100# SEAT PRESSURE ON ROLLER CAM

[cgarb]

So pulling the lifters to check the rollers was a major ordeal then. Kind of neat to see where a design started and where it evolves to.

[vwchuck]

I call bullshit. There is no way you can control with only 100lbs on the seat at 9500RPM... No way. Even if everything is titanium it isn't enough.

[Warp Speed]

I call bullshit. There is no way you can control with only 100lbs on the seat at 9500RPM... No way. Even if everything is titanium it isn't enough.

You need to get out more!

[kimosabi]

Cup engine valvetrains are scienced out pretty good. I assume very light valve side parts with a rock solid lifter side. No cheap stuff. They run shaft rockers?

[midnightbluS10]

how many remember the 1/4" X 1/4" steel bar that went into the lifter oil galley and fit thru a slot in the roller lifter to keep it from rotating ?? I remember using this in the 60s but I don't remember the brand

Something like these Pontiac lifters?



From

http://www.ebay.com/itm/Pontiac-389-421 ... 2257073634

[blykins]

Itty bitty titanium valves, small diameter springs/retainers, and no adjusters on the rocker arms.....very light. Doesn't take much spring pressure to gain control like that.

[perfconn]

VWCHUCK,
It is a fact that NASCAR engines are running 100# of seat pressure on their roller cams.I started this thread to try & learn how they are doing it ,not arguing about whether it is being done.This technology is not easy to come by and the shops that know how to do it obviously don't want to share their hard earned work.

[pamotorman]

how many remember the 1/4" X 1/4" steel bar that went into the lifter oil galley and fit thru a slot in the roller lifter to keep it from rotating ?? I remember using this in the 60s but I don't remember the brand

Something like these Pontiac lifters?



From

http://www.ebay.com/itm/Pontiac-389-421 ... 2257073634

these are isky out of jim halls chaparral.

[CamKing]

I call bullshit. There is no way you can control with only 100lbs on the seat at 9500RPM... No way. Even if everything is titanium it isn't enough.

We have a 4-valve setup that turns 11,000rpm with 70# on the seat, and 250# at max lift. In fact, I sell about 20 sets of cams and springs a year for this setup, and have had zero failures.

[T-flow]

I have no way to test this stuff but in the last few years we have been cutting seat pressure. Good stuff, semi light- Titanium intake valves and retainers. I have mapped the weights and look at cam profile. Only educated guess work here. But have had nothing but good success.
I'm a firm believer of good springs, light weight valves, and retainers. But don't forget the best pushrods you can fit or afford! Key part!
I only wish they made some springs for 2.150"-2.250" installed height without 350+ seat and 1000+ open and good for .875-1.010" lift .....

[user-17438]

I have no way to test this stuff but in the last few years we have been cutting seat pressure. Good stuff, semi light- Titanium intake valves and retainers. I have mapped the weights and look at cam profile. Only educated guess work here. But have had nothing but good success.
I'm a firm believer of good springs, light weight valves, and retainers. But don't forget the best pushrods you can fit or afford! Key part!
I only wish they made some springs for 2.150"-2.250" installed height without 350+ seat and 1000+ open and good for .875-1.010" lift .....

dr426r are less spring pressure. I think they are around 275@2.100

also to run low spring pressures you need to have the right lobes. you cant just cut spring pressure and expect to live.

[perfconn]

That's the bad part about this whole deal,The technology makes more HP but stuff like valve springs cost $2,000 for a set of springs that goes with the. Whole deal. Lol

[randy331]

That's the bad part about this whole deal,The technology makes more HP but stuff like valve springs cost $2,000 for a set of springs that goes with the. Whole deal. Lol

My son's 355 pulling truck engine has 2.055 steel valves, steel retainers and locks, stud mount rockers and 1/2 set of used Comp 954 springs on the ex. and 1/2 a set of un known used springs I bought on ebay for $18 on the intake. .80 wall 5/16 pushrods.
lift is .665 ish.

It gets spun past 8000 rpm for 20 seconds at a time.

8500 rpm rev limiter and it was on it most of the pull sat. night. Haven't heard any valve float and we just checked springs and lash before that pull.

Not a fast lobe and it has a progressive lash ramp so we have the lash tightened down some to help.

I'm sure if that valve was 70 gram instead of 115 and it had ti retainers and locks and a smaller diameter spring low MOI shaft rockers it could have less pressure.

Not my preferred method, but his budget couldn't do it my preferred way . LOL

Randy

[swampbuggy]

Camking, you bought to our attention REMEMBER 100 lbs. on the seat is 230 lbs.at the lifter with a 2.3 rocker arm ratio. This would be at .001" of valve lift i would assume . So do you have a close idea as to what the open pressure would be at appx. .800" lift ? Thanks Mark.

[swampbuggy]

Perfconn i do believe NASCAR cyl. head valves are now 6mm