Cam on throttle body options

[pippinmader]

Breaking this out as a separate topic. On the topic of throttle bodies - I went from an explorer 65mm to a BBK 70mm, definitely noticed a difference in the off-idle touchiness. The manual trans and good low-end torque definitely make it more noticeable.

It seem that one of those cam style swing/pivont things would be good, but haven't found one that seems right, any suggestions? (also what are those things called?).

I have done the gas peddle modification (cut/weld mounting bracket and arm to change the pivot point).

[crawlin68]

How much did you lengthen your gas pedal rod/arm? When I did this, it completely solved this problem for me. I don't remember exactly, but I think I lengthened mine by 2 to 3 inches.

[Lars]

Pippin, I get the urge to bump the throttle body size, but even on my 408, I'm sticking with a 75mm throttle body on the advice of others who have paved the way, rather than the drag race advice of bumping to a (gasp) 90mm t/b. Are you getting a noticeable/measurable improvement in performance at the high end from the 70mm t/b? My inclination would be to stick with the 65. Also, while I can't verify this from personal experience, all throttle bodies are not created equal. Again on the advice of others, I sprung for an Accufab t/b over a BBK.

[crawlin68]

I concur with Lars about the Accufab TB. I started out with BBK and did not like it at all. I went to the Accufab and never had any issues with it.

[pippinmader]

Here is my modified gas pedal. As I recall it is as modified as I could make it and still use the original bolt holes in the fire wall and keep the manual throttle cable work like stock. It definitely made a big difference at the time. I do wonder if the BBK is the issue, it almost feels like the butterfly valve is sticking when fully closed. I tried moving the stop a little tighter to hold the throttle open a tiny bit, seemed to help for a little bit but not the way I want it.

[crawlin68]

Is it dirty? Have you tried taking it off and giving it a good cleaning with some carb cleaner? It might have some build up in it causing the stickiness?

[Lars]

Here is my modified gas pedal. As I recall it is as modified as I could make it and still use the original bolt holes in the fire wall and keep the manual throttle cable work like stock. It definitely made a big difference at the time. I do wonder if the BBK is the issue, it almost feels like the butterfly valve is sticking when fully closed. I tried moving the stop a little tighter to hold the throttle open a tiny bit, seemed to help for a little bit but not the way I want it.

That pretty well describes the complaints I read about BBK throttle bodies vs Accufab throttle bodies. Sticky butterfly. The Accufab part wasn't that much of a premium over the BBK product. I'm a long ways from starting my 408 so I can't comment but hopefully I won't have the issue either.

[pippinmader]

I probably should have kept the 65 mm Explorer one. The OEM parts are hard to beat in the end. I traded the BBK for the Explorer one because it is larger and cooler - too bad it isn't better.

[Lars]

Updating this..

Now that I've gotten some experience with my 408 and Accufab 75mm throttle body, I can report that I'm extremely pleased.

Even with my gas pedal mods my previous engine was a bit touchy off idle. That was a stock Explorer intake, throttle body and MAF but obviously with cone filter and throttle body bolted directly to the upper intake (no elbow).

The 408 has a nasty cam lope at idle, and I expected some touchiness. There is none. I'm amazed at how drivable it is, both tip-in and small throttle openings at low speed. Without parts swapping it's hard to know why exactly, but I'm guessing the throttle body has something to do with it.

For what it's worth the current setup is cone filter again, 90mm LMAF, a slightly contorted intake tract for hood clearance, above-described throttle body, then Trick Flow R intake with 90mm inlet.

[pippinmader]

Thanks Lars! So I lookup up Accufab throttle bodies, WOW are they expensive! I guess you get what you pay for... I am hoping I can pay for some lubrication on the bearing/bushing.

BBK's website talks a little about sticking TB in their FAQ section. Basically they say it is not mechanical, rather it is the engine vacuum and the offset location of the throttle rod (axle thing). This is sort of similar to how the rudder rotation point effect the feel of an airplane or boat I think? It looks like the stock explorer 65mm throttle plate has a small hole on the larger side, but the BBK does not. Any thoughts on drilling a small hole in the large half of the BBK throttle plate?

[904Bronco]

Tossing in my .02

I ran a 70mm BBK/Edelbrock TB. And it was twitchy, hard to take off from a dead stop (manual Tranny) without lighting up the 31's. Roll up to a stop and it would die.

Got out the Mustang Coral info on adjusting the TPS and base idle and it was way off. That cured the dying rolling to a stop. Finally, I pulled out the Explorer 65mm and did a comparison. The springs on the BBK were significantlt stiffer than the 65mm. Swapped TB arms from a Mustang TB onto the 65mm and have never looked back.

Also running Mustang EGR spacer, so I have a Mustang throttle cable as well.