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What seat pressure and spring rate should I use on a 0.440" lobe solid roller cam?
steve25
10-13-2010, 02:35 PM
320 if use is under 7500, if over that than 350 to 360.
Max rpm will be 6500. I was thinking 220-240 seat and something with 550-650lb/in spring rate.
Steve C.
10-14-2010, 10:36 AM
Valvetrain weight might be taken into consideration. Differance in controling 6.200" long by 2.200" valve verses 5.300" long by 2.110" valve, 5/16 pushrods vs 3/8 pushrods, etc. Also the rocker ratio would play a part.
Valves are 5.275" long, 2.11x1.77", plan on using 3/8" pushrods and 1.5 rockers (E heads). I was thinking Comp 999 springs for my installed height, around 1.88".
Ron H
10-14-2010, 12:48 PM
Ask the cam company what springs they recommend. 260 on the seat is what most want minimum on a solid roller cam.
Skip Fix
10-14-2010, 12:58 PM
"I was thinking 220-240 seat and something with 550-650lb/in spring rate."
What most cam companies have told me for "average" cams. Now as Steve C. said heavier valves, higher rpm more aggressive lobes will need more. So double check on the particular lobe you are going to run.
Thanks for the replies. I'll check with cam co.
Probird
10-14-2010, 10:55 PM
Mine are set up at 230 lbs. on the seat with a .440" cam at a 1.95 IH.
steve25
10-15-2010, 07:51 AM
If you are revin to 6500 you need to spring for 7500.
2.19" intake valves really need more like 300 on the seat, but if you are running a 2.11 valve size I would still shoot for 260 untill you get some time on the motor and see how much pressure the drop off from the time of install.
Steve C.
10-15-2010, 10:34 AM
Hot Rod featured a Pontiac 505cid with 4.375" bore x 4.210" stroke, 742 hp at 6,200-6,400 rpm.
Cylinder heads were Edelbrock, with Manley 5.350" long x 2.180"/1.750" diameter valves. Pushrods were 9.150-inch-long 0.080-wall. T&D shaft rockers with 1.65 ratio on both intake and exhaust.
Cam was a Comp solid roller, lobes 4253 and 4214 with 276/284 at .050", 0.4400" lobe lift on both intake and exhaust, 110 LS / 107 ICL.
Theoretical lift at zero lash: 0.726"/0.726".
Valvespring installed height was 1.950-inch with Comp 26099 springs and 733 retainers.
So that's around 300# seat pressure. Looks like I should run somewhere between 240-300# seat pressure.
Ron H
10-15-2010, 01:54 PM
What did the cam company say?