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PROBE FORGED PISTONS & RINGS 4.040 BORE SIZE FOR SBC 383 ENGINES, -12cc RD DISH TOP FOR USE WITH 5.7. BUSHED OR PRESS FIT RODS. .040 OVER
Our PROBE Forged pistons are custom designed with an increase in compression height. This has many advantages. Here are a few facts about compression height and deck height.
Our custom made Probe pistons have a compression height that is .015 taller than nearly all catalog pistons on the market. We find this to be a very valuable feature. Since our pistons sit at a taller than normal compression height, you will only have to remove approx. .010 off the deck surface of a virgin block to achieve a zero deck. This also allows for future deck re-surfacing and still not ending too far below stock deck height.
Leaving the deck on your block thick makes for a stronger block that resists flexing and also runs cooler, as the deck thickness has a lot to do with the dissipation of heat. Blocks with decks cut down to any great amount are also prone to cracking. This is why our pistons are designed to sit flush, (zero deck) at .010 below stock deck height.
Since nearly all catalog pistons on the market sit .025 below the surface of a virgin block, the only way to achieve a zero deck using such pistons would be to cut .025 off the deck surface. This compromises the integrity of the block, in our opinion. Should you decide to leave the block deck higher up, using such pistons creates a new issue of having a very poor quench/squish zone. The only way you could really take advantage of a catalog piston is by having a block that needs to or has already been butchered down to 9.00 deck height. At that point, we don't think you should not use such a block. Having the piston sitting flush with the deck is very desirable, regardless of the fact that your overall compression ratio is slightly higher than if it were sitting below the deck.
We have found that 95% of our customers are using a virgin block or a block that is close to stock deck height. This is why we have designed our pistons to have a taller compression height. On very rare occasions, you may end up with a block that has the piston out of the hole by a few thousandths and this not a problem at all. Most head gaskets are approx. .040 thick, and should you end up with a quench zone of .035, then that is perfectly ok. If the quench zone ends up too far below .035, then there are plenty of .050 thick head gaskets on the market. One more benefit to this is that most machine shops charge much more to deck a block down from stock deck height to 9.00 than they would to do a light cleanup, and that's all that's needed when using our Probe pistons.
Another good feature about our pistons having a taller compression height is that the ring land above the top ring is much stronger by being .015 thicker. When pistons encounter the effects of detonation, it is not uncommon to see pistons with the ring land above the top ring broken off. The thicker ring land also makes a better heat sink.
Our custom made Probe forged pistons are made from 2618 aircraft alloy. We find this alloy to be much more suitable for high performance engines than the common 4032 forged alloy. You will usually see the higher end pistons on the market using 2618 aircraft alloy.
Why go with 2618 forged pistons? If you encounter certain tuning issues, detonation is highly probable, and its effects can cause severe damage to your engine. The 2618 forged piston is able to withstand the damaging effects from detonation to a higher degree than the lower cost 4032 forged pistons, especially non-forged hypereutectic pistons such as Speed Pro or Keith Black, and many others.
Our Probe forged pistons will clear most any valve size on the market with ease even with the use of large lift cams.
These pistons are also suitable for use with nitrous systems up to approx. 250hp and superchargers up to approx. 15 to 17lb.s of boost. For the slight increase in cost, this is the best value on the market.
PROBE FULLY FORGED REVERSE DOME DISH TOP PISTONS RATED AT 700+ HP. THIS SALE IS FOR A FULL SET OF PISTONS AND RINGS. PROBE PISTONS ARE 100% MANUFACTURED IN THE USA. THEY ARE ONE OF THE HIGHEST RATED PISTONS IN THE COUNTRY.
These pistons are for use with full floating bushed rods, or press fit. The compression height is 1.440 2 valve reliefs. Ring groove size 5/64 5/64 3/16. File fit Rings included. See full piston specs below.
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