 Break in Compression 2 Liter, Valve Adjust/Duration/Lift...etc |
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| newdeal2 |
 Dec 20 2004, 05:13 PM
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#1
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Unregistered  |
OK, here's the scoop. I have the car running [the infamous 2 liter D jet re build] reasonably well. I re did the compression test [all plugs out/Throttle open]and it ranges from 120 -140.
I have been told that the WebCam [by Raby] having a longer duration and better lift will throw numbers off since it is intended to improve the mid range. I have also noted from various sources that it could be a simple valve adjustment that will bring the numbers closer. Am I getting too anal here? (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif) |
 
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Replies(1 - 8)
| Jake Raby |
Dec 20 2004, 05:39 PM
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#2
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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 |
Did you have the throttle open when taking the numbers??
What cam are you running? |
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| newdeal2 |
Dec 20 2004, 06:49 PM
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#3
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Unregistered |
Yes, throttle open and it is your WebCam 73 grind
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| Jake Raby |
Dec 20 2004, 07:17 PM
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#4
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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 |
Have the rings had time to seat yet??
If not that could make a big difference. What static CR did you set it at?? |
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| newdeal2 |
Dec 20 2004, 08:05 PM
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#5
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Unregistered |
I ran in the motor for 20 min's @ 2000 rpm. and have put about 10-15 miles on it with periodic 75% throttle and engine breaking to load the pistons.
Since this is my first re build what is static CR? |
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| Jake Raby |
Dec 20 2004, 08:32 PM
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#6
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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 |
The calculated compression ratio...
Sounds liek the rings are not seated yet.. Unless the engine is dynoed it takes atleast 250 miles to get them to seat well. |
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| newdeal2 |
Dec 20 2004, 09:08 PM
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#7
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Unregistered |
Makes sense. I need to relax and drive, get the timing right, etc.
I didn't do any caculations since all I changed was the piston type [stock to euro] and purchused them with the cylinders as a set. I checked the deck height and moved on. The car is running a little choppy at 3-4000 rpm. No excessive noise so I think it's a tuning issue. Should I hold off on valve adjustment or do it now since I didn't do it after the run in? |
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| Jake Raby |
Dec 20 2004, 09:41 PM
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#8
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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 |
Oh no........
The first step to engine building is NEVER ASSUME ANYTHING! Every engine has to be built like all the tolerances are unknown.. How many ccs were in those heads?? |
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| newdeal2 |
Dec 21 2004, 06:29 AM
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#9
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Unregistered |
Everything was kept stock, only changes as noted [cam and euro pistons] in my earlier reply. Crank and heads as well as align bore was done by a Porsche mechanic locally.
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