ESC con rod failure and assorted questions

[bruce nickerson]

Reassembled my ESC which had been frozen solid. Used piston from CPC and salvageable rings from ESC. Tried to get flywheel off with the hold and bang method but since transmission, etc., were already detached, the remaining assembly evidently lacked necessary inertia to come free easily. Left as is. Reassembled all parts, looked good. Ran it in a barrel, was spitting water out proper hole, seemed to be running well, ran it at high speed for few minutes, heard a SNAP and motor stopped. Broken con rod. Broke at big end, left crank journal scored and unseable. Piston and rings and cylinder bore remarkably unmarked. Could I have bent the crank trying to free the flywheel? Could the journal have been corroded by the same problem that froze the piston in the block? What might I have done wrong?

Now, I have a CPC block, crankcase, crank and con rod, and useable ESC block. Can I use the ESC block and amal carb on the CPC crankcase, CPC crank and rod? The ESC rod has an I beam section, the CPC rod is flat/oval. Seems the operative questions are will the ESC block work with the CPC crank, crankcase and con rod? Was there a difference in stroke between the ESC and the CPC?

Oh, and what about the CD ignition on the ESC? The ESC flywheel does not want to come free, nor does the flywheel on the CPC. So, I am thinking of just using the whole CPC flywheel ignition system crankcase etc, with the ESC block. Is this doable?

Forgive me if this bastardizes the whole shebang, but I DO want to get underway at minimal cost, and it is my understanding that Seagulls lend themselves to this kind of mix and match.

Pls excuse me if this seems muddled, but I am a bit distressed right now and am using this posting as a way to cool down before any hasty reassembly action.

Much thanks for your patience.

[redclyffe]

shame that, i never run my motor for too long at high revs with the clutch disengaged, because there is no load on the engine. you may have simply overrevved it for too long. my forty plus runs at about half throttle speed when pushing a boat at full throttle, if you know what i mean

[bruce nickerson]

Redyclyffe

My bad- think u r right on that.

Now to reassemble a mix of parts. Would appreciate any advice anyone can give me on whther to use the ESC block, the CPC block, or whatever.

What about petrol/oil ratio?

[charlesp]

The ESC block will allow you to use the better carburettor. The CPC and ESC blocks have a different intake stub diameter.

By all means go with the CPC magneto.

You'll ened up with - effectively - a Silver Century Power head.

[bruce nickerson]

Charlesp:

May thanks for encouragement, especially about the CPC magneto.

BTW, I now have an extra piston, and probably should evaluate both pistons for reuse. On a budget, I want to reuse one of the pistons. The one from the ESC of broken con rod infamy while at first looking unharmed, has a slight ding/dent on bottom rim of skirt. The other piston has a frozen ring and slight scuffing. How much imperfection can I get away with on a piston if rings are ok?

[charlesp]

Scuffing is OK, a frozen ring is not. If the dent in any way interferes with the fit then don't use it.

But at any rate, that ring will have to be very carefully freed. If you break it, there are two spares on the other piston!