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Deputy Director Region 6
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Discussion Starter #1
My mechanic buddy told me if I wanted to wake up the 4.3L ! Is to put a early 90's throttle body from a truck 350 !
It looks stock & bolts right up ! He said he grinds just a little off the intake for better flow !
He doesn't know exactly what years to look for !
Any of you guy's know what year(s) throttle body to look for? Or Have a part/model # ?

Thanks !:beer:
 

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Chevy Silverado and Suburbans, I think from 85-92ish had throttle bodies. I have an 88 Suburban and it is throttle body(350 cid and 700r4, don't know if this helps or not). I have been thinking about putting in on my Elky to see how my mpg will be effected.
 

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Check online with Holley, pretty sure they have a larger upgrade for a 4.3 tbi. Also Howell efi deals with parts for swapping this kind of stuff.
 

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The only upgrade that will get you is larger injectors. Unless you're running lean at WOT you really wont notice any power improvements. Its my understanding that all the GM TBI units have the same connectors and just different size injectors. I know the F body guys use the 454 truck unit to hot rod the 350. You can also boost fuel pressure to gain more flow from your stock unit. But that requires an adjustable regulator.
 

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Deputy Director Region 6
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Discussion Starter #5
The only upgrade that will get you is larger injectors. Unless you're running lean at WOT you really wont notice any power improvements. Its my understanding that all the GM TBI units have the same connectors and just different size injectors. I know the F body guys use the 454 truck unit to hot rod the 350. You can also boost fuel pressure to gain more flow from your stock unit. But that requires an adjustable regulator.
I think he told me it's a bigger throttle body !
 

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I may be wrong but I believe they are all physically the same size. The only difference is the injector flow rating in pounds per hour.
 

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Discussion Starter #7
I may be wrong but I believe they are all physically the same size. The only difference is the injector flow rating in pounds per hour.
He said he had to gring the intake a little for better flow & clearance of the plates opening ?
 

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They do have different diameter bores for tbi setups. I don't remember what they are but you can google them. I think stock is around 40 mm on up to the 454 setup which is around 64 mm. I hope I am at least close, it's been awhile since I researched this topic.
 

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Deputy Director Region 6
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Discussion Starter #9
I thought they had different sizes !
Does anybody know the size of the 1987 4.3L throttle body (__MM) & they size of the early 90's truck 350's throttle body (__MM) ?
Thanks ! :beer:
 

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Deputy Director Region 6
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Discussion Starter #11
http://www.holley.com/502-7.asp 2" throttle body, larger injectors, listed for later model truck, may still work for you.
Joe
I'm not looking to buy a new one ! I'm going to try to find a used one ! I try to go to the upullits around here weekly ! That's why I'm trying to find a number or something to ID the bigger one !

Thanks !
 

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I was wrong. The 350 and 454 have bigger bores. I remember a guy in town had to bore his manifold out to run the 454 TB. I have one off an 87 350 Suburban if you want it. Ran when it was pulled a couple years ago. I have no use for it.
 

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Discussion Starter #13
I was wrong. The 350 and 454 have bigger bores. I remember a guy in town had to bore his manifold out to run the 454 TB. I have one off an 87 350 Suburban if you want it. Ran when it was pulled a couple years ago. I have no use for it.
PM sent !
 

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Just wanted to show you what the aftermarket listed as a 4.3 upgrade. You never know, you may stumble across one.:dontknow:
I understand budget, I just started building my own Bugcatcher style air intake with 4 butterflys from scrap billet & sheet aluminum. I'm even going to build my own ls1 aluminum cross ram dual plenum intake manifold.
 

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Deputy Director Region 6
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Discussion Starter #15
Just wanted to show you what the aftermarket listed as a 4.3 upgrade. You never know, you may stumble across one.:dontknow:
I understand budget, I just started building my own Bugcatcher style air intake with 4 butterflys from scrap billet & sheet aluminum. I'm even going to build my own ls1 aluminum cross ram dual plenum intake manifold.

That sounds awesome & A fun project Joe !! :beer:
Are you coming to the Gainesville get-together ?
 

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I converted my 350 to TBI about 6 years ago. I used an F-body TBI unit, but needed the truck/caprice injectors to feed it properly. I think my unit came off a 305 originally. 350 injectors would be an upgrade from the 4.3 units. I used an Astro Van Computer, painless harness, the sensors and chips recommended by painless, and it works great. The intake eventually came from a suburban. I tried adapting but it didn't work. You can get truck 454 throttle bodies and injectors but I think it would be overkill on your 4.3. My mileage is excellent. When I had the 2.5x rear gears, I got 19.5 mpg with 300 HP at 80 mph on a trip Chicago to Omaha. I changed the gears to 3.23, and the mileage tanked (with the 350C trans). I have a road trip coming up, and I have a 200-4R in it now. The mileage is better than ever in town, and I am sure on the highway it may go over 20. Worth the effort. It cost me around $700 to convert from a carb at the time. See This page:
JC
 
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