Shaved the deck

[my2nd40]

I cut the deck on my old 59ab .030 to make it flat again. What do you think?

[Bored&Stroked]

That is a lot more than I have had to shave on a deck - I'm typically under .015 . . . and that was only needed to make the compression height the same on both sides.

One really shouldn't decide how much to shave until the put the crank and a piston and rod in both sides - then you can measure the height differences (side to side) of the piston crown to the deck surface. Did the machine shop cut both sides the same?

In the end, what matters is the piston to cylinder head clearance. This needs to be accurately measured ---> with tinfoil balls, clay, etc.. You really want a consistent clearance over the pistons at about .040 to .045 (never less than .040 on the street). This is obviously done with a sample head gasket in place.

Have you or your machine shop put 2 pistons in the block and measured the compression height and clearances with your heads, your rotating assembly, etc?

Anything else is just a guess at best . . .

[Ronnieroadster]

That's way to much! Was the block deck warped that much? Or was it pitted so the machine shop decided to remove so much to eliminate the pitting?

As Dale wrote above a lot of measuring needs to be done to determine if there's going to be the proper piston to head clearance. You might be in need of extra thick head gaskets to get the needed clearance.
Good Luck.

[35fordtn]

Sheesh that’s at the point you’ll have to recess to valve seats and worry about piston to head clearance. Or go full blown hillbilly/redneck and run two head gaskets and have little valve seat area to work with.

[tubman]

I would do a lot of careful measuring before I decked one of these old blocks. On the last engine (an 8BA) I had built, I had told the engine builder to call me if the block needed decking. He did, and told me the while there were some minor variations in the surface, it would probably be good to go the way it was. Knowing the thin nature of flathead decks, I agreed with him to leave it alone.

When I checked the cylinder head to piston clearance prior to installing my Edmunds heads, I found that the left bank had variations in the clearance of .040" from front to back. I had .090 over the front piston, and .050 over the rearmost piston, with the middle cylinders in between. After conferring with the engine builder and some discussion on this forum, we came to the inescapable conclusion the the block had previously been machined at an angle from front to back. After further discussion, we decided that the solution was to mill the head at a corresponding angle; The engine builder said he didn't want to attempt this, but I was able to find an old guy with a mill in his garage who said he could do it. When I got the head back from him and fitted it to the engine, I had a consistent clearance on all four cylinders. During the final fitting with a die grinder, I found I had to take a bit more out of the rearmost combustion chamber, but I was able to achieve a consistent quench of .050" on all cylinders (I am not as brave as Dale).

Luckily, since it's an 8BA, the same head has to go on the left side if it is ever removed, and the engine runs strong. The bottom line is that you never know what these old engines have had done to them in the past, so measure everything; at least twice.

[Bored&Stroked]

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Also, the decks are very thin on these engines . . . you never take off more than is absolutely needed! Less is better.

[my2nd40]

Thanks for the replies. I know 030 is a lot, but I like playing with these old engines just to see what I can get away with. I will check all the clearances to make sure that things aren’t bumping into each other. Something happened to this old block sometime in the past. The best way I can describe it is it’s more like a dent in the deck maybe something fell on it, somebody hit it with a hammer I don’t know it’s a really pretty crack free block. If this works out, that’s great, if not, it’s a good garage Art.

[tubman]

As shown in my post above, you can sometimes solve these problems with unorthodox methods. It sounds like some head modifications may be in your future.

Good luck with it.

[Ronnieroadster]

Originally Posted by my2nd40

Thanks for the replies. I know 030 is a lot, but I like playing with these old engines just to see what I can get away with. I will check all the clearances to make sure that things aren’t bumping into each other. Something happened to this old block sometime in the past. The best way I can describe it is it’s more like a dent in the deck maybe something fell on it, somebody hit it with a hammer I don’t know it’s a really pretty crack free block. If this works out, that’s great, if not, it’s a good garage Art.

If your reason to remove so much is due to the dent this would work. Use JB Weld Epoxy to fill the low area. Then by using a straight edge drwan across the epoxy you can easily fill and level the low spot.

I know from experience the epoxy will hold up extremally well. Set many very fast records at Bonneville using epoxy on the decks of my very fast Ford flatheads. Also used epoxy to repair head deck surfaces as well. The material holds up perfectly.


Ronnieroadster

[Pete]

Originally Posted by my2nd40

I cut the deck on my old 59ab .030 to make it flat again. What do you think?

No matter how much you take off the deck, within reason and .030 is pushing the edge of reason, there are some things that ABSOLUTELY should be observed.
All measuring should be done in reference to the centerline of the crank.
The mainline should be checked first for being good.
The two decks should be 90 degrees apart.
Both decks should be the same height end to end.
Both decks should be corner to corner the same height.

Not all machines for surfacing decks set the block up on the mainline.