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Raider2532 Member
Joined: Dec 03, 2011 Posts: 27 Location: Cynthiana, KY
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Posted: Mon Apr 16, 2012 8:27 am Post subject: Gas Octane? |
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Should I be using the highest octane of gas in my 1955 M38A1 or the cheap stuff(87 Octane)? _________________ 1955 M38A1
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RICKG Member
Joined: Aug 31, 2010 Posts: 1741 Location: SO IDAHO
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Posted: Mon Apr 16, 2012 8:37 am Post subject: |
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There are dozens of threads and opinions on this subject posted here.
Try the search function for a ton of info on the subject. Currently i'm
running regular unleaded pump gas with no problems (so far) but i
probably just jinxed myself.. _________________ keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a |
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wesk Site Administrator
Joined: Apr 04, 2005 Posts: 16263 Location: Wisconsin
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Posted: Mon Apr 16, 2012 9:37 am Post subject: |
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The L134 was designed to run on gas as low as 63 octane. The military preferred the low rating so lousy fuel found in the field or accidentally diluted with diesel would not harm performance.
I mix 87 pump gas with 100 LL aviation gas in all my early engines. Pushes the octane up to about 90 even though I don't need it that high but more importantly it adds sufficient lead to protect the valves. I ran my M38A1 & CJ3B on 87 pump gas from 86 thru 98 without a lick of any problems caused by fuel type.
A word of caution to folks that add overdrives and push the old girls to 60 + MPH on long open highway runs you should add some lead or lead substitute. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php |
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53a1 Member
Joined: Jun 25, 2008 Posts: 583 Location: Kern Co.
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Posted: Mon Apr 16, 2012 9:44 am Post subject: |
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I took Wes' advise and I run 50/50 avgas & pump. So many benefits to doing this; shelf life, more lead, less ethonol. You don't need the extra octane points but it won't hurt. I've had the same tank of gas for a year now and it still runs great. My plugs look perfect so engine is happy. _________________ '53 M38A1 X2 |
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Bretto Member
Joined: Nov 24, 2010 Posts: 1390 Location: Orem, UT
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Posted: Mon Apr 16, 2012 10:13 am Post subject: |
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Can the average joe just go down to the local strip and buy avgas? Or do you have to know someone? If that is the case, I think I know of someone who would help me out. _________________ Brett
'51 M38
PHOTO DIARY OF MY BUILD |
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wesk Site Administrator
Joined: Apr 04, 2005 Posts: 16263 Location: Wisconsin
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Bretto Member
Joined: Nov 24, 2010 Posts: 1390 Location: Orem, UT
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Posted: Mon Apr 16, 2012 11:57 am Post subject: |
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I think I'll bring my aquantance along who has a plane there and have him help me out. I might end up looking like a fumbling idiot. _________________ Brett
'51 M38
PHOTO DIARY OF MY BUILD |
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RCFlyguy Member
Joined: Jul 27, 2011 Posts: 25 Location: 2 hours southwest of Chicago, IL
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Posted: Mon Apr 16, 2012 3:38 pm Post subject: |
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I do the same thing for fuel as Wes. Except, I mix 4 gal of unleaded with 1 gal of 100LL. The reason being: I believe 100LL actually has 4 times the amount of lead as a regular leaded gasoline...plus it's a bit more expensive. When I took my engine apart, the valves and spark plugs have a greyish appearance to them (sign of good lead lubrication I think). |
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magnum Member
Joined: Jul 15, 2010 Posts: 57 Location: Pine, Idaho
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Posted: Mon Apr 16, 2012 3:44 pm Post subject: |
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If you use the lead substitute will it protect the valves the way the old leaded gas did? _________________ 52 M38
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53a1 Member
Joined: Jun 25, 2008 Posts: 583 Location: Kern Co.
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Posted: Tue Apr 17, 2012 9:05 am Post subject: |
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I don't know about your area but we have a small airport that looks like a ghost town and they have a self serve pump where you can pull your plane up to and use your credit card to fill up.
I also use the stuff with pre-mix in my '74 two stroke Yamaha and that engine actaully appreciates the octane. _________________ '53 M38A1 X2 |
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wesk Site Administrator
Joined: Apr 04, 2005 Posts: 16263 Location: Wisconsin
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Posted: Tue Apr 17, 2012 10:03 am Post subject: |
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Since the unleaded debut in 1972 I have never thrown any of my hard earned money at any of the commercial lead substitutes. They just aren't lead and not really a 100 % answer to the need for lead in these old engines. The only reliable person to answer your question is someone who has used the product religeously for a full overhaul life of a Willys 4 banger. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php |
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magnum Member
Joined: Jul 15, 2010 Posts: 57 Location: Pine, Idaho
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Posted: Tue Apr 17, 2012 5:27 pm Post subject: |
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Thanks Wes. I think the best way to go is with the Avaition fuel. _________________ 52 M38
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