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| Down in the Hole? https://www.slantsix.org/forum/viewtopic.php?t=36034 |
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| Author: | bwhitejr [ Tue Jun 30, 2009 5:18 am ] |
| Post subject: | Down in the Hole? |
Is there a year to year difference in the "down in the hole" distance for 225 blocks? What is a typical number? What is the largest and what is th e smallest number anyone has seen on a stock block? The reason why I ask, is I am measuring 0.129 ('72) on a stock block. The others I have seen are much larger than that. Thanks bwhitejr |
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| Author: | 66aCUDA [ Tue Jun 30, 2009 7:12 am ] |
| Post subject: | |
Bob Ive seen .1 to .2 I would say about .180 is average. Most of the block I have are .180-.187. Hope this helps, Frank |
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| Author: | Dart270 [ Tue Jun 30, 2009 12:52 pm ] |
| Post subject: | |
Sounds like that block was milled. The least I have measured is about 0.170". Lou |
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| Author: | Rick Covalt [ Tue Jun 30, 2009 1:38 pm ] |
| Post subject: | Dart |
The block in Ryan's Dart (1972 block) was -140 before we milled it. Rick |
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| Author: | madmax/6 [ Tue Jun 30, 2009 8:05 pm ] |
| Post subject: | |
Tore down a 300 mile professionally rebuilt motor cause it sat for five years,front cyl was .170 down,rear was .145 ,,deck had a slant to it.My machinest couldnt belive how bad it was,had to be prior work,got them all straight now,Mark |
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| Author: | slantzilla [ Wed Jul 01, 2009 4:04 am ] |
| Post subject: | |
Quote: Tore down a 300 mile professionally rebuilt motor cause it sat for five years,front cyl was .170 down,rear was .145 ,,deck had a slant to it.My machinest couldnt belive how bad it was,had to be prior work,got them all straight now,Mark
I have seen that before. Certain mills will not accept a Slant block in a way that the deck comes out flat.
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| Author: | Wizard [ Wed Jul 01, 2009 1:24 pm ] |
| Post subject: | |
Quote: Quote: Tore down a 300 mile professionally rebuilt motor cause it sat for five years,front cyl was .170 down,rear was .145 ,,deck had a slant to it.My machinest couldnt belive how bad it was,had to be prior work,got them all straight now,Mark
I have seen that before. Certain mills will not accept a Slant block in a way that the deck comes out flat.Cheers, Wizard |
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| Author: | slantzilla [ Wed Jul 01, 2009 5:37 pm ] |
| Post subject: | |
Mike ran into it with a shop he used for decking a block. The fixture the machine had for mounting the block held one end slightly higher than the other. You could not tell with the naked eye, but Mike caught it when checking deck height on the pistons before final assembly. 
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| Author: | madmax/6 [ Wed Jul 01, 2009 6:51 pm ] |
| Post subject: | |
My machinist actually put a piece of paper under the front of the block after he got it real close to get it perfect,he is a friend and let me watch,was off a little sideways also,mark |
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| Author: | stonethk [ Wed Jul 01, 2009 7:04 pm ] |
| Post subject: | |
I cant find my notes for the measurements, but my #6 piston is down more than my #1...also the head I have from a completely different engine- the #6 chamber cc's less than the #1 chamber, oddly, the difference in the combined volumes equals out. Hehe, a slant-slant six....go figure 
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| Author: | Wizard [ Wed Jul 01, 2009 7:11 pm ] |
| Post subject: | |
So does the fixtures is slightly worn on one side or the engine block is springy on one end? What about the "bed" that everything are mounted to? Machining the diesel block is more critical as deck had to be absolutely parallel with the crankshaft center, even I had a note asking to check the rebuilt head deck for parallel-ness with the camshaft bore if head is for diesel also. Cheers, Wizard |
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| Author: | bwhitejr [ Thu Jul 02, 2009 4:01 am ] |
| Post subject: | Down in the Hole? |
I am curious now. When checking to see if #1 cylinder is down in the hole the same as #6 cylinder, do you use a different piston/rod combination to check each or use the same piston and rod? If there is a slant to the decking is it always #1 to #6 or #6 to #1 sloped (most depth to least depth)? bwhitejr |
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| Author: | 66aCUDA [ Thu Jul 02, 2009 6:23 am ] |
| Post subject: | |
Bob I use the same piston to mock it all up. Most people check the deck before they disassemble the engine. That tells them how much to take off. As for 1-6 or 6-1 I guess it would depend on which end they put where on the machine and how off the table is. Frank |
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| Author: | bwhitejr [ Mon Jul 13, 2009 4:35 am ] |
| Post subject: | Down in the Hole |
Well, I finally got a depth micrometer and measured my block. I was getting different readings depending on where I measured. 225 Rod with stock piston (no rings) Driver Side of block 0.172 Rear of cylinder 0.17075 Passenger side of block 0.16875 Front of cylinder 0.17025 Dead center of cylinder 0.17925 198 Rod with stock piston (no rings) Driver side of block 0.1385 Rear of cylinder 0.1395 Passenger side of block 0.1450 Front of cylinder 0.1435 Both pistons were pitted somewhat, so that accounts for the center being lower. The good news is the sum of the 225 down in the hole measurement and the 198 above deck measurement comes out very close to the difference in the rod length if you average the measurements for both cases. So, which measrement would be the more accurate one? It seems the one at the rear of the cylinder should be the most accurate, since there are no rings on the piston. Thoughts? bwhitejr |
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| Author: | 66aCUDA [ Mon Jul 13, 2009 6:15 am ] |
| Post subject: | |
Bob Depends on what you are trying to do. If you are going for Zero deck height then use the smallest number. If calc. the volume for compression then the average. Remember it may change by .005 or so when it get machined. Frank |
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