Ray Finkle

I am in the middle of building a mild LQ4. Brand new crank, Stock floating rods, mildish cam with some 799 heads. If it makes 450hp, i'll be thrilled.

I am needing advice on pistons. Going to be mainly a daily driver, so i'd like to stick with cast pistons. Block is being bored .030" over.

These are the pistons I am looking at, and they appear to have the correct pin diameter for stock rods. Does anybody have any experience with these? Or can a vendor here set me up with a proper set of piston that will fit my build.

With the .058" deep dish and the 799 heads slightly milled with stock gaskets, I am figuring 10.3:1 compression.

http://www.ebay.com/itm/301971410196?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

stock48

iTrader: (16)

Should be ok but but one thing I hate about rebuilder pistons is they put piston a little down in hole. The stock piston is around 1.340'' Compression height.

Ray Finkle

Do you have any recommendations to a better suited set of pistons?

Sounds like I'll be gaining almost 2cc more with the compression height, lowering my compression. Trying to keep this around 10.5:1. I guess the block could be decked.

Ray Finkle

If my math is correct (someone correct me if I'm wrong please).....

4.030" bore
3.622" stroke
1.328" compression height
.058" deep dish piston (stock is .050"??)
.051" head gasket
.020" milled off 799 heads (roughly 61cc)

Should net me between 10.22-10.32:1 compression. I would rather deck the heads than the block.

Ray Finkle

Or for the easiest route...

Use flat top pistons and leave the 799 heads unmilled. Will I have PTV issues with a TSP224R cam? 224/224, .600/.600 112 LSA.

1FastBrick

iTrader: (17)

Get an LQ9 or LS2 flat top piston and leave the 799 chambers alone. Minimal mill if needed for clean up.

Ray Finkle

This is what I idealy want to do and the easiest route. Will I have PTV clearance issues with this cam? If I'm good, consider it a done deal.

1FastBrick

iTrader: (17)

You realize if you mill the heads you bring the valves closer to the piston even with a dish in there?

The only way to know for sure would be to measure it on your set up. Even blocks can vary depending on core shift.

I don't see why it wouldnt fit based on what others have run in the past.

Ray Finkle

I understand, I wasn't aware or not if the dish in the piston added a "buffer zone" for PTV clearance. But it sounds like it doesn't.

gagliano7

Flat top and dish will have the same ptv. That cam is on the small side so your ptv should be fine but i would measure just to be safe. If you are changing pistons get some valve relief pistons and then you will have no worries.