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[Chief]

Not to be a fly in the ointment here, but something's been rolling around in my head all night.

If you had enough pressure in the combustion chamber to generate enough force to blow the ACR out of the head, stripping the threads, it is incomprehensible to believe that that excessive amount of pressure acting on the 4" diameter piston didn't do one he!! of a lot of damage to the reciprocating or rotating parts.

Maybe the ACR was loose and vibrated enough to screw up and weaken the threads. Because if the threads were not already damaged, I can't imagine the amount of pressure it would take to launch that piece. The spark plug should have gone before that piece, and the studs, all four of them, should have been ripped out of the case.

I hope you're right about the failure, but it just doesn't seem logical. That piece has the smallest surface area of anything in the combustion chamber. I'd think you'd tulip a valve before blowing that little 3/8" out.

[Talon]

Howie, glad to hear you motor is ok! Thermal coating is great, not sure why more companies don't sell their stuff already coated. Who's doing you coating? I'm going to get mine done when I pull the top end to upgrade.

[Twolanerider]

Not to be a fly in the ointment here, but something's been rolling around in my head all night.

If you had enough pressure in the combustion chamber to generate enough force to blow the ACR out of the head, stripping the threads, it is incomprehensible to believe that that excessive amount of pressure acting on the 4" diameter piston didn't do one he!! of a lot of damage to the reciprocating or rotating parts.

Maybe the ACR was loose and vibrated enough to screw up and weaken the threads. Because if the threads were not already damaged, I can't imagine the amount of pressure it would take to launch that piece. The spark plug should have gone before that piece, and the studs, all four of them, should have been ripped out of the case.

I hope you're right about the failure, but it just doesn't seem logical. That piece has the smallest surface area of anything in the combustion chamber. I'd think you'd tulip a valve before blowing that little 3/8" out.

Chuck, when Howie described it on the phone I had the same thought.  But he said then they had the head off and were able to visualize the rest of it.  Valve travel was fine.  Everything else that could be looked at look ok.

Always loose?  Bad casting?  Stripped so poor to begin with?  Who knows?  He sounded confident that the shop sounded confident that the release was the only point of failure though.

[Chief]

Chuck, when Howie described it on the phone I had the same thought.  But he said then they had the head off and were able to visualize the rest of it.  Valve travel was fine.  Everything else that could be looked at look ok.

Always loose?  Bad casting?  Stripped so poor to begin with?  Who knows?  He sounded confident that the shop sounded confident that the release was the only point of failure though.

Something had to be amiss there for that piece to be the first to let go. That's the only thing that makes sense. Otherwise, with that much pressure... motor go Boom!!!

But then again, I'm just guessing. I'm glad it could be traced to that piece.

[Twolanerider]

Something had to be amiss there for that piece to be the first to let go. That's the only thing that makes sense. Otherwise, with that much pressure... motor go Boom!!!

But then again, I'm just guessing. I'm glad it could be traced to that piece.

I agree.  In fast until it's all buttoned back up and he hears it run I'll still be at least a small bit concerned about what else might have or might still go boom.

They sound confident though.  And they actually got to see it.  And the wiring and acutation controls for those things certainly are a poorly designed CF.  So moving them to a servicable location and losing the current wiring/firing method is a gain in my mind.  But I still wonder why something else didn't go boom too .

[Chief]

I agree.  In fast until it's all buttoned back up and he hears it run I'll still be at least a small bit concerned about what else might have or might still go boom.

They sound confident though.  And they actually got to see it.  And the wiring and acutation controls for those things certainly are a poorly designed CF.  So moving them to a servicable location and losing the current wiring/firing method is a gain in my mind.  But I still wonder why something else didn't go boom too .

Sounds like I should find some hi-temp silicone wire loom to run my wires in when it is apart next week. 

Any suggestions?

[naitram]

http://cableorganizer.com/acrylic-coated-fiberglass-tubing/

[Chief]

http://cableorganizer.com/acrylic-coated-fiberglass-tubing/

Thanks Neal. That's a start, but at only 311 deg F (155 C), it's a bit short of my target. I'm looking for about 450 deg F.

[naitram]

a have a cataglog at home with this type of stuff i'll check it out tonight

[Chief]

a have a cataglog at home with this type of stuff i'll check it out tonight

Thanks Neal.

[skreminegul07]

The ACR blew out of the new heads, correct? not the HD SE heads.  Were the new heads made with the ACR threaded hole?
 
I agree, that must have been quite the pressure to force the ACR out with threads.  If the Cometic head gaskets survived that then they should survive Howie!

Will the MOCO cover the problem given that the wires were moved during the rebuild process? 

[Twolanerider]

The ACR blew out of the new heads, correct? not the HD SE heads.  Were the new heads made with the ACR threaded hole?
 
I agree, that must have been quite the pressure to force the ACR out with threads.  If the Cometic head gaskets survived that then they should survive Howie!

Will the MOCO cover the problem given that the wires were moved during the rebuild process? 

It's best of course for me to let Howie speak for his build.  I'm pretty certain, however, that the heads used were originally a set of SE 110 heads just as would have been on the motor to begin with.  It was a set supplied by Wes at CycleRama that had been reworked in that shop.  That's where the heads are currently winging back toward to be welded up and then fitted with manual releases.

[naitram]

Thanks Neal.

http://techflex.com/prod_FGN.asp

INSULTHERM (FG) is an extremely high temperature resistant sleeve commonly used as thermal protection for wires, cables and hoses that are subjected to continuous and extreme high temperature environments, such as engine manifolds and exhaust systems.

FG is braided from fiberglass yarns and coated with high temperature resins. FG is tough and durable, maintaining its tight structure under extreme vibration, abrasion, mechanical stress and temperature variations.

FG is available in a wide range of diameters in either Black or Silver. It installs easily over a variety of applications to either deflect or retain heat in environments up to 1,200° F.

[naitram]

http://techflex.com/prod_NXN.asp

Woven Nomex® clothing and protective gear has been used for years by race car drivers, municipal fire departments and oil rig personnel to provide that extra level of comfort and protection from the dangers that come with working in and around intense flame and heat. Our NX Nomex® sleeving will do the same for your wires, hoses and cables.

NX will protect your application in temperatures up to 700° F. It is unaffected by short term exposure to most acids, bases, solvents and common engineering chemicals. Despite the soft touch and smooth appearance associated with woven aramid fibers, NX is incredibly strong, with a tensile strength of 90,000 psi.

The densely braided sleeving provides full coverage and protection on even the most exposed applications.

NX sleeving cuts easily with regular scissors and the smooth surface eases installation even over long wire runs. The construction allows slight expansion to accommodate irregular surfaces and tight turns.

[naitram]

tis is where i bought from

https://www.wirecare.com/products.asp?prod=FG&prodline=ES