Deck-height tool - tighten to torque or not

[1950split]

Hi Guys,

I am rebuilding my 2276 and have a perhaps a silly question.

I read that some people tighten the deck-height tool to 3.2 Nm to ensure that measurements are 100% accurate and some don't.

I am asking this as I have noted that my current deck-height tool (the one you find everywhere) is slightly bent. I was very suprised to see this as I had not imagined that tightening the plate to the 3.2Nm could bend it.

Anyway, it seems to me that tightening to 3.2 Nm is perhaps overkill as I have custom made steel 2.5mm cylinder shims and that perhaps tightening to 1Nm or 2Nm is more than enough.

What do you think.

[Brian_e]

ALL measurements MUST be done with the engine as it will be when running. That means ALL fasteners fully torqued to spec when measuring main bearing crush and oil clearance, rod oil clearance, camshaft end play, etc. as well.

The cylinder shims will move around a bit, and without torquing them, you will see a larger deck height number than once its torqued. Your number will shrink which might become an issue.

Brian
_________________
www.type-emotorsports.com

[Dale M.]

[1950split]

That’s the tool. I guess it was either bent new or by torquing to 3.2 Nm.

[txoval]

Hard to imagine bending that 3/8” plate with 18-23 ft-lbs

Also assume you mean 32Nm?

[1950split]

Correct : 3.2 daNm or 32 Nm

[modok]

If the cylinder mating surfaces fit together perfectly I don't bother to install the studs at all.

You can answer your own question, try different ways and see if the measurement changes.

[74 Thing]

You should cut some pipe to use for spacers and also use the thick washers

[Ian Godfrey]

For fun I just did the experiment today. With my 94's I lost 4 thou of deck when I released the torque on the cylinder. (alloy cylinders, not iron, with 10mm race ware studs)
I also measured piston rock. The edge of the piston could rock 3 thou higher than the middle. (no rings) I thought this was interesting after following a recent thread on minimum deck height that might be safe to run.
I'm tightening mine up from 49 thou to 42 thou.

Another thing worth checking, after de burring some 20 thou CB shims they turned out to be 24 thou (.61mm), all interesting, you really have to measure everything.

I always torque everything to spec before measuring.

[1950split]

Thanks for your comments.

I actually do torque them to specs but never checked if the tool was well surfaced.

As I have measured 0.995mm with a depth micrometer for piston #3 and 1.05-1.08-1.13 on the others I checked the tool to assess the error from the tool I could get for the DH under 1mm.

Anyway I will probably surface the tool to get an accurate reading.

Now I am more bothered as to how I could increase the DH on #3 as the case was decked properly, rods measure out exactly the same between pin location and crank journal, pistons do also measure exactly the same (AA real forged pistons).

I think the throw of the DPR crank is probably the issue.

I don't want to increase deck-height on other pistons to compensate #3 @ 0.995mm. It should be ok provided it does not get tighter after surfacing the tool

What do you think ?

[RWK]

You are probably close enough...
There are too many things that are difficult to check that effect DH.
Starting at the beginning, crank throws (stroke) all the same +- .001
crank centered in case AND straight in case +- .001
decks to throws all alike +-.001, (accounts for crank not centered in case) also assumes deck plane is parallel to crank and all other decks.
rods alike +- .001 (we won't use bearing clearance)
Cylinder height, all same again +-.001
piston pin to top, all the same +- .001
Measuring with a caliper +- .002?
As you can see deviations of above numbers can throw you off many thou.

If your looking for +- a couple thou deck tolerance these dim's above should all be checked and correct.
The dim's you get thru the math will give you DH, numbers don't lie.
_________________
73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[bugguy1967]

That 3/8" plate does bend. I made a 1" steel bar to combat it
_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[M. Notary]

A light snug is all that is needed. The difference between a heavy snug and not tightening at all is negligible.

Use one of these:
https://www.amazon.com/Mitutoyo-129-132-001-Depth-...amp;sr=8-3

Or for you VW people:
https://www.amazon.com/PROLINEMAX-Micrometer-Toolm...amp;sr=8-5

That plate and the bolt is stupid.

Try swapping parts around. You will find .001 pretty easy.

[Pruneman99]

[modok]

I use a dial indicator mounted in a 1"x 1.5" steel block, cost 22$

I can estimate how much a cylinder squishes.
8mm studs and a thick cylinder, it is trivial.

But I can see how it could be a lot more with oddball cylinders and/or stronger studs.

[M. Notary]

[Dale M.]

[modok]

Sometimes the shims are springy and not flat, so need to be bolted down to sit flat, AND/OR since shims WILL be used then the opening in the block is left a sharp corner that will not clear the corner raduis of the cylinder... can't set the cylinder right on the block......so then you would need to bolt it down with shims to get an accurate reading. but only enough to make the shims sit flat.
Or
I have a few old sets of very thick shims that are very flat and accurate, so I can throw those on there and check. But i have been selling them off so...... oh well, I DO like to make sure the cylinder will sit flat on the block by itself anyway. Draw some maker lines on the opening and see that the cylinder wipes them off. just nice feeling.