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Heads/ precups options

Will L.

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So I finally started looking close at my optimizer heads.
Valve to valve dreaded line is starting in a couple cylinders. Not a killer, and quite normal. Definitely not enough to replace the heads for that alone.

Valve springs have 70k miles. Havent load tested yet but considering the aftermarket ones researched by Chris aka Twisted Steel Performance. Cam will be stock and stock rockers btw.

Then the precups. I have a full set of diamonds with about 70k miles on them and cracking stsrted but not into fire ring. Also have 7 of 8 squares with about 70k miles and equal amount of cracking. (1 damaged by bosch glowplug failure).

I am going 18:1 coated TSP pistons. Turbo will have to be stock centermount gm6 for now due to $. REALLY hoping for 35/40 hybrid or ATT in the near future. If I can keep extra costs down on things like the heads, maybe a turbo can go in right away. We all know the turbo has biggest affect.

I see in ebay diamonds for 85-130 a set, but BMI aka Bostic Motors doesn’t exactly have a steller reputation. And no returns allowed probably says it all...

I bear new head prices are down because of chinese heads. But as to price, what to get or avoid, etc. ??

Really at a crossroad and looking for options because I could run just what I have. But trying to figure where to spend the money I have left in best places. I posted in want ad for precups.

What say you all? I have my theories, but I often build a swiss watch when a sundial would do.

I really never want to open the engine again. Getting too many grey hairs for this to be enjoyable anymore.
 

n8in8or

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I can offer just limited personal experience for you regarding the Ebay Diamond cups. When I took the heads off of the Hoe's first engine, I found they didn't have Diamond cups in them. I found those Ebay Diamond cups and thought that was a great score, so I bought them. After I bought them I found that at some point my heads had been machined so the new cups were too tall. Without knowing any better I took them to work to machine the top down in the lathe. They machined fine. What does that tell me? I don't know a lot about Inconel, but I'm pretty sure I would have had a hard time machining the surface of them with standard tooling if they were made of Inconel....but these machined easy....pretty sure they aren't Inconel. Because of that, I have no idea how long they will last, but I wouldn't trust them very long - especially in a hot rodded engine. I only had the engine together in that configuration for about 4 months, so I don't have any durability report to offer. Hopefully this is helpful info for you.
 

Will L.

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I am seeing some oversized precups. I have never had any installed, what is done to fit them in the heads?
 

WarWagon

Well it hits on 7 of 8...
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Get some crack free used heads... Eventually the valve seats can crack and valve/seat burning isn't far behind.

Precup comparison:

Precups… 3 Bars came out of a NA 6.2 military CUCV engine, Square was in Patch when I bought it assumed 6.5 NA precup. And Diamonds.

56419


On the left is a head with Military precups on a 1986 6.2, 3 bars. The cups sitting on the head are 1995 turbo precups, round dot. The head on the left is 1995 NA 6.5 precups, square mark. This just scratches the surface of all the precups GM made and the 'opinionated best for turbo' latest Diamond marked ones are shown above.

56420
 

Will L.

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Square -10230426
Circle - 10149629
T - 10149630
Diamond - 10183926
triple square (6.2)- 10149688- not sure but believe stock not oversize
GEP Diamond Over sized - 12550985
Square .010 over is 10230425

So, I have been offered a new set of the 6.2 triple squares new for $100 but machining is definitely required. Diy option there obviously or does anyone have contact info to the former member that is machining these frequently? I would like to talk to him about price of him opening these 6.2 cups up.

Also, I found 10 new T cups but at $470 - ouch.

Seems oversized is more available and cheapest option currently.

Iirc Leroy had oversized diamonds available- but idk price? Or if still available? @Burning oil ?

Anyone who did this-
I take it the oversized is larger diameter and you have the opening enlarged? What does that cost?

Or am I misunderstanding and they are made 10 thou shorter for when you deck the head so no machining precups is required for them to sit flush?

Been pulled off this a while, but back on the hunt.
 

Will L.

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Something good to add here for general knowledge.

Chasing these crack prone suckers...

I just got off the phone with Pete the owner of 300 below. He’s going to have the pattern for the last 20 years or so for cryogenically treating airplane, NASA, race car stuff-absolutely the world expert in cryogenics to metals.
I was talking to him about the inconel pre-cups,
He said yes it will help the cracking. No it will not stop it he doesn’t think, but should greatly extend the life before the cracking starts a new ones.

After talking with him about what his results were on injectors and injector nozzles specifically, his wear results are back from
What we spoke of years ago. So I will be selling my extra set of Bosch German 311 nozzles, and chryo treating my set that will go in my engine. Not in a hurry to sell them, but know that on this set, top dollar is gonna have to happen. Anyone that recalls, i sold the sets for the same price I paid. The only price I know I would take for sure at this point is a full set of brand new real not chinese diamond precups.

For those that dont know chryo costs or where to:
“300 Below” is the company name.
Roughly $5 per pound is price, but if you send an entire engine, the price falls to $2 or $3 per pound roughly.
Shipping back and forth is usually more expensive and it is absolutely the best thing for strength and wear improvement you can do.
Do all machine work first. Ball honing an engine is usually 15 minute job, you’ll spend that amount on just one cylinder. That is an example of wear difference for ya.
I know what I know about wear, and we tested for strength using a bbc rod in a 200 ton press.

Back 15 years ago, we weren’t sure about tiny thin items resisting wear getting as much help from chryo. Now I know my 311’s after treatment and adding fuel lube will get all the miles I need.
And my son inheriting the hummer can just use regular injectors as backups.

My precups- well now that I know he can get good results from the inconel for thermal cycles and radius strengthening- I have hope for them to last longer. Should easily be worth the $10 cost.
 

Will L.

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Just website or phone number from website.

They do tons per year- literally.

Send everything disassembled. Pete is really helpful guy and crazy knowledgable. Every single metal part in the engine can benefit. My next ip rebuild will get built twice... that little sucker is easy to ship in pieces.
 

Will L.

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If you don’t mind documenting and sharing your experience for everyone else, I think it can help a lot of people. For some reason a lot of people don’t do it.

Shipping costs is a pain. Honestly there was a place in. Vegas that was owned by a guy that i think worked for him and stole his technology. Being able to put parts in the back of a truck and go do it was awesome. Then the vegas guy started going stuff for JPL/NASA and wouldn’t do anyone else’s stuff, and dumby me- is the one that put them together. Then he went out if business. I thought he just relocated. Turns out he was put out of business for running the shop illegally! Oops. Everything worked great though. After he quit doing our stuff i just told he guys that owned the build we were doing to call 300 below in Illinois.
There is supposed to be another knock off company in pheonix, but no idea on quality. @WarWagon know anybody near you doing it? His patent on it did just expire...
 

Rodd

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Since will and chris took the thread to cryo hardening, what parts can/should be hardened and what parts should not be? (Crank, cam, pistons, valves, rods, etc.) I don't think cast aluminum can be, can it?
 

Twisted Steel Performance

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The company I am sending my stuff to won't do piston pins by choice.. everything else can be treated, yes even aluminum. I have done extensive research and talked in depth with a local race builder and he sends a lot of parts to be treated, and we talked about our block cracking in depth, he believes a treated block would prevent cracking, but no way to know for sure. 99% of my long block is getting treated, about all I'm not sending is the piston pins..
 

Rodd

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The company I am sending my stuff to won't do piston pins by choice.. everything else can be treated, yes even aluminum. I have done extensive research and talked in depth with a local race builder and he sends a lot of parts to be treated, and we talked about our block cracking in depth, he believes a treated block would prevent cracking, but no way to know for sure. 99% of my long block is getting treated, about all I'm not sending is the piston pins..
So you have having your block treated as well? How come it is only 99%? what is the 1% that doesn't get treated? I am also assuming all your parts being treated do not have your coating on them yet? So by having everything hardened, does that mean it can handle higher temps? And if so how much higher?
 

Will L.

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Proper chryo treating increases strength and harness without increasing brittleness.
There is no specific “X” temp, “X” hardness, etc it creates.
The improvement is by base of the material.
The metal parts are stronger and more dense than before, but it’s not like you can say if 210f was ok before now 218 would be.
 

Twisted Steel Performance

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So you have having your block treated as well? How come it Tfis only 99%? what is the 1% that doesn't get treated? I am also assuming all your parts being treated do not have your coating on them yet? So by having everything hardened, does that mean it can handle higher temps? And if so how much higher?
Everything but the piston pins and some bolts. Then once it comes back I'm going to do a 100% internal coating.
 
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