1898 Nash Two Cylinder Build

[raveney]

Excellent work, not sure how I missed your progress previously.

For the crankcase oil leakage issue, can you sneak in a one way valve into the breather pipes, making them PCV valves (i.e. let the air out but not back in)? It should help by making the case pressure much lower or even negative, hopefully making any flow at the leaking joints move into the crankcase and not out.

Cheers,
Mike

Hi Mike,
Thank you for the suggestion to make PCV valves. How does one do that in a small scale? Do you use tiny ball bearings or such? The breather "tubes" that I installed are 1/4-32 thread.

 

[raveney]

Tear Down and Inspection

The engine seems pretty well broken in now and I thought I would try and make it more dependable when starting. I would really like to be able to start it by hand instead of using a drill, but that may be unrealistic with the strange firing order?

Here are some items that I found that could use improvement:

• Crankshaft key way was very sloppy. This might make the valve timing lead or lag differently as the backlash was severe. The gear tooth mesh was still nice. Brass was not a good idea so I will remake one from steel.
• Crankshaft endplay was excessive (0.020") the plan calls for 0.003". This may affect the hall sensor triggering reliably. I made a new brass bushing 0.017 longer.
• The valve spring keepers didn't stay put. They are made to compress the springs and then be tightened using #2 set screws and the set screws fell out. The valve lash doesn't change, but the valves may float due to lower spring force? I will make four small brass sleeves in case that happens again.
• Lower coolant manifold had a leak at the solder joint. This showed up when initially breaking in the engine and I sealed it with Loctite to stop the leak. It looks like it also closed the cooling water passage way into the cylinder. Cleaned and resoldered.
• Head gasket leak. Water was in the oil and on top the piston. Tough spot to seal as there are dozens of holes but I sanded the cylinders flatter using the granite plate and 220 garnet paper to give the gasket a better chance.
• Lower piston rings were sticky (hard to rotate) and needed to be thinned a little. They were shiny for the full circumference and I checked using the "Mayhugh" light test. I think they are still good so reusing them.
• Scoring on the pistons and two places of the cylinders. I had severely overheated the engine during troubleshooting my water pump. Actually ran it until it seized . I thought it would be worse. I lapped using 320 grit, washed with gasoline and then stoned with a brake hone and WD40.

Still need to remake the head gaskets, but I think there will be some improvement to the way it runs now.

 

[ninefinger]

Hi Mike,
Thank you for the suggestion to make PCV valves. How does one do that in a small scale? Do you use tiny ball bearings or such? The breather "tubes" that I installed are 1/4-32 thread.

I haven't made a "PCV" before, but I think its really just a check valve, for low pressure - lets crankcase pressure out and prevents flow in. In your case the valve lies sideways, so either you need to really limit the lift of the ball to ensure its sucked back onto its seat, or you'll need a gentle spring to help it. The pressure is really low (we are creating a light vacuum), I'd consider a nitrile rubber or Viton ball instead of a ball bearing.
Also, you could even do away with the screw in cap and just use a pressed or glued in retainer to keep the ball and spring in place. (keep it simple). Also with a rubber or viton ball the seat may be good enough just drilled (i.e. 118 deg tip), and not bother with making it nice a sharp like is done for ball bearings.

Looks like a 5/32" ball (or 4mm) is about right for a 1/4" fitting.
Attached is a quick drawing of what I came up with. I had already been drawing up a check valve for a locomotive water pump, this is a variant of what I was already drawing that would probably work for you.
BTW - the check valve parameters came from here: http://ibls.org/mediawiki/index.php?title=Design,_Care_and_Feeding_of_Check_Valves

Mike

 

[kuhncw]

The engine seems pretty well broken in now and I thought I would try and make it more dependable when starting. I would really like to be able to start it by hand instead of using a drill, but that may be unrealistic with the strange firing order?

Your Nash should start by hand cranking. When I built my Silver Bullet, I modified the crank and cam to give the same firing order (like a John Deere two cylinder) as your Nash. I hand crank the Bullet and it starts easily.

I'm looking forward to seeing your Nash run again after the changes you've outlined.

Regards,

Chuck

 

[raveney]

I haven't made a "PCV" before, but I think its really just a check valve, for low pressure - lets crankcase pressure out and prevents flow in. In your case the valve lies sideways, so either you need to really limit the lift of the ball to ensure its sucked back onto its seat, or you'll need a gentle spring to help it. The pressure is really low (we are creating a light vacuum), I'd consider a nitrile rubber or Viton ball instead of a ball bearing.
Also, you could even do away with the screw in cap and just use a pressed or glued in retainer to keep the ball and spring in place. (keep it simple). Also with a rubber or viton ball the seat may be good enough just drilled (i.e. 118 deg tip), and not bother with making it nice a sharp like is done for ball bearings.

Looks like a 5/32" ball (or 4mm) is about right for a 1/4" fitting.
Attached is a quick drawing of what I came up with. I had already been drawing up a check valve for a locomotive water pump, this is a variant of what I was already drawing that would probably work for you.
BTW - the check valve parameters came from here: http://ibls.org/mediawiki/index.php?title=Design,_Care_and_Feeding_of_Check_Valves

Mike

Thank you so much for the reference to an article and for taking the time to make a dimensioned drawing. Very much appreciated. My engine has been very stubborn to get running as I want it to. I think the blow-by and spitting oil was caused by not flushing the diamond grit paste completely and a small coolant leak into the #2 cylinder. I also switched to 90 W oil and lowered the oil level. It seems much improved after several days of rework.

 

[raveney]

Your Nash should start by hand cranking. When I built my Silver Bullet, I modified the crank and cam to give the same firing order (like a John Deere two cylinder) as your Nash. I hand crank the Bullet and it starts easily.

I'm looking forward to seeing your Nash run again after the changes you've outlined.

Regards,

Chuck

Thank you for the encouragement Chuck. Still not able to start by hand, but it does fire rather quickly using a powerdrill.

The first set of rings had a very large end gap upon inspection. (well over 0.030") I may have worn them down by not getting all of the diamond lapping compound out, or just messed up. They fit the OD and were still springy. I thought I had filed the end gap to 0.003".

I also had a tiny leak of coolant where I pressed the sleeve into the cylinder cooling jacket. Early on in the build I dropped one of the cylinders and had to rebraze it. It happens to be that one that leaked. I got lucky and heated it and cleaned with acetone, then let wicking green threadlocker seal it up. Dodged a bullet there. I tested the heads also and they were fine.

Four head gaskets, two ignitions, four spark plugs, two sets of rings, two water pumps, three fan belts, three coolant tanks later it is running on both cylinders and able to stay running when slowing the flywheels with a load.

I made quite a few mistakes and learned from them in this build. Thank you to all the people who followed along and gave such good advice. I really enjoyed posting the build on this forum.