Throttle butterflies

[mhurwitz]

I’m finally replacing the bushings on my 71E MFI throttle bodies. It’s got 140,000 on it and the throttle bodies have the typical wear groove from the butterfly movement. I bought the car with 101,000 in 1978 and was told they would probably need to be done then.
My question: How perfect is/was the gap between the body and the butterfly when they were new? When I shine a flashlight from the bottom with the flap closed, I do see a little light around some of the edges. When they are new or rebuilt , are they so perfect that no light would shine through. Will the car idle/run correctly if there are small gaps?
Thanks,
Mark

[gled49]

Try it and see. I’ve been doing this 45 years and always figured a specialist was necessary for this repair work. Every rebuild on MFI engines I did included pump rebuild along with throttles done by the Pros, every engine ran and preformed perfectly. It made my job easy.

[70etarga]

I got some lower milage T.B.'s for my E, but the lowest idle with closed bypass screws was still 1400 rpm which was the same as my old worn-out T.B.s.
I was able to adjust the butterfly stop screws down to 1000 rpm with the cylinders equalized with my Unisyn with all the bypass screws at around 1 to 2 turns- you have to readjust all the T.B. linkages of course.

If you can close the stop screws down enough to get a 1000 rpm idle, you should be good to go -- if not it's probably T.B. rebuild time $$$$.
This may not be the official approved procedure, but it worked for me.

[icarp]

The car should idle at 600 rpm, When I look at the sun through the butterfly I expect to see .01%
or less of the sunlight . .001" gap or less
Well done butterflies carb or injection should be the same
Ian

[mhurwitz]

Originally Posted by icarp

The car should idle at 600 rpm, When I look at the sun through the butterfly I expect to see .01%
or less of the sunlight . .001" gap or less
Well done butterflies carb or injection should be the same
Ian

Thanks Ian. That’s exactly what I was wondering.
I replaced the bushings in the bodies, carefully measured and adjusted the arms, cleaned the air adjustment screws and adjusted the butterfly stops to make sure no butterflies were sticking. I made sure to use Loctite on the butterfly screws. I could only see a sliver of light with a flashlight shining up.
Before rebuild of throttle bodies she was idling at 1200 and fluctuating....and always making that click click click sound.
After rebuild, she idles at 800, stays constant and is sooo quiet.
Total cost.....around $40 for bushings and gaskets.

[stownsen914]

Nice. Did you buy generic bushings and press install them?

[mhurwitz]

Originally Posted by stownsen914

Nice. Did you buy generic bushings and press install them?

I bought these on Amazon and they worked great. McM*--Ca** wanted $10+ per bushing.