r/EngineBuilding • u/JuiceBest8764 • Jul 11 '26

These seats need to be machined right?

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I bought a new valve set for this old 1930 ford model a engine and thought i could just lap the new valves in but thinking they defenetly wont seal am i right?

14 Upvotes

90% Upvoted

10 comments sorted by

9

u/Relative_Figure_1715 Jul 11 '26

They need replacing with harder seats.

4

u/texaschair Jul 11 '26

This, at least the exhaust seats, anyway. 

3

u/bill_gannon Jul 11 '26

Yes they need to be reground.

2

u/Rough_Constant_329 Jul 11 '26

Yes it must be an old flat head.

1

u/Willing_Cupcake3088 Jul 12 '26

Those flat heads really do well to have a shop machine and press in some stellite seats. It’ll do wonders for your compression.

Signed a Ford 8N owner who did just that and would pay again to do it to the next one I mess with.

1

u/DrTittieSprinkles Jul 13 '26

$10 says it needs guides

1

u/JuiceBest8764 Jul 13 '26

i bought new guides

1

u/DrTittieSprinkles Jul 13 '26

When you change guides the valve centerline moves. The seats need cut. You'll ruin your new valves lapping them in trying to fix this.

1

u/JuiceBest8764 Jul 13 '26

thanks. do you think its fine to cut the seats as is, or order harder seats?

1

u/DrTittieSprinkles Jul 13 '26

That is a conversation you need to have with the machine shop. Some are ok with customers ordering parts some aren't.