Thermostat + Damper Door Setup

[falude]

Hi Everyone -

My name is Matt and I have a 1965 Monza 110, with a 4-speed. I've been active on the CCF for a while (I don't post much), but I figured I should start posting over here.

I have a question related to setting up the bellows thermostats, and damper doors. When I bought my car, it came with the damper doors and thermostats removed. I have since acquired what I believe are all of the components necessary to reinstall thermostats on my Corvair, but want to make sure that I am setting up the thermostats correctly. For ease of assembly I am assembling everything off of the car.

Here are the questions that I have for the group:

1. I've attached pictures of how I currently have them set (without the clips at the moment). Does this look correct? I understand the thermostat can bind if installed incorrectly.
2. How tight should the bellows and swivel pin be? In other words, how tight should the door be against the shroud?
3. Is there a recommended adjustment method to ensuring the doors are set properly?

Any advice, or suggestions would be greatly appreciated. Thank you, and I am excited to be posting here now - Matt

[corvairsince70]

Your dampers and shrouds look great. If you had put the clips on you would have seen that the passenger side swivel is on the wrong side of the damper door. Both left and right thermostats connect to the door on the drivers side.
Do you have a shop manual? It is spelled out very clearly how to adjust the doors. The door must be connected to the thermostat at full travel against its stop. So when the thermostat is fully extended when hot the door is full open horizontally. Be careful not to adjust so the door opens past horizontal. The doors will be quite tight against the should when the thermostats are cold. This is normal.

[Dennis66]

MY EXPERIENCE has been to install everything except the doors (pivot pin removed) hook up the linkage, then pull th edoors into place and install the pins. Tension would be easiest set the way you have them in the pictures (except the flipped passenger side link). Dennis

[66vairguy]

MY EXPERIENCE has been to install everything except the doors (pivot pin removed) hook up the linkage, then pull th edoors into place and install the pins. Tension would be easiest set the way you have them in the pictures (except the flipped passenger side link). Dennis

CORRECT!!!!! Flip the psg link to make it straight. I tried a number of ways/tools to get the link on the door and the process Dennis describes works the best AND IS THE EASIEST on the thermostats. When cold try not to pull the thermostats open!!!!

I could not tell from your pictures, but there are plastic bushings that go in the doors where the pivot rod goes through.

I slide the door in (takes some wiggling) to the box and install the thermostat rod, then move the door into position (takes some wiggling) and install the door pivot rod. If the door is too tight or loose, remove rod - drop door again and remove and adjust. Yes tedious, but it is a one time deal. Sometime you have to bend some sheet metal so the door does not rub/bind.

NOTE: the metal tabs that hold the door pivot rod in place tend to break off. Some use screws or clips to hold the rod, just make sure it does not interfere with the door movement.

FINALLY -- a long time ago someone made replacement thermostats that have sharp edges on the pleats. The original syle had rounded edges on the pleats. You find these on ebay and Clark's sells them. I've had about 1/3 of the new style fail in short order. Others have reported the same failure rate. One fellow on the forums suggested I buy good "USED" original style thermostats (that still work obvously). I did and not one of the used thermostats I've used has failed. Good used is totally collapsed and will not easily pull open at room temperature. Failed and at room temperature the thermostat is relaxed - fully extended

[Dennis66]

Then there are the "new design" thermostats offered by a member here and available on ebay. Personally, I'm leery of trusting old thermostats, although they usually fail in the open position. Dennis

[RexJohnson]

They always fail in the open position. They were designed to do this.

[66vairguy]

Then there are the "new design" thermostats offered by a member here and available on ebay. Personally, I'm leery of trusting old thermostats, although they usually fail in the open position. Dennis

Just me, but I don't like "new" design on ebay. In spite of arguments I don't trust thermal coils to fail in the open position. Of course I'm old and remember when they were used on manifold heat risers and carburetor chokes. Always seemed to deteriorate over time and need to be changed.

As Rex said --- the original design only fails open. Yes used and old thermostats may be questionable, but as someone told me "If it is over 50 years old and still works, it will probably work for some time." All I can say is my used ones are still working after years of use. Nothing lasts forever and I have the warm feeling that if it does fail it WILL NOT cause the head too overheat. I have a couple spares to install when needed. Just me.

[Lane66Monza]

You might want to consider removing the rivets holding the thermostat bracket and heatshield to the lower shroud and replace rivets with blind nuts. It makes it so much easier to access the lower side of the engine for any reason. Pull 2 bolts on thermostat mount and all the bolts holding lower shroud to engine and cooling box and you are in without disturbing the thermostat adjustment. Plus you can setup the assembly on the bench, split lower shroud from cooling box to install them separately.

Here is aphoto of what I found on my Greenbrier 80 hp engine. GM had put the weld nuts on the bracket, but changed the design before the short rod system came into existence. That got me thinking I could use blind nuts instead of weld nuts. 2 engines now have the blind nuts. Made it easy to remove/install shrouds for engine repair on the More Door 3 years ago.

[Corventure Dave]

I have had no issues using Old thermostats that are still in working condition. I have, in general found the old ones are many cases more reliable than late production OEM or the Aftermarket reproduction thermostats that pop up from time to time.
Easy to replace when-if they fail. It's good to have a couple extras or more on hand. Swap meet time!

Corventure Dave

[falude]

Thank you all so much for the extremely helpful responses. I bought two new Clark's bellows so hopefully those hold up. If I have issues, I'll look for NOS or a working used set. I do have the plastic bushings, so I think I should be good to go.\

Drilling out the rivets and replacing with nuts and bolts sounds really smart.

I have one additional question. The pin looks like it has a provision for a very small cotter pin or clip to hold it in place. Is this just a cotter pin, or is it a a special clip?

Thank you all for the help! - Matt

[Lane66Monza]

Bolts yes, but not flat nuts. You will be unable to tighten flat nuts with lower shrouds installed. Need to use Blind Nuts. They are also called Rivet Nuts, Rivnuts, or Grip Sert Nuts,. These are installed similiar to how a rivet is installed. You put blind nut on a tool, then insert blind nut in a proper sized hole. Operate tool until the blind nut is gripping the metal, where it can not be turned unless extreme force breaks the blind nut's grip. Then remove the tool. You have to read the tool's instruction sheet to understand its operation. All are different.

I use 10-32 blind nuts and bolts for this application. The blind nut is installed in the thermostat mount bracket (upper side). I have used blind nuts inseveral places on the Corvair, Thermostat bracket mount, coil rear structuremount, heater box stud replacement, heater fan relay mount, electric fuel pump relay mount, electric fuel circuit inertia switch mount, electric fuel pump circuit power indicator light mount bracket,

This is a site that explains how to install the blind nut.

https://www.wikihow.com/Install-a-Rivet-Nut

Photos show 2 different styles of manual operation tools. Harbor Freight (HF) has both styles of yools. I prefer the Marson tool, (not at HF). The first tool example shows an example of the blind nut. But as age takes it toll, the Doyle is getting more use, as squeezing the Marson tool handles is beconing difficult. Unfortunately, Doyle tool only sets blind nuts up to 10-32. So for the larger blind nuts, I have to devise ways to help slowly squeeze the handles or call on a friend with more hand strength to install the blind nut for me. Tough to ask for this help when I need it as all my friends are in my age group. They may not be able to pull the handles either.

Marson Rivnut Setter Tool.jpg (41.63 KiB) Viewed 737 times

Doyle Rivnut Setter Tool.jpg (45.69 KiB) Viewed 737 times

[RexJohnson]

You could also just get some of the earlier brackets that already have the factory welded nuts.

[66vairguy]

I have one additional question. The pin looks like it has a provision for a very small cotter pin or clip to hold it in place. Is this just a cotter pin, or is it a a special clip?

Thank you all for the help! - Matt

If you are talking about the rod that goes through the door so it can pivot, some do drill them to install a clip or cotter pin.

Originally a metal tab held the rod in, but after a couple bends it breaks off. Installing a screw and washer to hold the rod in place sometimes interferes with the door (and the screw can come loose). I drill a hole in the end of the rod that ends up behind the rear mount access cover. It a little tricky to reach, but it is not like you are doing this very often. Just me - others may have better methods to hold the door pivot rod in.