71 Chevy truck ac cowl flap screw

[prateroad]

Anyone out there know the screw thread size for the cowl flap that the L-shaped arm attaches to? Can't find anything is my parts to match.

[Rick Bollinger]

The metal arm that attaches to the vacuum actuator? If that’s what you are talking about the fresh air flap to that arm I believe it is a #10 sheet metal screw about 5/8” long.

[71CHEVYSHORTBED402]

I do, but I'm not sure what you ask for. Are you talking about the screw in this pipe-rod connect link thing of jig for the vacuum actuator?

If the actuator is what you mean, here's that info. (bolded)

The upper cowl air door vacuum actuator installs as:

1. The oval nylon bushing slips over the air door’s front stem. The bushing’s flange mounts to the cowl’s front with two 5/16" hex flange tap screws. The screw threads are #10 x 1/2”, and the heads are stamped with 4 lines. The bushing is stamped “B”.

2. The upper cowl air door pipe rod slips onto the air door’s stem with their holes aligned. The rod mounts to the stem with one 5/16" hex flange tap screw. The screw threads are #10 x 1/2", and the head is stamped with four lines. Install this screw after the actuator is installed.

3. The upper cowl air door vacuum actuator was mounted to its bracket with 3/8" hex nuts and flat washers for #10 studs. The actuator’s port faces down and forward. Some actuators installed with speed nuts, which was optioned for this rebuild. The actuator is stamped “DELCO Made in USA REMY”.

4. The upper cowl air door vacuum actuator bracket secures to the firewall, located above the heater hoses. The bracket mounts with two 5/16" hex flange tap screws. The screw threads are #10 x 1/2", and the heads are stamped with four lines.

5. The actuator’s stem secures to the pipe rod with a push-on retainer nut installed onto its stud. A 1 MM push-on nut can be expanded to fit. Reference images.

[Rick Bollinger]

Thanks Tony, I was going off of memory I just assembled mine a couple months back and was going off memory. I believe he was asking about the #10 screw holding the arm to the post on the fresh air door. You nailed it.

[prateroad]

Appreciate the info, the screw thread size is what I needed.

[prateroad]

Well, #10 but what thread count?

[71CHEVYSHORTBED402]

Originally Posted by prateroad

Well, #10 but what thread count?

Nearly all small tap screws on these trucks are coarse thread, if not all.

[Rick Bollinger]

https://www.grainger.com/product/1MB...7950b63113f85e You don't want or need the slot but like this.

[prateroad]

Mine's not a sheet metal screw, it has factory tapped threads.

[Rick Bollinger]

Then you have a one of a kind.

[71CHEVYSHORTBED402]

You guys are going to make me pull my link screw huh?

Strikes me as course thread. Here's the small hardware I had refinished, formerly black phosphate. Does anyone see a tap screw (sharp pointed tip) with fine threads? Really, I'm curious. I don't claim to be an expert, I think I've had to use that gauge type 1-2 times.

Here's the exact screw, the entire unit (link, nylon bushing, bracket) mount with the same five screws, mine are stamped with 4 lines each. It was a kit in other terms. Doesn't mean there weren't variations. GM often did. For instance my 71 blower installs with #8. Tap screws if I remember right. They were #10 in my former 72 C20. All original hardware.

[Rick Bollinger]

71 Short That pile of hardware reminded me of the days I spent at my blast cabinet cleaning all the screws I could save. Then the powder coating which was much easier than blasting all of that crap. I bet I have 100 hours doing that stuff.

[71CHEVYSHORTBED402]

Originally Posted by Rick Bollinger

71 Short That pile of hardware reminded me of the days I spent at my blast cabinet cleaning all the screws I could save. Then the powder coating which was much easier than blasting all of that crap. I bet I have 100 hours doing that stuff.

I didn't know I could buy a tumbler. If I ever see another little brush on a Dremel, with the )*(&_( rabid wires coming at me again it's too soon. Paint remover on too many, degreaser, rinse, vinegar concoction for maybe a day, rinse & dry, stainless brushes, wash & dry, baking soda bath, rinse & dry, brass brushes x more than 1000 pieces, I even hit the nuts. I learned to very much dislike it, so tedious, but good results.

Never seen powder coated hardware before, seems people are happy with it. Hmm, I wonder how black ARP bolts are coated? GM hardware is awfully good, but ARP looks like another level.

[prateroad]

Well, I have 3 flaps and all are machine screw thread, even the one I bought new from Classic Parts.

[Rick Bollinger]

most of my hardware had some rust and or multiple layers of paint. So I needed some rust protection after bead blasting. It works well but, I feel your pain.