Rebuild my choke to Electric. What with the "holes"

[YOBE]

Hi,

As my old choke was "missing" (the type that uses the exhaust gases) I installed an electric Choke.
Of course on the manifold I have the tube that was connected to the old choke. I suppose I can close this off?
But I also noticed an additional hole in the manifold below the other one (not sure about is function). But I guess I can also close this one now. Right?

Thanks Yorick

PS: and I just want to share my gratitude for this forum. Already learned a lot!!

 

[Scott Danforth]

what is it we are working on?

 

[YOBE]

what is it we are working on?

I rebuild my Choke to an electric one, so I guess I can close the 2 holes on my manifold related to the old chocke system.
Perhaps I better include this picture.
In this picture you see the upper connection that I dont use anymore. But below this, theres another "hole" in the manifold.

 

[Grub54891]

" Usually there is a heat sink under the first tube. Tin cover where the tube connects. I haven't seen one with another hole below myself.

 

[kenny nunez]

If you are asking about the other hole are referring to the hole on the bottom of the manifold? If so be sure that there is not an exhaust leak in that area. The 1/4” tubing has to go all the way through to seal off the exhaust.

 

[YOBE]

If you are asking about the other hole are referring to the hole on the bottom of the manifold? If so be sure that there is not an exhaust leak in that area. The 1/4” tubing has to go all the way through to seal off the exhaust.

I’m referring to this extra hole (no idea why it’s there)

 

[Grub54891]

Hymn… thats weird. Never saw a hole there myself. If possible, tap some threads in it and install a plug.

 

[Scott06]

I’m referring to this extra hole (no idea why it’s there)

whats the serial number on the engine you are working on? this will help see in parts diagrams what should be there

Usually the hot air style chokes had a tube inside to heat the air to the choke from the exhaust gases. On an old V8 this would be in the exhaust crossover in the intake. The sheet metal tubes rust out leaving you with a hole. The one with compression fitting on it get a compression cap good to go, other one need to tap and stick a screw in

 

[Lou C]

OK if I had to guess, I think what was there, was a fresh air intake tube, that fits into the hole feeding the metal tube that's threaded into the exhaust manifold. The way it would work, is like this:
the tube that connects to the choke housing is under vacuum from a passage in the choke housing, this would suck fresh air thru that missing tube in the exhaust manifold which would then heat the air in the tube and that would be sucked across the choke thermo spring and open the choke as the engine warmed up. My 1970 Ford 302-2bbl had something similar but the Ford had that tube fed with air that was filtered by the air filter. I'll see if I can edit your pic to explain what I mean....
So where your finger is, the fresh air would get sucked in there, and then heated by the exhaust flow, and then sucked across the choke thermo spring....make sense?
If not using a hot air choke this hole should be plugged or else you'll have an exhaust leak there.
On my Ford there was a rubber tube at the end of that external tube (by your finger) and another tube was connected to that, which went up to the air filter to supply filtered air, but often these parts just rusted off and most never replaced them....

 

[Lou C]

Here's a pic of what I'm talking about, the tube with the insulation carried hot air up to the choke housing, the one with the rubber tube brought down fresh air from the air cleaner...

 

[Scott06]

OK if I had to guess, I think what was there, was a fresh air intake tube, that fits into the hole feeding the metal tube that's threaded into the exhaust manifold. The way it would work, is like this:
the tube that connects to the choke housing is under vacuum from a passage in the choke housing, this would suck fresh air thru that missing tube in the exhaust manifold which would then heat the air in the tube and that would be sucked across the choke thermo spring and open the choke as the engine warmed up. My 1970 Ford 302-2bbl had something similar but the Ford had that tube fed with air that was filtered by the air filter. I'll see if I can edit your pic to explain what I mean....
So where your finger is, the fresh air would get sucked in there, and then heated by the exhaust flow, and then sucked across the choke thermo spring....make sense?
If not using a hot air choke this hole should be plugged or else you'll have an exhaust leak there.
On my Ford there was a rubber tube at the end of that external tube (by your finger) and another tube was connected to that, which went up to the air filter to supply filtered air, but often these parts just rusted off and most never replaced them....

that is it

if you click on the pic of this intake manifold off a 165 (just swagging the engine has to be a 3.0 or 165 st 6 by pic) you will see the tube you mention

https://www.marineengine.com/newparts/part_details.php?pnum=MER58759A13

if you can find a welch plug like used in carbs that would probably pound in ok

 

[Lou C]

LOL
sometimes obsolete knowledge is useful to someone.

 

[Scott06]

LOL
sometimes obsolete knowledge is useful to someone.

Yes and we know you have enough pictures already to start your quadrajet only fans site… if you know the principles of how it should work you don’t need a manual and can figure it out.

 

[YOBE]

OK if I had to guess, I think what was there, was a fresh air intake tube, that fits into the hole feeding the metal tube that's threaded into the exhaust manifold. The way it would work, is like this:
the tube that connects to the choke housing is under vacuum from a passage in the choke housing, this would suck fresh air thru that missing tube in the exhaust manifold which would then heat the air in the tube and that would be sucked across the choke thermo spring and open the choke as the engine warmed up. My 1970 Ford 302-2bbl had something similar but the Ford had that tube fed with air that was filtered by the air filter. I'll see if I can edit your pic to explain what I mean....
So where your finger is, the fresh air would get sucked in there, and then heated by the exhaust flow, and then sucked across the choke thermo spring....make sense?
If not using a hot air choke this hole should be plugged or else you'll have an exhaust leak there.
On my Ford there was a rubber tube at the end of that external tube (by your finger) and another tube was connected to that, which went up to the air filter to supply filtered air, but often these parts just rusted off and most never replaced them....

AHA, yep, now it makes sense. There is a missing tube. Past night I closed both holes.
And thanks for the info sharing.

 

[Lou C]

That 1970 Ford had a choke that took forever to warm up, fixing it was how I learned about that system. No electric choke conversions were out there in 1977 or so when I had this car. What I found after thinking it thru & trying a new thermostatic choke spring to no avail….that choke housing has to be relatively air tight, if it leaks vacuum enough cold air will get sucked in that the choke never opens. So testing with a bit of motor oil I found that it was loosing vacuum along the choke shaft. 2 fiber washers one on each side of the fast idle cam fixed the vacuum leak!
Two different mechanics were unable to figure this out lol.
Electric chokes are easy BUT:
Keep in mind they must have an in-interrupted source of current or they will close and make your engine run way too rich
Sometimes they open too fast before those old cast iron beasts are warmed up, but you can adjust the spring tighter…