454 Throttle Body

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DTrain

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I have a 3500 pickup I’m pulling the old tired 350 out of and dropping in a 454 in it’s place. Other then headers and an EGR delete, the big block is a stock unit.

I currently do not have a throttle body. That and a tune are the last things on the list to order.

So I’m wondering about the route to go...

-I’ve read I could run the one from my 350, but my guess is it’s probably small.

-I can order a new stock throttle body that’s proper for my big block.

-Or the last option I’ve been contending with is a bigger, aftermarket unit, probably a BBK, which is 80mm vs the 75mm stock. I just wasn’t sure if this was worth it for a stock motor.

Thanks ahead of time for the input.

D
 

PlayingWithTBI

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Probably stick with the stock TB unless you're going to build it up more.
 

Supercharged111

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You're talking Vortec? Throttle bodies are the same diameter, but the 350 has a lip that the 454 does not. The throttle arms are also different. They pull from different directions and 350 has linear linkage vs progressive on the 454.
 

DTrain

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Yeah, I’m talking about a Vortec. I kinda figured a new stock replacement would be the ticket being a stock motor.
 

L31MaxExpress

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The 454 throttle body uses a different throttle cam since the cable pulls from the opposite direction of a 350. A DBC LS throttle body should be a good substitute if you cannot find the 454 one.

The 454 throttle bodies are slightly larger bore than the 4.3-350 ones. When you bolt a 454 TB to a small block plenum you can see the mismatch. From what I remember the butterfly is the same diameter as the small block throttle body tapers down to a smaller opening and the 454 TB is the size of the butterfly all the way through. When I ran the 454 TB on my 350, I swapped the throttle shafts, JB welded the gasket groove in the plenum, opened the plenum up to match the 454 TB bore and also had to remove the orange sealing ring in the TB bonnet. I also had to rebuild the throttle cable bracket. It was a big PITA!

The 454 also has a PCV vent port in the intake and the throttle body is machined for the opening. Without that port your 454s crankcase will not have a place to vent blowby gases at heavy throttle.


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DTrain

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I’m quickly realizing that the throttle body on my 350 currently, even though the lip has been shaved, is not the winner for my new big block.

I think I already knew that the bigger throttle body may have been a bit much. I guess I wanted to hear someone say it’ll be this magical bolt on unit that I should absolutely buy no question. But at the end of the day if it’s too much and not the winner, oh well.

I was leaning strongly to the proper stock piece. I just finished up installing new Bosch injectors and new Delco fuel rail and pressure regulator. So I think having the fuel system totally fresh and the Gibson headers to help digest, the stock TB will probably shine pretty good.
 

Supercharged111

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Stock sucks at part throttle. Good enough for WOT, but lethargic part throttle. I went with an 85mm and it was a step in the right direction for sure.

I realize to those of you who don't tune, I'm probably speaking Chinese so here's a comparison of a log I took that plots RPM against throttle position and spits out a MAP value. Very useful for determining downshift points. As you can see, the 454 needs a lot more throttle angle to produce the same MAP as the 1500. This is the 1500 before the supercharger.

350:

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454:

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Click the attachments, I don't know how to make them show up as a quote.

350 on top, 454 on bottom.

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I went with an 85mm throttle body. It includes linear and progressive arms. I went with the linear arm.

https://www.summitracing.com/parts/sum-227726
 
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DTrain

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I went ahead and ordered a new stock unit. I’ll report here in a couple weeks when I’m done with the swap how it feels.
 

BNielsen

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Stock sucks at part throttle. Good enough for WOT, but lethargic part throttle. I went with an 85mm and it was a step in the right direction for sure.



Click the attachments, I don't know how to make them show up as a quote.

350 on top, 454 on bottom.

You must be registered for see images attach


I went with an 85mm throttle body. It includes linear and progressive arms. I went with the linear arm.

https://www.summitracing.com/parts/sum-227726

Any clue as to where I could find this somewhere else? Summit says it's not available;
 
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