Any Continental W670 experts on here?

[TubularFab]

Hello - I found this forum while searching for a forum on radial engines. I have a Continental W-670 from a WWII landing craft / tank that I had set up on a stand for running at old engine shows. I had replaced the electric starter with a hand crack inertia starter and had it running great. Before starting I always removed the bottom cylinder spark plugs and hand turned it several revolutions to drain any accumulated oil - and it always had some if it sat very long. The last time I started it I had gone through this procedure. But, after priming it and winding up the starter it fired about 2 times then almost turned the stand over coming to an abrupt stop.

The only thing I can figure is there must have been some oil in an intake runner that didn't go in until it started moving faster than my hand cranking, and that it hydrualiced on it. This was about 15 years ago, and it's been sitting in the back of my shop since. I didn't want to tear into it and leave it as a basket case - and it's probably a good thing I didn't!

The crank turns freely about 355-360 degrees before it tightens and stops. I'm guessing a slave rod bent just enough that it is hitting the bottom of a jug - but that's just a guess.

I could use some advice on the best way (least disassembly) to figure out if it is just a bent slave rod and would be easy to repair. Is there any point of access that I could snake a borescope into the crankcase and try to see what damage was done? If it is damaged beyond repair I'd rather not disassemble and just try to see it for a display or parts. I am a mechanical engineer and an extremely experienced mechanic - just not with radials! The only radial I have partially dismantled is a little 5 cylinder Lawrance APU, and I didn't go in very far.

Any input would be appreciated!

 

[MIflyer]

I suggest you go over to Antique Aircraft Restoration Services and ask them. They restore biplanes and they probably known quite a bit about R-670's. There are differences between the R-670 and the W670 - like the type of pistons used and the length of the crank - but I doubt that matters for your problem. Also AirRepairinc.com does overhauls and may be able to answer questions.

Good luck!

 

[Jimbob]

Hello - I found this forum while searching for a forum on radial engines. I have a Continental W-670 from a WWII landing craft / tank that I had set up on a stand for running at old engine shows. I had replaced the electric starter with a hand crack inertia starter and had it running great. Before starting I always removed the bottom cylinder spark plugs and hand turned it several revolutions to drain any accumulated oil - and it always had some if it sat very long. The last time I started it I had gone through this procedure. But, after priming it and winding up the starter it fired about 2 times then almost turned the stand over coming to an abrupt stop.

The only thing I can figure is there must have been some oil in an intake runner that didn't go in until it started moving faster than my hand cranking, and that it hydrualiced on it. This was about 15 years ago, and it's been sitting in the back of my shop since. I didn't want to tear into it and leave it as a basket case - and it's probably a good thing I didn't!

The crank turns freely about 355-360 degrees before it tightens and stops. I'm guessing a slave rod bent just enough that it is hitting the bottom of a jug - but that's just a guess.

I could use some advice on the best way (least disassembly) to figure out if it is just a bent slave rod and would be easy to repair. Is there any point of access that I could snake a borescope into the crankcase and try to see what damage was done? If it is damaged beyond repair I'd rather not disassemble and just try to see it for a display or parts. I am a mechanical engineer and an extremely experienced mechanic - just not with radials! The only radial I have partially dismantled is a little 5 cylinder Lawrance APU, and I didn't go in very far.

Any input would be appreciated!

Did you turn the engine backwards? That would push oil into the intake tubes and return it to the cylinders when you tried to start it. I would suggest a compression test. Remember that your numbers will be low because it hasn't run in a while, but you are looking for one cylinder with a far lower compression. As far as bore scoping, I don't know if that would tell you any thing, but it is worth a try.

 

[bobm4360]

If it's a bent slave rod, you'll have to tear it down completely.

 

[XBe02Drvr]

Have you tried pulling one plug from each cylinder and then hand turning it? First remove magnetos and any other one-way accessories. The cylinder that has the master rod in it is usually top cylinder in aircraft application; in tank/landing craft - who knows? You can turn the propshaft til it binds, then use a long shank screwdriver with its tip protected with tape to probe each cylinder in turn to ascertain piston positions. Record them. Now turn it the other way until it binds and repeat. Now you know crankshaft positions either side of the bind. That should point to the damaged rod. I'm betting on the closest cylinder to BDC on the crankshaft. Pull that jug and take a look. If the problem is some metal part that has come adrift inside the crankcase, you'll probably find that too.
If you do in fact have a bent rod, bobm4360 is right, you'll have to do a complete teardown. Take heart, it's not that hard. We did one in A&P school. Much easier than the 1820 that came next. Work carefully, label everything, and follow the manual to the letter. If your engine has the cylinders with forward facing sparkplugs (aligned parallel with the propshaft), a screwdriver won't work for a probe. Take a small pocket tape measure (6' will do) with a flexible narrow blade and insert the first 16" of it into a piece of clear plastic tubing, covering the hook at the end with tape. Now you can probe "around the corner" to get your piston positions. Before you put anything back together, be sure to get hold of a maintenance manual.
Good luck!
Wes

 

[MiTasol]

I thought I had the complete manual as a PDF but all I can find are the fold-out PDFs and I gave the paper copy away years ago
I bought the whole manual even more years ago from Dusters & Sprayers Supply, Inc. ~ Manuals and they still sell them

 

[bobm4360]

Just added a W-670 manual in "Engines". HTH.

 

[TubularFab]

Hello and thank you for all the info everyone! I am aware of how far apart a radial has to be taken to swap a rod - and I have exercised great restraint in tearing into it so that it does not become a basket case mess. One of these days I'll have the time do it all at once and do it right.

 

[Djansen1]

Hello - I found this forum while searching for a forum on radial engines. I have a Continental W-670 from a WWII landing craft / tank that I had set up on a stand for running at old engine shows. I had replaced the electric starter with a hand crack inertia starter and had it running great. Before starting I always removed the bottom cylinder spark plugs and hand turned it several revolutions to drain any accumulated oil - and it always had some if it sat very long. The last time I started it I had gone through this procedure. But, after priming it and winding up the starter it fired about 2 times then almost turned the stand over coming to an abrupt stop.

The only thing I can figure is there must have been some oil in an intake runner that didn't go in until it started moving faster than my hand cranking, and that it hydrualiced on it. This was about 15 years ago, and it's been sitting in the back of my shop since. I didn't want to tear into it and leave it as a basket case - and it's probably a good thing I didn't!

The crank turns freely about 355-360 degrees before it tightens and stops. I'm guessing a slave rod bent just enough that it is hitting the bottom of a jug - but that's just a guess.

I could use some advice on the best way (least disassembly) to figure out if it is just a bent slave rod and would be easy to repair. Is there any point of access that I could snake a borescope into the crankcase and try to see what damage was done? If it is damaged beyond repair I'd rather not disassemble and just try to see it for a display or parts. I am a mechanical engineer and an extremely experienced mechanic - just not with radials! The only radial I have partially dismantled is a little 5 cylinder Lawrance APU, and I didn't go in very far.

Any input would be appreciated!

Do you still have the w670 for sale or any parts and where are you located?

 

[Djansen1]

I am looking for a wr670 can be out of tank or crop duster or stearman? If anyone has a parts engine I would be interested. Thanks

 

[XBe02Drvr]

Do you still have the w670 for sale or any parts and where are you located?

Have you checked with Airrepair (the certificate holder), Dusters & Sprayers Supply, Aircraft Spruce, or Yesteryear Aviation?
Good luck!
Wes

 

[Djansen1]

Have you checked with Airrepair (the certificate holder), Dusters & Sprayers Supply, Aircraft Spruce, or Yesteryear Aviationm?
Good luck!
Wes

Thank you very much I will check out those other sites . I have heard of airrepair it's kinda like looking for a needle in a world

 

[XBe02Drvr]

I have heard of airrepair it's kinda like looking for a needle in a world

They have a quite extensive website. I think you can get a fresh airworthy 0SMOH w670 for ONLY $29,975!! (exchange)
Cheers,
Wes

 

[XBe02Drvr]

Thank you very much I will check out those other sites . I have heard of airrepair it's kinda like looking for a needle in a world

Here's another one to try:
Radial Engines Ltd. They're out near Ok City.
Cheers,
Wes