flat topped pistons vs dished on 60 bore and gas effect

[frost1085]

ok my engine is gettin bored over 60 not by choice though, lol im trying to decide if i should get domed or flat topped pistons. and will the 60 over bore make me have to use a higher grade of gas and or will the flat topped piston do that also thanks in advance

chevy 350

 

[80malibucoup]

What are the specs on the heads your gonna run? The higher the compression ratio the higher the fuel grade,keep that in mind.

 

[frost1085]

What are the specs on the heads your gonna run? The higher the compression ratio the higher the fuel grade,keep that in mind.

all i no is that they are 193 swirl port heads been ported and polished

 

[80malibucoup]

You really need to find out before you put the pistons in.

 

[SSedan64]

Going from 4.00" Bore 350ci to 4.060" Bore 360ci. will raise the Cr. about .25 or 1/4 Point Cr.
You will probably be fine.
4.00" Bore X 3.48" Stroke.
64cc Head, .041" Gasket.
0 Deck Ht., 7cc 4VR Piston = 10.02Cr
With 4.060" Bore = 10.26Cr.

 

[frost1085]

ok, i do have my block back from the shop, and there is a small chip at the end of the cylinder wall, will this be ok since its at the very bottom what do yall think and thanks for all the help,

 

[frost1085]

last pix

 

[Doober]

193 heads are 64cc. They aren't the best for upper RPM but they make good down low torque... best guess is without pro port work they're only good for 350hp tops, and that's with home porting. Personally I'd stay under 10:1 and stick with as close to about .040-.045" quench as possible. What are your plans for the engine/car? Do you have pictures of the port work on the heads? I have a set I did a little bowl work on and i'm interested in what was done to them. Could you get info from the person who did the work (expected HP potential, etc.)?

 

[bracketchev1221]

Go with the flat top pistons. A flat top, small chamber head is more efficient than a large chamber big dome setup. The chip is not an issue, if it does not go into the water jacket. Maybe, see is you can get a dremel tool in there and smooth out any sharp edges on it to stop any crack formations.

 

[frost1085]

193 heads are 64cc. They aren't the best for upper RPM but they make good down low torque... best guess is without pro port work they're only good for 350hp tops, and that's with home porting. Personally I'd stay under 10:1 and stick with as close to about .040-.045" quench as possible. What are your plans for the engine/car? Do you have pictures of the port work on the heads? I have a set I did a little bowl work on and i'm interested in what was done to them. Could you get info from the person who did the work (expected HP potential, etc.)?

ill deffinatly try and get that info for you, im not sure myself if they were ported i was just told they were, but was also told the engine was already bored 40 over but in deed was worn and never bored with a bent valve guide. i got the engine from a friend who got played on his engine job and also on a transmission job, so when i got the car i had to swap transmissions, we actually went and got the bad transmission together from the guy and it burned out the same weaki drove the car acouple times around the block and the next time it stopped going foward, it was hard drivin either. so ill ask him and see what he says, but in the mean time ill clean the ports up and take a pix of them.and maybe u can lmk if they we actually done, ill take one with and with out a gasket, and 60 over is what i had to go with