|
| Author |
Message |
    
keith
Senior Member
Username: keith
Post Number: 176
Registered: 02-2002
| | Posted on Tuesday, December 28, 2004 - 08:37 pm: | 
|
I am looking for the expert advise that can be obtained from this board. A friend, who had seen my restored Fay & Bowen, droped off his engine, for me to try and get running. This engine is out of a 1903 18' Fay & Bowen Fantail Launch that has been restored. He has had several people work (restore) this engine, but has never been able to get it running. It has been honed with what I think are new rings but has very little compression. I have tried plenty of oil to help seal, but have not had any sucess getting even a strong pop. I even hooked it up to a electric motor and spun it for a couple of hours. I pulled it apart and it has taper in the cylinder. It's about .015 clearance at the top of the cylinder and about .007 at the bottom. The rings are 3/8 wide. My question is, with this being a working engine, vs a display engine, and it has to make horsepower: what is an acceptable taper or clearance for piston to bore? I am going to be out of town for a few days, but I will let you guys kick this around for a while. |
paulgray
Senior Member
Username: paulgray
Post Number: 118
Registered: 05-2003
| | Posted on Wednesday, December 29, 2004 - 05:44 am: |
|
Keith- When you say new rings, did the person who installed them check the side clearance? If the grooves are "v"-shaped a bit with the new rings it may not be sealing when you come up to compression. As to the taper, I can only offer an opinion that it should be OK to run; albeit on the edge of being acceptable. The other thing to check is if the bore is out-of-round. Check the side clearance, fix if necessary and if it runs OK stop. If it still refuses to get compression, you may want to drop back and think about having it bored slightly over to fix the taper and spray the piston; still the ring grooves may need attention. |
ernie
Senior Member
Username: ernie
Post Number: 453
Registered: 01-2002
| | Posted on Wednesday, December 29, 2004 - 07:07 am: |
|
Pauls comments above mirror my thoughts. The taper is on the large side, however if the cylinder is reasonabally round it should work. Additionally what is the end gap? .004 in per in of bore is a good number for any engine. Example .016 for a 4 inch bore. Check the end gap at the bottom and the top. It can be less than .004 per inch at the bottom.
Ernie |
rholcomb
New member
Username: rholcomb
Post Number: 3
Registered: 10-2004
| | Posted on Wednesday, December 29, 2004 - 10:47 am: |
|
last year the frisco did the same spin flywheel over pop pop nothing....
Turned out the shaft on the hammer of the ignitor had enough rust and grease to allow it not to ground took it apart cleaned and sanded all parts washed out with solvent and away we went... just an option????? |
jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 226
Registered: 07-2002
| | Posted on Thursday, December 30, 2004 - 07:29 am: |
|
For this engine to give dependable performance it will need good compression, a good bounce. I think the wide rings will be very hard to seat in a poor cylinder, the width will keep the top edge from touching in a tapered bore. Rings that have worn with the cylinder compensate for this. I've thought of making ring spacers and using an automotive type ring but I haven't tried it. The piston could be trued and the spacer, machined to fill the gap and hug the piston, placed on the top, allowing the ring to seal against the lower land of the piston. I improved compression on a farm engine with similar problems by machining a new ring groove above the existing grooves, this piston had a 3/4" blank space, room to put a 1/8" ring. The smaller rings flex better, have less drag and are more forgiving to worn cylinders. |
miro
Senior Member
Username: miro
Post Number: 161
Registered: 11-2001
| | Posted on Sunday, January 02, 2005 - 06:53 am: |
|
I think the main event here are the rings - as every one else has said.
If you can find 2 rings to fit in the groove - that might be the trick - and ring side clearance is the single most important thing.
The rings should occupy at least 90% of the groove depth. If you do use 2 rings, pin them if you can on opposite sides of the piston. And try to make sure the ends of the rings are not aywhere near the intake of exhaust ports.
You've probably checked for carbon clogging the exhaust port, and other obvious things. |
keith
Senior Member
Username: keith
Post Number: 178
Registered: 02-2002
| | Posted on Wednesday, January 05, 2005 - 10:05 am: |
|
Thanks everyone, for the response. Based on everyone's observation, I think I may try putting a .001 to.002 taper on the top two rings. The side clearance seems to be minimal. I will also look at the ignitor. It sparks fine when out of the engine though. I will let you know how I make out. |
|
|
|
|
