I'd like to install a Z head on my 24 touring. I just pulled the stock head off and measured the amount of piston pop-up. With a straight edge across the top of the piston, I measured the height above the deck. It was about .375" Is this enough clearance for the Z head?
Probably, but put the head on the block with no gasket. Use a couple of bolts just to hold it in place. Hand crank the engine to see it it hits the head. That is the way you will know for sure if there is enough clearance!
those are standard ford pistons, they all pop up like that.
Pistons hit on this install of a 'Z'. Approx .040 pop up.
A bit of grinding away in the head in a few spots got the fit right. Prussian Blue helped to check the hit spots.
really!? wow. thats surpising.
Not too surprising.
The high compression 'Z' head has a very tiny squish area over the piston. That is why you always check as Jack posted! Check with gasket off, and if no bumping, you are ok with a gasket.
My posted pics showed the spots that were bumping without a gasket....!! Tight! But very nice compression and great performance.
Stock iron and'Z' head combustion chambers.
Results with the 'Z' head
Dan - what tools did you use to grind the head for clearance?
Elec die grinder with a stone burr.
Thanks Dan. I was concerned with the amount of pop-up, but yours looks about the same. I can deal with a little grinding.
Check each cylinder with Playdough. Roll it out like pie dough, lay it over the piston and trim. Bolt the head with gasket on the block and turn the crank a couple of times. Measure the thin spots. And remember, though it looks and smells good, do not eat the Playdough.
Bob - thanks that sounds like a good idea. My son works at Toys 'R Us, I'll have him pick some up. What's wrong with a little taste? Seems to me I at my fair share as a little kid. Hmmm, maybe that explains some things...
I had the same exercise as Dan T. Mine was only on #1 cylinder.
On mine it was 1 and 4, found a four inch side grinder with the layup sanding discs worked well to clean up the clearance. 40 thou works fine with the head gasket in.
Used an old head gasket to test.
I'm not sure using Playdough instead of clay is a good idea. Many many years ago we checked the valve to piston clearance on a modified Olds engine using Playdough. When the engine was assembled and started we had some issues with valve to piston clearance. The feeling was that the Playdough maybe somewhat resilient and gave us false readings, subsequent checks were made with clay.
I like to use little balls of aluminum foil.
Much easier than clay.
plasticene works well, its cheap, and easily applied and removed, when you shave both the head and block and install hi dome pistons, its a great guage to know exactly how far you can go.
all kids have a bunch of grey ( was multi colored plasticene in an old icecream container ).