HELP: Power steering pump bracket needed (I think)

[GAc10boy]

In need of some assistance. I recently had the AC converted and fixed on my factory AC '85 c10. The motor was originally a 305 but has been motor swapped to a crate 350. I say all of that to say, i've developed a pretty bad vibration with the AC on while idling in gear.

The AC shop noticed that a bracket was missing on the back of the power steering pump. I'm turning to you all for help to help me identify the bracket for the pump to block. Please see pictures below. The truck has headers but it has the upper bracket from the top of the pump to the first header bolt. I'm kind of grasping at straws and unsure if this will help with vibration at idle but it appears something is missing there so I'll give it a shot.

Help!

[geezer#99]

IIRC my 84 never had any other bracket off that stud. Not that I can see in this pic. You can see that stud in my first pic.
Do you have an idle solenoid on your carb to increase your idle?
What's your initial timing? It might be idling rough because of timing causing a vibration.

[GAc10boy]

Thanks, Geezer. I could simply be missing a nut on the back of it to cinch it down to the bracket better. That said, I can't tell from your pics if yours has a nut on it. As for as timing, etc, that doesn't seem to be the issue. The truck actually idles/drives well and only has this vibration with the AC on and after the motor is warmed up. It's very strange.

And it totally sounds like something in the pulley system. The AC guys narrowed it down to the ps pump.

[GAc10boy]

I now think the vibration is coming from something else entirely, just feels like it's in the pulley system. The fact that it's noticeable only in D or R at idle and is felt/heard when AC compressor kicks on is beyond me, but other sites have suggested motor mounts (which makes the most practical sense) or torque converter. Guess I'm officially chasing a rabbit down a hole.

For what it's worth, I've looked over the power steering/ac bracketry and I just don't see how it could be either vibrating. There are multiple fastener points in front and rear of both and they are tight.

[geezer#99]

Does it vibrate if you bring the rpm up slightly?

[GAc10boy]

Originally Posted by geezer#99

Does it vibrate if you bring the rpm up slightly?

Not at all. It literally stops as soon as you give it the slightest amount of throttle in D or R. Doesn't do it all in neutral.

[geezer#99]

So it could be timing related.
The motor wants more initial. Your little rpm increase gets into the mechanical timing and it quits vibrating.
What is your initial timing?

[Jstock85]

Id go with geezer suggestion first. messing with timing will be a hell of a lot easier and cleaner than motor mounts and torque converter!

[GAc10boy]

Originally Posted by geezer#99

So it could be timing related.
The motor wants more initial. Your little rpm increase gets into the mechanical timing and it quits vibrating.
What is your initial timing?

Originally Posted by Jstock85

Id go with geezer suggestion first. messing with timing will be a hell of a lot easier and cleaner than motor mounts and torque converter!

Talked with Geezer via PM last night. Planning to try that first.

[Jake Wade]

I bet your A/C belt is jumping a lot when in D(low idle). I changed motor mounts and it fixed my problem. I used Pioneer brand.

[GAc10boy]

Originally Posted by Jake Wade

I bet your A/C belt is jumping a lot when in D(low idle). I changed motor mounts and it fixed my problem. I used Pioneer brand.

Thanks. Turns out it was my trans mount contributing to some of the vibration and a broken power steering pump bracket set-up down near the bottom where the pump bolts to the large bracket that ties the pump and AC compressor together. It's literally just hanging loose near the bottom left (when looking at motor).

I got lucky and found a whole new (well used) ps pump bracket and AC bracket set-up off of an 84 c10 sbc at my local yard. For what it's worth, that motor was complete and had nothing connected from that stud that I posted in the original post to the block.

Thanks to all for helping me think through this.