Setting deck height for 9:1 compression Options

[Chad911sc]

I have my short block built and I’m ready to set my deck height. It’s 96mm bore with stock 71mm factory crank. This is a 2.0 2056 build. I have a Web 86a cam calling for approx 9:1 compression. I have 60cc heads with 3cc valve reliefs on my flat top pistons. If I plug all this into the calculator, I get 8.3:1 for my compression ratio if I set the deck height to .040 inch
After I set up the piston on the rod and bolt down the cylinder to the block, I get .053 inch from the piston to the top of the cylinder.
My question is, what is the best way to proceed to get the 9:1 ratio with at least .040 inch total deck height.
I am thinking that if I take off 6 total cc’s from the head, that will leave me with 54cc heads with the 3cc valve pocket = total 57cc’s. Bringing me now to the correct 9:1 compression ratio with the .040 inch deck height.

If I am in the right ballpark, this means I need to have my heads fly cut….correct??
If this is correct, how do I go about calculating how many thousands of an inch do I need to have removed by the machine shop to remove 6cc from the head?

I obviously will need to remove at least .013 inch total deck height get to my .040 goal, and that’s with no shims or head gaskets being used.

Thanks for your time, Chad

[technicalninja]

The case line SHOULD be centered but...

Where it matters is a center axis of the crankshaft.

This is how shit can go wrong...

One of my other projects is a 91 MR2 Turbo.

After tearing the stock gen 2 engine down (all OK, just never touched and OLD) a built Gen 3 engine showed up on Craigslist here in DFW.
This engine was out of a wrecked car and it was cheap!

Gen 3 engines are SHITLOADS better. They never made it to the USA and this one was seriously built ($10,000 receipt). H-beams, Wisecos, billet cams, adjustable cam gears, whole list of good shit.

I went to look. Took a borescope and leak down stuff.
Minor vertical scoring lines in the bore surface. It had been run an extended time without an airfilter!
Leak downs sucked. All the valves had leakage and "bonking" them didn't improve it much.
It HAD been sitting 9 months.

I bought it for half what he was asking...

The receipt was from a well known shop who specialized in these.
I've purchased many things from them.

So, I've got this bad-assed 2.0l that needs a ring job and cleaning up the valves.

I rip it apart. Check deck height on all 4. I've learned to do this early instead of late.

.006 difference in deck height!!!!!! (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif)
I'm used to seeing deck height difference BELOW .001. I'm expecting "tenths" and have results that are HUGE!
I'm PISSED!

What I found, after swapping rods/pistons and then installing the crank out of my gen2 in it was two things.
#4 rod bearing journal was repaired via "off-set" grinding (this is a NORMAL thing for quicky machine shop repair) and the deck seemed to be ground at an angle to the crank.
I told the machine shop what I thought, and Eric documented what they found.
It took .0017" to clean it up. He did a final cut at 2 thousands. It WAS decked at an angle!
The crank journal was off-set ground right at .005"
I used the Gen 2 crank out of the car's original engine (never been machined and not damaged at all). Had it micro-polished/balanced and put it back together.

Deck height differences are .0003 now!

The shop in question is NOT a machine shop. They sub the work out
They OBVIOUSLY didn't check anything when they got it back.

The machine shop in question did a "quick production" job on the crank and they decked it from the oil pan registers instaead of the crank bore.
This is the FASTER way to complete the machine work and everything would have worked absolutely fine on a bone stock build at 200hp.

This build is targeted for 500hp (which as actually conservative) and that level of variation is unacceptable at that power level.

So, on another active build at 2.0L I'm shooting for 500 hp.

And parts for that puppy are CHEAPER than T4 stuff...