Original Posted By: "Jack Phillips"
Jack,I believe that there are a number of articles in old Sport Aviations thattalk about the Olds 215 conversion in detail. I also think that conversionplans are currently available from ACS. Look in the catalog front where theplans are for the Tailwind.If you have a small continental flat four and it gives zero psi oil pressureat idle when the engine warms up, it is because the cam bearings are worn.My opinion is that this the only weakness in a great bottom end of a greatseries of engines. There would be a lot more of these engines out theretoday if Continental had used bearing inserts for the camshaft.The continental series uses an annulus in the front cam journal to transferthe oil from the left side of the case to the right side. Therefore thatjournal has maybe two thirds the surface area and still takes a load fromthe valve springs. It is also the "end" of the camshaft so it can't sharethe load with the journals on either side of it like the center journal can.If you all go out and look at the A-65 cases you might have, look at thisarea and notice the grooves worn into the case by the cam journal. Thismakes for one huge oil leak that most owners discover only after the engineis assembled and run.Zero oil pressure at idle with a warm engine does not bode well forlongevity.Chris BobkaTech Counselor----- Original Message -----
Pietenpol-List: Olds 215 and camrunning directly on the aluminum
RE: Pietenpol-List: Olds 215 and camrunning directly on the aluminum
Original Posted By: "Michael Brusilow"
-----Original Message-----Jack,I believe that there are a number of articles in old Sport Aviations thattalk about the Olds 215 conversion in detail. I also think that conversionplans are currently available from ACS. Look in the catalog front where theplans are for the Tailwind.If you have a small continental flat four and it gives zero psi oil pressureat idle when the engine warms up, it is because the cam bearings are worn.My opinion is that this the only weakness in a great bottom end of a greatseries of engines. There would be a lot more of these engines out theretoday if Continental had used bearing inserts for the camshaft.The continental series uses an annulus in the front cam journal to transferthe oil from the left side of the case to the right side. Therefore thatjournal has maybe two thirds the surface area and still takes a load fromthe valve springs. It is also the "end" of the camshaft so it can't sharethe load with the journals on either side of it like the center journal can.If you all go out and look at the A-65 cases you might have, look at thisarea and notice the grooves worn into the case by the cam journal. Thismakes for one huge oil leak that most owners discover only after the engineis assembled and run.Zero oil pressure at idle with a warm engine does not bode well forlongevity.Chris BobkaTech CounselorI have to agree with you Chris. One of the last things I need to do beforerebuilding my A65 is to send the crankcase out to Divco to be overhauled bymilling the mating faces down and then re-boring the camshaft bearings. Imeasured the clearance between my cam and the bearings using plastigage andfound it to be right at the limits. I will need a new cam anyway (the oldone has the front lobe worn off) and don't want to run a new cam in old wornout bearings or it will be worn out in short order.The O-200 in my Cessna 140 has over 1400 hours on it and is beginning tohave low oil pressure at idle on hot days. I'm sure it too has worncamshaft bearings. My point in remarking on the Subaru was that it is quitepossible to get 1500 hours of operation out of such bearings.Jack________________________________________________________________________________
-----Original Message-----Jack,I believe that there are a number of articles in old Sport Aviations thattalk about the Olds 215 conversion in detail. I also think that conversionplans are currently available from ACS. Look in the catalog front where theplans are for the Tailwind.If you have a small continental flat four and it gives zero psi oil pressureat idle when the engine warms up, it is because the cam bearings are worn.My opinion is that this the only weakness in a great bottom end of a greatseries of engines. There would be a lot more of these engines out theretoday if Continental had used bearing inserts for the camshaft.The continental series uses an annulus in the front cam journal to transferthe oil from the left side of the case to the right side. Therefore thatjournal has maybe two thirds the surface area and still takes a load fromthe valve springs. It is also the "end" of the camshaft so it can't sharethe load with the journals on either side of it like the center journal can.If you all go out and look at the A-65 cases you might have, look at thisarea and notice the grooves worn into the case by the cam journal. Thismakes for one huge oil leak that most owners discover only after the engineis assembled and run.Zero oil pressure at idle with a warm engine does not bode well forlongevity.Chris BobkaTech CounselorI have to agree with you Chris. One of the last things I need to do beforerebuilding my A65 is to send the crankcase out to Divco to be overhauled bymilling the mating faces down and then re-boring the camshaft bearings. Imeasured the clearance between my cam and the bearings using plastigage andfound it to be right at the limits. I will need a new cam anyway (the oldone has the front lobe worn off) and don't want to run a new cam in old wornout bearings or it will be worn out in short order.The O-200 in my Cessna 140 has over 1400 hours on it and is beginning tohave low oil pressure at idle on hot days. I'm sure it too has worncamshaft bearings. My point in remarking on the Subaru was that it is quitepossible to get 1500 hours of operation out of such bearings.Jack________________________________________________________________________________
Re: Pietenpol-List: Olds 215 and camrunning directly on the aluminum
Original Posted By: "Jack Phillips"
Jack,It is good to see you checked that troublesome area. Milling the case opensanother whole can of worms. It moves the cylinders closer to the crankshaftcenterline. You have to also check the clearance on the connecting rodbolts to the bottom of the cylinder barrels (dry assemble one side and lookthrough from the other side and then swap side for side). Also, it movesthe tops of the valve pushrods out and you may wind up not getting yourdeflated valve lifter clearance we talked about a few weeks ago of .3 to.11inches. This would necessitate getting the shorter pushrods made up(someone says that Fresno Airparts has these). Also, if the valve seats areground deep, then you take away this clearance as well.An engine machinist friend says that bearing inserts are available in justabout any concievable size and even custom ones can be made for less thanthe cost of sending out the case.Your cam can have the lobe rewelded, ground, and hardened. If yo are tohave the case reworked, you could have the journals on the cam turned downand then have the case remachined to fit, that way you have material you cantake off next time you do and overhaul.Chris----- Original Message -----
Jack,It is good to see you checked that troublesome area. Milling the case opensanother whole can of worms. It moves the cylinders closer to the crankshaftcenterline. You have to also check the clearance on the connecting rodbolts to the bottom of the cylinder barrels (dry assemble one side and lookthrough from the other side and then swap side for side). Also, it movesthe tops of the valve pushrods out and you may wind up not getting yourdeflated valve lifter clearance we talked about a few weeks ago of .3 to.11inches. This would necessitate getting the shorter pushrods made up(someone says that Fresno Airparts has these). Also, if the valve seats areground deep, then you take away this clearance as well.An engine machinist friend says that bearing inserts are available in justabout any concievable size and even custom ones can be made for less thanthe cost of sending out the case.Your cam can have the lobe rewelded, ground, and hardened. If yo are tohave the case reworked, you could have the journals on the cam turned downand then have the case remachined to fit, that way you have material you cantake off next time you do and overhaul.Chris----- Original Message -----
Re: Pietenpol-List: Olds 215 and camrunning directly on the aluminum
Original Posted By: "Jack Phillips"
If you mill the case halves you will increase the compression ratio.Different pistons?Different rods?Morgan----- Original Message -----
If you mill the case halves you will increase the compression ratio.Different pistons?Different rods?Morgan----- Original Message -----
RE: Pietenpol-List: Olds 215 and camrunning directly on the aluminum
Original Posted By: owner-pietenpol-list-server(at)matronics.com
You might be talking an increase in compression of .5% which isinsignificant.The point is that many of the clearances in the valve train do not have thegive if things stack up agianst you rather than averaging out.Ususally you have one thing a little short and another a little long and thetotal number adds up to be what you want. In the case of milling the cases,it seems that it always goes against you.-----Original Message-----
You might be talking an increase in compression of .5% which isinsignificant.The point is that many of the clearances in the valve train do not have thegive if things stack up agianst you rather than averaging out.Ususally you have one thing a little short and another a little long and thetotal number adds up to be what you want. In the case of milling the cases,it seems that it always goes against you.-----Original Message-----