Gas in m38a1

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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Gas in m38a1

Post by Shug4 » Thu Jun 10, 2021 4:58 am

I need to know if I have to put leaded additive to my gas so my engine will run right. I had a valve job done to the head but not block.

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Re: Gas in m38a1

Post by dpcd67 » Thu Jun 10, 2021 7:15 am

No. But I use non ethanol gas in most of my MVs; it lasts longer in storage and won't vapor lock as easily as ethanol will. I have never used lead additives on any of my rebuilt engines and they are all fine, many decades later. (OK, the Dodges already have hard seats)
The lead was not to make them run; it was to make the valves last longer. I guess it would help protect the valves in long term use, but few of us drive our vehicles enough to need it.
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Re: Gas in m38a1

Post by KiwiMB » Sun Jun 13, 2021 9:53 pm

the primary benefit of lead in gasoline was that it effectively raised the octaine rating of the fuel thereby stopping knocking (aka/detonation/ping/pinking) which caused significant engine damage to piston rings, ring lands, rod bearings and valves.

In other words the lead also extended the life of valve seats and especially exhaust valves.


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1941 Willys MB
1942 Dodge WC 53
1953 M38A1 Nekaf

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