Rich & CO, Deck Height Pics |
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Rich & CO, Deck Height Pics |
McMark |
Apr 22 2006, 07:19 PM
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#1
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Here's the tool:
Here it is in a cylinder as you would check deck height. |
Ctrout |
Apr 22 2006, 09:30 PM
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#2
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Member Group: Members Posts: 377 Joined: 20-May 04 From: Mountain Home, ID. Member No.: 2,091 |
I've always wondered how that measurement should be taken. Thanks for the pics. How does this relate to the heads and how they are treated during a rebuild and how is compression affected by these variables? Also, don't forget to zero the caliper by extending the depth gauge slightly and then seating it against a perfectly flat and clean surface.
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McMark |
Apr 22 2006, 10:01 PM
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#3
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
This necessarily the best way to measure deck height, but for most stock type rebuilds it will work fine.
This measurement * pi * cylinder diameter + head cc + piston pocket/dome volume will let you calculate compression ratio. More deck height equals lower compression (fuel/air isn't compressed into such a small space). Less deck height equals higher compression. The more your heads have been flycut (which removes material and reduces combustion chamber volume) the more deck height you'll need in order to compensate to keep the CR to 8.5:1 for stock FI. |
Aaron Cox |
Apr 22 2006, 10:06 PM
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#4
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
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Type 4 Unleashed |
Apr 22 2006, 10:30 PM
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#5
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CREATIVE TYPE lV ENGINEERING Group: Retired Members Posts: 787 Joined: 20-June 04 From: Aliso Viejo, ca Member No.: 2,231 Region Association: None |
This is what I use, to bring it up to TDC, then I use a depth gauge.
Attached image(s) |
Brando |
Apr 22 2006, 10:50 PM
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#6
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BUY MY SPARE KIDNEY!!! Group: Members Posts: 3,935 Joined: 29-August 04 From: Santa Ana, CA Member No.: 2,648 Region Association: Southern California |
if you have domed or dished pistons, I assume you would measure from the highest part of the piston, no?
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Aaron Cox |
Apr 22 2006, 10:52 PM
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#7
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
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Rand |
Apr 22 2006, 11:20 PM
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#8
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Cross Member Group: Members Posts: 7,409 Joined: 8-February 05 From: OR Member No.: 3,573 Region Association: None |
I think Blair got some better photos, all I had was my cell phone. Here's Rich battling the ring compressor. Troy on the right.
How far did you guys get tonight? Attached image(s) |
MarkV |
Apr 22 2006, 11:22 PM
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#9
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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 |
I borrowed a depth gauge that was real easy to use.
Attached image(s) |
Type 4 Unleashed |
Apr 22 2006, 11:38 PM
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#10
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CREATIVE TYPE lV ENGINEERING Group: Retired Members Posts: 787 Joined: 20-June 04 From: Aliso Viejo, ca Member No.: 2,231 Region Association: None |
if you have domed or dished pistons, I assume you would measure from the highest part of the piston, no? NO, wether a dome or dish, for deck heigth, you would measure the flat side out side of the dome or dish. For the compression ratio, you would then either add -cc for a dome piston or +cc for a dish, to the chamber cc's, to figure the correct C/R. Example: In my picture I have a flat top, the Deck Heigth, is .015", used for the C/R calculations, but I have +8cc in the valve reliefs, so I add the +8cc to the Head cc, which is 48cc, so for the C/R calculations the head cc is 56cc. |
Type 4 Unleashed |
Apr 22 2006, 11:59 PM
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#11
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CREATIVE TYPE lV ENGINEERING Group: Retired Members Posts: 787 Joined: 20-June 04 From: Aliso Viejo, ca Member No.: 2,231 Region Association: None |
I borrowed a depth gauge that was real easy to use. Hi Mark I, dial indicate the piston to TDC, to get an exact reading of the deck heigth, I too have a depth gauge like yours, except it has a 6" base, what I used to do V8 motors. Trying to eye ball TDC, you can be up to .001" to .003" off on TDC, which throws C/R calculations off. |
messix |
Apr 23 2006, 12:35 AM
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#12
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
the short block is together, the heads are coming offthe engine thats still in the car. between the shmucks ring compressor and spiro locks, we looked like the short buss brought us to school. spent to much time b.s'n!
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MattR |
Apr 23 2006, 03:37 AM
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#13
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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 borrowed a depth gauge that was real easy to use. Hi Mark I, dial indicate the piston to TDC, to get an exact reading of the deck heigth, I too have a depth gauge like yours, except it has a 6" base, what I used to do V8 motors. Trying to eye ball TDC, you can be up to .001" to .003" off on TDC, which throws C/R calculations off. (IMG:style_emoticons/default/agree.gif) I happen to be lucky and have a dial gauge and depth gauge in my garage. Thats what I used on my engine. I'd also like to add the importance of torquing the cylinders to the block. Mark, I know you're clear in what you say about it being fine for stock rebuilds, but I really dont think a caliper is the right tool for the job. There are many machine shops with depth gauges that would probably let you use them for free if you ask. |
DNHunt |
Apr 23 2006, 07:45 AM
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#14
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914 Wizard? No way. I got too much to learn. Group: Members Posts: 4,099 Joined: 21-April 03 From: Gig Harbor, WA Member No.: 598 |
Good going you guys. I wish I could have come up. It looks like fun.
Dave |
Katmanken |
Apr 23 2006, 08:44 AM
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#15
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You haven't seen me if anybody asks... Group: Members Posts: 4,738 Joined: 14-June 03 From: USA Member No.: 819 Region Association: Upper MidWest |
AAron,
Cowpullers are fine... With Starret's they are dead nuts, with el cheapo harbor freights, they are +/- .001. You want to do two things. One, establish deck height depth more or less (for volume calcs) , and two, compare deck height on all 4 cylinders. Remember this my friend, even if the calipers .... er Cowpullers are rated +/- .001, the variance from cylinder to cylinder are probably closer. Why? That tolerance is for any mesurement UP TO 6 INCHES. For measurements less than 6 inches, the readings should be better. Yes, I agree, on cheap stuff, there can be tolerances of +/- .001 on readings less than 6 inches, but if you are measuring approximately the same dimension from cylinder to cylinder, the readings should be tightly grouped for better accuracy than that. Don't believe it? Sit down with a box of precison guage pins AND a caliper. Betcha you can get the same measurement off the same pin time after time. It may be off +/-.001 for el cheapo's but the same resut should show time after time. Go a little over or under on pin size and I bet it tracks off the original mesurement. That is, if the first pin diameter is .001 over, the next smaller pin diameter reading should also be .001 over as well, and the next pin size over original should track at .001 over. Ken |
914werke |
Apr 23 2006, 10:31 AM
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#16
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"I got blisters on me fingers" Group: Members Posts: 10,542 Joined: 22-March 03 From: USofA Member No.: 453 Region Association: Pacific Northwest |
Thanks to all that stopped by to pitch in (& McMark ) indeed after all the measuring math and assembly Blair came up with a 9.6 to 1 CR. (IMG:style_emoticons/default/smile.gif)
Im gonna spend today yanking out the 2.0 and stripping it and applying those heads to the 1911. (IMG:style_emoticons/default/smash.gif) BTW the freaking Ring compressor experiance reinforces why you buy quality tools (IMG:style_emoticons/default/headbang.gif) |
rhodyguy |
Apr 23 2006, 10:37 AM
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#17
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,188 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
after 0 decking it, what did you wind up with for a final deck height? what were the cc#s for the heads?
k |
McMark |
Apr 23 2006, 10:53 AM
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#18
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Sounds reasonable. Now use your numbers and the compression ratio calculator and change the deck height until you get the compression ratio you want. Looks like you'll probably need around a 1 mm shim to get 8.5:1, and half as much (0.5mm) for 9:1.
Did you compare the deck height readings for all four cylinders? |
MattR |
Apr 23 2006, 02:09 PM
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#19
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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 |
AAron, Cowpullers are fine... With Starret's they are dead nuts, with el cheapo harbor freights, they are +/- .001. You want to do two things. One, establish deck height depth more or less (for volume calcs) , and two, compare deck height on all 4 cylinders. Remember this my friend, even if the calipers .... er Cowpullers are rated +/- .001, the variance from cylinder to cylinder are probably closer. Why? That tolerance is for any mesurement UP TO 6 INCHES. For measurements less than 6 inches, the readings should be better. Yes, I agree, on cheap stuff, there can be tolerances of +/- .001 on readings less than 6 inches, but if you are measuring approximately the same dimension from cylinder to cylinder, the readings should be tightly grouped for better accuracy than that. Don't believe it? Sit down with a box of precison guage pins AND a caliper. Betcha you can get the same measurement off the same pin time after time. It may be off +/-.001 for el cheapo's but the same resut should show time after time. Go a little over or under on pin size and I bet it tracks off the original mesurement. That is, if the first pin diameter is .001 over, the next smaller pin diameter reading should also be .001 over as well, and the next pin size over original should track at .001 over. Ken The tolerance is not dependednt on the length measured. If its rated up to 6" with a +/- .001" tolerance, that does not mean a 1" measurement is only +/- .00017". Thats how the system works... The problem with calipers; they are an awkward tool to measure with in this application. They are perfect for measuring the length of a part or the diameter, but when you're trying to measure depth, there is no proper way to mount the caliper to get consistent readings. For example, your caliper can rock back and fourth because the reading surface is very narrow, which causes for huge discrepancies. Like I said, a depth gauge sits perfectly perpendicular to the measuring surface and there is no room for human error. |
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