Which Pistons Do I Have?

[choco 0]

Hi guys,

 

My car blew it's headgasket, so with the head of i was curious about the question that was bugging me for a while now. The guy that sold me the engine said it was a rebuild D6C engine, but it has a DFW plate on it. The only way to find out (i thought) is to look at the letter X or Z stamped in the piston. But mine don't have any, the only thing it has stamped in it is "distr" with an arrow (to tell which way the piston should turn i guess) and the size, 82.97 and 0.03 jeu (which means play in french i guess). Thats it. Is there any way to tell if they are D6C or DFW pistons?

 

Many thanks in advance,

 

Johnny

[welshpug 1,627]

The DFW plate would indicate that it is the lower compression engine, though if it has had new pistons of the correct type then it would be the same as a D6C in essence.

 

how far from Deck height do they sit? the DFW pistons are shorter.

 

 

 

I have a set of what I believe to be D6C pistons and they are marked "A" for size and have a circled "Z"

Edited March 3, 2010 by welshpug

[choco 0]

The pistons are in the locked position right now, don't want to risk the liners moving, so that's kinda hard to measure...

[welshpug 1,627]

subtract half the stroke from the measurement

 

or clamp the liners in place.

Edited March 3, 2010 by welshpug

[choco 0]

I'll do that, first thing when it gets light tomorrow. How much should the difference be? (BTW, the set you have is D6C, because of the stamped Z. I have a spare set at home with a X, those are DFW)

The reason i want to know is because i have a catcam, but it feels kinda tame, with or without the cam. Maybe of the low compression, timing should be ok. Thinking of investing in a pair of Wossner high compression pistons, if my pistons turn out to be DFW ones.

[welshpug 1,627]

Have you checked the cam timing?

[Miles 331 1 Cars]

Are the piston's, Flat toped, Flat Dished, or a dish with a slope in them?

[choco 0]

They are flat, with cuts in them for the valves. I didn't move them, but the discoloured edge at the top of the liners is 7.5mm, so i guess this is the distance from the pistons to the top of the liners.

[petert 555]

the only thing it has stamped in it is "distr" with an arrow (to tell which way the piston should turn i guess) and the size, 82.97 and 0.03 jeu (which means play in french i guess). Thats it.

 

They must be aftermarket then and most likely a D6C replacement.

 

With the piston at TDC, why can't you measure the deck clearance?

[choco 0]

They must be aftermarket then and most likely a D6C replacement.

 

With the piston at TDC, why can't you measure the deck clearance?

 

the pistons are still locked, i'm really afraid to disturb the liners, am in holland now but have to drive back to denmark in two days. But the 7.5mm, isn't that an indication of deck clearance? Guess that marking shows where the pistons is at it's highest?

[welshpug 1,627]

why are you afraid to disturb the liners? I would personally replace the liner seals whenever I remove the head

 

not a problem if you clamp them down, easy to do with some spacers and the head bolts.

[choco 0]

Can i do that with just the head off? Or should i remove the sump, oilpump etc?

[welshpug 1,627]

you would need to remove the sump to undo the big end nuts and pull the liners out, I would leave the pistons in the liners so save having to fit new rings.