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4.9 swap in a 88 Fiero
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Discussion Starter #1
I read somewhere that a Throttle Body Spacer might help a little bit on performance, and because I need to raise the TB a little bit, I am on the market to find a spacer.

I am doing a swap out of a 93 DeVille to a 88 Fiero.

I can not find any spacer specificaly made for the 4.9 TB, so I am wondering which other GM throttle body base plate I can compare with. On picture, TBI for 305/350 SBC looks alike. May I used a TB spacer for those on my 4.9?
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
The small block Chevy should work, same bolt spacing. But I dont think it will help. These spacers were used on the old 2 injectors in the throttle body systems used on 4.5 Cads, 4.1 Cads and Chevy trucks. Spacing the 2 injectors higher supposedly atomized the fuel better?? The 4.9 is port injected correct? 8 injectors, not 2.
 

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4.9 swap in a 88 Fiero
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5 Posts
Discussion Starter #3
You are probably right but, as on my Dodge Dakota,the throttle body spacer certainly fool the mass air flow. Anyways I need something to raise the air hat so why not at TB spacer?
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
Keep in mind this is a speed density injector system, not a mass air flow system. It already knows the designed air into the engine. So besides raising everything, it will not give more power nor torque.
 

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'85 Fleetwood FWD
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728 Posts
If the spacer has the correct bore diameter it shouldn't restrict flow. There are some that have swirl designs in the bores to atomize fuel better. Summit Racing has them. It's called swirl-torque. Made for GM engines/wTBI If your gonna buy a spacer anyway, might as well try one that could help a bit.
And if you do, report back here and tell us if it improved anything. People tend to be nay-sayers even if they haven't tried the parts in question.
Cadillacs can use all the help they can get with these engines.
 

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'87 Coupe DeVille 4.1L FWD(New engine '08) 1981 F100 '03FXDL
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879 Posts
I agree with steelybill. Check it out and let us know how it does. I've also considered a spacer, but hadn't found one correct for my application.
 

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4.9 swap in a 88 Fiero
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Discussion Starter #8
My 4.9 is for a project car, an 88 Pontiac Fiero, so I never drove the car with that engine in. I will then not be able to compare before and after.

 
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