FH deck and valve seats

3

3W Hank

Well-known member
I has 2 early Merc blocks and both need deck especially the one I just found.
A good block at std bore but factory sleeved ( not decided yet on bore dia )
Its not ported.
A question on deck, I guess this blocks not like deck but as erroed its need be decked, but if its straight would I leave it and gasket take care of that ?
If I do has a ’normal’ V8 to a customer I would deck as I get it clean but in this case (?)

2 cylinders are erroed around valve seats and one I asked said its need be new seats.
I said what if I sink the vales, but he mean you not get any valve spring pressuare then ( will use the Iskys, same as the LZ )
 

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3W Hank said:
I has 2 early Merc blocks and both need deck especially the one I just found.
A good block at std bore but factory sleeved ( not decided yet on bore dia )
Its not ported.
A question on deck, I guess this blocks not like deck but as erroed its need be decked, but if its straight would I leave it and gasket take care of that ?
If I do has a ’normal’ V8 to a customer I would deck as I get it clean but in this case (?)

2 cylinders are erroed around valve seats and one I asked said its need be new seats.
I said what if I sink the vales, but he mean you not get any valve spring pressuare then ( will use the Iskys, same as the LZ )
Click to expand...
588705
 
Looks like it had tin sleeves in that block originally. It surely needs new valve seats, and might be a good candidate to relieve too so some of the rusty area is smoothed out. Then just a light decking to make sure it’s flat. I always think a rust pit or two on a gasket surface just helps the gasket stay in position.
 
Just wondering. Is there a limit to how much you can safely cut the deck on a flathead engine?
 
19Fordy said:
Just wondering. Is there a limit to how much you can safely cut the deck on a flathead engine?
Click to expand...

Try cutting the seats first, they might work. My concern is the fine line where the 30 degree cut meets the 45 degree face I believe that if this fine line is unbroken by a rust pit, it will hold a seal. It is important that the seat is tight in the block. I take a small ball peen hammer and tap low on the seat. (Not the valve sealing part) Listen for a solid sound, not a dull thud.

Karl
 
Is it common the seats are kind of get lose ?
I will do the ’sound’ check, but I guess i need replace this 2 cylinders seats.
 
Flathead decks are thin, you want to machine as little as possible and make sure it is done in a machine that can "square deck" the block - by picking up the mains. Also, the driver's side valve seats are about .040 higher than the passenger side, so make sure somebody doesn't try to make the seat depth the same. The crankshaft is offset a bit - this causes the difference in valve angles side-to-side. I've seen shops ruin blocks by thinking the valve seats need to be the same distance from the deck!

I would blue die-chem the block and then take a big-bore gasket and see where the compression ring aligns on the block. If the pits are inside the ring, then you won't have an issue . . . if they are on the ring sealing area, then an issue can occur.

Also, make sure you measure the actual deck height with the crank, two rods and two piston pins (one each side). You'll probably find that one side is shorter than the other. Deck that side first (minimum amount possible), then use that final deck-height dimension to deck the taller side.
 
I read the crank is offset = 0.265” ( or 0.25" )
I wil CAD up this just for fun.
Was Fords ide to has both banks equal ?

If one bank has valves 0.04” higher that mean if heads is the same it would be more compression.

Just a thought.
 
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Dale, yes it must be as no matter what crank centre is ( in the block ) the deckheight need be the same if stroke/rods/CH is the same..
Otherwise deckclearance will be off, but it is still the height of the valves at one side is higher and that must effect chamber volyme.

One thing I had in mind some years ago was when I heard this engines ofcourse has flow issues from design, and all engines like compression ( no matter what ) but in this case as flow is critical factor to make HP it might be a 'compromise' to has lower comp but instead has the flow ( Read ; 'maybe better' ) and that might gain.

I newer read this was a cure from more than the source I had that idea from.
-What's your ideas on that.
 
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