Cock-eyed head, Thunder Tiger 15

[Keith Miller]

Have any of you seen this before?
Staring at it, I think the holes were drilled after the fins/head was cast, and the hole jig must have been off.

This has the baffled piston, and I suppose I'll have to pop the head to see if the baffle relief in the head is cock-eyed too. The engine turns over just fine with no physical interference at the top, but do you think that a misaligned baffle and baffle-relief groove would change the way it runs?

[L0U CRANE]

Keith, no I haven't seen this before, but...

The head looks like it fits the hole pattern and fins properly, and the hole pattern in the main casting is what's off.

If the engine is Schneurle ported and the piston top is smooth (flat or domed) it should have no effect. The slight rotation of  the hole pattern should not be so large as to affect porting.
 
Makes one wonder, tho...

[qaz049]

Have any of you seen this before?
Staring at it, I think the holes were drilled after the fins/head was cast, and the hole jig must have been off.

This has the baffled piston, and I suppose I'll have to pop the head to see if the baffle relief in the head is cock-eyed too. The engine turns over just fine with no physical interference at the top, but do you think that a misaligned baffle and baffle-relief groove would change the way it runs?

I've seen a CS Plain Bearing baffle .15 with a much worse fin alignment that this one. The baffled Thunder Tiger engines were usually good runners. More or less an OS 15 clone. The engine was also available as  a model car buggy version with a heatsink style rectangular head. The burr along the edge of the head in your pic suggests that one of these may have been turned down circular to make it a c/l engine. Otherwise it may have come from a different brand engine with larger diameter head screws on a slightly different spacing.

It looks like a bit of the piston baffle showing through the plug hole in the first pic. Seems to be correctly aligned to me. Still checking the setup by removing the head seems a good idea.

[Oldenginerod]

I would agree that the case appears to be the problem rather than the head, as opposed to a Tiger Shark .46 that I have.  On it, the head screws are clearly drilled wrong and sit unevenly in relation to the fins.  Can't say I've ever noted whether mine is a baffle engine or a schneurle engine.  Seems to run just fine, just looks wonky.

[Steve Lotz]

I have seen this on some old K&B greenheads. Doesn't seem to hurt anything.

[Brett Buck]

It looks like a bit of the piston baffle showing through the plug hole in the first pic. Seems to be correctly aligned to me. Still checking the setup by removing the head seems a good idea.

      The baffle is straight on, but you can't really tell if the slot in the bottom of the head is straight with the baffle, or what effect it might have if it wasn't.

   Just have to run it and see.

     Brett

[Oldenginerod]

      The baffle is straight on, but you can't really tell if the slot in the bottom of the head is straight with the baffle, or what effect it might have if it wasn't.

   Just have to run it and see.

     Brett

If there's no contact then it should be fine.  Normally the slot in the head has a fair bit of clearance.

[Brett Buck]

You can remove the head and put something, like a thin steel ruler, to the baffle slot. Then look again from the direction of fins. They shouldn't be parallel.
But propably nothing to worry about, most propably the bolt holes and groove are all cut during same operation. L

   Well, that would mean the slot is crooked WRT the piston baffle.     Most of these sort of engines I have seen have the baffle clearance slot cast in, rather than machined in. Many have the head fins made that way, too, and only the tenon, mating surface, and diameter are machined. I would put some modeling clay on the bottom of the head, bolt it down, and then run the piston into it, and see if it's crooked or not. But, it doesn't matter because you can't really fix it. Just run it and see, if it's not OK, then try to figure something out.

    I actually have an idea how  it might be "fixed",  but it's so hacky I don't want to say it in public.

     Brett

[Steve Helmick]

I've seen that before. I pulled all the screws, put the piston at TDC and wiggled the head to make sure the baffle cleared the trench in the head. Like the others said, there's probably no problem, but the one I had was the head and not the case that was just a bit off centerline. As a retired machinist, I know there are a lot of ways for things to go wonky, from a vise not dialed in, to a chip under a soft-jaw....something dumb like that. My fubars were usually right after break or lunch time...had my guard down.  Steve