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Discussion Starter · #1 ·
this to me is similar to the CTO but doesnt fit the opening or any other that I can see. it seems that I pulled it off my car but cant find a pic of where is or would have been mounted. What is it and do I need it? Please and thanks, Mike

it has letters D, C, and MT, one at a port right to left

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Discussion Starter · #3 ·

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It's a CTO (Coolant Temperature Override) ported vacuum switch. Such switches normally have a vacuum source attached (from carb or intake, depending on your setup). When the coolant reaches a preset temp, it allows the vacuum source to start pulling on whatever vacuum item(s) are attached to the other ports. At least, in theory, that's how it is supposed to work. The usual items attached are EGR valves and the charcoal/vapor canisters.

These switches come in multiple configurations (2, 3, 4, and 5 ports).

For illustration, here's the Howell vacuum routing diagram for a 258

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Discussion Starter · #7 ·
It's a CTO (Coolant Temperature Override) ported vacuum switch. Such switches normally have a vacuum source attached (from carb or intake, depending on your setup). When the coolant reaches a preset temp, it allows the vacuum source to start pulling on whatever vacuum item(s) are attached to the other ports. At least, in theory, that's how it is supposed to work. The usual items attached are EGR valves and the charcoal/vapor canisters.

These switches come in multiple configurations (2, 3, 4, and 5 ports).

For illustration, here's the Howell vacuum routing diagram for a 258

View attachment 4133238
.
this brings me back to my post that started this and that is pertaining to the CTO and its ports and this Howell TBI schematic which is where I am at on my project and my new question pertains to the canister and CTO. My 82 appears to have original canister and trying to follow Howell instrucs my question is the naming of the ports. On my canister, and facing the same direction as the schematic, my canister names are different as in Carb Bowl, Tank, PCV, Dist Vac in that order left to right. so I see that TANK and PCV are in same order and marked the same as mine vs schematic. And if the order is correct then I will cap the first port on mine which is named CARB BOWL. Which BTW all 3 of these ports are NOT restricted and are clear flowing in both directions. But that leaves the last port called PURGE SIGNAL on the schematic but called DIST VAC on my original. Therefore I am confused??? Surely I dont go here for my vacuum advance off the distributor do I? and BTW this port does not breathe and on the top of the cap it says do not remove cap. So is it a breatheable port operated by the CTO or is the port clogged and not repairable? And while I am at it is the 5th port on the CTO schematic called "Filter to atmosphere" do I just cap it or is it left open or what to do with it? Also I am not worried about emissions no EGR being done with this Howell TBI upgrade. So let me keep this simple as possible. Thanks, Mike

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The canister in your pic is exactly like mine.

Carb Bowl is a line that would normally go to the carb bowl vent like on a MC 2150. If you're doing EFI, sure, cap it off. If you're doing a carb that has a vent, it's your choice. The 2150 I have is happier when I actually run the vent to that port.

Tank is a vapor line coming from the fuel tank. You kinda want that as it allows the tank to vent pressure through the charcoal filter via a couple of valves tucked up in one of the corners on a baffle behind the tail lights, probably driver's side.

This is a GUESS on my part ... but I think the PCV line used to connect right there to help clean the fumes and oil mist from the PCV valve. I think.

The last one is the vacuum line that controls flow in the canister.

CTO:

Port 5 is left un-capped (filter to atmosphere).

The rest, just follow the diagram; don't get wrapped around the axle with labels. Just make sure the lines go where the diagram shows them going.

I STRONGLY recommend you get some heat shielding tubing to put on the lines going to the CTO just to keep the lines from melting. They get VERY close to the manifolds.

You might want to make sure to follow Howell instructions, which means you might need to have an EGR; otherwise, your O2 sensor readings may be off, which will translate into running like garbage. I had the Howell EFI ... had. I rebuilt the engine, bored it .020 over, which changed intake characteristics just enough to really throw off the TBI. Many folks have had fantastic luck with Howell; I am not one of them. I removed the Howell and went back to carb.

One last thing ... make sure there is a good tach signal from the distributor. If you don't get one, the TBI won't work, it won't flow gas.

Hope this helps some!
 

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Discussion Starter · #9 ·
The canister in your pic is exactly like mine.

Carb Bowl is a line that would normally go to the carb bowl vent like on a MC 2150. If you're doing EFI, sure, cap it off. If you're doing a carb that has a vent, it's your choice. The 2150 I have is happier when I actually run the vent to that port.

Tank is a vapor line coming from the fuel tank. You kinda want that as it allows the tank to vent pressure through the charcoal filter via a couple of valves tucked up in one of the corners on a baffle behind the tail lights, probably driver's side.

This is a GUESS on my part ... but I think the PCV line used to connect right there to help clean the fumes and oil mist from the PCV valve. I think.

The last one is the vacuum line that controls flow in the canister.

CTO:

Port 5 is left un-capped (filter to atmosphere).

The rest, just follow the diagram; don't get wrapped around the axle with labels. Just make sure the lines go where the diagram shows them going.

I STRONGLY recommend you get some heat shielding tubing to put on the lines going to the CTO just to keep the lines from melting. They get VERY close to the manifolds.

You might want to make sure to follow Howell instructions, which means you might need to have an EGR; otherwise, your O2 sensor readings may be off, which will translate into running like garbage. I had the Howell EFI ... had. I rebuilt the engine, bored it .020 over, which changed intake characteristics just enough to really throw off the TBI. Many folks have had fantastic luck with Howell; I am not one of them. I removed the Howell and went back to carb.

One last thing ... make sure there is a good tach signal from the distributor. If you don't get one, the TBI won't work, it won't flow gas.

Hope this helps some!
just the help I needed, thank you,.Mike P.S., the forum is always there when you need them!
 

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Discussion Starter · #10 ·
just the help I needed, thank you,.Mike P.S., the forum is always there when you need them!
As Columbo always said "just one more thing" your statement about "The last one is the vacuum line that controls flow in the canister" do I take that is the reason it appears to be plugged up and that it is controlled by the CTO as to when it opens ? thanks again.
 

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As Columbo always said "just one more thing" your statement about "The last one is the vacuum line that controls flow in the canister" do I take that is the reason it appears to be plugged up and that it is controlled by the CTO as to when it opens ? thanks again.
Wow, talk about a blast from the past! I remember watching Columbo as a kid.

As I understand it, it is controlled by vacuum. If I'm wrong, someone please speak up!!
 
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