Question about exhaust/heat exchanger Big Twin 40hp

Good evening folks,

Worked on my 1969 40hp Big Twin Lark this weekend. Began with some re-wiring on the engine as you will see in the pics below. Also removed the electric choke (as it was busted beyond repair) along with the exhaust/heat exchange conduit to the electric choke control (which was also busted).

I plugged the top heat exchanger hole with a plug (screwed in), but was wondering if the bottom heat exchanger hole needed to be plugged too? You will see in the pic below that I screwed plugs into both.

Am I OK in doing this? Does the bottom screw hole need to be left open for heat exchange/cooling of some sort? Should I leave both open?

Any help is good help...

http://i1072.photobucket.com/albums/w368/Jwdspics/5b5d35fb.jpg

Re-wired...http://i1072.photobucket.com/albums/w368/Jwdspics/f906a8ce.jpg

Thanx!

JD

Re: Question about exhaust/heat exchanger Big Twin 40hp

I have seen them plugged that way before.

Re: Question about exhaust/heat exchanger Big Twin 40hp

Since you removed the choke tube, the heat exchanger is doing nothing but going along for the ride. You can plug either hole, both holes, or neither hole. Unless the heat exchanger is rusted out, in which case you will have to plug both holes to prevent exhaust from blowing out.

Re: Question about exhaust/heat exchanger Big Twin 40hp

Mine are both plugged, but F_R is absolutely correct, neither needs to be plugged if the heat exchanger is intact.
I even have a plug in the side of the choke to keep the mud daubers out, but that is another story. They try to plug every opening in my boat, gas soaked or not.

Re: Question about exhaust/heat exchanger Big Twin 40hp

Thank you for the great info!

JD