 Stumped, Low Compression |
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| AKJammer |
 Sep 7 2016, 09:04 PM
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#1
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Newbie  Group: Members Posts: 6 Joined: 19-July 15 From: Alaska Member No.: 18,971 Region Association: Pacific Northwest  |
Engine: 1.8 1974.
I tore down the engine to replace Dead gaskets and seals. Purchased new jugs and pistons reassembled the engine. Fired it up and have 90 lbs of compression on 3-4 125 on 1-2. Completed a leak down test and all is good as it is holding what compression there is... Tore the engine down again and measured the cc of the heads and they are all the same. Part number 021.101.371S on both heads. Measured the deck height of the pistons at TDC and they are all the same.... Head gasket shims are all the same. What am I missing??? Thanks Jammer! |
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Replies
| rgalla9146 |
Sep 7 2016, 09:14 PM
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#2
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Advanced Member Group: Members Posts: 4,743 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None 
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Fuel injection or carbs ?
If carbs, were the carbs open on both sides ? |
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| AKJammer |
Sep 7 2016, 09:19 PM
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#3
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Newbie Group: Members Posts: 6 Joined: 19-July 15 From: Alaska Member No.: 18,971 Region Association: Pacific Northwest |
QUOTE(rgalla9146 @ Sep 7 2016, 07:14 PM)  Fuel injection or carbs ? If carbs, were the carbs open on both sides ? Dual 40's and just rebuilt. They were opening. Thanks |
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| rgalla9146 |
Sep 8 2016, 05:42 AM
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#4
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Advanced Member Group: Members Posts: 4,743 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None
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QUOTE(AKJammer @ Sep 7 2016, 11:19 PM) QUOTE(rgalla9146 @ Sep 7 2016, 07:14 PM) Fuel injection or carbs ? If carbs, were the carbs open on both sides ? Dual 40's and just rebuilt. They were opening. Thanks When doing a compression test the carbs must be propped open. "they were opening" doesn't sound right. |
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| Root_Werks |
Sep 8 2016, 12:15 PM
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#5
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Village Idiot Group: Members Posts: 8,667 Joined: 25-May 04 From: About 5NM from Canada Member No.: 2,105 Region Association: Pacific Northwest
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QUOTE(rgalla9146 @ Sep 8 2016, 04:42 AM) QUOTE(AKJammer @ Sep 7 2016, 11:19 PM) QUOTE(rgalla9146 @ Sep 7 2016, 07:14 PM) Fuel injection or carbs ? If carbs, were the carbs open on both sides ? Dual 40's and just rebuilt. They were opening. Thanks When doing a compression test the carbs must be propped open. "they were opening" doesn't sound right. I agree, it might be why a leakdown will show something like 80/79, but a compression will show 90psig. You need to allow air into the intake system. Prop the throttle to stay open and re-run the test. |
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| AKJammer |
Sep 8 2016, 01:07 PM
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#6
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Newbie Group: Members Posts: 6 Joined: 19-July 15 From: Alaska Member No.: 18,971 Region Association: Pacific Northwest |
QUOTE(Root_Werks @ Sep 8 2016, 10:15 AM) QUOTE(rgalla9146 @ Sep 8 2016, 04:42 AM) QUOTE(AKJammer @ Sep 7 2016, 11:19 PM) QUOTE(rgalla9146 @ Sep 7 2016, 07:14 PM) Fuel injection or carbs ? If carbs, were the carbs open on both sides ? Dual 40's and just rebuilt. They were opening. Thanks When doing a compression test the carbs must be propped open. "they were opening" doesn't sound right. I agree, it might be why a leakdown will show something like 80/79, but a compression will show 90psig. You need to allow air into the intake system. Prop the throttle to stay open and re-run the test. Yep will do! But either way the plugs were not firing on 3-4 side unless I had the rpms up. I installed new cap rotor pertonics points coil wire and plugs..... |
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Posts in this topic
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Just a thought.... Is the cam timing correct ? Go... Sep 10 2016, 04:03 AM |
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