 Compression Issues |
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| deloreandude86 |
 Oct 16 2011, 06:27 PM
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Austin Burkhardt  Group: Members Posts: 61 Joined: 18-August 10 From: Austonio, TX Member No.: 12,068 Region Association: South East States  |
Alright guys, we've been working on this for a while now and I'm starting to wonder just what the hell. A few weeks ago I checked the compression getting readings like 36, 42, 46, etc. so we tore the engine down, honed the cylinders checked the valves, rings, gaskets and everthing else, put it all back together and we're still getting the same readings, given it does have a little more power than it did before, as far as compression goes, its the same. Now this engine is intresting because during the rebuild we found out that it was originally a 72 1.7L. However, the bore is 94mm? could this have an effect on compression? and if so are my readings close to what they should be? Also is there a special technique to doing a compression check on the 914 that differs from a standard engine?
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| flash914 |
Oct 16 2011, 07:08 PM
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Member Group: Members Posts: 124 Joined: 1-January 11 From: littlerock CA Member No.: 12,554 Region Association: Southern California |
Normaly it's 3 compression strokes for a full test. Are you only doing one? This I think allows the hose on the gauge to "bleed" Kind of like getting the air out of a brake system. The other thing I would question, would be your compression ratio.
If it has 94 mm slugs and a 1.7 crank. ??? Heads over cut to the point that to much chamber. Also cam timing could be off allowing the valves to shut late. Don't know just things to check. Flash (IMG:style_emoticons/default/driving.gif) |
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| Cap'n Krusty |
Oct 16 2011, 09:37 PM
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
QUOTE(flash914 @ Oct 16 2011, 06:08 PM)  Normaly it's 3 compression strokes for a full test. Are you only doing one? This I think allows the hose on the gauge to "bleed" Kind of like getting the air out of a brake system. The other thing I would question, would be your compression ratio. If it has 94 mm slugs and a 1.7 crank. ??? Heads over cut to the point that to much chamber. Also cam timing could be off allowing the valves to shut late. Don't know just things to check. Flash (IMG:style_emoticons/default/driving.gif) Three? Try eight compression strokes, paying extra attention to the first two or three and the last two. This is done AFTER a valve adjustment and with the engine at normal operating temperature with all the spark plugs removed and the ignition disabled. The Cap'n |
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Posts in this topic
deloreandude86 Compression Issues Oct 16 2011, 06:27 PM
nathansnathan I'd try verifying the readings with another ga... Oct 16 2011, 07:03 PM
Vacca Rabite When you do a compression test you need to make su... Oct 16 2011, 08:11 PM
914Mels Somethings not right with your testing. I would su... Oct 16 2011, 09:09 PM somd914
Somethings not right with your testing. I would s... Oct 17 2011, 03:44 AM |
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