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General Category => General Discussion => Topic started by: brider on March 29, 2023, 02:08:34 PM

Title: Tonti's Revenge airbox drain?
Post by: brider on March 29, 2023, 02:08:34 PM
Now that MGC has the carb boots back in stock, I'm about to re-install my stock airbox on my Cal 2. There is a "port" on the bottom face of the box about 1/2" dia on the CARB-SIDE of the filter; now what the heck would that be for? I had it taped off when I previously used the box to prevent un-filtered air being sucked in, but it bothers me now that it's even there and I can't imagine what its purpose is. The "port" is actually a stub-tube sticking out that has a bulb-ed edge, as if a hose should be clamped to it.

It looks like it ALMOST lines up with the tranny breather screen on the topside of the tranny in that area, and if it was to be used as a PCV device, I could buy that. But it doesn't quite line up.

I'm going to install the box with this port blocked off again, but it just bugs me.
Title: Re: Tonti's Revenge airbox drain?
Post by: guzzisteve on March 29, 2023, 02:54:06 PM
A rubber boot goes on there and is connected to the frame breather system with a hose. Leave it taped off.
There is a pic of it in the Cal II workshop supplement.
Title: Re: Tonti's Revenge airbox drain?
Post by: Antietam Classic Cycle on March 29, 2023, 03:47:20 PM
#33 in this illustration. The 14 end goes to the small fitting up behind the steering head tube, the 35 end goes down towards the ground.


(https://i.ibb.co/PMJtJcx/Cal-II-airbox.jpg) (https://ibb.co/PMJtJcx)



(https://i.ibb.co/xqNhwp9/28157050.jpg) (https://ibb.co/xqNhwp9)
Title: Re: Tonti's Revenge airbox drain?
Post by: nc43bsa on March 30, 2023, 12:32:05 AM
It looks similar to the arrangement on my MilleGT, which goes to the valve cover vents.
Title: Re: Tonti's Revenge airbox drain?
Post by: Antietam Classic Cycle on March 30, 2023, 08:37:57 AM
Quote from: nc43bsa on March 30, 2023, 12:32:05 AM
It looks similar to the arrangement on my MilleGT, which goes to the valve cover vents.

Cylinder head vent hoses go back to the frame cross-member under the rear of the tank. The valve covers themselves have no vent - it's in the head.
Title: Re: Tonti's Revenge airbox drain?
Post by: brider on March 30, 2023, 12:25:23 PM
Quote from: Antietam Classic Cycle on March 29, 2023, 03:47:20 PM
#33 in this illustration. The 14 end goes to the small fitting up behind the steering head tube, the 35 end goes down towards the ground.


(https://i.ibb.co/PMJtJcx/Cal-II-airbox.jpg) (https://ibb.co/PMJtJcx)



(https://i.ibb.co/xqNhwp9/28157050.jpg) (https://ibb.co/xqNhwp9)


Thanks, Charlie, I knew there was a diagram somewhere.

Given those (2) destinations (steering head/overboard), I still am baffled by it's function. If the port was ducted to the valve covers I could understand, but it's in a negative-pressure region and that line going overboard is going to suck grit IN, won't it?

I'll just keep it capped off.