| DaveB |
Sun Jun 24, 2012 5:42 pm |
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Specs, Raby cam 9550, grind73/73 + 2.5, lift .426, Duration 262, Pistons are KB flat top 96mm setting on 94m barrels machines out to 96mm years ago to Jake's specs. Measured chambers some time ago to be 50cc (seems low going to double check this), Engine is going in a Splitwindow bus with a Beetle tranny beefed up. When I measure under straight edge with barrels held down tight I get .026. Shims that came with gasket kit were installed under barrels, assumed they were same as stock. I bought the parts some time ago but got delayed building due to medical issues and Honey Do list :)
Heads are Intake 42mm and Exhaust 36mm.
Now the Questions:
1. When they say min should be .040 to .070 is that total measured at TDC?
2. Is this to tight for valves, the .026 at heads?
3. I was going to shoot for 7.8:1, but could I shim it and get something around 8.6:1 out of it and run Regular gas (mid grade is probably a better choice I bet) |
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| skills@eurocarsplus |
Sun Jun 24, 2012 6:12 pm |
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1 yes at tdc. you need a dial indicator. don't even bother to try without it, cuz you'll never eyeball it
2 i am assuming it's a T4. ask jake
3 8.6 may run a tad hot? unsure on that one |
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| blue77bay |
Sun Jun 24, 2012 7:05 pm |
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[quote=
Now the Questions:
1. When they say min should be .040 to .070 is that total measured at TDC?
2. Is this to tight for valves, the .026 at heads?
3. I was going to shoot for 7.8:1, but could I shim it and get something around 8.6:1 out of it and run Regular gas (mid grade is probably a better choice I bet)[/quote]
1&2 go together,When the specs call for 040 min they mean min, 026 is too tight ,adjust your barrel shims to obtain 040-045 at TDC which is the closest the piston gets to hittin something.
3 currently you are calculating out at 9.8 with 045 deck ,so you really need to keep the tight deck which means your chambers need to be 65cc to get 8.1 ,try to resist the temptation to just shim the barrels to get the desired comp ratio it will just be a pig.You need to remeasure the chambers as 50cc is low |
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| DaveB |
Sun Jun 24, 2012 7:15 pm |
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| Only how to do it a feeler guage. Unzure on how to do it with a dail indicator. Know how to use one bug not to chew deck height |
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| blue77bay |
Sun Jun 24, 2012 7:29 pm |
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| put a couple of tubes over the head studs,then washer and nut, tighten a bit,that will hold the barrel firmly against the case,now take a good straight piece of flat bar stock and hold it edge on against the barrel thru the middle ,slide feeler gauges under it and between the piston .This is not exact but will be within a 3-5 thou range to get you started ,for the MOST accurate you need a depth micrometer like this http://www.ebay.com.au/itm/Digit-Reading-Depth-Mic...5d2fc9ed92 |
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| DaveB |
Sun Jun 24, 2012 7:37 pm |
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| Yea, that's the way I done it. Just have the concerns I ask above. Thanks though. |
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| DaveB |
Sun Jun 24, 2012 7:42 pm |
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| Thanks Bluebay, may have to shim and open the chambers. When you answered one confusion lit a bulb (dimly though) I was adding the measurement I took with the thickness of the shims, dumb. Of course the shims pushed the barrels up making the measurement the deck height, duh tome. |
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| SGKent |
Sun Jun 24, 2012 9:38 pm |
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| if you have .026 deck height with shims under the barrels better take a step backwards and rethink the situation. |
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| DaveB |
Sun Jun 24, 2012 9:46 pm |
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| There .004 shims |
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