Flat head seats 1947

[luisgmoral]

I would like to update my flat head six engine 1947 to a modern engine with gas without lead. I have heard that it is necessary to change the valve seats to more modern ones that resist modern gas with high octane and without lead. I would like to know your opinion on this subject because the original valve seats in my car are built into the block.



Thank you

[DJ194950]

All Mopar flat sixes (and 8's) can from the factory with  Valve seats (hardened).

NO need to change anything but maybe timing if you have been running a higher octane gas.

 

They have No problem running non leaded gas- never did!  😁

 

DJ

[D35 Torpedo]

And the compression is so low that high octane fuel isnt needed. However, I use to run 94 until they ruined it with ethanol. Now i just run 87. 

[keithb7]

In Canada I think Marine marked gas is still ethanol free. That’s what I run in my old cars. Illegal, yes. Lock me up! 
 

Hide behind pump so cashier cannot see. Show up with a legal gas can.  Cashier will check that you have a gas can. All good. Fill gas can. Stuff fuel nozzle in your car. Proceed to slam all you can in there. Cashier is too distracted with other customers. Pay for your gas and leave. All good! Or go directly to jail. Lol. 

Edited April 24 by keithb7

[Sniper]

You can buy non-ethanol gas around here for your car.  It's about a dollar a gallon more and it's 87 octane only,

 

I don't care one way or the other, I drive it enough that I don't have to worry about the gas going bad on me.

[Young Ed]

1 hour ago, Sniper said:

You can buy non-ethanol gas around here for your car.  It's about a dollar a gallon more and it's 87 octane only,

 

I don't care one way or the other, I drive it enough that I don't have to worry about the gas going bad on me.

It's interesting how the rules change so much. We pay typically about .75 more than the regular but the no ethanol is only available in premium. 

[Matt Wilson]

On 4/23/2024 at 6:31 PM, luisgmoral said:

I would like to update my flat head six engine 1947 to a modern engine with gas without lead. I have heard that it is necessary to change the valve seats to more modern ones that resist modern gas with high octane and without lead. I would like to know your opinion on this subject because the original valve seats in my car are built into the block.



Thank you

As others have said, the Dodge/Chrysler/Plymouth/DeSoto flathead sixes have hardened exhaust valve seats from the factory, and they are very capable of handling modern, unleaded gas without any issue.  They came that way starting in 1933 or 1934, and remained that way throughout all years that they were produced, which was well into the 1970's.  So you don't need to worry about that.

Edited April 25 by Matt Wilson

[D35 Torpedo]

On 4/24/2024 at 5:31 PM, Young Ed said:

It's interesting how the rules change so much. We pay typically about .75 more than the regular but the no ethanol is only available in premium. 

That's how it was here until the environazis changed it. I see a ton of hotrods having problems. They made the change quietly.

[Ivan_B]

Are we talking about updating valves or doing an engine swap? 🤨

I also use 87 regular. Thought about using non-ethanol, but it only comes with high octane, so I figured that I would rather deal with some ethanol than after-burn

As everyone else has already mentioned, you should be fine, no need to fix what ain't broke.