Precombustion chamber mess no more

[theman53]

http://www.cotronics.com/vo/cotr/ca_metallic.htm

check out the pdf files. These are stable at 1200F for the lowest and 2000F for the highest rated materials. This 954 at 1200F has a bond strength of 1400psi. AND it bonds to all metals and or different metals at the same time. I think I will glue in my next set of precups. 6 month self life and 90.00 for a pint, but 90.00 is cheaper than the 1600. I had in my last IDI engine.

[maxfax]

You think the different rates of expansion will come into play at all?? From what I read in the pdf's I guess not...   Otherwise, dare I say it, that stuff looks like a end all solution to pre cups falling out..   Wonder how it'd work on an 11mm block..   

[theman53]

I talked to the engineer and he was leary too, but said as long as the fuel didn't come into direct contact it "should" be ok. I figure it will help if nothing else. Getting them out...hopefully will never happen. I think with the ultimate strength of it hopefully it would hold the head tight on the precup and precup tight on the head no matter what. 24 hour cure and 2 hour pot life, I would think you have enough time to smash some cups into the head. Like I said before I think 90.00 is cheaper than my last build and really isn't that much coin even if it doesn' work perfectly. Plus I have a junk head to practice with.

[theman53]

Just another thought on precups...

The Swaintech coating is basically a ceramic coating that keeps the heat off the parts coated. If that is the case, would the adhesive be needed to hold them in, or the ceramic coating would keep the heat off the precup so it wouldn't be an issue...or that we could use regular old retaining compound to hold them in since it wouldn't be getting as hot.

Reason I am asking is the cotronics only has the 6 month shelf life, so it would be 90.00 everytime I would ever want to use it.

[Toby]

How can a precumbustion chamber fall out without massive trauma beforehand? They are squished between the head and the block, so they can't "fall out". They would have to punch down through a huge section of block before they could "fall out". You could have problems if they were sticking up (not fully seated) when the head was surfaced, giving them room to move and erode the head and block, but this is a pre-failure problem. If they are loose in the head strake them with a punch after making sure they are FULLY seated.

I have seen the pics of this kind of trauma and I suspect that it results from so much heat in the PCC that they get loose in the head and become little pile drivers banging back and forth between head and block, once the HG has been ground up. No adhesive will prevent that.

[theman53]

You would think, but my HG looks brand new.

That is what I think happend, the PC started getting loose and eventually made contact with the piston. I have another theory, but it is just a guess, that the Prothe pistons I used came with wrist pins that were fine on the piston, but I thought they were a bit loose on the con rod. Machinist said it would be good, but it has made me wonder since this happend.

I think the adhesive may work. I think it should be strong enough that when the 2 metals expand/contract at different rates it will hold it together. Or it will pull the head apart. Maybe not, but if I only got 40,000 miles with no adhesive, I hope the next one will get 150,000 with it.

[Toby]

If the gasket was not compressed the PCC should not have been able to contact the piston unless the protrusion was wrong for the HG used or the protrusion increased while running. This can happen when rod bearing clearances get huge allowing the piston to be thrown higher than normal while running, during decelleration or high rpms.

[theman53]

If the rod clearance is an issue than the wrist pin would do the same.

HG looks pretty much brand new.

[Toby]

True. I seldom see bad wrist pin bushings though, but I hardly ever see the inside of ones driven as hard as is typical here.

I sure would like to see some pics of the head damage, if you have any.
J

[theman53]