Need Advice On Solid Roller Cam Selection
12-10-2001, 10:01 AM
#1
Instructor
Thread Starter
Need Advice On Solid Roller Cam Selection
I"M building a 355 small block for drag racing only (no street use). The car weighs about 2300 lbs., 12 to 1 compression, Ported 461 big valve heads, 4.56 gears turbo 400. victor jr. w/ 750 holley. Since I have a cast crank I'll be shifting at 65oo rpm.I called three different cam mfgrs. and their recomendation s vary. Please let me know what you think.
Mfgr. Dur. @ .050 LIFT Lobe sep. rpm range
Crane 242-250 580-600 106 3500-7000
Lunati 254-259 622-618 106 4000-7000
Comp 260-264 660-630 106 4000-7000
Any and all suggestions welcome. Thanks
Mfgr. Dur. @ .050 LIFT Lobe sep. rpm range
Crane 242-250 580-600 106 3500-7000
Lunati 254-259 622-618 106 4000-7000
Comp 260-264 660-630 106 4000-7000
Any and all suggestions welcome. Thanks
12-10-2001, 10:03 AM
#2
Instructor
Thread Starter
Re: Need Advice On Solid Roller Cam Selection (Cruz 86)
Ishould also mention that it's got a 9 inch torque converter with a stall speed of 4000to4400 rpm.
12-10-2001, 12:26 PM
#3
Race Director
Re: Need Advice On Solid Roller Cam Selection (Cruz 86)
Well, the Crane is definetely too small.
The problem is that cast crank. All the other stuff is built for atleast 7k rpm, probably 7500. If you go with a small cam and a 6500 limit, it will slow it down as the heads, gears, and induction is all meant to rev higher. I would think you will hit the revlimiter before the end of the 1/4 mile.
I would replace that crank with a good forged one and go with the Comp 260/264.
The problem is that cast crank. All the other stuff is built for atleast 7k rpm, probably 7500. If you go with a small cam and a 6500 limit, it will slow it down as the heads, gears, and induction is all meant to rev higher. I would think you will hit the revlimiter before the end of the 1/4 mile.
I would replace that crank with a good forged one and go with the Comp 260/264.
12-10-2001, 01:06 PM
#4
Team Owner
Re: Need Advice On Solid Roller Cam Selection (Cruz 86)
I don't use cast cranks. If your going to spend all this money for 12 c/r balancing and solid roller cam. Why would you take a chance on throwing it all in the dumpster. I've had to throw nice motors in the dumpster, but I did everything I could with the amount of money I had to make them last.
If you want a 355 to go fast your going to have to spin lots of rpm. Or you can build a stroker motor and go just as fast with something that will last longer because of less rpm to make the same amount of power.
When your building a motor the higher the compression the bigger the bang. They are just hard on barrings and rods. If your going to make a race car why stop at 12 c/r I have ran 13.8 and 15 to one in 355's
Out of the above cam I would go with the crane. Much more lift than that you have to start thinking about .100 longer valve stems and retainers to set the installed height above 1.900. Even ported with 2.055 /1.6 valves your heads have flow limitations do to the small cc of the ports. things have come a long way in 30 years. Any cam this size is going to require big dual springs in the 190 lbs class 1.46 or 1.55 dia with 7/16 screw in studs and stud girdle.
When Crane rates a cam to 3500 - 7000 it doesn't mean that it shuts down at 7000. It's more of an indication that you past peak hp. So lets just say you have 485 at 6500 and 460 at 7000 and 410 at 7500
If you want a 355 to go fast your going to have to spin lots of rpm. Or you can build a stroker motor and go just as fast with something that will last longer because of less rpm to make the same amount of power.
When your building a motor the higher the compression the bigger the bang. They are just hard on barrings and rods. If your going to make a race car why stop at 12 c/r I have ran 13.8 and 15 to one in 355's
Out of the above cam I would go with the crane. Much more lift than that you have to start thinking about .100 longer valve stems and retainers to set the installed height above 1.900. Even ported with 2.055 /1.6 valves your heads have flow limitations do to the small cc of the ports. things have come a long way in 30 years. Any cam this size is going to require big dual springs in the 190 lbs class 1.46 or 1.55 dia with 7/16 screw in studs and stud girdle.
When Crane rates a cam to 3500 - 7000 it doesn't mean that it shuts down at 7000. It's more of an indication that you past peak hp. So lets just say you have 485 at 6500 and 460 at 7000 and 410 at 7500