Did my machinist screw up girdle installation?

[Turboholic87]

Before taking my block to the machinist I had the main cap mating surfaces cut .004" for a line hone and had fitted the girdle to 3-4 thousands pan rail clearence (preload) with the main studs tightened down. Was getting ready to assemble my engine this weekend and noticed that when I put the girdle on the block and tightened the studs all the pan rail clearence was gone. Long story short the machinist took everything apart, cut the caps again without checking first, and line honed with the girdle now having about 2-3 thousands negative preload. Called him up and he reassured me that everything would be OK and he had another motor in the shop machined with no girdle clearence like this making 750hp no problems. The sad part is he specializes in Buick engines around the Chicagoland area. I think this guy is blowing smoke up my a$$ , what do you guys think I should do? He said just shim it back up if I'm nervous about not having clearence but then whats the point of doing the line hone.

 

[Blown&Injected]

I too know a big time Buick machinist that seems to blow-off the super tight "Turbo-Buick" specs.

Got to say the cranks he has done have been 7's and lots of super fast street cars too; and yes they stay together.

Having said that, it still does not seem right. I do not know how he could defend the side of cutting (the caps) before measuring.

It sucks that you took the time to get one set of specs just right only to have it messed with to result in an out of, or less then, perfect spec but I have to say that there seems to be a communication that could be responsible for a process failure that may have been avoided if there was just one machine shop working on the project.

 

[turbofabricator]

Did he hone the main line with the girdle torqued at the pan rail? If so, then it will be OK. If not, then you "could" have problems. I have seen machinsts hone the block with the pan rail fasteners out. That is just WAY wrong! Have them read the instructions BEFORE they do the work. Some machinsts can't read, though. (not kidding) I usually hold their hand when ever they do ANYTHING of mine. One of the machinists I use will not touch anything unless I am right there telling him what to do. Good machinists are hard to find.
When I install girdles, I usually have to hand sand the pan rail down with a block to get an even .005" pre-load. It goes faster than you think. And, as I tell the new guys on the job........It's OK to sweat. There is nothing in the union contract that says you can't sweat!

 

[gnxtc2]

The Buick V6 pan rail is not level side to side. Some machinists like to mill the pan rail while some don't. The ones that don't, say the factory referenced the block off the pan rail hence those 2 big holes.

Did you achieve the preload with the girdle torque down on the mains and prior to installing the side rail studs? If so, then it is correct. When you install the rail studs, they tie everything together. The thickness of human head is .003". You by installing the 20 oil pan studs will most definitely bend the girdle .003"/.004" hence the reason for the preload.

You state that you have negative pre-load. Add more shims if you have the RJC girdle. If you have the Chinese one, then you must make some shims to put between the girdle and the caps.

Turbo Fab is correct in line honing the mains with the girdle secured. My engine builder goes a step further and installs a set of heads to the block during the line hone. I seen him drop a crank in a block that was machined for a girdle that would "drag" without the girdle fully fastened. Once the girdle was fastened, the crank spun freely. The 109 blocks do move around.

Billy T.
gnxtc2@aol.com

 

[bison]

He is wrong. The girdle is actually deloading the caps and pulling them downward. He f ucked up and should be happy you caught it. Thats the opposite of the desired outcome. It will crack the webbing in no time iy you dont have it corrected. Im my experiences the engine pan rail is not equal all the way around. The answer is to mill a few thousandths off one side of the girdle to get the .003-.004 preload. I wouldnt be too worried if there was .001 but none is a problem.

 

[bison]

The Buick V6 pan rail is not level side to side. Some machinists like to mill the pan rail while some don't. The ones that don't, say the factory referenced the block off the pan rail hence those 2 big holes.

Lol. I posted the same thing. I didnt read you post before i posted.

 

[Blown&Injected]

That loading of the caps sounds scary

 

[bison]

That loading of the caps sounds scary

You mean de-loading, right?

 

[Dusty Bradford]

Install the front cover and mill the pan rail and front cover together. The pan rail most likely isn't flat anyway.

The line bore would have to be re-checked after you achieve the correct pre-load again.

 

[Blown&Injected]

I mean that the way it seems to be loaded is scary but to be clear I was going to write that the retroversional nature of the antipodal loading is scary

 

[turbows6]

If you are interested I have a bunch of leftover RJC shims. Approximately half of a set if you decide to shim the girdle up. I would just make sure to check the main clearances whatever you do. Girdled engines are more sensitive to making sure you duplicate the conditions of when the line hone was done.

 

[Turboholic87]

All right here is what I did to clear up the confusion.
1. had another shop machined cap mating surface 4 thou
2. milled tops of caps flat at home
3. installed shims to get the 3-4 thou gap between girdle & pan rail
4. took the engine assembled to the machinist for a line hone.
5. he took every thing apart and took another 4 thou off the cap mating surfaces without checking the bore
6. he bolted up everything (main & pan rail studs) then line honed the block

Based on my notes that I took when I measured the cap height I have negative preload of 3 thou. This means that the pan rails are pushing up on the girdle with the mains tight and yes that means that the girdle is pulling the mains out from the block instead of adding additional preload like Bison said. Now if I add more shims to get rid of the negative preload doesn't that throw off the line hone? Even if I get it to no preload or +- 1 thou zero preload aren't my main journals going to distort? The bad part is that even if I wanted to do it right again I may not be able to since the block was line honed at least 1 other time. Can it take 3 line hones?

I'm really fired up about this whole mess since I spent about 16 hours getting everything PERFECT by hand sanding the rails and making sure the caps were all within 0.5 thousands of each other. Now they're crooked with about 2 thou difrence from driverr to pass side and one cap is even 3 thou higher than all the rest. I also can't completely blame the machinist since I did not give him instructions but instead relied on the fact that he said he's done girdled blocks before. Appreciate any advice you can give.

Thanks

 

[gnxtc2]

Now if I add more shims to get rid of the negative preload doesn't that throw off the line hone? Even if I get it to no preload or +- 1 thou zero preload aren't my main journals going to distort?

No. You are not touching the main caps. You are "raising" the girdle for proper clearance.

The bad part is that even if I wanted to do it right again I may not be able to since the block was line honed at least 1 other time. Can it take 3 line hones?

You better check your timing chain tension. You might have to use a tighter chain/over size gears

I'm really fired up about this whole mess since I spent about 16 hours getting everything PERFECT by hand sanding the rails and making sure the caps were all within 0.5 thousands of each other. Now they're crooked with about 2 thou difrence from driverr to pass side and one cap is even 3 thou higher than all the rest.

Your hand is not that accurate compared to a machine. Drop the caps off to a machinist and have him/her mill the tops of the caps.

Which girdle do you have?

Billy T.
gnxtc2@aol.com

 

[Underboost]

All right here is what I did to clear up the confusion.
1. had another shop machined cap mating surface 4 thou
2. milled tops of caps flat at home
3. installed shims to get the 3-4 thou gap between girdle & pan rail
4. took the engine assembled to the machinist for a line hone.
5. he took every thing apart and took another 4 thou off the cap mating surfaces without checking the bore
6. he bolted up everything (main & pan rail studs) then line honed the block

 

[bison]

Id have the line bore and hone checked. You may not be able to simply hone it since the caps may be out of round when torqued and preloaded instead of deloaded which would cause an inconsistent bore location front to back. It needs to be verified that its ok. Honing will follow the relative position of the caps and wont necessarily line them up. Only the boring process can do this.

 

[750H.P.V6]

At the point you're at I suggest that you shim the girdle to get the preload back and then re-check the main bearing bore to see if it's still round. Based on what you stated I wouldn't be suprised if the machinist honed the block without the girdle on it. If it's any concelation, the last girdle motor I built I had the machine shop surface the pan rail to make everything "right" and it ended up that I had .008" on one side and .003" on the other when I checked their work.

Neal

All right here is what I did to clear up the confusion.
1. had another shop machined cap mating surface 4 thou
2. milled tops of caps flat at home
3. installed shims to get the 3-4 thou gap between girdle & pan rail
4. took the engine assembled to the machinist for a line hone.
5. he took every thing apart and took another 4 thou off the cap mating surfaces without checking the bore
6. he bolted up everything (main & pan rail studs) then line honed the block

Based on my notes that I took when I measured the cap height I have negative preload of 3 thou. This means that the pan rails are pushing up on the girdle with the mains tight and yes that means that the girdle is pulling the mains out from the block instead of adding additional preload like Bison said. Now if I add more shims to get rid of the negative preload doesn't that throw off the line hone? Even if I get it to no preload or +- 1 thou zero preload aren't my main journals going to distort? The bad part is that even if I wanted to do it right again I may not be able to since the block was line honed at least 1 other time. Can it take 3 line hones?

I'm really fired up about this whole mess since I spent about 16 hours getting everything PERFECT by hand sanding the rails and making sure the caps were all within 0.5 thousands of each other. Now they're crooked with about 2 thou difrence from driverr to pass side and one cap is even 3 thou higher than all the rest. I also can't completely blame the machinist since I did not give him instructions but instead relied on the fact that he said he's done girdled blocks before. Appreciate any advice you can give.

Thanks

 

[Turboholic87]

No. You are not touching the main caps. You are "raising" the girdle for proper clearance.



You better check your timing chain tension. You might have to use a tighter chain/over size gears



Your hand is not that accurate compared to a machine. Drop the caps off to a machinist and have him/her mill the tops of the caps.

Which girdle do you have?

Billy T.
gnxtc2@aol.com

Well the thing with having negative preload is that when the main studs are torqued down the center of the girdle that is over the studs bows into the block pushing on the center of the caps. Remember, the girdle is 3/4" thick steel and it's highly unlikey that it does not distort the softer cast iron caps when it itself is distoring by 3 thou. Now I should probably check to see how out of round the bores are if I shim it up but I doubt that it's going to be round. I mean why do the directions tell you to do a line hone with the girdle, because it does distort the mains no mater how the preload is set pos or neg.
As far as my my hand not being accurate, that's right but I have a vertical mill at home which I used to mill the caps all to the same height except the rear. Used a micrometer to check them all, they were perfect side to side and between each other the same height. I sanded the pan rails and checked the preload with a feeler gage between the rails multiple times & sanded down the high spots using the girdle itself as a sanding block with self adhesive bodywork sandpaper (good for making your arms strong). I did all this to save on the cost of a girdle install and I also have a hard time trusting others to do things the right way (even more so now!). If I had a line hone machine I would have done that myself also.

You also raise a good point with the timing chain. The machinist did provide a tighter rollmaster chain. However, if I did another line hone should I worry about:
-front seal leaking due to crank being up higher and seal not being concentric?
-rear seal leaking for same reason?
-trans misalignment due to crank being up higher, should I get offest dowels?