Fly cut the case for the bigger bore, and the 320 cylinders bolt up.
No worries about stud wall thickness, clearance issues, stroke, etc.? COOL!
That'll be the best news I've had in awhile!
Thanks.
Tom
Fly cut the case for the bigger bore, and the 320 cylinders bolt up.
Check Six said:Fly cut the case for the bigger bore, and the 320 cylinders bolt up.
No worries about stud wall thickness, clearance issues, stroke, etc.? COOL!
Tom
Steve Pierce said:I have to talk to Ken today on about an engine. I will ask him.
Steve Pierce said:Ken didn't know for sure but said if the bolt pattern was the same it should work. They do it all the time to make a 580 out of a 540. Might be worth looking into for an STC with no new O-290 cylinders out there.
I looked at the sump for a 290 and a 320 and it appears the mount and intake inner diameter for the carburetor are larger for the 0320 and therefore changing sump would be required. A MA4-spa carb would be required. Anyone have tips on jetting needed or would any ma4-spa work?
For the case: yes a 0320 is a punched out 0290-d2 as far as I have heard, makes sense. Any machine shop should be able to do it for your air boat. Would you have to machine out a 290d case to accept hydraulic tappets? I bet the d case would only work for the conversion if you stuck with manual tappets and the lower lift D cam.
Camshaft: the cam for the d2 has the higher lift than a d cam. Are 0320 and d2 cams the same part number?
There are two types of cams. Integral and seperated. Does anyone have any pics of the different tach drives required for each?
Crank: the 290 crank would have a thinner flange than a 320 crank. This is the only area that makes me uncomfortable. Possibly welding on the half moon doublers from aircraft spruce would suffice? A 290 crank is I believe 10lb lighter than a 320? I wouldnt go over the 150hp pistons without a 320 crank and or the reinforcement welded in.
Prop: I would go catto. It's lighter so stress should be less on the crank from each ignition stroke right?
Perhaps we can compile some real information. All I have found on this conversion so far is speculation. Lets get some part numbers going etc.. if people are really interested.
I am curius if the new d crank I have will work for the conversion. What's the difference between d and d2 cranks?
I also read something about the 320 cam being put in a 290 and since it was longer it caused oil to sling out the breather? Anyone know anything about that?
The 320 crank will bolt in the 290 case, the 320 crank just has a thicker prop flange. No difference between the290- D and the D2 crank.
As I posted earlier, I used a 290-G cam and solid lifers because I had then on hand.
Also used 290-D2 pistons and 320 carb.
If you don't like the thinner flange on the 290-D crank, there used to be a flange reinforcement kit for the thin flange cranks on the Lyc-290-G conversions that you could use to the 290-D crank.
....Crank: the 290 crank would have a thinner flange than a 320 crank. This is the only area that makes me uncomfortable. Possibly welding on the half moon doublers from aircraft spruce would suffice? .....and or the reinforcement welded in.
I have been reading this thread only out of curiosity with no intention of performing any of these mods myself. However, your above statement gives me pause. Welding on a crankshaft flange?? This seems a bit risky without further explanation. I assume that these half moons are placed behind the flange and are welded around the outer circumference only? And, that the crank was checked for magnetism and balance afterwards? How does this extra flange thickness transfer the stresses into the crankshaft? Through the old thin flange? I am assuming (hoping) that you did not weld the inner portion of the half moons to the crank where the stresses from the propeller loads are the highest and where the flange could crack from the welding? Just asking. And asking that you please not invite me for a ride.
As an aside, I have seen crank flanges which were cracked between the lightening holes in all but one section. The propeller was close to departing the airplane. This was on a TriPacer. Just food for thought.
Dan D, wrote: The prop flange reinforcements that was sold for the Lyc-290-G conversions back in the 60's/70's was two half moons that fitted together behind the prop flange and bolted to the crank flange with the prop bolts. I had one at one time back at that time and think I gave it to someone that needed it. The 290-G ground power unit crank had a prop flange thinner that the aircraft 290-D. I think it was the same as the Lyc-235.
Dan. Dan, I think the 0-290 "G" crank was indeed a crank from a lyc -235. I have a 0-290 "G" without the flange reinforcements...was wondering where I might find a set of them...
Is the cracking through the lightening holes the reason they say max power only for 5 minutes? What is the origin or reason of this statement? Perhaps I should make sure that's on my annual inspection list.
That was back in the early 80's and I don't remember what the C/R was. But I loved that engine. If I have it today it would go in my Bearhawk project. I live on a runway and one of my neighbors was a IA and he always thought it was a Lyc-360 by the way the aircraft performed until I told him what it was. Dan
Did you have to do any jetting when swapping to the 320 carb and sump? Smoothe acceleration, or any coughing?