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Fri Jul 04, 2014 7:48 pm

Hello again,

Today I ended up setting my deck height and found some discrepancies. My case has been decked by a local vw machine shop along with aligned bored for this new build.

When I set my P&C kit up I didn't use any cylinder shims / gaskets. Please correct me if there is a "must have" gasket between the jugs and the case.

I built some deck height "tools" using 3/8 flat bar and drilled all my holes out. I didn't see the need to buy a $40 tool times qty 4 that was laser cut when drilling shouldn't distort metal. I drilled the holes out one at a time and let the metal cool before drilling the others, being very safe to not over heat the metal and using lots of lube... After all the holes were made for the studs I made a 1 1/4 center hole with a new hole saw and then lightly sanded with 400 sand paper to deburr the face. Using my snap-on "head" straight edge I made sure the faces were flat. All 4 came out great.

After installing all the P&C's and torquing down the plates I found the following.

Piston
#1---- .017 :D
#2---- .017 :D
#3---- .022 :?
#4---- .026 :shock:

Being that the sides mimic one another I'm pretty sure my cases crank centerline is off by .010 or close to. Please insert your thoughts and expertise.

To build this engine I believe I have 3 options please inform me of the correct method I hate hillbilly and slacker methods just a FYI.

Option one
Machine down the case to correct the deck.

Option two
Machine down the jugs on the 3/4 side to balance the set.

Option three, the used car salesmen style
Forget it and use .20 shims on one side and .10 on the other, forget the CR difference on #3 or is this a dick move down the road.

The plan is to use John's L3 ACN heads with a custom combustion chamber of .046 If i stick with a corrected deck of .047 that gives me the correct deck and Head CC to hit my 8.5 CR.

Lastly and most importantly. How close are the tolerances meant to be on deck height, Head CC, and CR between one another? Still learning here hang with me please.

With not modding the P&C kit I get 8.5 CR on three pistons and 8.6 on the last. Is this just down right disgusting to a real engine builder who does this for a living?

Thanks again just trying to do it right the first time.

1600 8.5 CR
Used case freshly machined align bored, decked
CB counter weight crank 69mm
CB ultra light lifters
CB 1.1 rocker arms and solid shafts
Web 218-119 split duration cam
Mofoco -2 Cam gear
Scat I beam 5.394 stock sized rods w ARP 2000 3/8 bolts
AA 85.5 P&C kit
I did a full flow with all plugs removed and taped
26mm Shadek pump opened up
Dual 40 IDFs

No heads yet but planning on ACN's L3's or L5's

Fri Jul 04, 2014 7:57 pm

Shims under cylinders is about only simple fix and your deck height is to small want to be in the .040 to .060 range....

Where crank is "centered" in case is probably non issue.... Besides you can not change it....

Dale

Fri Jul 04, 2014 8:01 pm

Yeah Dale, I understand there is no fix to my crank vs my case. Just trying to figure out how to get the deck set correctly. I understand that my deck must be .040 - .060 thats why I was looking at adding .020 shims and .030 shims to the correct sides or just machine off the head side of the jugs then using the same shims under ever cylinder not mixing them. Both ways gives my the .047 - .042

Just trying to do it correctly and not sure what way to go.

How close do the pro's get there deck and CR?

EDIT: I guess in my first post I didn't explain no matter what way I go I'm going to have to use the .020 - .030 minimum no matter what option I went with. Sorry Thought it but didn't make it clear in text.

Fri Jul 04, 2014 8:25 pm

If they are all within .010" then build it. Worrying about getting them all exactly the same is just plain anal and overkill.

Fri Jul 04, 2014 8:28 pm

The simple answer is deck the 3-4 side of the case by .005” , or use thinner cylinder shims on the 1-2 side, this will give you .017, 017.017 and 021 for #4.
For a simple motor with L3’s “they told me” you’ll be OK with minor difference.
You could also try swapping rods & pistons & cylinders maybe the difference will come out in the wash that way.
It sounds like you’re using 4 different deck plate tools? How thick is your deck plate tool?
If so use one tool and one plate to be sure you’re not measuring difference in the plates you made.
When I did my deck height measurements I used the same plate for each cylinder, I also measured from the cylinder edge to the piston.
When I tourque my deck plate to stock torque, I found the plate deformed. I bought a new plate, and did all my measurements with the plate torqued to 5 ft-lb
By the time I got done I was good at getting repeatable measurements, and found I also had some difference like you.
My numbers were not as clean as yours, otherwise I would have had gone for the .005 deck job on the 3-4 side like I’m suggesting.
My deck heights will range from .046 to .051, and was advised that .005 difference wasn’t that big of a deal.

Fri Jul 04, 2014 9:21 pm

Use two .010 shims. Fyi, from EMPI I find that they always measure out to .012 instead of an actual .010.

Fri Jul 04, 2014 9:38 pm

I would torque the 3/4 side and see if the top of the cylinders are out the same amount, if so then it is the case, deck case os shim accordingly, thats up to you. also be sure the cylinder is not hanging up on the case savors(thresd incerts). be sure the cylinders are not hitting a step in the case cut. i would not on pourpoise cut the cylinders rong lengths'.

Sat Jul 05, 2014 9:37 am

:) For whatever all cases will have a small dot made with a punch on #1/2 side showing the center of the crank. It will be close to the case seam and all cases will show the small dot due to original factory boring...no two the same.

That is why when assembling and engine there will be a difference in deck height between both sides.....after rebuilding over 1000 engines as a builder have seen them all.

I made a pr of steel bars for each side to hold the cyls down when assembling.....still have them for sale (I'm retired).

Sat Jul 05, 2014 9:46 am

when I bought my new mag case 7 years back,the cylinders mating serface were not anywhere neer flat&square to eashother, they were tilted inward as I recall.I decked it on my mill,got both sides withen .002". i did however have brainfade when shortening the cylinders......#4 has a .010 shim. I did them before I had the dro on my lathe. not sure where I went rong, probably a song on the raidio. I did not have to deck my aluminum case.

Sat Jul 05, 2014 10:05 am

I would wonder about the difference between 3 and 4, even though it might not make a difference, but I would figure it out. Is it a difference in the way the cylinder areas are decked, or the height of the piston top? Swap pistons and see if it's the piston (doubtful though). I even had a rod where the pin bushing had been honed offset a bit, and it gave me a mystery reading till I figured it out. The best way to deal with it would be to deck the offending side, if that's the problem, so the engine uses one size barrel spacer. Next would be to shim the side differently, but then you have to but another set of shims..
Turning down the cylinders just means it's a headache down the road for someone.

Sat Jul 05, 2014 11:51 am

For an engine of this level there is nothing wrong with putting .020" shims on the 3/4 side, and .030" shims on the 1/2 side.

Sat Jul 05, 2014 1:22 pm

I hate shims but they work fine , I would rather deck , I just decked my aluminum block .065 to get my pistons at .040 , then I had to take .002 of the 1 and 2 pistons to make it all perfect ...

Sat Jul 05, 2014 2:09 pm

Is it possible the discrepancy is in your homemade tools? If you swap the tools around do you get the same numbers?

Sat Jul 05, 2014 2:31 pm

Thanks everyone for their replies.

To answer a few things one being my tools / plates. The first thing i did was measure the deck on all four jugs, I took 3 measurements on each and stuck with the repeated measurement. I then swapped all my plates to the other sides and had the same results. One varied by .002 but that was the only discrepancy on #2.

HRVW, you got me thinking about my first post and this mystery case that ended up being from ATK / Verg. When doing my research not only did I find out about those bad BRASS case savers I recall a article saying they used mix match case halfs in the 70's. $100 says thats my luck and what I'm dealing with.

Next question would be on the decking procedure. Wouldn't a machine shop measure from the crank position in the bearings out to the deck surface?

They don't just set the depth from the case half on the table and cut the same amount down, do they?

Sat Jul 05, 2014 2:41 pm

mraaronc wrote: Thanks everyone for their replies.

To answer a few things one being my tools / plates. The first thing i did was measure the deck on all four jugs, I took 3 measurements on each and stuck with the repeated measurement. I then swapped all my plates to the other sides and had the same results. One varied by .002 but that was the only discrepancy on #2.

HRVW, you got me thinking about my first post and this mystery case that ended up being from ATK / Verg. When doing my research not only did I find out about those bad BRASS case savers I recall a article saying they used mix match case halfs in the 70's. $100 says thats my luck and what I'm dealing with.

Next question would be on the decking procedure. Wouldn't a machine shop measure from the crank position in the bearings out to the deck surface?

They don't just set the depth from the case half on the table and cut the same amount down, do they?
Your stuck with the position of the crank , what you need to do now is either deck the case to make them even or use shims or a combination of both, you have to little of deck height so you will have to use shims to get at least .040 or if you want to get crazy cut ur piston tops and use no shims , then you have to balance ur pistons .. its either get complicated or keep it simple . u have to make a choice ...

Sat Jul 05, 2014 3:01 pm

These are small discrepencies in deck, should be nothing to worry about. If you want to add to your worries, though, swap rods around... last time i had an issue similar, found differences in rod lenghts. Just another variable to consider...

Sat Jul 05, 2014 3:37 pm

Remember that two rough casting halves are torqued together...installed into an align boring machine to make the initial crank cut as is the cam cut done also.

They then punch that small "dot" that I alluded too in some of my past posts "when talking about TDC 7.5 degree accuracy". seam that many use.

As for the rods measurements my friend (machine shop owner) did most of my rods and if I recall correctly measurement was from wrist pin center to main bear center on a special machine.

When surfacing the cyl area on the case, it is placed on a flat table and the cutter lowered down (perpendicular) cleaning one cyl and then moving over to the other at equal depth....same procedure when flycutting heads....no difference.

As for the small difference of under 010 I added paper gskts or cleaned up some older metal spacers until I found the right numbers...takes time.

Invariably #3/4 will have a lower deck height with the crank bore being over towards #1/2 side via the punched "dot"..

Sat Jul 05, 2014 9:31 pm

if you use the flat serface of the case you are assured of it being correct.probably wont be.I take the deck mesurements with all the same piston,rod,bearing,cylinder to deck the case.I wright on the case as to what it needs in 5 locations on each cylinder (top,bottom,front&rear,center,and amount of rock) then you can duplicate it and deck it flat. you might be surprized on how far out some engines are.and the worst Ive ever seen....the 340 mopar block is oh so effed up,twisted and .020 out end to end and some .030 or more out total side to side squared. every effing one I ever did was effed up like that & I did a lot of them/ funny thing the 318 witch is about the same engine but smaller bore&low performance was almost dead on correct&square.go figure., but remember the vw has seprate cylinders that seat into a single head on each side.if you dont want to bend the head to form or have leeks get them as close as possiable or use copper head gadgets.there soft&very forgiving.

Sun Jul 06, 2014 8:52 am

I've found discrepancies when checking deck without a shim under the cyl's. The cylinders aren't machined square but are rounded/radiused where the skirt meets the cast fins.
Get two shims that measure the same and take your measurements on adjacent cyl's. Then switch sides and check.

Good luck finding shims the same size all the way round.

I get more concerned that the cylinder tops are flat to each other and not tipping away fom each other. Getting cyl's to seal with tops twisted is impossible.

Sun Jul 06, 2014 9:11 am

Dougy Dee wrote:
Good luck finding shims the same size all the way round.

This is important to check, I had bad luck with scat shims. The guys at Rimco made a set to my measurement and they measured the same all of the way around.