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FSB Pimpster & Recruiter
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5,708 Posts
Discussion Starter #1
Hi all, is anything needed to be upgraded when going from a stock throttle body to a 61MM one? I do have a '95 with MAF

Thanks in advance,
Allcruisen :imp :usa
 

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Super Moderator
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there is one mod to a set screw or something that is weird on the BBK. I dont remember exactly but its a simple fix. Check SeattleFSB build thread. I know he has one and it may be in his writeup. I just cant remember where I saw it. Other than that, you can port match the intake to the TB to make it flow smoother. Intake tubes might need a silicon adapter if they are bigger.
 

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FSM Lifetime
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674 Posts
What are the performance results from a swap like this? I've looked into them but they didn't seem to be worth the cash. I'd be running it with the Edelbrock truck intake.
 

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Premium Member
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3,988 Posts
The stock Bronco Throttle Body is 51mm.

The BBK #3501 is a 56mm Throttle Body. If you go aftermarket, this is what you want.

The BBK #3503 is a 61mm Throttle Body for high RPM performance applications and 460 engines. It also requires port matching the intake manifold and a tune correction prior to installation. This tends to be a big mistake for many stock or mild build engines.

When I originally installed the BBK 56mm on my stock 5.8L, I did not have mod or adjust anything. It was ready to run. After I installed it on my newly built 408, I had to adjust the minimum airflow. I do have a BBK 61mm and will install it when I can port match the intake and retune the EEC.

I did notice a significant improvement over my original worn Throttle Body.
 

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Ford Hoarder
78 & 92
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I have the 56 on my Built 351 and it does just fine, as Seattle mentioned the big one is for bigger engines or to support higher rpm operation, or both. If you do the math on the area the 56 twin is a fairly large size if you multiple it by 2.
Some BBK's have an issue where the throttle shaft that is pressed into the throttle body comes out. I fixed mine as it started to get loose after some miles. What I did was drill a hole and add a setscrew to the throttle body where that shaft goes in at. I then ground a small flat only where the head of that set screw contacts the shaft. Re-installed with Loctite on everything, no problems since. Effectively the shaft would have to pull past the set screw for it to come out now. It is the small setscrew in this pic, I think I used a 10mm but only as I also have r/c cars and happen to have the drill, tap, and set screws handy.
 

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is gas mileage impacted by this? i know some mods can increase efficiency and power with a net gas mileage increase or at least break even.
 

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FSB Pimpster & Recruiter
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Discussion Starter #8
Thanks guys, It was a 61MM and the guy just sold it from under me. Things happen for a reason, I guess it would have been to big for my application any ways...

Allcruisen :imp :usa
 
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