How much variation in Deck Height, do you tolerate? |
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How much variation in Deck Height, do you tolerate? |
nebreitling |
Mar 10 2005, 05:06 PM
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#1
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
title says it all. How much variation between cylinders in Deck Height do you builders tolerate? i'm shooting for no more than .001, but i'm curious how steadfast i need to be in this...
damn KB 96's stick out of the jugs, mmm, just a little bit... current deck height: #1 -.204 #2 -.203 #3 -.215 #4 -.214 Desired deck height: 055-056 off to have the machinist whittle out some .25 cylinder spacers (!).... (IMG:http://www.914world.com/bbs2/html/emoticons/givemebeer.gif) |
Demick |
Mar 10 2005, 05:16 PM
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#2
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Ernie made me do it! Group: Benefactors Posts: 2,312 Joined: 6-February 03 From: Pleasanton, CA Member No.: 257 |
I assume you missed a decimal place in those numbers, and meant:
#1 -.0204 #2 -.0203 #3 -.0215 #4 -.0214 But I don't know how you measured deck height to the nearest 10 thousands of an inch. So you really need .035" shims. Just be sure and tell your machinist to make some .035" shims - not .25 (he is not likely to read your mind and know you missed a decimal point). Demick |
MecGen |
Mar 10 2005, 05:16 PM
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#3
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8 Easy Steps Group: Members Posts: 848 Joined: 8-January 05 From: Laval, Canada Member No.: 3,421 |
Hi Dude
Both motors I did, stuck to the 001 - 002. But neither needed spacers machined, Its been a long time, 10 years, but I remember finding spacers locally. I think you might have a spacer issue, but maybe double check the piston hieght to make sure its not a "machinist" error. Take your time here, very important to check/fix deck hieghts, makes it very reliable. Maybe some engine guru gonna help... maybe even by the time I post... Thumbs up Cheers Joe (IMG:http://www.914world.com/bbs2/html/emoticons/beerchug.gif) |
Demick |
Mar 10 2005, 05:18 PM
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#4
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Ernie made me do it! Group: Benefactors Posts: 2,312 Joined: 6-February 03 From: Pleasanton, CA Member No.: 257 |
Hold on a sec. If the KB's stick out of the barrels, then you have negative deck height. Your shims would need to be .020+.055=.075" thick.
Demick |
bondo |
Mar 10 2005, 05:33 PM
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#5
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Practicing my perpendicular parking Group: Members Posts: 4,277 Joined: 19-April 03 From: Los Osos, CA Member No.: 587 Region Association: Central California |
Hmm, what if he didn't miss a decimal place but has the wrong pistons or rods? That would be quite a shim!
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Britain Smith |
Mar 10 2005, 06:06 PM
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#6
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Nano Member Group: Members Posts: 2,354 Joined: 27-February 03 From: Hillsboro, OR Member No.: 364 |
Well, my engine called for a 0.09 shim but I am running 7.4:1 compression. Can you say BOOST!
-Britain |
nebreitling |
Mar 10 2005, 06:23 PM
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#7
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
well, it would appear that i may have the wrong pistons....
yes, they stick out of the jugs about .200 (yes, nearly 1/4 inch) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) |
lapuwali |
Mar 10 2005, 06:28 PM
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#8
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743 |
As I recall, the pistons you seek have the wristpin bosses located much closer to the crown. It's also possible you have the wrong rods. Insert the usual "combo" comment here. |
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nebreitling |
Mar 10 2005, 06:39 PM
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#9
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
yup, all checked. it's the wrong pistons... (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif) i'll get this bitch put together some day....
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redshift |
Mar 10 2005, 07:05 PM
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#10
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Bless the Hell out of you! Group: Members Posts: 10,926 Joined: 29-June 03 Member No.: 869 |
Nathan... I am sorry, buddy.
Never helpful, always empathetic.. M |
MecGen |
Mar 10 2005, 07:13 PM
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#11
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8 Easy Steps Group: Members Posts: 848 Joined: 8-January 05 From: Laval, Canada Member No.: 3,421 |
Cool
Better now than later $$$ At least its gonna be rite (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif) Its a burn when you get f**ked by new parts, the first one I did, I took telephone advice and ended up building a completely mixmatched bullshit motor, my loss = 1500$ Glad you didn't go my way cheers Joe (IMG:http://www.914world.com/bbs2/html/emoticons/beerchug.gif) |
nebreitling |
Mar 10 2005, 07:32 PM
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#12
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
thanks guys. the vendor is making good on this, so that's as good as the situation can get. what's another weekend, really? i should recieve the new pistons saturday. back to the machine shop on monday for balancing..,. and then,,,, whenever i have the damn time, put it together.
should be a fun little 2056 at 9.5:1 compression, mildish cam and carbs. |
Jake Raby |
Mar 10 2005, 09:07 PM
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#13
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
My tolerance is .004 between ALL cylinders and .001 between cylinders on the same bank.... More than that and you are asking for a head leak.
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Mueller |
Mar 10 2005, 09:09 PM
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#14
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
hopefully I'll be doing this testing very soon...I noticed my credit card has been charged so that is a good sign that my 78mm crank and other goodies are on the way (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/smash.gif) |
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MattR |
Mar 10 2005, 09:10 PM
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#15
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Advanced Member Group: Members Posts: 3,279 Joined: 23-January 04 From: SF Bay Area Member No.: 1,589 Region Association: Northern California |
I had the same problem with my KB cylinders. The supplier sent me the wrong cylinders. No package... I had to figure out the hard way that they were the wrong offset pistons. I got new pistons, a little work to trim the piston to get the desired cr, and i was good to go!
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nebreitling |
Mar 10 2005, 11:11 PM
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#16
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
i can do that. thanks, everyone, for the input! |
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Jake Raby |
Mar 10 2005, 11:12 PM
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#17
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Mueller...
Your stuff is all done and shipping tomorrow... Came out really sweet! |
Demick |
Mar 10 2005, 11:34 PM
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#18
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Ernie made me do it! Group: Benefactors Posts: 2,312 Joined: 6-February 03 From: Pleasanton, CA Member No.: 257 |
.020 variation translates to about 1/2 point of compression. That's an awful lot! That's kind of like installing USA pistons on 2 cylinders and Euro pistons on the other two. I wouldn't build my engine like that. Demick |
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nebreitling |
Mar 10 2005, 11:58 PM
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#19
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
i agree! i assume he meant 002...
still, it doesn't take an enormous effort to spec these things out to the thousanth... |
MarkV |
Mar 11 2005, 04:44 PM
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#20
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Fear the Jack Stands Group: Members Posts: 1,493 Joined: 15-January 03 From: Sunny Tucson, AZ Member No.: 154 Region Association: None |
Question?
I measured my deck height and it is .013 to .014 on all 4 cylinders. Going to run .040 spacers to give me a deck height of .053 to .054. The problem is that one of the combustion chambers measures 59cc's and the other 3 measure 57cc's. Can I make up the difference by running bigger spacers on the 3 - 57cc cylinders? Won't that cause a leak in the 4th cylinder? If I just put it together with the .040 spacers I will have one cylinder that is 8.7 to 1 compression and three that are 8.5 to 1. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif) |
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