 Compression Ratio, Will I be able to tell the difference? |
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| sdoolin |
 Feb 7 2025, 04:42 PM
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#1
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Member  Group: Members Posts: 414 Joined: 1-May 14 From: LouKY Member No.: 17,299 Region Association: None  |
Rebuilding(ish) my 2056. On my first build I was able to achieve a compression ratio of very nearly 9.0:1. With this build, I am having to add .020 spacers below the jugs to get any measurable deck height in the jugs. I am calculating a compression ratio of 8.6:1.
Will I notice the loss in compression ratio? |
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Replies
| sdoolin |
Feb 22 2025, 01:05 PM
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#2
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Member Group: Members Posts: 414 Joined: 1-May 14 From: LouKY Member No.: 17,299 Region Association: None |
So, I re-measured crank end play. Installed flywheel (no RMS) with two shims behind it. Measure end play with dial indicator on the flywheel tip of dial indicator on the case. I can't move the crank noticeably for and aft by hand. Prying very gently on the flywheel in the direction away from the cases I measure .43mm (.0169"). This is repeatable.
My manual says to subtract .004" from this, which yields .012". I have a shim of that thickness. I'm not sure what value I am ultimately looking for after I install this third .012" shim? Am I looking for .004" thrust with all three shims? |
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| Superhawk996 |
Feb 22 2025, 01:16 PM
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#3
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914 Guru Group: Members Posts: 6,814 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch 
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QUOTE(sdoolin @ Feb 22 2025, 03:05 PM)  Am I looking for .004" thrust with all three shims? Yes |
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Posts in this topic
sdoolin Compression Ratio Feb 7 2025, 04:42 PM
technicalninja You need AT LEAST .036 with cast and .040+ with fo... Feb 7 2025, 05:38 PM sdoolin Measured deck height in the jug, with an .020 spac... Feb 7 2025, 06:02 PM Superhawk996 Sounds like you are playing with fire.
Without se... Feb 7 2025, 06:21 PM
sdoolin
Sounds like you are playing with fire.
Without s... Feb 7 2025, 07:26 PM Superhawk996
Sounds like you are playing with fire.
Without ... Feb 7 2025, 07:30 PM technicalninja
Measured deck height in the jug, with an .020 spa... Feb 7 2025, 06:57 PM sdoolin Yep, I don't want this help. Y'all go buil... Feb 7 2025, 07:27 PM worn
Yep, I don't want this help. Y'all go bui... Feb 14 2025, 07:12 PM sdoolin
Yep, I don't want this help. Y'all go bu... Feb 15 2025, 08:44 AM sdoolin I especially like the turd bit. Feb 7 2025, 07:29 PM sdoolin Superhawk thank you for your reasonable response. ... Feb 7 2025, 07:33 PM Superhawk996
Superhawk thank you for your reasonable response.... Feb 7 2025, 07:44 PM Jack Standz
Rebuilding(ish) my 2056. On my first build I was ... Feb 8 2025, 03:05 AM sdoolin
Rebuilding(ish) my 2056. On my first build I was... Feb 8 2025, 07:35 AM sdoolin Bolted things up on one side of the engine today a... Feb 8 2025, 12:37 PM Superhawk996 0.100” clearance to the exhaust valve is startin... Feb 8 2025, 01:43 PM Jack Standz
Bolted things up on one side of the engine today ... Feb 8 2025, 03:04 PM sdoolin Thank you both for the thoughtful replies. My orig... Feb 8 2025, 04:32 PM Superhawk996 0.140” - 0.150” clearance to exhaust valves is... Feb 8 2025, 10:28 PM sdoolin Measured valve lift a bunch of times today. Worst ... Feb 9 2025, 05:03 PM sdoolin I'll likely button this engine up this weekend... Feb 14 2025, 02:27 PM Jack Standz Modified #2.
Bolt transmission to engine. Remove... Feb 14 2025, 04:41 PM sdoolin
Modified #2.
Bolt transmission to engine. Remov... Feb 15 2025, 08:38 AM 930cabman Have you checked crankshaft end play? Feb 14 2025, 04:52 PM sdoolin
Have you checked crankshaft end play?
So I re-c... Feb 16 2025, 04:08 PM Al Meredith Years ago when Len Hoffman was rebuilding heads he... Feb 15 2025, 05:02 PM worn
Years ago when Len Hoffman was rebuilding heads h... Feb 15 2025, 08:49 PM Superhawk996 No discernible crank end play is a no-go.
Redo ... Feb 16 2025, 04:30 PM sdoolin
No discernible crank end play is a no-go.
Redo... Feb 17 2025, 08:09 AM stownsen914 Separate from the crank end play, if you are askin... Feb 17 2025, 08:15 AM sdoolin
Separate from the crank end play, if you are aski... Feb 17 2025, 01:16 PM sdoolin I have measured all of the shims I have on hand (6... Feb 18 2025, 05:25 PM sdoolin Thank you Superhawk. Installed third shim, remeasu... Feb 22 2025, 02:04 PM Superhawk996
Thank you Superhawk. Installed third shim, remeas... Feb 22 2025, 07:09 PM Jack Standz Add a cable from the negative side of the battery ... Feb 22 2025, 02:24 PM Superhawk996 I’m going to ask a question that I’ve assumed ... Feb 22 2025, 07:17 PM sdoolin
I’m going to ask a question that I’ve assumed... Feb 23 2025, 09:20 AM Jack Standz It's a good idea to fill the oil filter with o... Feb 23 2025, 02:51 PM sdoolin I have confused myself. It happens.
Having re-in... Feb 27 2025, 10:37 AM Superhawk996 Follow the Haynes or factory manual to instill the... Feb 27 2025, 12:15 PM sdoolin
Follow the Haynes or factory manual to instill th... Feb 27 2025, 04:02 PM sdoolin Engine went in on Friday. Easy peasy. After I pour... Mar 2 2025, 05:23 PM sdoolin Could this be a faulty oil pressure sending switch... Mar 3 2025, 10:30 AM VaccaRabite
Could this be a faulty oil pressure sending switc... Mar 3 2025, 11:35 AM Superhawk996 If it were me I would not be starting the engine j... Mar 3 2025, 12:53 PM sdoolin Installed my brand new oil pressure test gauge (Ha... Mar 3 2025, 04:20 PM VaccaRabite Your pressure is high because the oil is cold and ... Mar 4 2025, 06:20 AM rfinegan Woohoo
glad you get the pressure...sounds like the... Mar 4 2025, 09:03 AM sdoolin Yep, cold oil and running (expensive) Brad Penn 20... Mar 4 2025, 09:10 AM sdoolin She's alive, and running well(ish). Drove abou... Mar 11 2025, 10:55 AM 930cabman
She's alive, and running well(ish). Drove abo... Mar 11 2025, 12:17 PM friethmiller @sdoolin ,
Congrats! Glad the build was succ... Mar 11 2025, 11:54 AM sdoolin Moving on to some other fiddly projects. Oil press... Mar 11 2025, 02:56 PM |
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