Spring pressure

[Twin Turbo T]

This maybe opening a can of worms. So here goes, I got a stage II with stage II heads.Tim at comp cams told me to put 275# the seat,but would like to see more. So I've told my machinist, he is argue with me. He said "that to much seat pressure,the cam bearings would not live, and that I need to have roller cam bearings. Any input on this, from you stage II guys?

 

[gnxtc2]

I used 275lb on the seat with Crower solid roller lifters on my Comp billet hydraulic roller cam in my 109 block. I used teflon coated Durabond cam bearings. When I took the motor apart, the cam bearings were perfect.

Hope this information is useful even though it's not in a Stage block.

Billy T.
gnxtc2@aol.com

 

[Nick Micale]

Ditto what Billy said.:smile:

Guess you need to get a machine shop familiar with Buick V-6 race engines?

 

[Buzzard]

295 on the seat, stage 2 block, no problems yet. Going on a year since the heads were freshened and new valve springs installed.

 

[GARY HARVEY]

Boost level, RPM, Profile and such all need to be added to this!
If you are setting up for a 10/10's journey, more is better.
On the other hand if you're more of a street racer or on a more limited budget and would like to keep expenses in check, a touch lower spring pressure will work well.
Coated bearing and micro polishing the cam will help whatever pressure and is cheap insurance against bearing problems. Coated bearings everwhere are a no brainer... IMO
(i use Calico BTW)


IMO.

 

[turbodave231]

I'm running 330# on the seat with S2 heads. No cam bearing problems. If you plan to twist it up to 7500 or more, you will need lots of seat pressure.

Tim Cole at Comp Cams knows what he is talking about. He is a Buick V6 Racer. On the other hand, sounds like your engine guy doesn't know too much about these engines.

 

[Twin Turbo T]

Well, I've took it to another machinist. So, right now I have the new ERSON professional racing springs #E915170 came with paper where each springs is pressure check, checked HT, dated, rated. They are a long spring @ 2.100 in pressure is 310 LB.

 

[turbodave231]

I found that I couldn't use springs like that. When you get them down to a reasonable installed height (1.800-1.900) you will have way too much seat pressure.

If I used valves with longer stems, I ended up with geometry problems (T&D rockers). I ended up with a Comp Cams spring. I'll look to see if I still have the box or the receipt for the spring #.

Dave

 

[GARY HARVEY]

I'm using a PSI spring. If you have an idea of what you need, let them know and given a few weeks (since it's not at the start of the season) you'll
have a nice set of springs. You could also touch base with Chapman, they had a few sets the last time I called.

 

[Twin Turbo T]

This are long stem valve. I could see geometry problem with shaft mounted rockers, but there not.