Where to get Pistons

[abelincoln]

I think Tom was right, the Egge V-12 pistons hit the roof of the cylinder head chamber.  No, 3 has a mark on the swirl ridge in chamber, see below.  So What to do?

1. Who makes pistons that are not Egge?

2. Would it be advisable to cut top of pistons?

3. I hate to touch the Hogan heads, but one could machine or even die grind the swirl ridge?

4. Might thicker head gaskets be available?

 

I suppose one should make a trial fit with some play-do, grease, or foil on top of the piston, but the aluminum heads are difficult to get on and out, and the head studs are stuck really good.

Thanks

Abe

[Ray500]

Try Earle Brown listed on the club website for engine parts.  With all the aftermarket parts out there, mostly old one never knows.  I would think the mechanic doing the rebuilding would check the clearances of the pistons. And when you're over-boring and using larger pistons I think most bets are off as to the outcome.   You could shave them off, but you might upset the balance of the engine.  In race engines they balance every moving part, I doubt over the counter parts are balanced.  A quality machine shop should be able to rebuild the engine properly.  Good Luck!   

[19tom40]

Can you post a photo of the pistons at TDC? I will look for the photos that I took, I might still have them. I would use clay the check the clearance, it would be a lot easier than fitting new pistons.

 

Grinding the top of the pistons is not a good idea. The best way to do it would be in a lathe, and then I would only do it if I could not get new pistons.

 

Did you check the valve guide keepers (horseshoe clips) to make sure that they are in the guide groove and seated?

 

Edited May 11, 2020 by 19tom40 (see edit history)

[abelincoln]

Piston no. 3 shown below.  Seems that edge comes slightly above desk.  Valve guide clips seem firmly in place.  I had trouble earlier with keepers falling out when I went to adjust valves, and they now seem to go up and down without drama when engine is turned with the starter.  I suppose if one piston hits, the rest must be close.

Thanks

[W_Higgins]

I ran into a similar issue on the rebuild of an EV8 Ford.  New OEM style aluminum cylinder heads were used.  A couple of years later it had an issue that necessitated removing the heads and skim cutting 0.010 off to make them flat again.  I got them both on, fired it up, and it clattered horribly.  In my case the valves were spanking the inside of the combustion chambers.  Fortunately, not enough to bend them, but pretty consistent on both sides.  In that case it turned out the combustion chambers of the new heads were shallow and the rebuild shop took it for granted they were correct because they were new (huge mistake!).  At any rate, in that case the solution was to have cylinder head spacer shims cut.  When you find a place that offers the service, if they don't have a program on file to cut what you need, you supply them with good correct head gaskets to use as a template.  Since the only other option was to recut the combustion chambers, the labor would have been tremendous compared to using the shims.  They aren't visible once installed and have been in use several years now.

 

You have a lot to measure to determine where the fault truly lies.  The combustion chamber is the easy one if you have an original uncut head to compare, otherwise the block deck could have been heavily cut at some point, wrist pin placement is wrong, or maybe something else.  Investigate the shim option and see if it's right for you.  Good luck!

[19tom40]

 

That piston doesn't look like it has been hitting the head, but the final check would be to put a thin layer of clay in the top of the piston, replace and torque the head, turn the engine over with the starter and ignition off. Remove the head and measure the thickness of the clay at points across the piston.

 

The clips can seem firmly in place even when they are not in the groove of the guide. Use a mirror to see that they are all in the groove of the guide. Crank the engine over with the starter and watch the guides to see if any of them move.

[abelincoln]

Thanks guys, here is the plan.  I contacted H&H flatheads who can have Ross make some pistons for the Lincoln V-12, but they are quite costly.  A second e-mail from H&H noted that the Hogan NZ heads do not have polished chambers, so I should feel free to grind in the offending area.  This sounds good to me.  Closer inspection finds a few casting flashings in the the chambers, so I plan to de-burr and polish with increasingly fine sand paper.  Mean time, we'll pull the pan.  I've got a Moroso dip stick that needs a welded bung, in the lower pan and I suspect the rear main oil drain pipe is loose, leading to low oil pressure.  With any luck, will be running again by end of summer.

Abe

[19tom40]

I made a big mistake in my previous post, when using clay to check the clearances, you should turn the engine over by hand, turning it over with the starter could cause more damage.

 

The correct way is to put a thin layer of clay (3/16"-1/4') on the top of the piston and turn the engine over until the piston is on it's way up. Oil or grease the combustion chamber so the clay does not stick to the head. Install the old gasket and head. Tighten the head nuts enough to make sure that the head will not lift up during the test, and then turn the engine over by hand for 1 complete turn or until you feel the resistance caused by the clay compressing. Remove the head and measure the thickness of the clay.

[W_Higgins]

Silly Putty is a less messy / more user friendly option than clay.

 

Turning over by hand can still be risky with the head tightened down if interference is suspected, particularly if the periphery of a valve head it catching on the edge of a wall.  Personally, I think it's best to run things up and press the head down by hand, or add springs so the head can lift if hard interference is encountered.  When all is said and done it ought to be able to go around with minimal clearance with no head gasket so that when things are assembled you are in the safe zone and have some grace if you ever need the heads surfaced.    

[Ken/Alabama]

16 hours ago, abelincoln said:

Thanks guys, here is the plan.  I contacted H&H flatheads who can have Ross make some pistons for the Lincoln V-12, but they are quite costly.  A second e-mail from H&H noted that the Hogan NZ heads do not have polished chambers, so I should feel free to grind in the offending area.  This sounds good to me.  Closer inspection finds a few casting flashings in the the chambers, so I plan to de-burr and polish with increasingly fine sand paper.  Mean time, we'll pull the pan.  I've got a Moroso dip stick that needs a welded bung, in the lower pan and I suspect the rear main oil drain pipe is loose, leading to low oil pressure.  With any luck, will be running again by end of summer.

Abe

So how does the rear main drain pipe affect oil pressure??  My 1940 V8 doesn’t even have one