jester1614

iTrader: (13)

ok so i am starting to find parts for my build
build will be a high rpm 350 with forged pistons and rods and stock crank with a 242 242 572 572 112 cam with 1.5 rocker arms. heads will be stock castings porting is to be determined.

my question is

i found these pistons
http://www.summitracing.com/parts/TR...art=TRW-L2304F

on some scat 4340 5.7 inch forged rods for 150 and I thinking about getting them.

now using the specs from this site
http://www.camaroz28.com/forums/arch...p/t-52671.html
for stock head specs and deck clearance

and this compression calculator
http://www.kb-silvolite.com/calc.php?action=comp

I have come up with these pistons giving me a static compression ratio of about 12.1:1

are these calculations correct and is 12:1 compression too high for pump gas and thats with 54 cc cylinder heads every site i have found has an argument on the cc either 58 or 54 cc

i know that dynamic compression ratio is equally important and and i will update this thread with that as soon as i can find my cam car

the car is a 94 lt1 ta with a 3200 rpm stall built trans with a shift kit and 4.10 rear end gears. it will have long tubes and ported heads as well

jester1614

iTrader: (13)

anyone have any advice???

mrchyzy16

iTrader: (1)

Question for you. You say that you want to build a high rpm 350, but your only gonna use 1.5 rockers? Why is that? I would be using atleast 1.6 maybe even 1.7 depending on circumstances.

jester1614

iTrader: (13)

I have 2 different sets of 1.5 rockers already one for 3/8ths studs and one for 7/16ths studs that i will be using with guideplates. i might purchase 1.6 studs rocker arms later but that might necesitate different springs also.

jester1614

iTrader: (13)

any other input

RamAir95TA

iTrader: (2)

Sorry if my post comes off as rude, but that build has fail written all over it. To build a "high RPM 350" without at the very least boring the cylinders to ensure concentric cylinders is a mistake, IMO. Perhaps you could get away with it on a lower RPM street motor, but if you're going to be spinning this thing to the moon, it's foolish to not have it machined to clean up the cylinder walls.

To have chosen a cam already without knowing what kind of headwork you have goes against all ideology for what it takes to build a well-thought out purpose-built motor. IMO, it's WAY too big for a 350, ported heads or not. And why a 112 lobe? With your target RPM range, you'd want a wider LSA because you're obviously not going for torque with a 350.

Depending on the cam, using 1.5s would be a step backwards. Use a full-roller 7/16th stud 1.6 rocker.

Don't get so hung up on static compression. Since you likely don't know the valve events for that particularly bad choice of a cam, you don't even know your dynamic compression ratio, which is FAR more important than your static in determining the octane requirement for your motor. The good news is you understand that already.

I suggest you research what other people have done right since you are headed in the wrong direction.

jester1614

iTrader: (13)

ok now let me clarify i plan to spin the motor to probably 6700ish so i dont know if "to the moon" is the right phrase for this motor and this motor is gonna be a strip street machine

and with "Since you likely don't know the valve events for that particularly bad choice of a cam" i do have a cam card somewhere i just dont know where i put it.

and I am going to have the block fully checked out and in the end will be going with what the machinist says when it comes to the bore of the block. So it may end up being a 355 if it needs to be.

jaycenk

iTrader: (1)

6700 is not to the moon and it isn't that high BUT the cam determines when it's done making power not a the driver. You can spin a stock LT1 there with the right parts but it isn't gona make any power getting there. You should really start looking at heads and find someone like Lloyd Elliot or advanced induction to talk to about what head, cam and what intake work needs to be done and ask them what piston and rod to go with. Before you do any of that take the short or long block to a machinist and let him figure out what you have to work with. Have him inspect everything and see where your at. At the least you need a bore, align hone and size the crank for bearings and then you can do rods and pistons based on what the top end is going to look like. It sounds back wards but you really have to work from the top down to at least the pistons and if it requires a better set of rods or crank then you go all in.

jester1614

iTrader: (13)

now i am looking at 383 cranks with 3.75 stroke for 5.7 rods and I know i cant afford a 600 dollar forged crank but i can probably scrape together enough for a cast one. for 200-300 bucks the options are scat and eagle.

now iirc eagle cast cranks arent worth their weight in dog s#it so that leaves scat. are scat cranks any good.

looking at this one
http://www.summitracing.com/parts/SCA-935050L/

and lt1s are internally balanced correct

96AZHAWK

iTrader: (19)

let me know if you want me to get you a price on a scat crank locally, new.