Me too. Jim Carter parts has a bimetallic spring, but there is no picture next to the part number and price, so I am not 100% sure it is the right one.
I have Split 3 different Chevy 6 exhaust manifolds. The first I left the flap free to operate at 1/2 range. The second was 3/4 range and the last was Full blocked. I think the 3/4 block had the best results. In each case I fitted the exhaust system with a crossover pipe and 30" Fiberglass mufflers.
Thank you for the explanation. My 1962 235 is very similar, although the weight and spring is broken off. I have read it needs the warmth to keep the fuel from puddling. On cold start ups the is no heat to begin with. The whole system is contrary to cold air intakes. Since I live on the Tennessee/Georgia line and don't drive it in stupid cold weather, I need to make sure it is closed all the time. Thanks again.
Well done video and explanation! These are called heat riser valves, and the shaft had a tendency to seize, making the valve inoperable. GM supplied a special lubricant to treat them. The counterweight and bimetallic strip control must have been too simple; later ones on V engines used a vacuum servo control.
The springs would eventually corrode, break, and fall off, leaving the flap in the open position and not able to warm the manifold properly in colder temperatures. The springs are also a pain to find these days. I knew someone who used a pull choke under the dash and wired it to the heat riser weight and would operate it manually because he couldn't get the heat sensitive spring anymore.
This is an excellent explanation. I have been looking far and wide for information on this intake/exhaust configuration. I am in the process of restoring a 1967 Pontiac Tempest with the OHC inline six. The exhaust part of my manifold is shot; it has cracks and a couple of the wings are broken off. I cannot for the life of me find the part anywhere. My last ditch effort is to ask a shop to manufacture a header for me. If that does not work, I may need to abandon this engine altogether. The OHC was only manufactured for a few years yet it has historical significance, as it was the first American engine with the timing belt. Are you familiar with this engine? Do you think I have any other options aside from having a header manufactured? I was really hoping to keep this engine, as the car has only 62,000 miles on it.
I am not familiar with the Pontiac engines. Sorry. I know there are cast iron headers for the Chevy 230, 250 and 292 engines. It might be worthwhile to check if they would work with the Pontiac engine since GM shared a lot across from Chevy. I’m glad you found the video helpful.
@@Lugnutz65 thanks for the fast response. I have been trying to match them up and the shape of the holes is definitely different. If I had a manifold in my hand, I could tell at least if the dimensions were similar. Either way, the gaskets are different so that says right there it's probably not a match. Sometimes there is anecdotal information out there but the truth is, this six-cylinder has been abandoned in most restorations because of low performance and reliability issues. That is why I'd like to keep the original engine - it's a unicorn! Thanks for the fast response.
Looks like my 194 inline 6 intake and exhaust manifold. Small amounts of heat(exhaust)rise and help atomization and vaporize gas, so if your heat riser is stuck shut by to much carbon your car may run a bit ruff, should be checked, it should move freely.The coiled spring is a thermostat.
But the exhaust gas doesn’t mix with the intake. The holes on the bottom side of the intake simply give it more surface area but don’t communicate with the intake passages.
OHHHHHH So the fumes don't actually go into the manifold... that book I'm reading doesn't specify that... or maybe it does, only the drawings aren't too clear about it. I knew something was off. Thanks a bunch!
No, because if it did divert exhaust directly into the intake manifold it would ignite the fuel/air mixture in the manifold itself. It's job is to warm the manifold so the fuel becomes a mist and atomizes, otherwise in cold weather it will turn into a liquid and sit in the manifold and not spray into the cylinders for combustion.
I wonder how effective this mechanism actually was. Seems kind of gimmicky, but maybe it was effective. Mine is stuck, but it's stuck in the warm-weather position, so I plan on leaving like that. I wouldn't mind fixing it for the sake of "doing it right", but I can't imagine it's really worth the effort. I'll won't ever run the old Suburban in the winter. Thanks for the vid.
Hi thanks for video, what the proper way to install the gasket in between exhaust and intake, metal side down towards exhaust ? Have mine apart and installing a heat riser spring, previous owner had it tied up. Living in New York it should work the right way not tied up
@@nickpanhead7209 Felpro website says “When installing Fel-Pro exhaust manifold gaskets, if there is a smooth, metallic side and a composite side, the metallic side should be installed facing out, meaning toward the exhaust manifold.”
Thanks! Had the same question about the L6 230 in my 69 Camaro. The spring and the post are "gone". EFI was just added. I'll make certain that my diverter is in full divert down. With EFI, I don't think I'll need the initial heat up.
A number of these engines were converted to run on propane during the gas crises of the 1970's. In that case the entire opening of the exhaust manifold was blocked off with a plate to prevent the heat from evaporating the propane in the manifold. From what I recall these motors ran quite well on natural gas.
@@BillySBC Gasket kits for these engines included one that blocked off the heat passages, and I never knew what application they were for. Now I do. Thanks.
UNTIL... the flap spring gets old, corrodes, breaks, falls off, and then the flap defaults to the open position all the time... Then you get to try to find out exactly WHERE you can get another little spring from for your 250 straight six. Hope this helps.
Vendors sell a block that bolts under the intake manifold. It used coolant from the radiator to warm the intake. If you live in a warm climate you won’t need it.
That will cause the intake manifold to be warmer than it should at operating temperature. The manifold I show is for 1963-19?? Chevy in-line 6 cylinders. Typically 230, 250 and 292 engines.
Worked on these things half my life and never really completely understood how it was supposed to work. Thank you for your clear, concise explanation.
THANKS, I have acquired a 292 and have been rebuilding back to stock. Lots of fun but sure required RUclips along the way.
Me too. Jim Carter parts has a bimetallic spring, but there is no picture next to the part number and price, so I am not 100% sure it is the right one.
I have Split 3 different Chevy 6 exhaust manifolds. The first I left the flap free to operate at 1/2 range. The second was 3/4 range and the last was Full blocked. I think the 3/4 block had the best results. In each case I fitted the exhaust system with a crossover pipe and 30" Fiberglass mufflers.
Thank you for the explanation. My 1962 235 is very similar, although the weight and spring is broken off. I have read it needs the warmth to keep the fuel from puddling. On cold start ups the is no heat to begin with.
The whole system is contrary to cold air intakes.
Since I live on the Tennessee/Georgia line and don't drive it in stupid cold weather, I need to make sure it is closed all the time. Thanks again.
Thanks for sharing 👍 wondered what that was about. I change my exhaust to headers .
Makes sense. There needs to be auto shop back in high schools.
THANK YOU YOUVE ANSWERED A HUGE HEADACHE OF AN ANSWER! THANKS FOR THE INFO I APPRECIATE IT!
rickcasanova4863 Glad to hear it was helpful.
Glad to hear it was helpful.
Well done video and explanation! These are called heat riser valves, and the shaft had a tendency to seize, making the valve inoperable. GM supplied a special lubricant to treat them. The counterweight and bimetallic strip control must have been too simple; later ones on V engines used a vacuum servo control.
The springs would eventually corrode, break, and fall off, leaving the flap in the open position and not able to warm the manifold properly in colder temperatures. The springs are also a pain to find these days. I knew someone who used a pull choke under the dash and wired it to the heat riser weight and would operate it manually because he couldn't get the heat sensitive spring anymore.
This is an excellent explanation. I have been looking far and wide for information on this intake/exhaust configuration. I am in the process of restoring a 1967 Pontiac Tempest with the OHC inline six. The exhaust part of my manifold is shot; it has cracks and a couple of the wings are broken off. I cannot for the life of me find the part anywhere. My last ditch effort is to ask a shop to manufacture a header for me. If that does not work, I may need to abandon this engine altogether. The OHC was only manufactured for a few years yet it has historical significance, as it was the first American engine with the timing belt. Are you familiar with this engine? Do you think I have any other options aside from having a header manufactured? I was really hoping to keep this engine, as the car has only 62,000 miles on it.
I am not familiar with the Pontiac engines. Sorry. I know there are cast iron headers for the Chevy 230, 250 and 292 engines. It might be worthwhile to check if they would work with the Pontiac engine since GM shared a lot across from Chevy. I’m glad you found the video helpful.
@@Lugnutz65 thanks for the fast response. I have been trying to match them up and the shape of the holes is definitely different. If I had a manifold in my hand, I could tell at least if the dimensions were similar. Either way, the gaskets are different so that says right there it's probably not a match. Sometimes there is anecdotal information out there but the truth is, this six-cylinder has been abandoned in most restorations because of low performance and reliability issues. That is why I'd like to keep the original engine - it's a unicorn! Thanks for the fast response.
Looks like my 194 inline 6 intake and exhaust manifold. Small amounts of heat(exhaust)rise and help atomization and vaporize gas, so if your heat riser is stuck shut by to much carbon your car may run a bit ruff, should be checked, it should move freely.The coiled spring is a thermostat.
But the exhaust gas doesn’t mix with the intake. The holes on the bottom side of the intake simply give it more surface area but don’t communicate with the intake passages.
Awesome video! Thanks for sharing!
OHHHHHH So the fumes don't actually go into the manifold... that book I'm reading doesn't specify that... or maybe it does, only the drawings aren't too clear about it.
I knew something was off. Thanks a bunch!
No, because if it did divert exhaust directly into the intake manifold it would ignite the fuel/air mixture in the manifold itself. It's job is to warm the manifold so the fuel becomes a mist and atomizes, otherwise in cold weather it will turn into a liquid and sit in the manifold and not spray into the cylinders for combustion.
Very helpful, thank you.
I wonder how effective this mechanism actually was. Seems kind of gimmicky, but maybe it was effective. Mine is stuck, but it's stuck in the warm-weather position, so I plan on leaving like that. I wouldn't mind fixing it for the sake of "doing it right", but I can't imagine it's really worth the effort. I'll won't ever run the old Suburban in the winter. Thanks for the vid.
Thanks for the video.
Hi thanks for video, what the proper way to install the gasket in between exhaust and intake, metal side down towards exhaust ? Have mine apart and installing a heat riser spring, previous owner had it tied up. Living in New York it should work the right way not tied up
I installed mine metal side down. I’ll look at my service manual to see what it says.
@@Lugnutz65 thank you I would appreciate that. I would think it would be metal down towards the heat.
@@nickpanhead7209
Felpro website says “When installing Fel-Pro exhaust manifold gaskets, if there is a smooth, metallic side and a composite side, the metallic side should be installed facing out, meaning toward the exhaust manifold.”
@@Lugnutz65 thank you very much can't wait to put it all back together, and hear a smooth running motor, thanks be safe
Thanks! Had the same question about the L6 230 in my 69 Camaro. The spring and the post are "gone". EFI was just added. I'll make certain that my diverter is in full divert down. With EFI, I don't think I'll need the initial heat up.
I agree. Good luck with the EFI.
A number of these engines were converted to run on propane during the gas crises of the 1970's. In that case the entire opening of the exhaust manifold was blocked off with a plate to prevent the heat from evaporating the propane in the manifold. From what I recall these motors ran quite well on natural gas.
@@BillySBC Gasket kits for these engines included one that blocked off the heat passages, and I never knew what application they were for. Now I do. Thanks.
Great video!
Thank you, so much...
On the '67 292 I am rebuilding, the bimetal spring is completely gone. Where can I buy a replacement bimetallic spring?
Try Jim Carter. That’s the name of a vendor. Also try 12bolt.com.
@@Lugnutz65 Thank you.
Can I just add a plate to block off the heat to the intake manifold, would that work? My exhaust manifold has no plate
@@ParablesPulse I wouldn’t block it off completely. Maybe add a few 1/4” holes. Even the stock heat riser plate doesn’t block 100%.
@@Lugnutz65 perfect !!!! Thank you God bless you !!!!
UNTIL... the flap spring gets old, corrodes, breaks, falls off, and then the flap defaults to the open position all the time... Then you get to try to find out exactly WHERE you can get another little spring from for your 250 straight six. Hope this helps.
Vendors sell the springs. All mechanical parts require routine inspection and service. Some more than others.
Jim Carter parts says they have the bimetallic springs but there is not picture of this part yet.
Ty
THANK YOU
Odd that the 292 setup i have foes NOT and never had a flapper... the setup was off a dump truck originally.
That is odd.
I'm replacing my manifold with a custom split but just it doesn't have a flap, what problems will come??
Vendors sell a block that bolts under the intake manifold. It used coolant from the radiator to warm the intake. If you live in a warm climate you won’t need it.
@@Lugnutz65 I'm in Cali do ots always warm....thank you for responding...
Does this not apply to the 194 l6?
Yes, I believe the 194 I6 manifold operates the same.
Yes,also check your manifold bolts they get loose over time (25 foot pound tork)
My manifold has no flap and spring, just a hole. Its never had one.
That will cause the intake manifold to be warmer than it should at operating temperature. The manifold I show is for 1963-19?? Chevy in-line 6 cylinders. Typically 230, 250 and 292 engines.
@@Lugnutz65 i think this particular manifold was changed in the early 70s, I have a 1967 with this exhaust manifold and flap
@@nicholascastor1746
Perhaps it changed with the introduction of the integrated head. Maybe?
@@Lugnutz65 I believe you hit the nail on the head!