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Center of carb to firewall

PostPosted: Sun Dec 09, 2007 7:39 am
by b1x4nqb
Could someone give me a measurement from the top center of either carb to their firewall?  It's related to mounting an airbox.


PostPosted: Tue Dec 11, 2007 10:24 pm
by stede52
I have mine mounted with an airbox and it is 8.5" to the firewall from the top center of left carb.  that gives me .25" clearance between the airbox controls and the firewall.  I also needed to cut about .25" off the connecting hoses from the airbox to the carbs to get that clearance using the JA 912 airbox motor mount. Are you planning on shimming out your motor mount or getting the airbox motor mount from JA?


PostPosted: Thu Dec 13, 2007 2:40 pm
by DaveU
On 973U, the standard mount, no modifications or shims, my measurements from the top center of the carbs to the firewall are:

Left  7 1/8"  (7.125")
Right 7 7/8" (7.875")

What has changed that everyone is using the airbox?  I was not aware that any Just Aircraft bird has used an airbox until this year.  Did some safety issue arise?  I am assuming that the airbox is just to get carb heat.  I am not sure of any other reason to use it.

Correct me if I am wrong.


PostPosted: Fri Dec 14, 2007 1:23 am
by stede52
Dave, you're correct it does give you carb heat capability and an additional 5 hp if you use fresh air into the airbox.  the 912S is rated at 100Hp only if the airbox and fresh air is vented into it.  I'm using an airbox becasuse here in the NW we get such moist cold air in the winter and I want to be absolutely sure I don't get iced up, especially over the mountains.  :)

PostPosted: Fri Dec 14, 2007 1:35 am
by stede52
Dave, by the way, I think I was only the second person to order the new airbox mount from JA and that was only 3 months ago.  It was tested on a Cornell airplane for fit and function only only a couple of months before that. The others before that were shimming the standard mount to get the airbox to fit.