which will give you better compression. hypertuetic flattop pistons or hyperteutic dishtop pistons.

Define "better".

Too many variables come into play.
1.) Deck height
2.) Compression height
3.) Gasket thickness
4.) Combustion chamber size and design
5.) Timing curve
6.) Camshaft
7.) And a whole lotta other things.

What are you looking to do exactly?

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350CID, Vortec 062 heads, Magnum 280, Performer Intake, Holley 650 DP, 3.42 rear w/ Auburn posi, 2600 Stall/TC
"Things are more like they are now than they ever were before."
Former U.S. President Dwight D. Eisenhower

im wanting to build a 350 for street. i want to put a compcams 274h extreme energy cam 487/490 lift 110 lobe seperation. the motor is gonna be mostly stock i was wanting to just boost the compression enough to run that cam without any problem. im gonna be using stock 350 heads with comp cams valve springs to match the cam and maybe 1.5 ratio rocker arms.im using stock crank and connecting rods. the main thing i was wanting to do is build a motor that can handle a larger cam.

get those jegs 1.5 extruded aluminum roller rockers (great deal for around $200). I suggest that because i killed a stock rocker arm with a similar cam and was lucky not to do bigtime damage.

Unless the heads are extremely low cc,you can probably use the flattops. Its all about the combo!

A true flat-top piston with a quench between .035" and ,045" along with the needed headgasket to create numbers like that with whatever your piston's "down-in-the-hole" dimension happens to be WITH a sized combustion chamber head to give you the compression ratio you want is the best for our motors!!

It is a flame-front thing where a small chamber and flat-tops creates the most eff. burn b/c the burn doesn't have to go over/around a domed piston that's needed to create CR with big chambered heads..

This is why they make 40 and 50 cc heads for real high compressioned REAL race motors that burn race gas.

pdq67

does anyone know the difference between 305 adn 350 heads ive got a set of both and i cant tell the difference. does the 350 heads have a larger cc or not. i thought the only difference was valve springs, but i don't know for sure.

Go to mortec.com with the casting numbers and the data there will tell you the differences.

Usually, the 305 heads have a smaller chamber on them somewhere around 55 CC which could help raise the compression a little BUT the down side is that they usually have smaller runners (intake & exhaust), thin castings, along with small valve too. Without a ton of porting and having bigger valves installed, they usually aren't worth spending money on.

305HO, -601 and -416 heads are pretty darn good for smaller motors, imho..

pdq67

the motor is not going to be a race motor, i was just wanting good performance for street use. im probably going to put performance heads on later but for now i'll use stock.

Go with a flat top then and choose the head to make the compression you need.

There are 'D' dish pistons that keep most of the quench adavantage of flattops out there if your heads are a tad too small to live with flats.

a full dish like the old SB400 motors had isnt that great, kills quench. Domes have problems too as mentioned above.

i was wanting to use 350 heads, what would i have to do to them to get the kind of compression im looking for around 9.25:1. and how much will it cost