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I think I've had a dozen different engines in this car.

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Did some measuring and figuring today.

Studs torqued to 90lb-ft deflect the bore the same as OEM bolts torqued to 90lb-ft. Same as close as I can measure anyway. Pulls the bore about .0015-.002 on diameter or .00075-.001 under each fastener. I thought it was more because there is about .001 taper in the bore from the last build. I torqued the studs to 80lb-ft and the next step will be to hone. I think I can get the bores round or nearly so at 3.937 top and 3.936 bottom. Pistons are 3.932. JE specs .004 minimum clearance for these pistons so I'm in good shape.

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Honed the bores today. Rigid hone is Lisle brand, not sure of the grit but guessing 280-ish by the look of the stones. Didn't take much out. Basically just knocked off the high spots then ran the dingle ball hone though to make it pretty. Next up is a thorough cleaning and trial assembly.

http://i965.photobucket.com/albums/ae131/strokersix/DSCN3825.jpg

Last edited by strokersix; 02/19/11 10:03 PM.
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Nice to have your own tools?

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Stroker, how do you like the Lisle hone?

I've only used a Sunnen, looks like the same setup though.


My, what a steep learning curve. Erik II#5155
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This Lisle hone is the only one I have any experience with. I expect Sunnen is much nicer but the Lisle seems to work OK. It's a lot of work to hone .002 and have to be careful to hold size for the length of the cylinder. I try to run the boring bar as close to size as possible to minimize honing.

I would rather buy a tool than pay someone else. I'm sure many members here feel the same way. I like to figure out how to do it myself. There are limits though. Pretty tough to justify a crankshaft grinder in my shop.

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 Originally Posted By: strokersix
I would rather buy a tool than pay someone else.


Amen to that.

Thanks for the insight. \:\)


My, what a steep learning curve. Erik II#5155
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Any udates on your positive deck height remeasurment?


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Nope, not yet. Honing result is cold clearance .0045-.0055 against JE recommended minimum .004.

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Polished the crank with 500 grit and measured main clearances. Had to dance to follow the crankpins. 1-6 are right about .003 on the diameter while 7 is .002 with thrust at .008.

Measured crankpin to deck, all within .001 resulting in the piston proud of deck by .003. Right where I wanted it for .037 piston to head clearance.

Rock the piston with my thumb and the quench side is up .018 and the opposite side up .012. What's the deal here? Another rookie engine machinist mistake, that's what. When I set up the block to machine the deck I had equal packing under the oil pan rail. If I had laid a level across the bellhousing dowels I would have caught the error. Should have shimmed to cut level relative to the dowels or dialed in the bore.

http://i965.photobucket.com/albums/ae131/strokersix/DSCN3827.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3842.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3843.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3846.jpg


Last edited by strokersix; 03/07/11 09:52 PM.
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Stroker, you made the cut to your deck correctly, based on the method in which you checked deck with. And as you confirmed, it is now .003 out of the bore as you intended. Initially, you only checked the deck height of your pistons in the center of the bores....which as I pointed out in an earlier post, is not the correct way to check your deck. And you can see know how inaccurate that using the center of the bore method truly is because it doesn't account for piston rock on either side of the piston, which is more critical. Many people have made that same mistake because they just dont know. You can still cut the pistons to compensate, which is very common to have to do anyway to obtain the right deck height. I think you mentioned that you had already taken your setup down before I mentioned this to you, but if you had been able to check how much piston rock you had before cutting your deck, you still would have seen around +.015 difference from the center of the piston as you are seeing now.



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My deck isn't square to the bore. The bore could be off but I don't think that's it because I checked the distance from dowels to oil pan rail and that dimension is off the same direction. If I had leveled to the dowels my piston would rock proud .015 on both the quench and opposite sides instead of .018 and .012.

Checking the deck height in the center eliminates skirt clearance from the equation. Then deal with the skirt clearance as another variable.

I expect the piston rocking to be less at operating temperature when the forged aluminum piston has expanded more than the iron bore.

Last edited by strokersix; 03/08/11 09:57 AM.
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I set up and cut the deck again. Square this time. I leveled off the dowels and ran an indicator down the bore to check.

Should give piston proud of the deck by .005 inch above the wrist pin and .018 on each side when rocked. .022 inch clearance to head when cold and loaded with my thumb.

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Loved the pictures of the crank. I can see where you turned it down to just above the crankpin rod faces, then milled for piston skirt clearance. What suprised me was the amount of balance drilling after that, I would have thought that Mallory metal would have been needed after all that metal removal. And what's with the big notch ont the weight next to #2, was that to hlep balance? Wow that's a lot of metal gone!

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The guy who balanced it for me did a good job balancing but not such a good job making it look pretty.

The skirt clearance cuts will clear 5.7 inch rods. I am using 6 inch rods this build. I used a big lever to swing the crank on crankpins under the milling cutter to make the cuts.

No Mallory required. Balance the crank all by itself or with damper and/or flywheel but no bobweights like you need for a v8.

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Stroker,
What head gasket are you going to use? Thickness?


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I measured the fire ring thickness on the used gasket I have hanging on the wall at .040 inch. It's a "Printo-o-Seal" or something like that. Maybe Felpro, not sure. I think (hope?) I have a couple new ones just like it in my gasket pile. I'll need at least two. One for run-in and a second for after I pull the head to check for witness marks on the pistons!

Open to suggestions.

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A Felpro performance 1025 is .041 thick. That is the one ran on the dyno mules. Ran the exact same gasket with all the head changes.

You may consider turning your piston crown down a few thousanth's. Best time to do it.


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Do you really think I'm in trouble with .022 piston to head quench clearance cold? I think clearance should increase to .030 or so when hot. The piston should rock less when it expands and reduces bore clearance from .005 to let's say .002 at temperature.

I've read in various magazines that .035 is a good clearance and .030 bare minimum. I always assumed that was a measurement taken on center? My on center clearance is .035. Bad assumption, poor source?

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Yeah, don't believe everything you read in magazines :D. I have seen pistons hit the head at .035 quench. At .030, the pistons can hit hard enough to close the ring gaps up and cause cylinder wall scoring. As close as your going to be running it, you can pound the bearings out of the rods and even bend some if you dont shut it off quick enough. Also, you loose piston to head clearance when the engine heats up, not gain it. So you will end up almost even .005 closer to the head than you are now....You need to cut your pistons before you damage your engine beyond being able to fix it.



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 Originally Posted By: CNC-Dude #5585
you loose piston to head clearance when the engine heats up, not gain it.


???? Won't the tighter bore to skirt clearance at temperature reduce rocking and therefore increase clearance? What am I missing here?

Granted, piston rocking loads are greater than my thumb pressure, I've made no allowance for rod stretch at TDC exhaust nor crank deflection under load. And I'll lose .001 or so due to rod bearing clearance and maybe another .001 for main bearing clearance. Maybe all that adds up to more than .020 inches? I'm not so sure.

Please tell me what engines you've seen contact on, what pistons and bore clearance, and how may rpms you were running when it happened.

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One thing that you are not thinking of is thermal expansion. When these components get hot, they expand, not shrink. The cylinders get larger, not smaller. The pistons, being aluminum, grow more than the cast iron block does, so you do have some reduction in piston rock to some degree, but all dimensions of the piston expand along with its diameter. The pin bores gets larger, the ring grooves get wider, etc., all concievable components grow and expand from the heat. The rods get longer also when they heat up, and possibly stretch as well. When exposed to the near 1000°F combustion chamber temps, aluminum can have an expansion of 1/32" of an inch, compared to what it mics sitting on your workbench. It doesn't have to be race type engines at racing RPM to have these problems, i've seen many stock rebuilds experience damaging results because of trying to run the quench too tight. As far beyond what I would consider a safe margin of quench as you are right now, i've seen similar engines have the closing of ring gaps and beating the bearings out at break-in RPM before they could even shut the engine down. Just trying to keep you from tearing up good parts.....Your just so far beyond the safety net, I hate to see you have problems needlessly.



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 Originally Posted By: strokersix

No Mallory required. Balance the crank all by itself or with damper and/or flywheel but no bobweights like you need for a v8.


Interesting. I asked this on a different forum and was told that it needed bobweights. if you are truely making the crank neutral balance than you would be able to swap rod/piston sets (assuming each rod/piston in a set is the same mass)without rebalancing the crank. Thus you can change rod length and piston height at will, using the same crank?

If so, this would save a lot of $$ and time when trying out several combinations.

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Correct. No bobweights required. Swap out rods and pistons all you like as long as they are matched sets of six.

My cut down crank probably has more bending loads because I've reduced the counterweights but I think my light pistons should offset this somewhat.

The counterweights on inline six are there to reduce crankshaft bending loads only. v8 cranks are different story. v8 counterweights reduce crankshaft bending loads but also make a tradeoff of the unbalanced force directions. Inline six does not have the unbalanced forces.

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There are only a few exceptions, but inlines as a rule do not require bobweights. You can compare them to a see-saw, if you remove 1 pound of material from the counterweight side of the crank, then you have to remove 1 pound from the rod throw side to keep it balanced.



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And what determines the counterweight mass?

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 Originally Posted By: strokersix
Correct.
The counterweights on inline six are there to reduce crankshaft bending loads only. v8 cranks are different story. v8 counterweights reduce crankshaft bending loads but also make a tradeoff of the unbalanced force directions. Inline six does not have the unbalanced forces.


For a great case in point of these unbalanced forces in action go find a 1960's GMC V-6 or early Buick V-6. Nothing like odd fire engines!

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 Originally Posted By: panic
And what determines the counterweight mass?


In my case the counterweight mass is determined by how much clearance I needed. I expect I'm paying a penalty of increased crank bending and main bearing loads compared to a stock 292. Hopefully offset somewhat by lighter pistons. My rods probably weigh about the same as 292 rods but my pistons are much lighter at 403 grams. Don't know what stock 292 pistons weigh but I would not be surprised if they are 700 grams.

This is likely the biggest reason for the change from 6 weight to 12 weight cranks. Reduce main bearing loads and improve crankshaft durability.

Last edited by strokersix; 03/12/11 09:52 AM.
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Nothing new here, just a trip to the car wash for one last cleaning. Also 5.7 rod and 4.000 piston from last build versus 6.0 rod and 3.935 piston this build. Same crankshaft.

http://i965.photobucket.com/albums/ae131/strokersix/DSCN3850.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3852.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3848.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3849.jpg

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I took comments to heart and trimmed my pistons. About .006 inch off above the skirt tapered to nothing above the wristpin.

http://i965.photobucket.com/albums/ae131/strokersix/DSCN3854.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3855.jpg

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Looking good! \:\)


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I think you will sleep better, having done that.

You are quite Houdini when it comes to running your mill. Nice job!


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Good looking set of connecting rods you got in there!



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Crower rods and JE pistons are nice parts for sure. About $1300 nice! The rest of the build is fairly low budget.

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Here are some oil pump clearance photos. Stock 250 parts. I also decided to add some more clearance between the fuel pump lobe and connecting rod. 4.062 stroke, trimmed corner on rod, and reduced lobe diameter (.100 inch if I recall) gives about .030 inch clearance. When I swap cams I'm going to have to alter the fuel pump lobe again or use a 292 cam and electric pump.

http://i965.photobucket.com/albums/ae131/strokersix/DSCN3874.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3873.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3872.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3868.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3869.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3875.jpg
http://i965.photobucket.com/albums/ae131/strokersix/DSCN3876.jpg

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Good progress.
Do you have any side shot pics of your intake port?

What mod, if any have you done to your intake manifold?

MBHD


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Someone once said "one thousands too tight and everyone knows, One thousands too loose and no one knows".. Maybe you can get someone to stand on the pan when you button it up. Stay with it STROKER..It will either be OUCH or AMEN


Jerry Davis II#4711



ol Smokey said "one test is worth a thousand expert opinions."
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