manifold heater

Timgr, I read your response to Bobfortier's question and I thought I'd get some info for my situation.
I'm putting an 83 intake/exhaust combination on my 73 258 and need info on what's required for proper operation of the manifold heater. Is the relay you speak about an aftermarket unit? I noticed in my wiring diagram that it needs a manifold mounted temp sender. Is this a flaps available part also? I'll dig into on my own soon, but I saw your answer to the other question and thought I might as well see what I could find out from someone who knows the topic.
Thanks

 

I'll let TIMGR elaborate but for a quick, short response, let me see if I can help you

The relay is just a typical Bosch relay you could pick up any place.


A couple other important players are the oil pressure switch usually "T"eed in with the oil pressure sensor just above the starter motor.


And the temperature switch you mentioned mounted on the intake manifold


The oil pressure switch draws it's power normally from the Backup Circuit Fuse but you can use any fused 12 volt source.




When there is enough oil pressure, the switch then supplies power to the relay AND the electric choke.

You can see the two red wires running to the electric choke in the previous picture. One wire runs to the oil pressure switch and the other runs to the relay.

The relay then close and power is supplied to the electric manifold heater. I think the power for the Electric Manifold heater comes from a fusable link connected to the starter solenoid.

As long as the water temperature is below 165* the temperature switch in the manifold remanes closed and so does the relay. Once the temperature is above 165* the switch opens and the relay cut out and power is no longer applied to the intake manifold heater.



There is a third connection (not shown above)that goes to the computer and the sol-vac that kicks your idle up a bit to allow the alternator to put out more current output at idle. This is because the electrick chokes opens early and the idle speed cam will drop out early before the the engine is warmed up.



Now if your not going to use the BBD carb, Some of this stuff is not needed or will require some inspiration and innovation on your part to connect it up.
Hope this helps a little.

 

Great answer John - not much I can add. I have '85 manifolds on my '77 truck, and I left the carb heater disconnected. I also have a manual choke.

 

If he goes with a manual choke he probably can run without one also.
What happens is that on a cold stone moring in winter the electric choke will open quickly. Since the manifold is freezing cold a lot of the gas will condense on the floor of the manifold causing a "too lean" mixture for the engine to run.

With a manual choke all you have to do is keep the choke closed a little until the motor warms up. Might not be the best situation if your running a catalytic converter but I never had any problem with running mine without a manifold heater (exhaust heated in my case) and running a manual choke.

The only thing I'll miss when converting mine over to a later manifold is not being able to run my faithful YF carb. I think it's the best carb ever put on the 258.

 

WOW!! GREAT answer, John. That's just about everything I need to know!! Thanks to both you and Timgr for the responses. I'm going to the 2100 carb, maybe I should consider the manual choke. At this time it doesn't look like it will be a middle of the winter vehicle. Mostly spring, summer and fall, so the heater is probably not required. I thought it might cause operational problems if I eliminated it. If you have any oyher suggestions please feel free to add them.
Thanks again, Rick

 

I'm going to install this manifold heater according to the diagram presented here, but was looking for the value of the fusable link that's shown feeding the heater thru the relay.
It seems that although a 25 amp fuse is listed in the manual for the electric choke, all I find is fusable link listed for the manifold heater. Never dealt with fusable links in the past so I'm flying blind here. :?
Thanks

 

I would go ahead and put the link in instead of a fuse.

I was told that on higher current circuits, a fuse could melt down structurally and still have continuity. This would be enough to start a fire leading to a Car-B-Cue. The fusible link is engineered to just burn OPEN before any copper wiring would get hot enough to combust.

 

I recall that Mad Electrical sells the fusible links ... they also have some advice http://www.madelectrical.com/catalog/fusible-link.shtml

Pick the link based on the size of the downstream wiring.

 

I just read that link and it explains everything I need to know.
Thanks

 

napa sells em too