Got the block back from the machine shop last week and upon first inspection it looked great. Anyways started to clean it up for painting and assembly and noticed a problem near cylinder one. I could see a "groove" that looks like it was caused by the decking machine cutting head, I could actually feel it with my finger. So I take my machinist straight edge lay it on the deck surface and sure enough there is some "daylight". I took out some feeler guages and it appears that the groove is about .019" deep. I'm pretty upset about this but can see no way to fix this problem and I'm concerned that I won't be able to get the head gasket to seal properly. I actually bought a Cometic and there is no way that I'd even consider running that gasket with this gouge. The gouge by the way is about an inch and half wide and is on the exhaust side of the block on piston number 1. Do you guys think that a standard Felpro would seal over this gouge? Or should I just scrap the block and start over, painful because I have about 2k in this block already but I want this right, too much other work has gone into this project for it not to be right. I've got another stock block in the garage that I could use as a beginning. I can get a block stroker prepped for about 1200, including four bolt splayed caps, boring, honing, stroker clearanced etc. I'm thinking that this might be the way to go, cut my losses and know that my block is right.

This really sucks as this has already been a long, expensive process.

 

If there is any real visible marks in the deck surface then you most likely have way to rough of a surface finish for the Cometic anyways.

I would try the Copper Gasket maker in the grove and a Fel Pro gasket and see if it works. At worst you could deck the surface again to get that out of the block. I wouldn't scrap the block just yet.

BTW I wouldn't worry about paying for the work if you are going to scrap this block, they should at least understand what a **** up this is.

Bret

 

Thanks Bret. I might try the copper gasket/Felpro method, but it sure would be alot of work if it doesn't work. I'd have to pull the engine again, tear it down etc. etc. More decking probably won't work, It's already down to 9.005, so about the max they could remove would be maybe .010, which would leave my pistons "out of the hole" about .005. With a .040 gasket that would be .035 quench, about as tight on a street driven motor as I'm willing to risk. I don't have the specs where my ring lands start on the piston but they are a pretty good ways down, about how far out of the hole can you run a piston anyhow. I'm guessing that too much and the natural "rocking" motion of the piston in the bore becomes a major factor.

I'm going to bring it back to them this coming Monday and see what they say. Even if they agree to do another block for no charge, I'm wondering if I really want them too.

Double by golley Darn. (This is CamaroZ28 cussing BTW), my actual language concerning this matter is somewhat more colorful.

 

The crown being proud to the deck will not effect piston stability. I'd deck the block now rather than face another R&R, because that is such a painful process on a 4th gen. If it will cost you $2K to redo another block, wouldn't it be cheaper to get a set of pistons with a custom CH anyway, if needed?

Rich

 

You're right Rich that would probably be the cheapest route. Deck the block until it's right, measure it and order a new set of pistons. What a frickin nightmare this has been. I'm thinking I should have taken up say quilting as a hobby.

Again more golly, dosh garn, heck.

 

I've never tried this on an engine block, but on industrial steam turbines it is not unusual to get pretty bad steam cuts on the high pressure barrel parting surfaces (they don't use gaskets and the surfaces have to be true to hold up to 2500 lbs of steam pressure @ 1000 deg F). The standard repair is to use a ball burr on a die grinder to clean out the gouge, and then silver solder it up to just above the parting surface. Then we machine it back to the proper finish. I think that would be worth a try before scrapping the block.

Chris

 

They could always weld it and deck it. If it is a small gouge you should only loose 5-6 thou. off the deck after warpage from welding. If your machine shop is equipped to do it they should do it on the house. They need a stick welder and use nyrod. We do it all the time and don't have problems. The nyrod is accually harder than block material. If you paid the shop money to do the work I wouldn't scrap it, thats wasted money you could buy other parts with. If you want to know more about welding the block let me know.

 

I'm interested in the welding because I'm willing to bet this is what the shop proposes. This gouge is about an inch maybe an inch and half wide, looks to be about the width of the BHJ Decking Machine cutting head. Never having actually seen one, (milling machine), I'm actually guessing that it was the cutting head, I'm going more on the way the gouge looks, semi-circle and you can see the grooves from the cutting. Thing is the rest of the deck is perfect, supposedly very good RA from this head, the machinist tells me that he gets a very good RA value because he uses diamond bits.

What is Nyrod, the machinist actually had already TIG welded O-ring grooves and did a very good job, which is the reason that the block was decked in the first place, I didn't want to run a copper gasket and my quench was going to be in the .055 area with .040 copper gasket. I wanted it to be in the .035 - .040 range and not run copper, this is why the block went back to the machine shop.

 

It could be from when the ran the cutter head down on the block to rub off, then it may have hit hard and backed off a touch or something.

Either way, they should pay for it all IMO.

 

I agree, I'm going to take this thing back tomorrow and have him look at it. Shouldn't really cost me a penny, no matter what option is chosen to fix the problem.

 

Nyrod is a welding rod w/ high nickel content (+50%) which makes it very hard. The grooves are definatley from the cutter. The machinist prob messed up after the last cutting pass. It has happened to us a few times, after the last cut you may have to lower the block and run the cutting head back over so it can be removed(not touching it). He miss judged it. The difference is we fixed our f-ups at no charge b4 sending it out.. The thing is if he welds it w/ Nyrod chances are if he tries to deck it in his fly cutter machine it will destroy his big $$ cuttin bit. We use a wet stone type machine that has no issues w/ that. Ask the machinist about it, he may special bits or a capable machine. When u say he tig welded o-ring grooves do you mean he filled in the grooves w/ a tig welder. If he did I hope he bored and honed after he welded. If not your bores will be out of round from the heat of welding so close to the cylinders. Be sure to ask them bout that when u go back. If you get some pics I could tell u what happened 4sure. I am gonna try to find a pic of a weld job I did.

 

Wont that normally tiger stripe the entire deck surface?

 

He should be using diamond for aluminum surfaces and CBN for iron. CBN will cut nyrod no problem, just need to only feed it .002" per pass on that hard stuff otherwise it will kill the puck.

 

None of this is giving me a warm fuzzy feeling about my block. He did torque plate hone the block after welding the 0 rings, but they were already bored. I'm beginning to think that the best option might be to start over using the stock block that I have sitting in my garage. It will of course need everything, 4 bolt main caps etc. I can get that done for about 1200.

I borrowed a dial bore guage, but I can't seem to take any repeatable measurements with it, so I don't have any confidence in it's accuracy.

 

Just discussed options with my machinist. One would be to deck the groove completely out of the block and use a different crank, (his expense), with a 3.750 stroke instead of the 3.850 stroke that I'm running now. That would put zero deck at 8.975, plenty of room to work with.

Is there a risk running this deck height with an LT1 block, would this possibly make the deck surface too thin? He want's to look at the block before even choosing this option to see if it is thick enough to handle this. What do you think, I'd be getting a better crank that what I have now.