Originally Posted by
affas
@njmheli
Did you some temp measurements before and after gas cnversion? I do have the same engine in my Corsair with Adrian ignition but still on glow. Thinking of gas conversion but always running hoter and a little weaker..
Hi Alf.
I did another run with the 7-77,so here are some figures for you................I guessing you already have some for your 7-77 running on glow...?
I am running a fuel mix at 16:1 ( but will change to 20:1,as the plugs are getting a little "oiled" at the higher mix ).........prop used was the Biela 22" x 10 x 3BL....The ambient temp was 11 degrees C...........@ 1022mbar pressure. The Max RPM's today were 5950.......I didn't want to go any higher at the moment,the UN-COWLED readings were :
1400 RPM ( very stable ).........................22 to 30 degrees C
4500 RPM ( held there for 3 minutes ).....46 to 52 degrees C
5000 RPM ( held there for 3 minutes ),,..49 to 58 degrees C
Readings were taken at the front centre of the cylinder head area................the #2 cylinder for some reason was giving the lower readings mostly..?
I have decided to go back to using the stock cowling on the Corsair,but I have moved it FWD by 12mm,using "slit blocks" of ply".... Stablitt Expressed to the mountings on the cowl.
By doing this,you can take advantage of the "open-cowl flaps" and increase the area for the air to exit the cowl,always good to get as much cooling air out !!!!
I also think that for 7-77 users to change to gas,If using the 84 Carb set-up....? will be very easy and still will use the 25mm Ply mounting "bock" ( if using that method )...........
Using 45mm ( 6mm bore ) engine stand-offs to make room for the 84 carb,between radial body and mounting flange + 55mm long countersunk M6 bolts..........on my set-up,the distance from the face of the prop-driver to the mounting flange face is 160mm ( FG 84 is 172mm )...........so roughly calculate,that with moving the cowl 10mm or so FWD and still using the 25mm mounting ply block,you will end up pretty good..in relation to the rear of the prop / front of cowl...?
The velocity stack protrudes 20mm from the face of the 7-77 mounting flange...............so no problem there...?
Carburetor complete G84R3..............pt # SAIG84R3821
see photos below..........
Kind regards...................Nick (UK).