stunthanger.com
Engine basics => Engine set up tips => Topic started by: proparc on February 04, 2015, 06:31:50 PM
-
This may have been covered before,(what hasn't) but, can anyone tell me anything about the Rojett 67 Long Stroke. I am specifically interested in the side exhaust version,(if it exists).
-
Hi Milton, Yes the RO Jett .67 has a side exhaust version and rear exhaust. I have both. Per the horses mouth Richard Oliver 7,000-11,000 RPM
may be used with a pipe or without. Mine were used with a custom RE muffler by Scott Dinger. Kaz Minato was selling The SE with a muffler I
think the SE muffler was made by Dubb Jett? Lots of torque Richard Oliver said he can use the same size props as he did on the .76. Since PA.65
is no longer available this is a great option. Mine used 6 oz of fuel for the pattern( RE Muffler)
-
I picked up a ROJETT .76 & .67 RE I run them both on a Header Baffle no pipe setup . I use a high pitch prop . I use an APC 12-7 . I opened the venturi to .205" it starts first flip runs like an electric motor smooth. Wide power band . I will get another this month. I cant tell the difference between the . 67 & .76. Not as powerful as my PAs but powerful & easy to use. They are physically identical. 12.6 ounces without header.
John
-
Not as powerful as my PAs but powerful & easy to use. They are physically identical. 12.6 ounces without header.
John
Those PA's must have been seriously powerful. :o :o
-
Those PA's must have been seriously powerful. :o :o
A 12-7 with an in-flight revs of around 8500 isn't much prop for a 67 or 76, so he is nowhere near the limit. People have run that on an stock ST46 in hot weather. Sounded bad on the ground but OK in the air.
I think most people running the 76 on a muffler wound up with something like a 14-6 and 15-6 would not be out of the question (as far as the engine goes). PA75, I would expect about the same but maybe even a 15-5 2-blade. I have run 13.5-3.75 3-blades at a launch RPM 0f around 9700 on the teeny little RO-Jett 61. Engine didn't mind that, but my right wrist did.
No one is coming close to the limitations of these engines because you run out of tolerance for larger props long before the engine runs out of capability. And in any case, larger diameter is the '70's way of defining power.
Brett
-
One of the Las Vegas guys competes with a Shark 45 w/SE RO-Jett 67 so I know it exists. I'd just call Dubb and check on availablity. Most are custom ordered. BTW-it sounds GREAT! 8)
-
I picked up a ROJETT .76 & .67 RE I run them both on a Header Baffle no pipe setup . I use a high pitch prop . I use an APC 12-7 .
John
John, is the Rojett 67 more economical on gas than the 76.
-
The interesting/cool thing about the RO-Jett BSE's is that you can send them to Dubby and he will convert them from SE to RE or RE to SE for a pretty reasonable charge. I'd guess that if you wanted SE but on the other side, he could do that easily.
I bought Walter Hicks' (used) RO-Jett .76 SE and sent it in to get it changed into an RE. I talked to Dubby on the phone about doing this, and figured a new piston would be in order, so extra charge. "Nope, these things are round" Compression is just fine, too. D>K Steve
-
Hi Mr. Proparc , my .67 & 76 use the same amount of fuel. I think its 5 ounces for over 7 minutes, that's in a solid 4 stoke the whole flight , very little break in maneuvers.
-
Hi Mr. Proparc , my .67 & 76 use the same amount of fuel. I think its 5 ounces for over 7 minutes, that's in a solid 4 stoke the whole flight , very little break in maneuvers.
What % nitro are you running ?
-
15% All synthetic