066 Cross Topend

[Glock37]

I put a 066 Cross Topend in a tree trimmers 660

Well he got a monthes worth of cutting untill it hung a ring in the exhaust port

I got to think how to progress ?




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[Frank bierce]

Oh no :/. Just sand it out...it'll be fine.

 

[paragonbuilder]

Damn Mike!
Did you do any cleanup or install it as it came?


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[Glock37]

I sanded the ports alittle beveled them a little but i geuss not enough

they said it ran great before it ate itself

 

[drf256]

I'd powdercoat it if I were you Mike.

 

[PA Dan]

I'd powdercoat it if I were you Mike.

+1...lol!

 

[Duane(Pa)]

I'd Tannerite it if I were you Mike.

 

[Glock37]

I'd powdercoat it if I were you Mike.

Smart ass !!!

 

[cus_deluxe]

Bummer dude. Bevel on that exhaust roof looks good, it must be pretty flat eh?

 

[Lightning Performance]

Roof pics from the exit straight in.

 

[X 66 stang347 X]

Bummer dude. Bevel on that exhaust roof looks good, it must be pretty flat eh?

I beveled mine also. I was wondering about the flat roof. Here's mine

 

[wcorey]

The two I have are pretty flat on the exhaust roof, sort of a well documented issue with these.
There's been some concensus that it should be ok being that they're not excessively wide (and making sure there's a good bevel) but...
I don't plan on running them like that and this certainly reinforces that sentiment...

 

[Lightning Performance]

I would have tappered the bevel up 0.010 in the center third of the port roof. It helps rig wear. It moves timing slightly. 1* maybe.

The floor is too flat in the center. Checking with a ring in sight is best.

 

[MustangMike]

Isn't that piston damage indicative of the lower ring hanging on the FLOOR of the exhaust port, not the roof?

I did not like the way my floor felt to the touch, so I sanded the crap out of it with 220 grit. Have about 8-10 tanks through it, mostly milling, with no issues so far. Hopefully, it continues to hold up.

 

[Terry Syd]

Another trick I use for flat exhaust roofs to put put a bit of 'bevel' on the tops of the rings in the area of the exhaust port. Not a lot, just enough to make sure it doesn't want to grab anything.

 

[Terry Syd]

In regards to the above post, we determine port timing from the TOP of the PISTON not the top ring. Yes, if you shave a 'bevel' into the top of the ring with some very fine sand paper, there will be a slight venting down earlier than before, but there isn't much clearance between the piston and cylinder to make it a big deal.

I'd rather have the extra reliability of a smoothly closing ring than some negligible increase in power. I smooth the top of the edge of the ring a bit more in the center of the ring - to give it the same closing speed as a properly shaped closing port.

As far as ring wear, how many thousands of ring wear occur over a ring's life? - You don't need much 'bevel' on the ring to make it work.

 

[sawmikaze]

I'd powdercoat it if I were you Mike.

Thats why i call him powder mike.

 

[wcorey]

Exhaust tracing from one of mine, top line is rough due to the plating crusties.

 

[wcorey]

Isn't that piston damage indicative of the lower ring hanging on the FLOOR of the exhaust port, not the roof?

You'd think so but the whole lower portion of the piston on the way up is going to be a lot harder to shear off than the just the top above the ring.
Could have caught the ring on the way up, levering the ring up against the top, then the dislodged bits really hang up on the way back down.

I can't imagine the crazy dynamics going on in there when something goes wrong at 10k rpm...