MPI throttle body options

[JeepsAndGuns]

Now that I have my bling MPI intake, I am ready to top it off with a throttle body. There was just no way I was gonna pay almost $500 for the (very nice) edelbrock unit that may have had tps and iac that might not work with the gm system.
So I was looking at my options.
1. remove the injector pod and use my current 454 tb.
I dont really want to do that. I would kinda like to be able to sell it to get back a little money.

2. Use a dodge tb found on every 5.2 and 5.9 magnum engines in trucks, durangos, and jeep grand cherokees. Its made by holley, has a compatable tps and iac, and 1.92 in throttle blades. (only a tiny hair smaller than my 454 tbi's 2in blades)
I picked up one at the pull a part and test fit it. The throttle lever is gonna hit the fuel rail, it would have to have a thick spacer to make it clear. And this intake is already a TALL one. I am afraid I will start running into hood clearance issues real fast if I dont be carefull!

3. Use a large single blade tb, such as the ones on the LSx engines.
Looking at them on ebay, seems the cable operated ones have a tps and a bolt on iac. Any chance these could be compatable with the 7427 pcm? Also anyone know what the bore of a stock one is? I find conflicting info from google. Some says 75mm, some say 78mm. What are their cfm ratings? Whatever I get, I want it to atleast equil the cfm of the twin 2in blade tb I have now. Anyone have any specs?

If I wanted a large single blade tb that equils what my current twin blade one flows, is it as simple as adding the two together (two 2in holes, equil one 4in hole? witch translates to 101.6mm?) Or is there more to it than that?

[EagleMark]

The Big Block throttle body you have would be the easiest with adapter. You could look for a old four barrel holley that had old injectors that are worthless. Pretty sure there's a four barrel throttle body on a grand cherokee. And if you go the big single barrel LS type I have one brand new!

[Six_Shooter]

The LS TB would be compatible. The TPS for sure, and I believe the IAC was a carry over from the older design, so it should be compatible as well.

No, 2 - 2" holes do not = 1 - 4" hole.

You have to look at area. I can't seem to work out the equation right now, but a 4" hole would have almost twice the area of 2-2" holes.

[1project2many]

Jeep used a 4bbl TB??? I never knew.

I used a monoblade TB with a homemade adapter on my 4bbl smallblock Vortec intake.
http://home.metrocast.net/%7Eshannen/efistuff/S10/MarineIntake1.JPG
http://home.metrocast.net/%7Eshannen/efistuff/S10/MarineIntake3.JPG
The TB is from a 350 Vortec engine. The 4bbl intake to TB adapter is made from a piece of 1/2" aluminum plate I picked up from a local scrap metal guy. The TB is bolted to a 1" TB spacer purchased from Ebay. The manifold inlet has 4 smaller holes instead of one large opening so the spacer provides room for the throttle plate to open and also allows the throttle linkage to pivot without hitting the adapter plate. A big block L29 TB wouldn't work because the cable angle is all wrong for my application. Can't say much regarding the LSx TB but the 5.7 TB was a very nice fit.

The area of a circle is pi r squared. r is radius, 1/2 of diameter, so two 50mm TB blades provide 3927mm squared while a single blade 75mm TB provides 4419 square mm of area. This is also true of exhaust... one 3" pipe will provide better flow than two 2.25" pipes. Anyway, there are a few other considerations for TB. When opening throttle plates, the first 20 degrees of throttle angle provides something like a 35% change in airflow. With large monoblade TB's this means a little throttle can make big power changes. The Vortec truck TB uses a progressive linkage under the throttle cable to slow the throttle opening from idle to maybe mid throttle. This is nice if you don't want to light the tires up at every light, and it's great if you're a serious wheeler and need good throttle control at low speed. Also, the IAC tapers are different so you might have to play with a few IAC parameters to get idle speed correction to be a smooth process.

Edit: Accell has a pretty neat (but pricey) 90 deg adapter for TB to 4bbl carb pattern. For the monoblade TB, GM has three different 90 degree intake air elbows which fit the top of the TB. First is from an S10 blazer from 96+. This one is angled to the driver's side of the engine. Second is from a fullsize pickup 96+, it's angled toward the passenger side of the engine. Third is from a 97+ G van with 5.7 which is aimed straight forward.
Here's an aftermarket elbow but you get the idea:
361

[JeepsAndGuns]

Humm. Good info there. A few questions.
So if the single blade tb has a significantly diffrent air flow, would that cause any negative diffrences in what tps % equils what airflow/map reading with what the 7427 might be expecting? Meaning, if I am reading it right, the single blade tb flows more air at a lower tps% than the twin blade tb. Would this make the 7427 go haywire because its expecting less air at that lower tps %? I have never worked on a vortec or LS engine, and they are still too new to be showing up at the local pull a part. Do you have any pictures of this pregressive linkage?
So you saying a 75mm single blade tb gives more surface area/cfm than a twin 2in blade tb? Is 75mm the stock dia of the ls tb?

The other problem I was running into with the twin 2in blade tb, was that its slightly wider than my intake opening. If you look at the picture in my injector thread, you can see the opening and bolt pattern is not the standard square bore. I was gonna have to do some grinding to the sides of the opening to clear the blades. Not much, but about 1/4in or so per side. With it being a open pleninum, I dont think I would have any clearance issues with a single blade tb. I am starting to think it might be the easyest option right now.

What grand cherokee uses a 4bbl tb?? I have never see one, unless its on the new ones?

[cmaje72]

I don't think there was a 4bbl on any of the ZJ's. Same as all the other 5.2 and 5.9's in the dodges. Another option may be the ford 5.0 throttle bodies. They are easy to come by cheap but I am not sure on the IAC and TPS compatibility. I'm going to have to go back and look at my ford tuning info. Its been a few years.

[EagleMark]

What grand cherokee uses a 4bbl tb?? I have never see one, unless its on the new ones?It may have been the Dodge 2 barrel I was thinking of made by Holley... still think... IIRC there's a four barrel somewhere, may be wishful thinking and confused info.

[Six_Shooter]

I have not seen a stock application with a 4 BBL TBI, only aftermarket units.

[JeepsAndGuns]

For the monoblade TB, GM has three different 90 degree intake air elbows which fit the top of the TB. First is from an S10 blazer from 96+. This one is angled to the driver's side of the engine. Second is from a fullsize pickup 96+, it's angled toward the passenger side of the engine. Third is from a 97+ G van with 5.7 which is aimed straight forward.

There was a few of those vortec S10 blazers at the local pull a part. No trucks or tahoes/burbs/etc with the V8's though. So I will probably have to source one on ebay or somewhere like that. Unless eaglemark wants to sell the one he has for cheap :innocent2::laugh:

[JeepsAndGuns]

Ok, my head is hurting from all the conflicting info out on the net.
I have been searching for the past hour on these tb's and finding a lot of diffrent stuff. I am finding stock bore dia everywhere from 71mm up to 78mm. I am finding info that says the 4.3, 5.0, and 5.7 all use the same tb, and others say no. I am finding diffrent looking tb's from the same year and vehicle range.
Is the diffrence one is for vortec engine, the other for ls? Are they diffrent engines? I know verry little about the chevy engines. (I know more about the injection systems than the actual engines themselfs....lol)
Does anyone have a link to, or have any known correct info? 1project, you have one, could you mabey shed some light on this? Just wondering what vehicles/engine have what tb, and what the stock bore dia of those tb's are.

[EagleMark]

All I ever found was same conflicting information. One difference is Drive By Wire and one cable.

I have no use for mine if you want it? Sure it would be not only fair but lower than any new price you can find. IIRC it's 68mm. Looks just like one 1project2many posted but does not have big vacuum line on front/side, but inside has passage way for it.

[1project2many]

The TB in my picture is the Vortec 7.4 / 454 / L29 part which I didn't end up using. If you look at the side view, you can see the progressive or cam shaped throttle linkage. Notice how the general shape of the linkage isn't a circle? This makes the throttle open slower at first then faster later.

The VE and spark tables are based on manifold pressure (MAP), not TPS. So changing the TB size won't matter there. Accelerator Enrichment (same as accelerator pump on a carb) and Power Enrichment (similar to the Power Valve) are both based on TPS and will be affected. But you're using a different manifold and injectors on a non-gm engine so those are going to have to be adjusted anyway.

There is a bunch of conflicting info on these TB's. Gotta love the internet. I used 75mm because that's what I remember the Vortec 5.7 units being from when I built that setup 3-4 years ago. This ad (http://www.ebay.com/itm/Vortec-96-2009-75mm-bored-ported-throttle-body-V6-V8-/150365771341?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item23027f964d) on Ebay says they're 71mm stock and 75 after porting. There's one on the bench at work (we're replacing the 350 in one of the vans) and I'll try to take a measurement tomorrow. The 5.0 / 305 / L30 and 5.7 / 350 / L31 units are the same. The 4.3 is somewhat different. There's an air deflector welded to the bottom of the plate on the V8 TB's which I don't remember seeing on the 4.3 units. AFAIK the throttle blade is the same diameter for all three but there may a differences in the vacuum fittings. The 454 TB is a very different beast and is designed to be mounted vertically, not horizontally. We have a couple of 6 liter LS series engines in buses at work and at least one of them uses a cable, but it's rarely in the shop and with all the vehicles I have down right now there's no way I can take it off the road or spend the time to check the TB size.



The 4bbl Jeep thing... maybe you saw an aftermarket 4bbl TBI conversion with the injectors mounted almost horizontally? There were a couple of kits, I have a TB from one here.

[EagleMark]

The 4bbl Jeep thing... maybe you saw an aftermarket 4bbl TBI conversion with the injectors mounted almost horizontally? There were a couple of kits, I have a TB from one here.Nope, I know what your talking about. It's just a memory I had from reading a EFI conversion somewhere so I may be just mistaken...

[1project2many]

Note to self: Take half recommended dosage tomorrow...
Here at the shop we have all sorts of airborne solvents. Safety rules say these are hazardous, but I know full well they're a benefit. They're the real the reason I'm happy to be at work!

Update on TB sizing. Throttle blade is 80mm. Throttle is... ummm... throttled to 71mm below blade. Intake opening (for anyone looking) is 72mm. So the guys looking to buy a 75mm TB and bolt on power increases will not see any gain.

[JeepsAndGuns]

Update on TB sizing. Throttle blade is 80mm. Throttle is... ummm... throttled to 71mm below blade. Intake opening (for anyone looking) is 72mm. So the guys looking to buy a 75mm TB and bolt on power increases will not see any gain.

So basicly the throttle body/blade is 80mm in dia, then directly under the blade the tb bore tapers/funnels in to 71mm? The stock chevy intake opening is 72mm? That means even if you machine out the taper (to where its straight through) you will be wasteing your time. But on my engine, its wide open under the tb, so boreing it out would help.
The tb on my wranglers 4.0 straight six was like that from the factory. The tb blade and bore was 60mm, and directly below the blade it tapered in to 55mm. I took it off and removed the blade and shaft, and had a shop remove the taper and reinstalled it. The intake opening is 62mm on the intake. So I saw just a hair improvement. I have seen aftermarket tb's up to 65mm, and those require the intake to be opened up.

So the tb you just measured, do you happen to know the exact year/model/aplacation it was from? I may call around to some of the other junkyards in tow before I resort to ebay.

Yopu mention the 4.3 tb. While at the pull a part, I have ran across a few of the 96+ vortec 4.3's. I looked at a few just out of curiosity (thi was before all this research on these tb's) and the ones I looked at, I remember seeing that air deflector on the bottom of the blade. I thought it was kinda odd. If all of them are in fact the same, would the air deflector on the 4.3 units simply be to restrict air so it doesnt flow as much, for the smaller 4.3?

[EagleMark]

Mine measures 75mm at bottom, has small lip before blade 74.5mm but above blade is a lip that is less but can't get to to measure. Looks like some kind of venturi effect for air just above blade.

[Six_Shooter]

The 4.3 Vortec TB does have the added on air diverter/flow reducer/restriction/progressive opening assist/whetever you want to call it piece.

[jameslleary]

I dont know where my post went from yesterday, but you can find 4bbl t bodies on old early mpfi caddys.

[EagleMark]

Nothing has been changed or removed but I will watch for issue, you may have made a mistake in posting with Quick Reply? I did that twice now.

So there is a four barrel TB! :rockon:

[1project2many]

How early for the 4BBL Caddy? Are you talking about the EFI'd 472 / 500 from '76?? I have owned a few Caddy TBs and I have one from a 4100 in the barn. All that I've seen going back to 88 or so are 2bbl. Caddy did a strange thing in GM land and used an external motor that operated the throttle linkage to control idle speed. There was a switch in the motor that would close when the throttle was closed to let the ecm know to resume active idle speed control.

The Vortec 5.0 / 5.7 TB is the same from introduction in 1996 to 2002 when the engine was phased outl Yes, anyone buying a bored L30 / L31 TB without making changes to the manifold is wasting $$. My understanding about the air deflector is that it helps create turbulence which better distributes EGR in the maniflold. I removed it from the TB I used on the intake in the picture. If youve seen a bunch of 4.3 TBs maybe it's easier and cheaper to remove one and take measurements? I could snap some pictures of the V8 TB's I have here for comparison. Also, Im not sure of pricing there but I can probably get a cheap V8 TB here. Those vehicles are old enough the salt has turned most of them into garbage. I'm likely heading to the yard on Thursday to get some parts for my Yota.

Six, thanks for confirming the air deflector on the 4.3 units.

[JeepsAndGuns]

Ok, 1project, the TB you have is a 454 one and has a 80mm blade?, and eaglemark, yours is 75mm and is from what? Guessing 350?
So am I reading the info right, just like the tbi units, the 454 has a larger bore than the 4.3/5.0/5.7 tb?

Also pics would be great!! Most of the pics I see on ebay are not that great.

Oh, one last request. Can anyone provide a rough measurement from the cnter of the tb to the outer part of the throttle linkage? Just wanting to make sure I have clearance for it. Cause the dodge tb is too wide. I have roughly 3.5 in from intake centerline to the rail. I think one of the biggest problems was the dodge linkage hung down below the shaft center.

[EagleMark]

I took pictures already but can't find my camera cable... I don't know what it was off of, it was brand new, trying to figure that out here but still no clear cut answer to what mine measures? I got it for $50 shipped if thats fair? I had it 2 years for the six cylinder 258 jeep motor in my scout but it got sold. Would look better on your project then my wall! :happy:

[1project2many]

Jeepsandguns,

The throttle body in the pictures of my intake is from a 454. That picture is several years old. Ultimately I used a 350 / L31 throttle body with that manifold. I do not believe I still have the 454 TB although it may be in a box of parts in the barn. If I don't have it then I can only guess that I gave it away.

The measurements are from a 350 / 305 throttle body that was on the bench at work this morning. It is not mine. It belongs to the company I work for and was on an intake that was being removed from a junk 350 to be reinstalled on a new engine. That TB is now installed in the van with the new engine. Next week I will have access to another TB as we have another engine to change.

I wouldn't make any guesses about the 454 TB at this point.

[jameslleary]

Im thinking the 79ish models...saw a 4 barrel on a 4 6 8 and some of the others, non multiple displacemement models.
EM...I may have fat fingered something on my orignal post....not the first time. trying to get used to the touch screen on this new I pad.

[JeepsAndGuns]

Ultimately I used a 350 / L31 throttle body with that manifold.

Just out of curiosity, what made you sawp tb's? Too much air flow, or other reasons?

[1project2many]

The throttle linkage doesn't work. The 454 TB is designed to be mounted vertically with the cable pulling from the manifold side. The 350 is designed to be mounted horizontally with the cable pulling from the front.

The 350 TB provides more air than that engine needs. It's a 302 Chevy with LT4 cam. It may top 350 hp but probably not.

[JeepsAndGuns]

Well I was bored this moring while waiting for it to be time to go to work. So I was googleing this illusive 4 barrel caddy tb, just cause I wanted to see what it looked like. (I had no luck, all I could find were 2 barrel units)
But while looking on ebay, I found this:
http://www.ebay.com/itm/Cadillac-Deville-THROTTLE-BODY-00-04-seville-eldorado-/140358189526?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item20ae0001d6
Looks almost identical to the tb style we have been talking about. I remember seeing 2-3 of the 00 and up northstars at the pull a part when I was looking for a dis coilpack. (noticed those didnt have it) Now I dont know what the bore dia of these northstar tb's are, but its worth a trip to drive down there and see, cause tb's are dirt cheap there.
Guess I know what I am doing this weekend. :laugh:

[JeepsAndGuns]

Well made it back from the pull a part. Those 2-3 00 and up northstars disappeared (crushed mabey?) and only one was left. I got to it and the engine was gone (****), I walk about 2-3 cars down and theres the engine setting upside down on the ground in front of another random car. Whatever that was all about...but anyways. I looked at the TB and it had a chip knocked out of it where the intake/air filter hose connects to (****!!) I pull it off anyways so I could measure it. I removed the blade so I could get a accurate measurement. It sits dead on 75mm. The bore of the tb itself is exactly the same all the way through (where its machined that is) No taper above or below the blade. Looks identical to the one in the ebay link in my last post. Because it had the chip I set it on the engine and go looking for other ones. I check out the older northstars. I pulled one of those and measure it, and it measures dead on 73mm, and tapers in just below the blade. They also have a funky bolt on air intake hose. I move on. I get to a vortec 4.3, pull the tb and measure, its the same as the northstar, 73mm and has a taper below the blade, and then also has the deflector riveted to the blade. I actually found a vortec v8 (dont know if it was 5.0 or 5.7) but someone had robbed the heads off it and set the intake in the cab. I pull it and measure. same as the older northstar and 4.3, 73mm and tapers in below the blade. It was identical to the 4.3 tb and had the air deflector thingy on the bottom of the blade, but was only about half the size of the 4.3 one.
A full sweep of the yard nets me no luck on a better caddy unit. So I go back to the chipped one and I think I can fix it with some JB weld and it be fine. They knocked a few bucks off the price because of the chip. Dont guess its too bad for $27. If the JB weld doesnt work, I'm not out much money. Once I get home and start carrying my tools and stuf in, I set it on the bench and then accidently bump it and knock it off. Falls straight on the IAC and busts the plastic part of it the wiring plug goes in, into 1000 peices :mad1::mad1: TPS is still fine though. Looks like I will be going back to get another IAC. May wait a few weeks and they might get another late model caddy in. The IAC and TPS on it and the vortec tb's all look the same, not sure if the iac pintle is any diffrent though.

A little test fitting on my intake and I'm still not gonna have enough clearance to put it on vertical. The throttle cable linkage still hits the fuel rail :mad1:

So, I am holding it and playing with diffrent ways to mount it, what, if any disadvantages would it do to make a 90* elbow to where I could bolt it on facing forward? Actually, when playing with it, if it could be done without it affecting any performance or cause any airflow problems, is there any reason I couldnt put it at a 45* angle to the engine centerline? Meaning have the elbow point the tb forward, but pointing to the drivers side (almost facing the headlight). That would give it clearance for the thermostat housing and oil fill tube, and also point it right at a nice area to mount a air filter.

[JeepsAndGuns]

I did a little looking online and found out (from simply looking at pictures) that this 00 and up (I think to 04?) northstar tb is a mirror image of the LS tb's. With the inlet facing you, the northstar throttle linkage is on the right, where the LS is on the left. Everything else on it is a mirror imige of the LS unit. Only thing I saw diffrent was there are two little vaccume hose tubes on the bottom of the LS units, where the caddy does not have them. The bosses are there, but not drilled.

So does anyone have any opinions on the mounting position I mention in my last post???

[EagleMark]

Since it's MPFI I don't think it would matter if you mounted it flat or built an adapter with elbow. Lot of work to build an adapter with the elbow. Since there's differences in these as far as which way the throttle cable works I would rather start with one that pulls just like a normal carb or TBI that came on the vehicle and keep that mounting position.

Can you make the adapter thicker to raise the throttle body to get clearence needed? I just looked at mine and could whack off the extra throttle cable linkage that would hit adapter plate when at WOT. But it is still front pull, not rear pull. Which was what I wanted for the six cylinder I was going to use it for. But now looking at it if it were on an elbow adapter pointing forward the rear cable pull would work.

[JeepsAndGuns]

It could be spaced up enough to get fuel rail to throttle linkage clearance, but this is already a tall intake and I am very limited on how much height I can have before I hit the hood.
I'm gonna do some more playing around with diffrent ideas I have and see what I can come up with.

[1project2many]

Here's a thought. There are 4bbl throttle bodies available which bolt to a Holley carb pattern. There's a company calt Auto-Nomics which had piles of new old stock TB's left over from an aftermarket EFI system from the '80s and a couple of years ago they were selling them for about $200. For that price you get a TB with no TPS or IAC but those things can be added at the time of purchase. The site's still up but there are no prices so it might be worth it to contact them. Here's a little blurb about their TB's in other applications: http://www.auto-nomics.com/faq-altapps.html

[JeepsAndGuns]

The biggest problem with that, is this intake does not use the standard square bore pattern. The pattern is smaller, and if you look at my intake thread at the pics, you will see the pattern is specific to this intake.
Measured and the pattern is 3 3/4 wide, by 4 7/8 long.

[1project2many]

Well, if you can build an adapter for a 3 bolt TB or an LS series TB then why not for a 4 bolt carb flanged TB? It doesn't have to be very thick. Anyway, I believe the TB has a dual bolt pattern. I'll check mine next trip out to the barn.

[JeepsAndGuns]

I understand what your saying. Yes, it would probably be just as easy to buld a adapter for that style as it would the single blade unit. But I am trying to use as many common junkyard parts as I can. That 4v tb is real nice, but $200 is a far cry from $27 for a junkyard chevy unit.
I'm still playing around with some diffrent mounting and throttle linkage possiabilties with this caddy tb, but have not decided for 100% on running it just yet, I am still open for other options.

[1project2many]

Just thinking about the amount of time that will be involved in making an adapter to mount the TB at 90, or 45, or whatever. You might try getting some aluminum tubing that's bent at 90 degrees and using that for a starting point. Then make a plate to bolt to the manifold. Then weld pipe to plate. Then determine necessary angles and length for TB end of pipe and cut. Then make plate that bolts to TB. Then weld plate to pipe. You do have an aluminum welder, yes? Then put both end plates on belt or large disc sander to get 'em flat. And hopefully that combination won't be taller than the TB mounted flat on the intake with one of the "hats" I mentioned earlier.

But I have to ask, why does the throttle linkage have to be inline with the fuel rail if you mount the TB flat on the intake? If your vehicle uses a cable can you turn the TB and get a different length cable?

[JeepsAndGuns]

That was my main idea about a 90* adapter, was to take and make two plates, one to bolt to intake, then the other to the tb, then weld a pice of pipe between them. Probably something like a mandral bent peice of exhaust pipe. I have a 230v mig welder, but no aluminum wire. I was just gonna use steel because I already have plenty of plate here.

I went out and tried what you said about turning it sideways, and that wont work because of the width of the opening in the intake. Its longer front to back, than it is wide. So it covers up about half or more of the iac passage. A adapter could be built to funnel it into the opening, but again, it would need to be thick and the hood clearance comes back into play.
Another problem that I didnt really think much about till now, it throttle cable hook up. It didnt really dawn on me when I bought it, or while doing this test fitting. The caddy tb, the cabel pulls from the front of the tb. So if mounted straight up, the cable is also going to be pointing straight up. If I point it forward, the cable is gonna be pointing forward, and will have to make a big loop back around to the firewall. That could probably be made to work, if I could find a cable long enough.

So lets talk CFM. Lets put this 75mm caddy tb aganst the 73mm vortec one. Just how many cfm diffrence is there gonna be? Whatever tb I use, I dont want it to be too small, but at the same time, I dont want it to be too big. I would definately remove that air deflector from the blade, but I noticed it was riveted to the blade, and when removed, its gonna leave two holes in the blade.

Eaglemark, you said yours measured with a 75mm blade? The ones I measured were 73. You think yours could have come off a 454 or something? You ever get any pics of it?

[EagleMark]

I had pictures, but now I have a cable to hook camara to computer too!

Measures 74.85MM on bottom.

[JeepsAndGuns]

Thanks for the pics!
Looking at it, and the pics 1project posted in the first page, and also the pic of the vortec one he posted too. It kinda looks like yours is made to mount facing forward with the cable pulling from the backside. Where the vortec ones that face up, pull from the front of the engine. Comparing the pics of yours to the pic of the vortec with the aftermarket elbow on it in the first page of this thread. The throttle lever itself looks the same, but the clocking of it looks diffrent.
I am gonna continue to do some more research.

However, on the other hand, I did play around with my jeep some more. I measured and compared this intake to my current one. (rough eyeball measurements with a tape measure) It appears this intake is the same height of my old intake with a 1in thick adapter on it. So its around 1 inch taller than my current intake. I also measured hood clearance, taking into account the height of this new intake, I am limited to 6.5 inches of height. Thats the height of the adapter plate, throttle body, and air filter, or air filter elbow/adapter. It cant go over 6.5in tall. I also played with the caddy tb and stood it up under the hood in about the area it would be in, if I was to stand it up with a elbow. Hood clearance would be good, and the caddy throttle cable would actually be ok. Length looked ok, and even though it would be facing forward, it would simply loop around and go back to the firewall.
But still exploring other options.

[1project2many]

So lets talk CFM. Lets put this 75mm caddy tb aganst the 73mm vortec one. Just how many cfm diffrence is there gonna be? Whatever tb I use, I dont want it to be too small, but at the same time, I dont want it to be too big.

You're starting to pick at nits. Get something built first, then make changes if you don't like the result. It's a small difference to be letting it stop you.

When I put the marine intake in the Chevelle, I had a monster long cable that came from a mid to late 90's van IIRC.

The air deflectors on the trucks are spot welded in. You can drill the weld out of the deflector without drilling through the plate. I'm surprised that GM used rivets in a TB.

[JeepsAndGuns]

I guess thats just the way I am. I like to try and have all my ducks in a row, and as many possiable problems solved before I start on something. I guess you could call it annal.

Looking at pics online and ebay. It appears marks tb is from a 4.8/5.3/6.0 vortec series engine.

[1project2many]

LOL... I think you're bordering on OCD. :)

I spent a little time with mine worryong about the air deflector. On, off, what's it do, what's it for. After spending about 2 hrs online looking, I decided my time is worth more than that. Like you, the junkyard TB doesn't cost much so if I don't like the results I can try again.

The engine that intake was built for has never been installed. I spent a bunch of time working out a cam choice and ended up buying a factory stock LT4 part used on Ebay. Now I look at my ZZ3 cam and I'm thinking I'm going to install it instead. And I've got to change the timing cover. The engine was going to be used with a 7427 but now it's going to be used with the OBDII Vortec pcm so I'll be installing a late model plastic cover, crank sensor and wheel, and I'll be shortening the balancer. And I'll probably modify an old Mallory distributor instead of a plastic Vortec unit, unless I decide to use a metal Vortec part.

But at least I'm doing something. :)

[JeepsAndGuns]

Ha, well yea, I do actually have some very mild OCD. Not as bad as some, and not as bad as other members of my family. But it is still there. :innocent2:

[JeepsAndGuns]

Here's an aftermarket elbow but you get the idea:
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Bringing this thread back up just to ask one question. Where can you get this elbow? I have been searching online but havent really come up with anything like that one. You dont happen to know who made this one do you?
I looked at a few of the factory ones and didnt care anything for them. One like the one pictured above would be pretty much perfect for me.