spring pressure soild cams
- Thread starter lyonsy
- Start date
There are lots of variables on that one. The early grinds had a longer ramp with slower opening and closing rates. Those profiles used about the same pressure as hyd cams. Some of todays solids have very aggressive profiles that require very high rates. RPMs also change how much pressure you need.
Seat pressure keeps the valve from bouncing. Remember the old screen doors? When you ran out the door and let it slam, it would bounce, and you could hear one loud bang followed by two or three smaller bangs, then you would hear your mother say, "come back in here and close that door properly" If you installed a large enough spring on that door, it would only bang once, no bounce.
When you aproach the threshold of valve train stability you will start loosing power.
The early, milder, grinds will be around 80 to 110 lbs seat pressure, with early racing grinds being about 125 to 135lbs seat pressure.
I have installed some solids that required about 165lbs to 185lbs of seat pressure. this is what early rollers required. Most rollers now require about 225 to 265lbs seat pressure.
The open pressure works similarly, but it works at the other end of the lobe. It must keep the lifter from jumping off the backside of the lobe and crashing into the cam.
If you know the grind number, call the cam company and verify. If you are experiencing rpm related issues and strange valve train issues. (valve locks are shiney and appear to be moving around or wierd rocker problems like flat or broken rollers) You can up the pressure some and see if that helps settle it down.
Seat pressure keeps the valve from bouncing. Remember the old screen doors? When you ran out the door and let it slam, it would bounce, and you could hear one loud bang followed by two or three smaller bangs, then you would hear your mother say, "come back in here and close that door properly" If you installed a large enough spring on that door, it would only bang once, no bounce.
When you aproach the threshold of valve train stability you will start loosing power.
The early, milder, grinds will be around 80 to 110 lbs seat pressure, with early racing grinds being about 125 to 135lbs seat pressure.
I have installed some solids that required about 165lbs to 185lbs of seat pressure. this is what early rollers required. Most rollers now require about 225 to 265lbs seat pressure.
The open pressure works similarly, but it works at the other end of the lobe. It must keep the lifter from jumping off the backside of the lobe and crashing into the cam.
If you know the grind number, call the cam company and verify. If you are experiencing rpm related issues and strange valve train issues. (valve locks are shiney and appear to be moving around or wierd rocker problems like flat or broken rollers) You can up the pressure some and see if that helps settle it down.
ive been having drama with droping valves most after sustained time of high revs but the most recent was a new engine.
i have been running hydrolic and standerd rockers on the crossflow (think clevland rocker gear)
i think some problems are lifters pumping up and holding the valve open at rev up or above 5500 even using anti pump up lifters.
so iam looking at goin stainless valves incase its a heat problem along with rollers and soild lifters.
anything else you recomend doing apparently anther good thing is to leave a 1 thou grove in the lifter bore to help oil the cam works good.
i have been running hydrolic and standerd rockers on the crossflow (think clevland rocker gear)
i think some problems are lifters pumping up and holding the valve open at rev up or above 5500 even using anti pump up lifters.
so iam looking at goin stainless valves incase its a heat problem along with rollers and soild lifters.
anything else you recomend doing apparently anther good thing is to leave a 1 thou grove in the lifter bore to help oil the cam works good.
Statement of opinion coming!
The multi groove collets on clevelands and crossflows are designed not to be tight on the valve stem, this allows for rotation of the valve, unfortunately it seems to allow for stem breakage at higher rpm.
Also be warned that the valve spring retainers used on stock engines are sometimes sintered and not up to anything beyond stock use.
If you must use stock valves then gring the collets so they do not butt together on the stem and use aftermarkect retainers.
Stock rockers are OK up to a point, but are known to fail with heavy loads, the pushrod can be forced through the rocker arm.
If your serious, use stainless single groove valves with hard retainers and go the full screw in stud roller rocker route a la cleveland HO.
A7M
The multi groove collets on clevelands and crossflows are designed not to be tight on the valve stem, this allows for rotation of the valve, unfortunately it seems to allow for stem breakage at higher rpm.
Also be warned that the valve spring retainers used on stock engines are sometimes sintered and not up to anything beyond stock use.
If you must use stock valves then gring the collets so they do not butt together on the stem and use aftermarkect retainers.
Stock rockers are OK up to a point, but are known to fail with heavy loads, the pushrod can be forced through the rocker arm.
If your serious, use stainless single groove valves with hard retainers and go the full screw in stud roller rocker route a la cleveland HO.
A7M
