Exhaust Thermostat on my 239 Y-Block???
 

Well,
I got my exhaust manifolds cleaned up and put on and I'm ready to put the crossover pipe back on. I was wondering if I needed to put the exhaust thermostat back on, so I began to look for a replacement.....well, It's not in my parts catalog and Dennis Carpenter has one for 1965.

What's up with that? The engine was rebuilt sometime around 1970. Was this added on at that time? Is it necessary? If I don't put it on, will it mess up the spacing?

Here is the one I have
http://i1225.photobucket.com/albums/...ps7edd3931.jpg

By the way, I was able to get the exhaust studs at Orschlen's. :-jammin I guess those studs are still used everywhere. (But they didn't have the nuts for the open end, they don't carry much fine thread stuff. Off to Ace Hardware tomorrow.)

If memory serves me right, they're called heat risers. Diverts exhaust through the intake manifold when engine is cold. If you leave it out, the crossover pipe will not fit exactly right. Yours appears to be in decent shape. Free it up and install it. Last time I saw a new one advertised, it was big $$$.

Thanks Ray,
The one from Dennis Carpenter for the 1965 was listed at $50.
I didn't think the crossover would fit right if I didn't have it, thanks for the assurance.

So I have a couple of questions. Where does the lose end of the spring attach?
Also, more academic here, how does it divert the exhaust to the intake?

Parts like these make me wish I had a sand blasting cabinet.

Joe,
I think you're missing a pin that the spring hooks to. I bought a NOS one about a month ago on eBay for 25-30 Bucks. Mine was missing and I couldn't get the cross over pipe to seat without leaking without it. Here's a picture out of my 56 Manual.
Attachment 93800

OBTW with the butter fly closed the exhaust gases take the path of least resistance and back up through the intake manifold and into the other exhaust manifold bypassing the valve until it gets warm and opens up.

That's my story and I'm sticking to it}>

Do your intake, and yourself, a favor. Unless you live in cold country, tie it open. When these stick shut, the driver's side head cracks between 6&7. That's my story and I'm sticking to it. That's why Albatross now sports a 292 and a new exhaust.
Well, it's because a PO thought that they were fixing the broken spring and tied it shut by mistake. Sad, but true.
They are needed in the exhaust to get the spacing right. You could braze or weld it up open and never miss it if you don't live in cold weather land. Otherwise, buy a good used one. They're out there. I got manifolds, crossover, and a good valve for ~$70 shipped. The guy wrapped them all together with shrink wrap, boxed the mess with extra cardboard for packing, and they arrived in great shape.

Cut the butterfly out and weld up the holes and never look back.
That's my old school story that I am sticking to. It's way better than having it stick
shut and try and trouble shoot it. Ya will think all kinds of things are wrong except
that damn valve being stuck.
So it may be a bit cold blooded in the dead of winter. But ya most likely
will never miss it. But ya need it for the spacer to get the exhaust header
pipe to fit. Think about it, aftermarket headers don't come with that do they? :-jammin

Whoa! Read the manual, that's crazy talk. Actually the 54-55 Manual doesn't mention it. I did see it in the complete engine picture. (I didn't think to look at the manual until after I read this. :)

That's what I was thinking. I will get that valve either tied open or removed and go from there.

Thanks guys!

Back from the Dead
 

Ok, I bringing this thread back after our discussion this weekend in Branson, about the heat risers correct position. This was a concern of yours 8 years ago Joe. LOL Does any one know if this is in the correct position?. It is always in this position weather my truck is hot or cold? Does it ever change positions temporality? How do you know if it is working?. I guess I'm asking for some one to draw me a picture please. Im a slow learner! LOL Thanks

https://cimg2.ibsrv.net/gimg/www.for...985140ec0e.jpg

I forget the correct "home position" but yes it moves. Offhand, I would say it is in the "home position" as shown. With the engine idling, blip the throttle to get the engine to a thousand rpm and if the weight moves, the unit is working. It should move freely by hand. Rapid exhaust movement thru the valve opens it.

Oh I was thinking heat made it move but air flow does make more sense. I have pictures on my pic. When I get home I will look them up.

The valve when closed forces hot exhaust gasses thru the passage of the intake manifold to aid in quicker engine drivability, warm up.

Well I guess I will have to have someone watch it while my my truck is hot and reve up the rpm. Someone also suggested to but your hand over the exhaust pipe to see if it is moves more air in the down position. If it only opens at high rpm though, it would think that it would "trap" the heat while setting at idle. That's not good. That's why I thought it moved when hot and stayed in that position. I guess I can take the cross over pipe off and I will know exactly the position it is in.

My understanding is that is exactly what the design of the device is. It directs hot gasses thru the intake manifold to heat it up thus making quicker warm up and drivability. The device supposedly prevented carburetor icing.
You can control engine speed while under the hood by working the throttle rod that runs to the carburetor.

Now that I'm home I found the two pictures I have. It looks to me like pointing straight up is closed and to open fully it has to be all the way down.
Dave, I don't know if yours will go all the way down. When we were playing with it we only moved it 90 degrees.
https://cimg8.ibsrv.net/gimg/www.for...86336a8500.jpg
https://cimg9.ibsrv.net/gimg/www.for...e89c06f665.jpg