KB pistons, installed backwards?

[PolloLoco]

This has bugged me for two years since I built my stroker. The blue instruction sheet that came with the pistons contradicted the forward facing arrow stamped on the pistons. I installed them with the arrow facing forward. I trusted the stamp for my application-specific piston more than the everyone-gets-one sheet of instructions.

What happens if I install the pistons backwards so that the D is facing the wrong direction?

[IH 392]

Your quench goes to hell and if they have an offset wrist pin they may be a little noisier, you'd have to have a TON of valve lift before the valves even start to get to close to the piston.

[SilverXJ]

I believe the sheet was wrong. Do you recall which side the quench pad was on?

[PolloLoco]

I'm not worried about the valves hitting the piston, I'm just worried about proper air/fuel mixture. The KB945 has a very shallow dish. Is the quench pad the straight part of the D?

[amcinstaller]

yea, the D is the dish, and the flat part beside the dish is the quench pad

[PolloLoco]

I believe the sheet was wrong. Do you recall which side the quench pad was on?

I think that I put the quench pad on the camshaft side. Either way I put the arrows facing forward. When I ordered my pistons from Summit I paid for six and received eight so when I get home from training on Wednesday I will check my "spare" pistons to see how they would have been installed.

[SilverXJ]

If you put the larger flat spot on the cam side you put them in back wards. The larger flat spot goes on the manifold side to meet up with the flat in the head.

[PolloLoco]

I looked at my two spare pistons and they did not have arrows on them, that's when I worried more. After building the stroker I packed everything up just before the Army moved me and I threw every piece of paper related to the stroker in one folder (I fired it up for the first time and broke in the cam at 1PM the day before the movers came). I pulled out the Piston Orientation sheet and it shows to install the quench pad towards the cam. I know for a fact that I did exactly the opposite of the instruction sheet. I can finally put my mind to rest and know that I did it right. Now that the Army has moved me twice since I built the stroker I can tally up all my receipts and contribute to the "How much are you going or did you spend on your stroker?" thread.

[amcinstaller]

so you put them in like this guy did?
http://www.jeepstrokers.com/forum/viewt ... ?f=8&t=411

[SilverXJ]

That is the correct way to install them. Some of the KB instructions are incorrect. Another thing to watch out for is the oil hole in the big end of the rod, if you are concerned/using this hole. IIRC that should point to the cam side.

[amcinstaller]

yes, it does but that assumes that the engine builder/machinist noticed that too and put the piston on the rod the right way. they should have though, but id check anyway.