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Old 04-09-2012, 12:41 PM   #21
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ctdrftna... That a Storm Vulcan? I can tell it is a wet segmented stone machine. That is a hoss of a machine.

I see That you set up off the oil pan rail, not the mains. What was your reasoning for that?
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Old 04-09-2012, 05:41 PM   #22
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Winona van Norman machine, it's easier to hold like that, I use shim stock to square the deck
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Old 04-09-2012, 06:05 PM   #23
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Quote:
Originally Posted by ctdrftna View Post
Winona van Norman machine, it's easier to hold like that, I use shim stock to square the deck
Yes it is quick and easy to set off the oil pan rails, and if the block was machined correctly to begin with then you are fine, but most block decks are not machined parallel to the oil pan rails.

Did you check your piston to deck clearance at tear down?

If your block had a .003 tilt from front to rear, with your set up you cut that tilt back in it.

Now if you look at the attached pics, you see #1 cyl is .016 on the hole and #4 is .025 in the hole, so I am showing a diffrence of .009

When I had the block set up in my machine, I found .006 tilt on the block, and was able to mill to correct this tilt.

Now about the other .003, during the factory maching all the parts have a tolerance, so part of the remaing .003 can be in the ground stroke of the crank, in the center to center of the con rod, the maching of the crown of the piston or in the wrist pin location of the piston.

But I know I have the same distance from the main centerline to the deck surface now.
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Old 04-09-2012, 10:59 PM   #24
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i totaly agree with what your saying, i dont remember what i had for piston to deck heights, but i know they were not that far off. The shop i worked at did mostly V8, we used BHJ blok-tru fixture for decking V8's that sets deckheights and squares the block, This was the best i could do at the time, it worked out good if i have out of wack piston to deck i would have corrected it
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Old 04-19-2012, 06:24 PM   #25
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Quick question, when you deck a block/head, what do you do about the new lost clearance between the valves and pistons? Is this a concern on Miata engines?

Just from what little knowledge I have, push rod engines would run slightly shorter pushrods to make up for this, but what about with our engines?
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Old 04-19-2012, 06:41 PM   #26
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karter, Most of the time .010 or less is milled, unless you do a correction mill, or milling to raise compression.

In the common 4 cyl, you will not even notice a diffrence in Piston to valve clearance.
The BP is a non-interferance engine from what I have been told.

For a push rod V8, even at .010 milled will not call for shorter push rods, due to the ablity of the hyd. lifter to compress.

On a solid lifter cam, still will not make a differance, beacuse you have to set the lash.

I just built a hyd lifter 283 SBC, the block was milled appox .015 on one bank, and about .020 on the other bank to get all the pistons .030 in the hole, the 305 heads were milled appox .025 so I would end up with a 50cc chamber for a 9.5:1 engine.

Even after all the milling, stock push rods were used, the pattern of the rocker arm was slightly off from ideal on the valve tip, but still acceptable.
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Old 04-20-2012, 07:43 AM   #27
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yeah miata's and most 4 cyl are not an issue, i decked my block .01 and my head .01 and my cams are massive to the point where i had to mill clearence into the head so they could spin ( .495 in and .455 ex lifts) and i still didnt run into piston to valve problems. though i would imagine I removed the non interference part. you really dont start running into issues with that untill you go with big compression, v8's are really bad with piston to valve. we were always flycutting pistions.
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Old 04-20-2012, 07:46 AM   #28
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keep in mind, the shop i worked for built race motors, so when i say v8 i mean bb chevys, with 14.0:1 and huge .800 lift+ cams. when you run into interference wether it be axial or radial you normaly flycut the valve reliefs
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