Help Identify these pistons

[Farmer]

I pulled my L16 head off my race engine and this is what I found.  I remember hearing something from the last owner talking about using some other piston from a foreign car. MGB or something like that. Domed with valve reliefs.  Definitely have to use an open chamber head.

 

[datzenmike]

Here is an after market L28 domed piston...

 

I think skib had a set a long time ago but I can't find my picture of it. I think it had the valve reliefs like that too.

[Colbino]

My pistons look exactly like yours and are 87mm Venolia pistons. With the pan off you should be able to look up into the block under the piston for a brand - at least that's were I found mine.

[Dime Dave]

Those are a typical domed race piston. Could be one of many manufacturers (Venolia, Wiseco, JE Piston, Arias).  These do not fit with closed chamber stock heads. The spark plug side of the chamber needs to be opened up to the cylinder bore to clear the dome.

 

This is a stock 219 SSS head (you can see the flat area of the head inside of the cylinder wall/gasket edge that the domed piston will hit)

 

This area needs to be removed for the piston to clear the head. The open chamber may have enough room to clear the dome, but you will need to check before assembling the head to the block.

 

Here is a race head with the spark plug side of the head opened up to the cylinder wall line for domed piston clearance.

[Dime Dave]

This is a custom Wiseco 86mm domed piston in an L18 engine I built.

 

[Stoffregen Motorsports]

I am amazed every time I see a "race engine" with unmodified custom pistons installed. They come out of the box with lots of sharp edges that can aid in detonation. I usually smooth out the dome with a flap wheel or a cartridge roll on a porting tool. Also, the area that will hit the head can be cut down on a lathe to help with piston to head clearance. This doesn't typically need to be done on small bore (L16) pistons, but on the bigger bore L motors it is a must. And yse, the chamber usually needs to be relieved as well.

 

I have a few old pistons in the shop I will post some pics of so you guys can see what I'm talking about.

[Stoffregen Motorsports]

Here are some pics. First pic is of random pile of pistons. The next 4 illustrate how one piston design can be reshaped to suit a specific requirement. Sometimes you reshape them for fitment issues, sometimes to lower compression, sometimes (always) to better aid in combustion.

 

Here's random.

 

These are 3 L series pistons. One is a JE, one is a Wiseco and one is a Cosworth, but they all had identical dome shapes when new.

 

Here is an uncut piston. Actually it has been valve clearanced, but otherwise is straight out of the box.

 

Next is a gently massaged piston. Notice the edge taken off the apex of the dome and the slight unshrouding (or radiusing) of the valve reliefs. Also notice the ring cut around the dome to fit inside a combustion chamber of a cylinder head.

 

Last is a highly massaged dome with the valve reliefs completely radiused back. Also notice the spark plug side, how a good portion of it was cut to fit inside the comustion chamber.

[Stoffregen Motorsports]

Hey Farmer, did you ever figure it out?

 

Also, I'm curious what kind of racing the motor is for.

[Farmer]

Hey Farmer, did you ever figure it out?

 

Also, I'm curious what kind of racing the motor is for.

 The motor was from an early'80  build ( not mine)  and was in my last truck I  bought.   Trucks gone  and had this motor  for a couple of years.  Tried to sell it  awhile ago.  I  was curious, So I remove the head  to  sell ( sold)   to check out what  piston  were used.  And  that why I  ask about the pistols.  The head that came off it  was a A87  open chamber  with a ricer brown cam (.475 lift)