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  #31 (permalink)  
Old 06-19-2010, 01:50 PM
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Checking deck clearance pics up!

Ok guys so I bought the necessary tools I needed to measure my deck clearances. I wasn't able to find one of those specialty deck clearance dial indicators so I basically am using a magnetic base dial indicator on the piston center to find exact TDC then using a straightedge and feeler gauges to determine the distance between the deck surface and the piston surface. This seems to work fine and I don't see anything wrong with using this measurement method. Below are a few pics of the setup I just explained.





The only problem is the piston will rock because the rings aren't on so the one side will read lower than the other. In the pic below the right side of the piston has been pushed down so it is reading a good 8 to 10 thou. lower than the left side.


If I take the measurement right dead center of the piston on the pin centerline I will get a reading dead in between the far left (lower reading) and the far right (higher reading). My question now is which one of these measurements should I be using as the piston deck height? One would assume use the left side reading (lowest numeric reading) for safety reasons as that is the absolute highest point the piston face will travel. However, once the rings are on the piston I would not be able to rock it like that as it would be physically impossible and all readings should be the same reading that I am getting at the piston centerline, correct? So far I am finding a max of 0.002" difference from left to right bank so I don't think the second machinist was taking the measurements from all the same locations on each piston (be it extreme right, left, or centerline). I am going to have to take my lowest number (highest piston) once all 4 corner cylinders are measured and base my head gasket thickness on that to come up with a quench between 0.040"-0.050", correct? The only part I am not sure about is do I go on the safe side and take my lowest number (would be on the left side of the piston in the pic) to base my calculations on or do I use the piston centerline measurement since this number should be where the piston sits with the rings on. Please correct me on anything I have wrong here but so far it is looking like I can just taylor my gasket thickness to my lowest reading and be ready to roll with a good quench.

That's all for now,
Keith

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  #32 (permalink)  
Old 06-19-2010, 02:04 PM
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In my experience, I use the measurement that is taken directly above the pin, and I basically ignore the piston "rock".

At the center above the pin to the deck, plus the gasket is what I use to shoot for a 0.040" quench. I feel that with steel rods and a 7K RPM redline, the 0.040" quench has the needed "safety factor" built in already. Others may well disagree w/this, and that's OK.
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  #33 (permalink)  
Old 06-19-2010, 02:11 PM
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Good Direction

You can't lose now. My money's on you, because you're into the details and specs and developing your own collection of instruments. We measure with the wrist pin. I'm all for determining the actual height this way, as long as you're using your piston/rod in the bore they will live in. When setting up our rod indexing fixture I was surprised in rod length variation. Since this thread started I decided to recheck all of our balanced rod sets. We had five sets of factory rods balanced to themselves. I found two rods that were more than .001" long or short. Checked to sets of new aftermarket "h" beams, different brands and they varied by several .0001", but better than I said.
I'll be interested to see how this comes out. Good luck..

Last edited by Duntov; 06-19-2010 at 03:05 PM. Reason: spelling
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  #34 (permalink)  
Old 06-19-2010, 06:15 PM
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You know most mahine shops go by reputation and what a lot of guys tell ya.They can't be all wrong.But like everyone else is telling you the second guy is jiving you.You may have possibly told him where it it was before,and has a case of the red *** or just plan is knocking the guy for other reasons hint-[$] How many blocks and engine parts were on the floor waiting for work,what was the time frame for your work to be done?.Many variables and money involved here.Did you get a sheet back from the first machinist for the work and specs he did?.If not you should have! With all the money the 2nd guy wants,you might be able to pick up an aluminum block somewhere!Paisano
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  #35 (permalink)  
Old 06-19-2010, 06:27 PM
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SorryI almost forgot,how come you took it to another shop,most machine shops will either do most work in house or else send out to someone else that they trust.For exampole the balance job.They wouldn't want their work that they did to your stuff not to get screwed up.They want it done right the first time.And wou will get a sheet as to the total weight of the rotating mass also on a balance job. Believe me that makes a diferrance if they care about there work.
Paisano
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  #36 (permalink)  
Old 06-19-2010, 07:44 PM
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The Economy

This is off subject a bit, but I just realized you're in Vancouver. I feel free to drift from subject, because I don't think you have any kind of sbc problem you can't handle here, and that you just needed to hear a few people say what you were already thinking.


I just started wondering if the dollars were that far different from the South Eastern US to Vancouver, BC? I started thinking about it yesterday afternoon driving back from the machine shop; where I picked up a 638 block and a 0010. The total bill for the pair was $100. Both were decked to 9.004".
I know I get an exceptional deal on decking there, but ..Really.. What would it cost in Canada done by a typical honest shop? How about Washington State?

Which by the way Bills Machine on hwy 99 in Lynnwood, Wa, outside Seattle is suppose to be a really good shop. Anyone know those guys well enough to recommend them? Bill and Jim Grader?
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  #37 (permalink)  
Old 06-19-2010, 11:34 PM
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I did not receive any paperwork after I had all that machining done at the first shop, the only paperwork I got had $800 on the bottom . At this point, however, it is appearing that all of my questionable machined measurements are actually well within the realm of a street/strip build and that I was a little mislead by the second machinist (I think he was adding a couple thou. to his measurements as well). It is a shame that the first shop did not give me a sheet with all the machining measurements they did but I plan on taking absolutely every measurement and recording it myself so I KNOW for sure what they are. I'm definately blueprinting everything myself. As far as that deck height issue is concerned, I am going to assemble the entire shortblock (after I get my rotating assembly balanced, might throw a third shop in there for this) and once assembled I will take my shortest deck clearance measurement to determine my head gasket thickness. Duntov, thanks for your overwhelming interest and information you have provided in this thread, it's of great help. To answer your question, I haven't been able to find a shop anywhere in my area that can deck a block for under $60 CAD a side, $120 for the block. It's not that there is a shortage of machine shops in Vancouver but business for them is dead so they make up for it by jacking up prices for everything. I thought after hosting the Olympics this winter our economy was supposed to change for the better, but with all the machine shops I have dealt with it seems that if you don't know the owner on a first name basis they won't be doing you any favours, quite the opposite actually. If all the rest of my measurements check out within the allowed tolerances, I will be satisfied and confident with the support from you fine fellows to bolt it together and hold on for dear life

Keith
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  #38 (permalink)  
Old 06-20-2010, 02:38 AM
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Hi Keith, yeah, when doing the piston deck height measurements, stand at the side of the block and measure at either 3:00 O'Clock or 9:00 O'Clock on the piston, along the pin line. Never mind the piston rock. Put it together at 0.040" and you'll be fine. Vizard had to go down to 0.026" before he got piston to head interference.
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  #39 (permalink)  
Old 06-20-2010, 04:01 PM
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I did not read through all 3 pages of posts so if someone already suggested this sorry..

You need to measure the block from the main to the deck in all 4 corners? See if its square to the mains. I've seen so many cranks that are ground wrong and rods that are bushed to short and piston pins that are in the wrong place. You can not go off the piston in the bore. Try and move a rod and piston around and then measure..

MItch
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