: Will machined heads mess up the ECU due to increased compression ?



JaxxMan
03-06-06, 12:37 PM
During my headgasket job I found my leak at cylinder 1. The water jacket area and the gasket eroded (Pls see attachment)

The pitting looks fairly deep so it might need at least .020" taken off. I was told that 20 thousands will increase compression ratio .2 to .3 This information was e-mailed to me by a Perforance engine shop when I ordered headgaskets from them.
Their gaskets are thinner than OEM ones which I will now have to use if machining is effective. I'll have to save the high end gaskets for another engine.

I am shopping around for new heads as they are not very abundant in Canada as a backup option if maching fails.

Secondary question does anyone have the GM part number for the hollow locator dowel pins ? or know an aftermarket place to order them ?

Katshot
03-06-06, 01:03 PM
Other than a slightly higher chance of detonation, the milled heads (and corresponding increase in compression ratio) shouldn't have any adverse effect. My guess is you should DEFINATELY use premium octane fuel now though. I would think it would be logical to see a slight increase in performance. It'll probably be so small that you might not notice it but, you never know.

Ranger
03-06-06, 06:10 PM
I would think it will also make "Cold Carbon Rap" more likely.

eldorado1
03-06-06, 07:01 PM
In theory, I don't think the ecu would notice. You're increasing compression ratio, but you're also decreasing quench distance with the thinner gaskets, giving it more detonation resistance. Using thinner gaskets will also likely help to keep carbon *off*. If you can imagine the piston rising towards TDC, it squeezes the air/fuel mix into the center of the combustion chamber from the outsides of the chamber. The closer the piston gets to the head, the harder that air is going to get squeezed out... along with any carbon that made it's way there.

That being said, I wouldn't use anything other than premium anyways...

zonie77
03-06-06, 07:41 PM
Factory heads usually have larger combustion chambers than the spec. CC'ing is done to measure them and then the heads are machined to match the minimum spec. Are they so big that .020 isn't too much? I don't know for sure. Old style heads could be milled .030 and still not be to minimum.

The knock sensor will control timing but you may find a benefit from premium because you will actually be closer to spec.

If you can get somehing to accurately measure the combustion chamber you could make a better decision, but I think they will be fine.

davesdeville
03-07-06, 04:19 AM
In theory, I don't think the ecu would notice. You're increasing compression ratio, but you're also decreasing quench distance with the thinner gaskets, giving it more detonation resistance.

What's the stock quench distance on the northstars? I know if you run a real "loose" or wide quench, like .100+ you're less prone to detonation, or if you run a real tight quench you're less prone to detonation, but if it's somewhere in the middle you're more prone. So if it's a loose quench and you go with a thinner gasket you can end up more prone to detonation.* I'd suspect a very tight quench on these motors, especially with 10.3:1 but I've never had the head off a northstar or seen specs.

*(Disclaimer, the shallow extent of my knowlege about quench is based on the old big blocks, not the newer small displacement V8s... the theory should be the same but the numbers might not be.)

JaxxMan
03-07-06, 07:22 AM
Thanks for everyones input so far, I just wanted to clarify I will not be using the thinner perforance gaskets now. I will use OEM ones now and save them for when I get a set of preformance heads.

I will be using ARP Studs instead of head bolts (I posted ARP part #'s in another thread) and I've almost completed TimeSerting, the outter holes remain due to stuck dowel pin locators. Speaking of dowel pin locators anyone know a cheaper place then the dealer to get them? The dealer in my area wants over $12 each.

Thx Again JaxxMan

Katshot
03-07-06, 08:16 AM
That's probably a good idea since other than the milled heads, you're having to deal with "production tolenances" and probably a good deal of wear among other parts. These two combine to create what "could be" less than optimal. That's why the OEM leaves the squish area rather large (in the area of .050"-.060"). Even pro builders generally don't go below .040" from what I've seen. The effect of increased squish on timing requirements is kind of hazy IMO. Yeah the increased squish (lower piston to head clearance) DOES lead to a better A/F mix but it also DOES increase static compression ratio. I'm not sure you can make a blanket statement on the subject. I'd feel better to say that it depends on the engine (combustion chamber design). It'll be interesting to see how this turns out for you. Not surprisingly, you "may" not even notice a difference.

eldorado1
03-07-06, 11:23 AM
What's the stock quench distance on the northstars?

I don't know, I've never measured, and nobody will give me specs on deck height and compressed gasket thickness.

zonie77
03-07-06, 11:57 AM
Jaxxman, if you still have the stock gaskets can you measure the thickness and post it?

Eldorado1 asked about this a while ago but if no one saved the gasket...,I sure didn't, you can't measure. Maybe you still have yours.

haymaker
03-07-06, 04:01 PM
I just checked the thickness of the old blown head gaskets that came off my ’97 N* and after checking several of the fire rings found the average thickness to be + or - 0.070” the other areas averaged + or - 0.075”. I checked both head gaskets BTW. These old head gaskets have been setting in the garage for nearly two years so IMHO if anything they may have relaxed and measure a tad thicker than right after they were first removed.

chevelle
03-07-06, 09:48 PM
Milling the heads 0.020 won't bother anything. You will end up with a little higher compression ratio which is good if you are interested in performance. The knock control will pick up any increased tendency for detonation so you will get a little more spark retard on average unless you run premium fuel. Otherwise, there will be no effect on the PCM or anything.

I would recommend the OEM gaskets regardless of whether you mill the heads or not. The compacted graphite gaskets are the best known parts for longevity and the thinner aftermarket gaskets are not going to live as long with the all aluminum engine.

Milling the heads will have no effect on the tendency for "cold carbon rap" or carbon formation. In any case, this owner would seem to keep the throttle at WOT sufficiently to keep carbon at bay. Even with more moderate operation, the compression ratio has little to no effect on the formation of carbon. Milling the head doesn't change the squish on the Northstar. The squish is controlled by the head gasket thickness and the piston/deck relationship at TDC. The main variable that influences the "cold carbon rap" tendency in the Northstar is the proximity of the piston to the flats on the head at TDC...which will not be changed by milling the head. Going to a thinner head gasket would definitely increase the chance of cold carbon rap...the clearance or squish reduction would increase the tendency of carbon buildup and less carbon buildup would make contact with the piston sooner...if you catch my drift. Later model Northstars high slightly increased squish to lessen the likelyhood of cold carbon rap. The squish is very important for good in-cylinder mixture motion and good combustion.

eldorado1
03-07-06, 09:58 PM
Going to a thinner head gasket would definitely increase the chance of cold carbon rap...the clearance or squish reduction would increase the tendency of carbon buildup and less carbon buildup would make contact with the piston sooner...if you catch my drift.

I understand having less space would make it more prone to contact if carbon did buildup... but why would less squish mean more carbon buildup? It seems like less space means a greater force of air to "wash" the carbon off...

Katshot
03-08-06, 08:29 AM
Milling the heads 0.020 won't bother anything. You will end up with a little higher compression ratio which is good if you are interested in performance. The knock control will pick up any increased tendency for detonation so you will get a little more spark retard on average unless you run premium fuel. Otherwise, there will be no effect on the PCM or anything.

I would recommend the OEM gaskets regardless of whether you mill the heads or not. The compacted graphite gaskets are the best known parts for longevity and the thinner aftermarket gaskets are not going to live as long with the all aluminum engine.

Milling the heads will have no effect on the tendency for "cold carbon rap" or carbon formation. In any case, this owner would seem to keep the throttle at WOT sufficiently to keep carbon at bay. Even with more moderate operation, the compression ratio has little to no effect on the formation of carbon. Milling the head doesn't change the squish on the Northstar. The squish is controlled by the head gasket thickness and the piston/deck relationship at TDC. The main variable that influences the "cold carbon rap" tendency in the Northstar is the proximity of the piston to the flats on the head at TDC...which will not be changed by milling the head. Going to a thinner head gasket would definitely increase the chance of cold carbon rap...the clearance or squish reduction would increase the tendency of carbon buildup and less carbon buildup would make contact with the piston sooner...if you catch my drift. Later model Northstars high slightly increased squish to lessen the likelyhood of cold carbon rap. The squish is very important for good in-cylinder mixture motion and good combustion.

How do you figure that? You say milling the heads will have no effect but a thinner head gasket will? I think you're a little confused here. You DO know what milling the heads is, right? :hmm:

davesdeville
03-09-06, 02:21 AM
Kevin, I think he's right. Talking about quench distance, milling the head would have no effect, the milled surface would be in the same place as the old surface would've been. But, with a change in headgasket thickness, the head surface would be closer, causing a smaller quench area.

Katshot
03-09-06, 05:02 AM
I guess you're not understanding what milling a head means. It means milling away material on the gasket mating surface of the head, generally for the purpose of removing runout. A common practice among builders is to use a thicker head gasket after milling heads in order to compensate for the removed material.

dkozloski
03-09-06, 08:49 AM
If you're worried about 0.020" off the head you're really picking the fly poop out of the pepper. You'll get bigger changes than that from day to day as the barometric pressure varies with the weather. You would be better spending your time concerned about crop circles and UFO's.

clarkz71
03-09-06, 10:27 AM
I guess you're not understanding what milling a head means. It means milling away material on the gasket mating surface of the head, generally for the purpose of removing runout. A common practice among builders is to use a thicker head gasket after milling heads in order to compensate for the removed material.

Milling the head DOES NOT put the piston closer to the head, it only reduces the cc of the combustion chamber. A thinner head gasket is like milling the deck of the block.... which DOES put the piston closer to the head, reducing deck height. Both increase compression, only one (gasket/deck milling) decreases deck height. To make it simple, if you measure deck height and you have .040. Then you mill .020 off the head, the deck height is still .040 but the compression is increased. If you mill .020 off the deck of the block you now have more compression AND a deck height of .020.

Katshot
03-09-06, 10:58 AM
Milling the head DOES NOT put the piston closer to the head, it only reduces the cc of the combustion chamber. A thinner head gasket is like milling the deck of the block.... which DOES put the piston closer to the head, reducing deck height. Both increase compression, only one (gasket/deck milling) decreases deck height. To make it simple, if you measure deck height and you have .040. Then you mill .020 off the head, the deck height is still .040 but the compression is increased. If you mill .020 off the deck of the block you now have more compression AND a deck height of .020.

I see what you mean. On heads that do not actually have a squish area built-in to the combustion chamber, milling won't effect the squish. I get what you were saying. This diagram shows your theory.

ewill3rd
03-09-06, 12:30 PM
Inside the combustion chamber there is a flat spot, it's called a "gage pad".
The distance from the gage pad to the deck surface must stay above 10.5mm.
The manual doesn't say much about how much material can be milled off, but it does specify that this dimension must remain above 10.5mm.

The distance from the piston to the deck is not the issue, the issue is if the valves are moved closer to the piston by milling material off of them then they are going to start whacking the pistons. Not to mention that other things that bolt to the cylinder heads and the block are not going to mate up properly. Milling the heads moves the lands for the intake manifold slightly closer to eachother as well. Mill them far enough and you won't be able to bolt the intake or the coolant crossover back onto the engine properly.


If resurfacing is required, the dimension between the combustion chamber gauge pad and the deck surface (1) must be at least 10.5 mm (0.413 in).

clarkz71
03-09-06, 12:47 PM
Yeah, unless your a mechanic or engine builder it's easy to get confused about what affects what. Just like when we had points ignition, adjusting the gap/or dwell changed the ignition timing. But... changing the timing obviously did not affect the gap of the points.

clarkz71
03-09-06, 12:54 PM
You are correct ewill3rd. Thats another thing, milling the head changes piston to valve clearence only, milling the deck or thinner head gasket changes both piston to valve and piston to head clearence. Sometimes we forget how much you need to know to be a pro technician. I was an ASE Mercedes Benz tech for 25 years.

Katshot
03-09-06, 01:04 PM
You are correct ewill3rd. Thats another thing, milling the head changes piston to valve clearence only, milling the deck or thinner head gasket changes both piston to valve and piston to head clearence. Sometimes we forget how much you need to know to be a pro technician. I was an ASE Mercedes Benz tech for 25 years.

Hell, I still am an ASE tech but being out of the business for so long let alone away from turning wrenches takes it's toll. :bigroll:

clarkz71
03-09-06, 01:10 PM
I hear ya, I'm still certified ASE, just don't work right now due to a disability.

ewill3rd
03-09-06, 05:39 PM
Sadly the Northstar engine is pretty much engineered to "throw away" anything that is worn out.
When I took the N* training class in St. Louis the instructor told us that if the cylinder wall is scored and you can feel it with your fingernail to throw the engine block away.
You can't do many of the procedures to "save" parts like you could on older engines.

chevelle
03-09-06, 11:50 PM
How do you figure that? You say milling the heads will have no effect but a thinner head gasket will? I think you're a little confused here. You DO know what milling the heads is, right? :hmm:


No, I am not confused and yes, I do know what milling the head is. The question is do you know what milling the head is and what the squish area is and what relationship it has relative to the piston and deck.??

Milling the head will reduce the combustion chamber volume but will not move the squish area any closer to the piston than it already is. The squish area is on the same plane as the head deck surface so it is milled when the head is milled thus it stays at the exact same distance from the piston.

Using a thinner head gasket will indeed reduce the clearance in the squish area since the thinner head gasket will move the squish area closer to the piston.

Sounds like you need to actually took one of the Northstar engines apart and see what makes them tick instead of spending all your time criticising them...... Then you would understand all of this stuff....LOL.

chevelle
03-09-06, 11:58 PM
Sadly the Northstar engine is pretty much engineered to "throw away" anything that is worn out.
When I took the N* training class in St. Louis the instructor told us that if the cylinder wall is scored and you can feel it with your fingernail to throw the engine block away.
You can't do many of the procedures to "save" parts like you could on older engines.


Not sure of your "instructor's credentials...but....the Northstar engine is as repairable and rebuildable as any engine out there. Nothing about it indicates it is a throwaway. The cylinder liners are designed to be overbored by as much as 1mm in cases of repair, damage or a re-man situation. The real issue is lack of repair parts for the engine as most warranty repairs involve simply replacing pieces. There is very little demand for the aftermarket repair parts so very little is available. That doesn't mean the engine is a "throwaway"...it really indicates the engine is pretty reliable and that there is very little call for aftermarket repair parts. It is pretty rare to have a cylinder wall defect like you describe. Many many people on the forum over the years have reported on engines dissassembled with well over 100K on them and the cylinders are perfect, there is no ridge on the top and the OEM honing patttern is still visible. Repair requirements on the cylinder walls and block like you describe are almost nonexistent. If they are needed for some reason they can be done just like any other engine.

If you can think of one single feature of the engine that indicates it was engineered to be a throwaway I would be interested in what it is....

Katshot
03-10-06, 04:45 AM
No, I am not confused and yes, I do know what milling the head is. The question is do you know what milling the head is and what the squish area is and what relationship it has relative to the piston and deck.??

Milling the head will reduce the combustion chamber volume but will not move the squish area any closer to the piston than it already is. The squish area is on the same plane as the head deck surface so it is milled when the head is milled thus it stays at the exact same distance from the piston.

Using a thinner head gasket will indeed reduce the clearance in the squish area since the thinner head gasket will move the squish area closer to the piston.

Sounds like you need to actually took one of the Northstar engines apart and see what makes them tick instead of spending all your time criticising them...... Then you would understand all of this stuff....LOL.


Dude, try reading the last few posts. Water under the bridge at this point.

ewill3rd
03-10-06, 06:29 AM
Well, it was at a GM training center and he was a fully certified tech with a few dozen years of experience under his belt. He was trained by the engineers that designed and built the engine so maybe there is an outside chance that he didn't know what he was talking about.

Go take a piston rod out of a northstar to a machine shop and ask them to recondition it for you. Tell me what they say. Ask them how much to machine the journals on the crankshaft and how much a set of undersized bearings are.
If they are damaged you throw them away and replace them.
Yes the block can be machined, however the instrctor's point was that if it's damaged to a certain extent you are very limited in what you can repair.
I am not so certain there is a large array of service pistons available for this engine. You can bore an old chevy smallblock out to like .060, because there are pistons you can buy to fill those holes. I think N* only has one oversize available, from GM anyway. You can do anything you want but the reliabililty of what you end up with may be questionable.

I wasn't in any way trying to say the N* was unreliable so please don't misinterpret my meaning. I only meant to say that you'd be better off replacing components that are beyond service, and that you shouldn't be afraid to admit to yourself when it's time to let go and get another part.

Katshot
03-10-06, 06:53 AM
Whether it's a "throw-away" engine or not is beyond me but I can say that for an engine that has been around for well over a decade, companies doing rebuilding of them are still not real plentiful. I haven't followed the Northstar much but I can tell you that even the OEM didn't support rebuilding of them for a long time. Warranty was "component replacement only" as I recall.

dkozloski
03-10-06, 12:41 PM
Because of the hi-tech design there are a lot of components that cannot be reconditioned by the ordinary "dirt floor" garage operation. "Cracked" connecting rod cap design and rolled fillets on the crank journals are very difficult to deal with. Fortunately they rarely need work at overhaul. Rebuilding a high milage engine and trying to reconstruct a failure are two different animals. Worn is a long ways from burned and broken. Getting more good use from a tired motor is one thing and resurrecting a cratered out hulk is another.

Dooman
03-10-06, 02:05 PM
When my motor was torn down, my heads were milled "about .020". Runs great, no adverse effects. Been almost 2 years now and about 25,000 miles... I insisted on it..

Katshot
03-10-06, 02:11 PM
I agree that worn and broken are two different things but when a company is going to take an engine and rebuilt it, then give it back to the customer with a warranty, my guess is they probably get treated pretty much the same. Maybe a local rebuilder will take the time to do just what's needed but the larger guys will most likely just run it through their normal rebuild procedure. I've never really dealt with a small rebuilder so I can only really comment on the big guys.

dkozloski
03-10-06, 05:00 PM
The big guys parts pool these things. The source of motors is returned cores and junkyard purchases. The core motors are torn down and the parts are all cleaned and inspected. After what can be repaired is repaired a motor is put together out of the parts pool. Such is the benefit of the concept of interchagable parts. A bad connecting rod means nothing. It is thrown away and replaced with another. If the block is shot it goes to the recycler and the next in line is used. The little guy has to scour the junkyards for parts like the rest of us.

ewill3rd
03-10-06, 05:30 PM
I think it's a very reliable engine, I think everyone misunderstood what I meant by throw away. I don't mean the engine is junk, I mean when something goes wrong you just have to replace that part.
The crank is specially made and you cannot machine it. The rods have fractured caps and are not reconditionable. I checked with my shop foreman, the block is not boreable, there are no service oversized pistons. If the cylinders are out of spec you need a new block... etc.
It's a great engine and just because one part is bad doesn't mean the engine is garbage, it just means you need a new part.

It's not as rebuildable as "any engine out there" meaning that the parts cannot be reconditioned. I have had cranks milled and installed undersize bearings, I have had engines line bored and installed oversize bearings, milled heads, milled block decks, bored out cylinders and the like. Not much of this is possible on the N*, that was my only point.

chevelle
03-11-06, 02:46 AM
Fractured cap rods can be reconditioned. Just like there are undersized bearings for cranks that are ground undersized a fractured cap rod needs a special "oversize" service bearing for a re-man situation. The bearing would have a slightly larger OD on the shell to account for the resizing of the big end.

The cranks can be ground .010 under without a problem from the rolled fillets.

The aftermarket makes all sorts of under and oversized parts to recondition engines that demand them. There is very little demand for reconditioning Northstar engines. by and large they are very reliable and rarely need that sort of treatment. Maybe in 20 years the aftermarket will tool up the parts needed to reman one.

Just because reman parts are not available does not mean the engine cannot be remanufactured or serviced. The comment implied that the engine was designed such that it cannot be remanufactured, when, in fact, it is just as repairable should it turn into a basket case as anything else out there.

The fact is that the cracked cap rods rarely need any work done to them. If a rod bearing spins with one of them it is easier to replace the rod (they are plentiful and available) than recondition it. In the future, if the aftermarket generates an oversized bearing for them, they are just as reconditionable as any other sort of rod. In the mean time the cracked cap PM rods offer significant performance advantages. Just because they require a different sort of process to recondition them does not mean they cannot be reconditioned.

ewill3rd
03-11-06, 06:30 AM
Okay guys, here are some excerpts from the GM factory service manual.
I am sure a bunch of you will tell me they are wrong but here goes anyway.


Compare your measurements with those listed in the Engine Mechanical Specifications . If the crankshaft journals are worn beyond the specified limits, the crankshaft must be replaced. Crankshaft machining is not allowed and there are no undersized bearings available for service.



Compare your results with the engine mechanical specifications. If the cylinder diameter exceeds the specifications, the cylinder block must be replaced. There are no oversized pistons available for service


You must replace the piston if any of its dimensions are out of specification. There are no oversized pistons available.


Typically when a rod is "reconditioned" they machine down the flats on the mating faces of the rod and then bore the rod journal the same diameter back to the original spec. Some places just make the hole bigger and you have to use an oversized bearing. You can't machine the rod faces on a cracked cap. No oversized bearings are available for this engine.
You cannot machine the crank due to the formulation of the steel. It has a hard outer shell on it and if you machine it, the outer surface is not durable enough to put back into use, period.
Its the composition of the crank that is the problem... oh and the fact that there are no undersized bearings for it. Why would there be? You CAN'T machine the crank?

Anybody who still thinks I am saying the engine can't be rebuilt is confusing me. Someone please tell me how many times I have said it's possible but some parts are just not servicable?
If you can't read that part how can you read this post?

I don't care how many times you guys tell me it's black, I know for a fact it's white.

Katshot
03-11-06, 07:11 AM
In all fairness, it sounds like you're quoting "factory" literature, right? Just because GM doesn't offer these parts, it doesn't mean they aren't available from the aftermarket. Maybe they are.

ewill3rd
03-11-06, 07:22 AM
Then someone make some phone calls and post where they have these parts.
I want to know where they sell oversized or undersized bearings for a Northstar engine, pick a year... any year. I'd also like to know where they sell oversized pistons.

I also want the phone number of a machine shop that will do this work, because I'll call them and ask them some questions.
If someone else wants, ask them if they will:
Bore the cylinders
Recondition the rods
Machine the crankshaft

I am not trying to "be right", I am trying to keep someone's misperception from being interpreted as fact.
This misinformation could end up costing one of the forum members thousands of dollars as opposed to going and buying a replacement part for something that can't be machined.

The service manual is documented information from engineers. I haven't seen anything in this post other than speculation and supposition based on rebuilding a Gen II chevy small block.

How does the fact that it's "factory literature" invalidate it?

If someone can present me with a documented fact I'll be more than happy to acknowledge that it's "possible".

JaxxMan
03-11-06, 02:51 PM
Sorry I've been sick a few days (working too late on the car and a newborn in the house boy #3, it's taking it's toll)

Zonie77 Sorry I haven't had a chance to measure the headgasket rings the rest of the gasket was falling apart and soaked with coolant in the leak area. The shop's an hour drive to my brothers house so I'll make note to check them next time.

The pic I posted looks worse then it actually is. Picture was taken in Macro mode for great detail. The shop thinks that .010" thou should clean up the surface nicely. Dooman thx for your post I got a little worried about intake & waterpump crossover alignment until I read your post.

ewill3rd As far as after market parts I found a lot at www.rockauto.com. for my 94 Concours .25mm,.50mm & .75mm oversize pistons & rings. Also oversize crank & connecting rod bearings in the same .25mm,.50mm & .75mm sizes. I would have to agree with Katshot about the aftermarket possibilities. When the manuals were printed, GM must have decided they were not going to produce parts, is my theory.

Also ewill3rd thanks for the great post about the gage pad measurement, I didn't have that in my manual. I sent a link to the engine building shop where the heads are.

chevelle thx for all your posts great info, Oh $#!& I hope I didn't forget anyone.

dkozloski
03-11-06, 03:49 PM
The crankshaft will be ruined if ground undersize because it has rolled fillets to prevent cracking. This can be ignored but if the engine is pressed it will grenade. The machine required to reroll the fillets is so expensive I doubt that more than one or two shops in the country has one. Someone on this forum had a crank repaired and when he questioned the shop about rolling the fillets they went stupid on him. There is a lot of ignorance out there among the rebuilders. Above information per "Beezlebob". Because a lot of the motor is of this hi-tech nature that makes reconditioning difficult it makes more sense to go to the junkyard and get a "blown headgasket motor" or similar low timer and use those parts with standard sized bearings and rings. In fact I'll bet you could get several of these things for a reasonable price and do your own parts pool deal. Something like three to make two.

davesdeville
03-12-06, 02:36 AM
The crankshaft will be ruined if ground undersize because it has rolled fillets to prevent cracking. This can be ignored but if the engine is pressed it will grenade.


The cranks can be ground .010 under without a problem from the rolled fillets.

:eek:

ewill3rd
03-12-06, 07:44 AM
Jaxx, glad that measurement info helped you.
I'd hate to see them mill it too far.
Good luck with your project.