TBI Adapter Plate Finally Finished

[Chris in Idaho]

After some test fitting and revising it fits. This mounts on top of the stock carb insulator. More info at TBI Adapter Plates.

Top:

Bottom:

Prototype on F engine:

 

[Downey]

Nice machine work dude. I'm slightly confused, my guess is you are using GM throttle body on an F engine intake manifold. That manifold puts the throttle body closer to the valve cover than the 2F manifold, consequently the throttle body would end up inside your valve cover???? That is why our adapter turns the throttle body 90 degrees. Gosh dude, what do you know that we don't know???

 

[Chris in Idaho]

Thanks for the compliment on the machine work! I wouldn't say I know something you don't, but it does work. The 1F powered cruiser in the picture is up and running with this setup. The throttle body is not inside the valve cover, but the connector on the IAC solenoid is pretty tight to the valve cover so I'll probably add a little bit of offset to the adapter plates to make it easier to get on. When I get that done, I'll post a pic of the new plate.

 

[CruisinGA]

Slick!

Is that a 4.3L throttle body?

Have you test fit with a 2F aluminum valvecover? (Maybe the dimensions are different?).

 

[Chris in Idaho]

Thanks,
Yes, it's a 4.3L throttle body. No, I haven't had a chance to test fit with a 2F yet, but as I understand it the 2F should have more clearance since the intake manifold sticks out further from the head.

 

[CruisinGA]

Are you using a GM computer, or aftermarket?

 

[Chris in Idaho]

Are you using a GM computer, or aftermarket?

I'll ask for you, it's actually my customer's cruiser in the pic.

 

[CruisinGA]

Thanks!

 

[lcwizard]

Are you going to market these. Is so I've got a bunch of TBI to 2F air cleaner adapters I'll make a killer deal on.

 

[FJ40Jim]

That manifold puts the throttle body closer to the valve cover than the 2F manifold, consequently the throttle body would end up inside your valve cover? That is why our adapter turns the throttle body 90 degrees.

Jim,
Do you mean "Turns it 180 degrees"? I haven't seen a downey adapter for a while, but if the TB was clocked 90 from the pictured unit, the throttles would be running longitudinal, while the intake manifold plenum is longer in the transverse axis.

Just wondering how that would work...

 

[Chris in Idaho]

I'm planning to sell them on ebay and through my website TBI Adapter Plates. If you're interested in selling your air cleaner adapters I can include your info with the plates.

 

[cruiserbrett]

Jim,
Do you mean "Turns it 180 degrees"? I haven't seen a downey adapter for a while, but if the TB was clocked 90 from the pictured unit, the throttles would be running longitudinal, while the intake manifold plenum is longer in the transverse axis.

Just wondering how that would work...

check trollhole's BG2F thread.

 

[Trollhole]

After some test fitting and revising it fits. This mounts on top of the stock carb insulator. More info at TBI Adapter Plates.


Prototype on F engine:

I like the concept. I like how the fuel lines go out the back. Would make routing them easier. Also makes fewer bends for the throttle cable.

Comments.

1. IAC is to close to valve cover (looks like you have a fix for it) Would make taking it out or getting the connector off a real pain.
2. The MAP port goes to the fitting between the two fuel lines. Makes for a cleaner look.
3. If you could make it thicker and take away the need for the carb insulator that would be a better product.
4. Carb insulator needs to have the inside ridge closest to the valve cover ground away.
5. Would be nice to have the plate extend under the throttle linkage to have a mounting surface for the throttle cable if they wanted to go that route.
6. Remove the area around the manifold bolts where they mount to the head. Would allow for easy tightening without removing the adapter.

Nice machine work dude. I'm slightly confused, my guess is you are using GM throttle body on an F engine intake manifold. That manifold puts the throttle body closer to the valve cover than the 2F manifold, consequently the throttle body would end up inside your valve cover???? That is why our adapter turns the throttle body 90 degrees. Gosh dude, what do you know that we don't know???

While Jim I do agree you adapter had some good thought that went into it the machine work to finish it is horrible. At least on the two I have seen so far. Whoever is drilling the 4 holes for the bottom mount is way off. Without grinding the adapter there is no way you can get the bolts tight without them eating into the adapter. Also top side of the adapter has poor machining where the air flows in. Also get rid of the plate that has to go on top and have it be part cast. Having to have another gasket is a pain in the ass. You have to have the plate because without it the adapter will have some serious leaks. Probably be cheaper to eliminate the plate and incorporate it into the adapter anyway.

2 extra min making sure the 4 holes are drilled correctly as well as cleaning up the top side would fix 90% of the problems with your adapter. Even so it's a nice adapter.

Thanks,
Yes, it's a 4.3L throttle body. No, I haven't had a chance to test fit with a 2F yet, but as I understand it the 2F should have more clearance since the intake manifold sticks out further from the head.

Maybe but still not going to be enough to make it work well. If you really want to machine something that will sell and you will be the only one making one. Make an adapter for a turbo. Pretty sure Mace would be willing to help.

Jim,
Do you mean "Turns it 180 degrees"? I haven't seen a Downey adapter for a while, but if the TB was clocked 90 from the pictured unit, the throttles would be running longitudinal, while the intake manifold plenum is longer in the transverse axis.

Just wondering how that would work...

Works just fine. It's tall enough to where it's got plenty of room. I just wish it was finished better. You can see where the bottom bolt holes are off and where I had to grind it to make the bolts fit.

I'm planning to sell them on ebay and through my website TBI Adapter Plates. If you're interested in selling your air cleaner adapters I can include your info with the plates.

 

[Downey]

Jim,
Do you mean "Turns it 180 degrees"? I haven't seen a downey adapter for a while, but if the TB was clocked 90 from the pictured unit, the throttles would be running longitudinal, while the intake manifold plenum is longer in the transverse axis.

Just wondering how that would work...

Regarding the top machining, I agree that a billet adapter will be smoother than a fly-cut adapter, but the gasket will seal either way. Regarding the bottom allen head mounting screws, not much we can do about that clearance issue except give allen head mounting screws since their head O.D. is small. We did (past tense) have some mis-machined adapters that we reworked, I was not proud of them, but other than appearance, they did get the job done.
Some adapter features:
(a) Yes we run the throttle body at 90 degrees (longitudinal) since we had clearance issues otherwise!!
(b) The 90 degree twist gives us a taller adapter, which gives us a larger open throat plenum chamber, which gives us higher performance than a shorter adapter.
(c) The laser cut base plate acts as a block-off plate AND throttle linkage (cable) mount. The casting that eliminates the laser cut cost twice as much as the laser cut. Our design choice was merely based on simplicity and cost.

 

[Trollhole]

After some test fitting and revising it fits. This mounts on top of the stock carb insulator. More info at TBI Adapter Plates.

Top:

Bottom:

Prototype on F engine:

Nice machine work dude. I'm slightly confused, my guess is you are using GM throttle body on an F engine intake manifold. That manifold puts the throttle body closer to the valve cover than the 2F manifold, consequently the throttle body would end up inside your valve cover???? That is why our adapter turns the throttle body 90 degrees. Gosh dude, what do you know that we don't know???

Thanks,
Yes, it's a 4.3L throttle body. No, I haven't had a chance to test fit with a 2F yet, but as I understand it the 2F should have more clearance since the intake manifold sticks out further from the head.

Jim,
Do you mean "Turns it 180 degrees"? I haven't seen a downey adapter for a while, but if the TB was clocked 90 from the pictured unit, the throttles would be running longitudinal, while the intake manifold plenum is longer in the transverse axis.

Just wondering how that would work...

I'm planning to sell them on ebay and through my website TBI Adapter Plates. If you're interested in selling your air cleaner adapters I can include your info with the plates.

Regarding the top machining, I agree that a billet adapter will be smoother than a fly-cut adapter, but the gasket will seal either way. Regarding the bottom allen head mounting screws, not much we can do about that clearance issue except give allen head mounting screws since their head O.D. is small. We did (past tense) have some mis-machined adapters that we reworked, I was not proud of them, but other than appearance, they did get the job done.
Some adapter features:
(a) Yes we run the throttle body at 90 degrees (longitudinal) since we had clearance issues otherwise!!
(b) The 90 degree twist gives us a taller adapter, which gives us a larger open throat plenum chamber, which gives us higher performance than a shorter adapter.
(c) The laser cut base plate acts as a block-off plate AND throttle linkage (cable) mount. The casting that eliminates the laser cut cost twice as much as the laser cut. Our design choice was merely based on simplicity and cost.

Good stuff. Thanks Jim. As always honest.

 

[Chris in Idaho]

Trollhole:
Thanks for the good suggestions!

Here's what I have as of now, and it should be test fit soon.
I moved the whole plate over until the right hand throttle body bolt lined up with the intake manifold/carb bolt. That gave me .350" offset which isn't much but should take the strain off of the connector/wires (everything already fit with the centered one, this just makes it a little more comfortable).

Remember, this offset is only needed for 1F's, 2F's can use the centered version.

Now the pics:

Sorry I didn't have time for a nicer mockup, the black bolt on the right is metric and goes all the way through to the intake manifold.

 

[FJ40Jim]

That looks good. If I was installing it on an engine, I would spend a few minutes w/ a grinder, matching up the adapter to the insulator, and knocking off most of the idle turbulator step in the insulator (as mentioned by Troll).

Retaining the stock phenolic insulator has the advantages of reducing temps when operating, and reducing heat soak temps. Both are good things on a low pressure EFI system.

With the added offset, that will fit easily on a 2F manifold, and w/ even more clearance on the low profile 81-87 valvecovers. Your original design will work fine on the 81-87 engines. The 2F manifold moves the carb 15mm further from the head, which is even greater than the offset gained by rearranging the bolt pattern as above.

One potential drawback W/ the second design is it may direct flow into the #3-4 runner. The problem w/ an F series w/ a wet manifold is the center two cylinders get too much fuel, while the front 1&2 & back 5&6 are lean. But the stock phenolic could act as a flow straightener to get the airflow from the outer barrel going straight down into the plenum.

Try it and see. If the distribution is a problem, the O2 sensor(s) will tell the story.

 

[Downey]

What Jim C said, plus if you open up the space between the two separate ports in your adapter, you will be increasing plemun chamber area, which in turn will improve even distribution. Then if you really want to get slick (and increase the price) you could use a thicker piece of billet, taller adapter, bigger plenum, increased h.p., the works!!!!!

 

[Trollhole]

After some test fitting and revising it fits. This mounts on top of the stock carb insulator. More info at TBI Adapter Plates.

Top:

Bottom:

Prototype on F engine:

Nice machine work dude. I'm slightly confused, my guess is you are using GM throttle body on an F engine intake manifold. That manifold puts the throttle body closer to the valve cover than the 2F manifold, consequently the throttle body would end up inside your valve cover???? That is why our adapter turns the throttle body 90 degrees. Gosh dude, what do you know that we don't know???

Thanks,
Yes, it's a 4.3L throttle body. No, I haven't had a chance to test fit with a 2F yet, but as I understand it the 2F should have more clearance since the intake manifold sticks out further from the head.

Jim,
Do you mean "Turns it 180 degrees"? I haven't seen a downey adapter for a while, but if the TB was clocked 90 from the pictured unit, the throttles would be running longitudinal, while the intake manifold plenum is longer in the transverse axis.

Just wondering how that would work...

I'm planning to sell them on ebay and through my website TBI Adapter Plates. If you're interested in selling your air cleaner adapters I can include your info with the plates.

That looks good. If I was installing it on an engine, I would spend a few minutes w/ a grinder, matching up the adapter to the insulator, and knocking off most of the idle turbulator step in the insulator (as mentioned by Troll).

Retaining the stock phenolic insulator has the advantages of reducing temps when operating, and reducing heat soak temps. Both are good things on a low pressure EFI system.

With the added offset, that will fit easily on a 2F manifold, and w/ even more clearance on the low profile 81-87 valvecovers. Your original design will work fine on the 81-87 engines. The 2F manifold moves the carb 15mm further from the head, which is even greater than the offset gained by rearranging the bolt pattern as above.

One potential drawback W/ the second design is it may direct flow into the #3-4 runner. The problem w/ an F series w/ a wet manifold is the center two cylinders get too much fuel, while the front 1&2 & back 5&6 are lean. But the stock phenolic could act as a flow straightener to get the airflow from the outer barrel going straight down into the plenum.

Try it and see. If the distribution is a problem, the O2 sensor(s) will tell the story.

What Jim C said, plus if you open up the space between the two separate ports in your adapter, you will be increasing plemun chamber area, which in turn will improve even distribution. Then if you really want to get slick (and increase the price) you could use a thicker piece of billet, taller adapter, bigger plenum, increased h.p., the works!!!!!

Hey you two. Here is a question.

Whould using the old 69?? manifold with the longer runners help in getting more air to the motor?

 

[YotaJosh]

Great job!

Now, how about a plate for the 20R/22R 4 cylinders? Not everyone wants to perform a 22RE swap, and I'd really like to build a 20/22R hybrid and use GM TBI injection.