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1950split Samba Member
Joined: December 08, 2005 Posts: 454
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Posted: Thu Oct 21, 2021 8:10 am Post subject: Deck-height tool - tighten to torque or not |
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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. |
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Brian_e Samba Member
Joined: July 28, 2009 Posts: 3292 Location: Rapid City, SD
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Posted: Thu Oct 21, 2021 8:42 am Post subject: Re: Deck-height tool - tighten to torque or not |
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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 |
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Dale M. Samba Member
Joined: April 12, 2006 Posts: 20379 Location: Just a tiny bit west of Yosemite Valley
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Posted: Thu Oct 21, 2021 9:03 am Post subject: Re: Deck-height tool - tighten to torque or not |
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1950split wrote: |
Hi Guys,
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.
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And what tool is that, can not imagine putting enough pressure on plate to bend it..... _________________ “Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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1950split Samba Member
Joined: December 08, 2005 Posts: 454
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Posted: Thu Oct 21, 2021 9:40 am Post subject: Re: Deck-height tool - tighten to torque or not |
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That’s the tool. I guess it was either bent new or by torquing to 3.2 Nm.
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txoval Samba Member
Joined: January 23, 2004 Posts: 3552 Location: The Woodlands, TX
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Posted: Thu Oct 21, 2021 10:51 am Post subject: Re: Deck-height tool - tighten to torque or not |
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Hard to imagine bending that 3/8” plate with 18-23 ft-lbs
Also assume you mean 32Nm? |
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1950split Samba Member
Joined: December 08, 2005 Posts: 454
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Posted: Thu Oct 21, 2021 11:19 am Post subject: Re: Deck-height tool - tighten to torque or not |
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Correct : 3.2 daNm or 32 Nm |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Thu Oct 21, 2021 5:07 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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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. |
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74 Thing Samba Member
Joined: September 02, 2004 Posts: 7393
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Posted: Thu Oct 21, 2021 5:18 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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You should cut some pipe to use for spacers and also use the thick washers |
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Ian Godfrey Samba Member
Joined: September 25, 2006 Posts: 1137 Location: Melbourne Australia
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Posted: Fri Oct 22, 2021 1:58 am Post subject: Re: Deck-height tool - tighten to torque or not |
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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. |
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1950split Samba Member
Joined: December 08, 2005 Posts: 454
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Posted: Fri Oct 22, 2021 2:54 am Post subject: Re: Deck-height tool - tighten to torque or not |
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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 ? |
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RWK Samba Member
Joined: June 24, 2009 Posts: 1349 Location: S.W. MI
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Posted: Fri Oct 22, 2021 6:32 am Post subject: Re: Deck-height tool - tighten to torque or not |
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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 |
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bugguy1967 Samba Member
Joined: January 16, 2008 Posts: 4343 Location: Los Angeles, CA 90016
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Posted: Fri Oct 22, 2021 6:44 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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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" |
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M. Notary Samba Member
Joined: February 19, 2004 Posts: 77
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Pruneman99 Samba Member
Joined: February 22, 2012 Posts: 5013 Location: Oceanside
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Posted: Fri Oct 22, 2021 9:39 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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You wouldn't be saying VW owners are cheap would you???
I got a Starrett depth micrometer like that in a nice wooden box from Ebay cheaper than the cheap one there.
I'm cheap, but still like nice things. |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Fri Oct 22, 2021 9:53 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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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. |
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M. Notary Samba Member
Joined: February 19, 2004 Posts: 77
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Posted: Sat Oct 23, 2021 12:46 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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Pruneman99 wrote: |
You wouldn't be saying VW owners are cheap would you???
I got a Starrett depth micrometer like that in a nice wooden box from Ebay cheaper than the cheap one there.
I'm cheap, but still like nice things. |
Yes, but was it NEW?
Do you think a like button would help clear out some of the meaningless and stupid replies throughout the forums? But who am I to ask for a change to something I don't even pay for. |
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Dale M. Samba Member
Joined: April 12, 2006 Posts: 20379 Location: Just a tiny bit west of Yosemite Valley
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Posted: Sat Oct 23, 2021 5:18 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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modok wrote: |
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. |
Same here..... _________________ “Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Sat Oct 23, 2021 5:33 pm Post subject: Re: Deck-height tool - tighten to torque or not |
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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. |
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