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pre cups

L

Larry

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st.joe,mo.
does any body know if the pre cups can be changed or machined to a bigger size and how big.Thank you for your help.
 
machine shops around here will not touch pre cups,they say there to hard to machine but they will gladly change to diamonds
 
They won't machine them? Yes Inconel© which I believe they are made of is pretty hard, but they should definitely be able to machine it. I can run my titanium carbide cutter through one, and if that cuts it out good, then the machine shop doesn't have the right tools.
 
He's probably talking to engine rebuilders and not an actual machine shop. Engine shops don't usually have milling machines
 
I don't know what there made of I'm assuming Stainless Steel because a magnet won't stick to the Precups.I called Noland head service in Kansas City and they said they would resurface the heads,but they can not touch the pre cups because they are to hard,they will resurface the face of them to match the heads but thats all they will do.Its kind of funny when machine shops can work with cobalt and D2 steel,you need diamonds to work with that shit.But nobody can open open up the pre cups and nobody sells the diamond pre cups either.Nobody around here has a clue what the hell they are.But Nolands said he might have some diamonds he will have to look and if he does he would change them for me.So I guess thats the route I will have to go.
 
Typical Incolel© alloys used in automotive applications aren't magnetic. But yeah, you are going to have to find a real machine shop, not just one that works on engines.

The dealership does have the precups, but they are expensive.
 
Kindred chevrolet in Smithville doesn't have a clue,and GMC Westfall in Kansas City thought I was a couple straws short of a bail.They said any kind of head work like blown head gaskets they send the heads out and if the machine shop called and said the pre cups are cracked that they wouldn't bother with it and order a new head.Thats Jacked up. I guess thats just another way to give it to the customer up the ass.
 
Yep Larry. I've gotten some odd-n-ends type 6.5 parts at Kindred Chevy - stuff that only GM carries. But have also found some surprising knowledge limits considering they're a genuine GM dealer with access to all the tech bulletins etc.

I inquired about the Castrol Syntorq gear oil the NV4500's require. They couldn't find anything indicating it was spec'd to use that specific gear oil. Then tried to sell me common gear oil as they were certain it would be fine.

Prolly should have simply shown them the owner's manual, much less the GM tech bulletins, but didn't figure it was likely to be appreciated - as they're certified techs, & service mgr's.......
 
chevyinlinesix said:
Typical Incolel© alloys used in automotive applications aren't magnetic. But yeah, you are going to have to find a real machine shop, not just one that works on engines.

The dealership does have the precups, but they are expensive.
Click to expand...

Inconel is a nickel based superalloy and is not used in automotive applications(that I know of, may be in some exotic applications) I have machined alot of this and Waspaloy and Hastaloy all nasty stuff to machine it ruins carbide in a big hurry. They use these alloys in aerospace and aircraft applications. It is very resistant to extreme heat and vibration perfect for aerospace. We made alot of parts for NASA and most was Inconel. Tough ass stuff way to expensive for automotive applications.

As far as the precups they are hard but not bad at all to hard to machine, they are butter compared to Inconel Not sure what material, havent inquired about what they are because they cut fine.
 
There are some automotive turbocharger turbine wheels made of cast Inconel, but you're right, they're not commonplace & rather expensive.
 
Inconel is used in motorsports exhaust header/ turbo applications also. Tubing. It can take the heat.

The idea of doing cups with a CNC mill is to get each one exactly the same. Somebody in their garage with a dremel ain't gonna cut it. (no pun)
 
I seriously considerd modifyng my 6.2 precups actualy did drill one one with a 1/2 inch carbide drill bit, I put the dianond cups in instead, pretty shure I wont mess with them, does any fuel get past the precup? The way I understand it the explosion must all fit out that small hole.
 
I have a video, but a couple pictures will suffice right now for you guys :p
precupburnpattern.jpg


precupburnpatternstar.jpg
 
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That awsome, how did you do that,is it just a torch or did you make your own explosion? Also real world with cylinder compression might change things a little ,I often wondered if my high boost pressures push that all back in ,I guess timing would play a bigger part in that. Every body says idi is a problem when your trying to build a lot of horsepower, of course Bill got 500 in his race truck.
 
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