minor details to address. I am going to make a more robust fuel rail mount as I'm not satisfied with the one pictured.

I have to do a final mount of the TBs and then balance them. Next build up the injector pods and pressure test the whole system.

Then the whole assembly gets shipped to its owner who will be doing the install and air cleaner. That should be interesting to watch also!

Ronny

iTrader: (1)

Stock air cleaner assembly?
You added a mounting plate (TB to Offy top plate).

Clearance to hood?

simpson36

I looked at spacing the TBs so that an original crossfire air cleaner could be used, but that moved the huge MOATB throttle plates off the carb hole in the top plate, so no stock air cleaners for this setup.

As to what will be used, I can't say as I am not doing the air cleaner for this project. My part is what you see here; the UltraMod TBs, linkage and fuel system. The setup is going on an '84 Vette, and I don't have one of those to measure anything.

I did get manifold measurments from the owner, so I could probably figure out the clearance for an '82, but my Vette (my wife's actually) is a stock CE so no way it's ever going to have a setup like this Offy . . .

Ronny

iTrader: (1)

I would suggest a Holley(?) AC set up called Hi-Tech. $$$$$$ ultra low profile. Super Steve used one(82). Or do the dual carb bonnet like I am doing. That might look trick too!

Saber

iTrader: (2)

I cant wait to see a finished product on the car, my roommate has an 84 vette and all i hear is how he loves the crossfire but hates how he cant do anything to it, needless to say ill be showing him this thread.

simpson36

Direct your room mate here for crossfire info:

http://thecubestudio.com/CrossfireTechSeriesIndex.htm

simpson36

OK here is the final assembly photos. Sorry it took so long.
Owner requested the whole fuel system be moved down and sent this sketch:

So, I took a deep breath and asked for a photo showing how much space I had below the rim of the lid and got this back (I added the red line):

The redesign resulted in these parts getting the axe:

Note that the 'Y' block had already been replaced once due to an SFU (Simpson Foul Up) so I just played around blinging up the old one.


----------
So after a fuel system redesign and making the new parts, it was time to start the final assembly. But that lid . . . not purdy enough . . so bling that up a bit:

The thing was rockin' and rollin' all over the place, so I made up some little legs to sit it on and got started by torqueing down the adapter plates. The gaskets had to be re-cut for the huge bore . . note the stock throttle plate for comparison:


Next comes the Mother Of All Throttle Bodies 2.375" 1,100 CFM Ooooh Yeah!


The Injector pods have to be spaced up to restore the proper relationship between the injector cone, the throttle plate and the bore wall. Calculations showed I needed another 1/4" and I don't like stacking that many fiber gaskets together, so I made up aluminum spacers.
The spacers required longer bolts and also machined clearance for the fuel fittings . . . (detailed in earlier posts). Progress at this point:

simpson36

Hanging any weight (or stress) on aluminum tubing in vibration is a definate engineering no-no, so solid mounts have to be provided to keep the hose/braid used for the tie-ins from stressing the tubing. These are the mounts for the return 'Y' block and the supply rail. The throttle/cruise cable bracket is also incorprated into the mounting setup. The stock crossfire bracket has an odd hole in the base because I 'borrowed' it from my 'BIG TB' project to do the design:

Put together the return lines. I've been engineering prototypes for a long time, so I learned very early to make sure things on paper can actually be built . . things like wrench clearance will come back to haunt you if you don't keep that in your brain as a criteria right from the get-go:

And finally the supply side. The original schedule on this project was 6 months to a year, but I only had it for two months. The owner's plans changed and he needed it back way early, so I did not have time to put the injectors in. I actually found genuine GM 90# injectors for this project! A few weeks after this project shipped, I finished developing pressure taps for the pod covers and a new regulator spring which goes from 15.5 to 30 lbs. These developments made it into my next project (bored TBs on an in-line dual quad manifold - see the new thread for that one), but were not ready for this Offy project, so this is how she shipped out:


The unfished plate at the back of the manifold ios the mount for the Trans TV cable bracket. The owner is goung to position the bracket optimally during the install and then trim the plate to match.
----------
Throwing a bunch of harware together is one thing. But making sure it performs as designed is the last step in any good project. I do a lot of work with crossfire throttle bodies and I have a bench setup to balance them on the crossfire lid . . but this ain't no little crossfire . . .


After staring at that for a while, I decided that a couple of machined PVC adapters and some strapping tape made the mods needed to hook up to the big ol' Offy:


Once that setup was running, I could tame the beast. Everyone has their own opinion on this, but MY opinion is that any multi carb setup MUST be balanced properly, so the ability to properly balance MUST be designed in. All of my TB's, even these MOATBs have functional balance ports. It required some delicate micro machining to cut the ports into the sleeves, but let's see if the effort was worthwhile:

6" on the manometer, just like the Dr. (General Motors) ordered, and she's VERY sensitive with a slow and predictable reaction to the idle stop screw.
All of the effort boils down to this last piece of the pie . . must achive balance, grasshopper:

That's a live shot. Even more important than the static balance is the behavior with throttle movement. I've seen plenty of setups that balance out at idle, but as soon as you touch the throttle, they go wildly out of sync . . (the dreaded crossfire stumble).

Maximum deviation on Mr. Offenhauser is less than 1" total from idle to WOT and anywhere in between. Better than I hoped for! Off-idle is steady and tip-in is smooth. Returns to the perfect idle balance every time. That's a wrap! :buhbye:

jwscab

very very very nice. Great machine work there.

A question about the balance ports. Are they ports that tap into the throttle bore above the throttle plates, or is this a slot of some type that straddles the blade? I'm in the process of building a home brew stack injection system and currently have a below-plate port for IAC/vaccum block, but no balance ports at this point. trying to figure out if I need them or if i can trim the blades using the peice of paper trick.

incidentally, I also have an offy sitting on my shelf here with twin tbi's all plumbed up with no place to go. I'll post some pics if you want, but I don't want to hijack this thread....very similar except I'm using the dual blade tbi's and 4 55lb injectors. custom top plate and tbi spacers. I've also got them so that the blades open side to side rather than front to back.

js292

as usual, nice job

simpson36

js292:

Thanks bud. Long time no speaky.


jwscab;

Anything you punch into the bore below the plate will see vacuum which will not work for balancing.

A balance port reads FLOW and if placed properly will not be effected by vacuum so you can still balance no matter what cam you have. You need the balance SLOT to be right at . . in fact straddling the edge of the throttle plate. When the plate just starts to open, the airflow past the slot creates a very tiny vac signal which is what the manometer is showing.

I am very aware of the 'slip of paper' method, but there is just no way that can compare to the sensitivity of a manometer. If paper is your only choice, then that's better then nothing, but a turn of one flat on the screw head of the fine thread crossfire balance screw is easily detectable by the manometer. Same with motorcyles I used to tune in my younger days. Calculate the amount of throttle paper thickness that translates to and you get the point.

Tuning multi carbs with a slip of paper is similar to setting timing by 'sound'. Some people swear hey can tell the difference between 4" and 6" with paper and between 4 degrees and 6 degrees by listening, but I prefer to rely on a manometer and a timing light.

I'd love to see pics of your Offy with the interestng TB arrangement. I'm doing ANOTHER Offy with MAOTB as soon as I get done my other projects (oh yeah, and I have a REAL job also). I just shipped out a classic dual quad manifold with a pair of UltraMOD TBs on it . . way fun! I'm doing a thread on that when I get time. I also did 'BIG TB' which is a flat aluminum lid for the crossfire with a 454 TB mounted in the middle. TB's are pretty simple really, and fun to mess with. They go anywhere a carb goes and don't have all of the carb problems.

Ronny

iTrader: (1)

My buddy ran 4 Weber carbs on a Chev 350 engine. I have to ask him how he balanced those! seems like a Nightmare. I bet he used the Uni synch device with the tumbling ***** in a tube. I used that for my Mikuni triple carbed sleds.

js292

Saw you inlines on the other site, those turned out nice too.

About ready to start up the 85 so I'll be over here a little more often working on my tuning gremlins

jwscab

cool, thanks for the info on the balance slot, I figured it straddled the blade. I can see how accurate that has to be, cross-section-wise in order to work properly. Since 4 blades at a time are tied together in my stack setup, I think I will be OK if I focus on balancing the left and right bank. I'll post some pics when I get a chance, and of the offy as well. I can easily trim all 4 butterflys by hand so that there is no light shining through the bore. I'll start there.

jwscab

found the pics. the fuel lines weren't perfect, but everything is removeable, etc without taking the lines apart. everything is still pretty much rough machined too, so it's not 'pretty' yet.

simpson36

OK, that's very cool!

The EBL setup can run 4 injectors, so your creature could actually come to life.

. . . "It's Alive, . . it's ALIVE . . . !!!"

Creative linkage setup.

There was a guy on some forum that actually took two throttle bodies . . cut them and made a single 4bbl TB out of them! Been a while back, and I don't recall which forum, but I thought it was a way cool project . . if a touch impractical.

Gotta love the crazy stuff!

jwscab

yep, EBL is the plan eventually....the whole assembly was fun to build, especially since I made the drawings, and had my dad fab up the parts. Sometimes it's tough get the ideas across to the machinist but it came out well.

the fuel lines were fun to bend also...a combination of 3 different benders and some creative vise work....

I saw that post with the 2 throttle bodies, looked interesting. Looking forward to checking out that dual quad setup info. was that an offy dual quad manifold?

simpson36

The 'Dually thread is started here:

https://www.thirdgen.org/forums/tbi/...tbis-dual.html

But I haven't had time to flesh it out.


The manifold is a Wieand (sp) single plane from the 1960's. 'Dually' as I call her is a one-of-a-kind becuase of that manifold.

I'm going to build more of the Offy setups, but if I ever do another in-line Dually, it will be with a currently available manifold.

Interestingly, with the Offy, the mounting the TBs and making the linkage was cake and the fuel system was very complicated (hence the full mock up). With the in-line, the TBs were 90% of the job. The rear TB even has an entirely new shaft and arm. The fuel system on the in-line project was simple enough that I just built it with no mock up.

KITT1983

iTrader: (3)

Do you still makes these?

82tarecaro

iTrader: (4)

I sent him an email once. He told me he is done for now. Maybe one day he will get the itch to get back into it.