Firewall hole for ram air cable

[John Martindale]

Hi folks

My 1977 M20 J (S/N 24-0039) with quadrant controls has all the  fittings for a ram air cable that was removed some 40 years ago. However, I cannot find where that cable passed through the firewall; there is no obvious hole to spare!! The Parts Catalog (76-00-01) shows it to be close to the throttle cable but that diagram relates to later models with push pull controls. Annoyingly, the diagram (76-00-00) relating to my serial number does not show the location on the firewall. Could someone with an early 201 please enlighten me as to where I should be looking....preferably with a photo of the location. The -dash suffix on each of the cables differ, suggesting they are different in length and thus mount in different locations both at the firewall and the dash panel.

Thanks in anticipation and please stay safe over there.

Regards John in Australia.

[carusoam]

John,

While we wait for the white night to arrive...

If your intake was updated to eliminate the value of the ram air system... much better intakes were available on newer Mooneys...

Are you trying to put it back?

Best regards,

-a-

[John Martindale]

Geday -a-

Seems to be a bob each way here by Mooney. Mine was only the 39th J off the factory floor and the second to be imported to Australia in 1978, perhaps before any bets were laid.

It has the panel hole, microswitch bracket and wiring, panel warning light, cable brackets, butterfly in the intake (wired shut) but no cable or hole in the firewall that I can find. It also has the main air intake mounted up in the LH engine cooling inlet like the later J's, not down low above the nose wheel like the F's.

but....yes, I do want to reinstall the cable appreciating the advice already received here and via the Mooney SB that it is no longer considered necessary.

I suspect the firewall may have been re-manufactured minus the hole after a heavy landing around 40 years ago but there is nothing specific in the logbooks to confirm that.

Regards John

 

[carusoam]

John,

Great details in your question..!
 

We can ask the doc... @M20Doc (question about control cable for early J’s ram air )

Its a bit late on the East Coast... so it may take a while to see the request... 

Best regards,

-a-

[Skyland]

John,

I just recently did the SB to remove the ram air system on my '79 J.  Picture shows a 7/16" (as I recall) nut and bolt used to plug the firewall hole from the removed cable.

---Ken

[Bartman]

I snapped this during my engine removal. It’s in the pilot side footwell behind the right rudder-brake pedal. In this picture it is the cable coming out of the firewall. If yours has been removed I bet someone used it for wiring such as engine monitor. 

[John Martindale]

Geday Ken and Bart

I swear that hole you guys have pictured does not exist in my firewall SN 24-0039 (1977), viz, I guess only the 39th J off the floor. If your J's have the quadrant controls (SN less than 24-0377) found in the really early Js then the cable would have to take a god almighty S bend behind the panel to get from the knob on the passenger side to above your right feet as the pilot and the later cables are just not long enough to do it.

I had my re-installation finished last week (bought it out through the firewall above the throttle cable) and today took it for a test flight. At 3500 feet there was only a 3 knot difference in TAS using the CSG network GPS derived calculator http://www.csgnetwork.com/tasgpscalc.html  ) and about 5 knots at 8500 feet. Is it worth it? As many have said, probably not but it has been an interesting and educational exercise and the support on this site has been invaluable. Thank you all.

Regards John

[carusoam]

John,

If you can...

Have a look at the updated parts for improvements in the other things it can do...

Somewhere along the way... there were improvements in how the air separates out rainwater on the way to the filter...

There may be a different door used for when the intake gets filled with ice... (Alt air system)

Stuff I remember, barely...   not a sales pitch... or ringing endorsement...

Congrats on getting to the break-in flights...

Best regards,

-a-

[mike_elliott]

On 5/31/2020 at 5:38 AM, John Martindale said:

Geday Ken and Bart

I swear that hole you guys have pictured does not exist in my firewall SN 24-0039 (1977), viz, I guess only the 39th J off the floor. If your J's have the quadrant controls (SN less than 24-0377) found in the really early Js then the cable would have to take a god almighty S bend behind the panel to get from the knob on the passenger side to above your right feet as the pilot and the later cables are just not long enough to do it.

I had my re-installation finished last week (bought it out through the firewall above the throttle cable) and today took it for a test flight. At 3500 feet there was only a 3 knot difference in TAS using the CSG network GPS derived calculator http://www.csgnetwork.com/tasgpscalc.html  ) and about 5 knots at 8500 feet. Is it worth it? As many have said, probably not but it has been an interesting and educational exercise and the support on this site has been invaluable. Thank you all.

Regards John

wow, to gain 5 kts has to be a significant increase in HP. Im not so sure this can be achieved by the ram air open on a J model by itself. 

[OR75]

Changed the oil today ... took a few pictures.... hope this helps 

quadrant controls and still have the Ram air 

Ah for whatever reason ... the last picture which shows where the cable goes through the firewall is rotated 90degrees 

 

 

Edited June 9, 2020 by OR75

[carusoam]

See if this helps...

-a-