Head leak bubbles help

cribbs74 wrote:Are we talking about an insert head?

If so perhaps the insert just needs to be lapped.

If that's the case, I would even up the head with fine sandpaper on a piece of glass.

BTW, I found a great tool thanks to my Lowes halogen lamps always frying. The 1/4" glass plate in front of the lamp housing is a great flat sanding surface for things like heads and crankcase backs, crankcase shoulders for adjusting port position etc.

RknRusty wrote:

cribbs74 wrote:Are we talking about an insert head?

If so perhaps the insert just needs to be lapped.

If that's the case, I would deck the head with fine sandpaper on a piece of glass.

BTW, I found a great tool thanks to my Lowes halogen lamps always frying. The 1/4" glass plate in front of the lamp housing is a great flat sanding surface for things like heads and crankcase backs, crankcase shoulders for adjusting port position etc.

Good idea, BTW how are you installing the bulbs. They are very sensitive to oils from hands.

If lapping does not solve the issue, check to make sure the threads are not damaged on the cyl.

Best of luch

cribbs74 wrote:

RknRusty wrote:

cribbs74 wrote:Are we talking about an insert head?

If so perhaps the insert just needs to be lapped.

If that's the case, I would deck the head with fine sandpaper on a piece of glass.

BTW, I found a great tool thanks to my Lowes halogen lamps always frying. The 1/4" glass plate in front of the lamp housing is a great flat sanding surface for things like heads and crankcase backs, crankcase shoulders for adjusting port position etc.

Good idea, BTW how are you installing the bulbs. They are very sensitive to oils from hands.

Yes I know. I was in the copier business for decades and we used 3500w halogen fuser lamps. Arcing contacts was a constant problem until they started designing them with lamps that had wires with spade plugs at each end instead of leaf spring contacts like the Lowes units. That fixed it for good. When the one I have now first started arcing, I took the bulb out and applied conductive grease to the contacts. It worked for a while, but it's about to pop again now. Can't touch the quartz tube.

shell shock wrote:If lapping does not solve the issue, check to make sure the threads are not damaged on the cyl.

Best of luch

Or on the head. The same head leaks on two engines if I understand correctly.

See, it might be a combination. The op claimed that one head won't run on either engine, yet the non plug head runs only on one engine

It is a glow plug head for threaded glow plugs, not inserts. I am not leaking around the plug, just the thread to the cylinder. I checked with fuel for bubbles.

One engine is leaking with both the glow plug head and the regular head.

The other engine had the regular head on it, and is leaking with the glow plug head, I have not tried swapping back.

I did think about lapping, and will give it a go later today or tomorrow. How fine of grit do I need to go? 400? 1000?

I assembled the first engine from spare parts. I have run the cylinder and piston previously with no problems. I reset the piston (first time ever doing this) and doubt that affected anything. I cleaned the parts with a toothbrush and tissue (Kleenex). I haven't checked the threads yet and will.

Phil

OK...I grabbed the 800 grit since that pack was on top.

I inspected the glow plug adapter and noted it had hard edges with very fine burrs. I could not feel the burr, but they were plainly visible under a 30x loup. I lapped the head, but not very much. It lapped evenly with no effort. I also chamfered the outside edge, and used my finger with the sand paper and twisted to chamfer the inside edge slightly.

Still no compression on both engines. The head also had no compression on both engines...Hmmm...

I pulled the gaskets and inspected them, they look fine.

I cleaned the threads and seat on both cylinders with a bamboo skewer.

I wiped the gaskets down carefully and stuck both gaskets in one engine and tried both heads. Still no compression, seemed much less than before. Did I damage the gaskets?

Pulled out fresh gaskets, again used a bamboo skewer to clean the threads and gasket seat in the cylinder, wiped the heads down with paper towel for the umpteenth time, installed with fresh gaskets and now I have compression in both engines

I have looked at these two gaskets under a 30x loup and they look clean with no visible damage to them. I can't figure this out.

maybe I can run them later today.

Phil

Looks like you've been busy! Glad your making progress. Good luck on your run.

I got both engines to run, the one I took the head from is very unsteady with the head that was on it and I don't know why.

The other ran on the glow plug adapter head but I think the hand cut brass reed in it is a problem. I'm going to put a stock oblong reed in it and see what happens.

Both need a look-see...again.

In other news:

I even got to bench my baby stunt bee (a third engine in this thread now), but it was less than cooperative and was self-needling rich Rich RICH! (this is an easy fix with the silicone fuel tube) Ran 2 full tanks through it nice and strong.

I can do a perfect figure 9...broken fuse on a maiden flight but not with either of these two engines. That had my tach race engine on it (a fourth engine in this thread now). I think it is tail heavy. Fixed already and nose weight added.

Phil