Egge Pistons and Aluminum Heads
 

Our 48 V-12 was assembled with Egge pistons and Hogan aluminum heads, resulting in a terrible knock. Upon removing heads and intake, notice a mark in no. three chamber where swirl casting likely meets domed piston. What to do:
1. Get new pistons, if so who makes 2 7/8" pistons, 0.060 over?
2. Modify piston, is so how?
3. Use two head gaskets? Maybe additional problems.
4. Other suggestions?


I understand grinding the swirl casting would not be recommended.

Re: Egge Pistons and Aluminum Heads
 

I'd first clean up the heads and check the dome shape of them as compared to the EGGE pistons. I've seen two distinctly different dome shapes on the V8 Flatheads - some of the cast pistons have very different more elliptical profiles than pistons like Ross - who have a consistent radius. Once you know if you have a chamber shape issue, then you can review your options. Just to bring up an issue - one should never assemble these engines with aftermarket heads/pistons without claying the chambers and seeing what clearances you have. The goal is to get to .040 to .050 over the pistons (with gaskets installed) - this gives the best performance. Given you already have the heads off, it would seem like the easiest solution is to modify the profiles in the head chambers. It would be easy to use a CNC milling machine to redo all of them with a chamber that works with your pistons - that would be my approach.

Re: Egge Pistons and Aluminum Heads
 

The above information is spot on except it need not be done on a CNC, could be done on a manually operated milling machine

Re: Egge Pistons and Aluminum Heads
 

Hi; I have measured pairs of heads that were miss-matched. different combustion chambers and/or different dome sizes from milling. I have a V12 head available for $10+shp dated '47 Lft side, OOPS! iron head Newc

Re: Egge Pistons and Aluminum Heads
 

I;ve used Egge oistons in most of mt builds ans never had a problem with them. However, that said, time to stat measuring.

Re: Egge Pistons and Aluminum Heads
 

If you can locate exactly where the pistons need modifying they could be modified on a lathe

It depends on your skill level and what you are confident to do.

Personally I'd just do what ever mods are needed to make it work myself.

On my roadster I took a small amount out of the chambers and a little bit off the pistons. But that's me and the heads are much more common.

I know what I'd do, but what I should advise you to do is more difficult.

A question, though. It has only made contact on one cylinder. It would be reasonable to assume the pistons are all the same. Therefore the heads need to be carefully measured to see if that chamber is different to the others. If it is different, then that one should be carefully clearanced to match the others.

The clearance can be checked with aluminium foil and grease.

In reality both the chambers and pistons would tolerate some careful trimming.

I would await the results of careful measuring before considering the best way to proceed.

Mart.

Re: Egge Pistons and Aluminum Heads
 

have the heads been decked? every time lately that I have used old aluminum heads there has been a problem because of decking, we have manually removed some dome from these heads with good results. make up a template of the piston dome and one of the heads and begin comparing. we did have one set of unknown origin pistons with different dome heights

Re: Egge Pistons and Aluminum Heads
 

And the rest could be almost touching, I'd check them all to prevent noise in the future.

Re: Egge Pistons and Aluminum Heads
 

Nearing the end of last year I installed a Lincoln v12 in a '39 L.Z Coupe. The engine is bored .060 over 2 7/8 and I used Egge pistons also Hogan heads. The pistons did not have the Ford dome, they were more angled to the top center. I told the manufacturer about this and they agreed. I don't think it would work if too much material was taken off stock heads. I purchased some Hogan heads unmachined and I machined them taking about 3/16 off casting surface. With a cutter using same piston profile, plunged to form that part of the combustion chamber. Clearance above piston with gasket is .053.

I think with those pistons, or the ones that I bought, may not work with stock heads. I will try to locate some pictures of the heads and send them tomorrow.

Re: Egge Pistons and Aluminum Heads
 

Hogen heads machined with proper clearance. Engine turns over fine but it hasn't been started yet. Good luck !

Re: Egge Pistons and Aluminum Heads
 

Note, what cdan34 is talking about is exactly the issue I have seen with some of the domes on certain Egge (and other)cast pistons - they are not a consistent radius, they are more of an elliptical arc sort of profile (and more pointed in the middle). Ford made some pistons like this as well. I made a 3D CAD model to match the profiles and used this to put a new set of Edelbrock heads in a CNC mill to "fix" them to match the pistons.

Re: Egge Pistons and Aluminum Heads
 

I turned the pointy domes off a set of French pistons in one of my recent videos. I'm a hack though, I used a lathe but with a big dreadnought file.

Re: Egge Pistons and Aluminum Heads
 

Beats a hand held disk grinder - have seen a few pistons that have been "pruned" via that method! LOL

Re: Egge Pistons and Aluminum Heads
 

Mart, your not a hack. Your smart and know how to innovate. You also realize you not trying to modify the Space Shuttle. You can still be reasonably accurate enough with your method.

Sal

Re: Egge Pistons and Aluminum Heads
 

Where did you find a cutter matching the piston profile?

Re: Egge Pistons and Aluminum Heads
 

Mt doming tool is mad from a piece of file welded to a shaft. THe radius was ground in a lathe in a fixture that held it at the proper radius. After the shape was determimed, the cutting edge was hand formed. I made this about 40 years ago, when a fellow builder showed me his. I don't think t eradius is critical in a streer engine as long as it's less tham the dome. This allows the outside edge of the piston to make a good quench area. I think the Ross piston comes with a 7" radius.

Re: Egge Pistons and Aluminum Heads
 

With the Bridgeport Mill there are different tool holders you can use. What I did is make templet using shim stock as profile from piston. Hand fit this to piston top. You've now got the piston template. You then hand grind a hss tool bit to template. Mount in your tool holder and your set to go. Pics are tool with Egge piston profile !