I have a roller cam that's 765/748 lift. There are 1.560. Any idea on open and closed seat pressure? The springs in it I think are to small. They are 240 closed and 590 open. For a max 750 lift.

Possible a 1.625 should cover it. What cam and number?. Enough room in the pockets for cups?

quote:

Originally posted by TD3550:
Possible a 1.625 should cover it. What cam and number?. Enough room in the pockets for cups?

Its a Strub Technology camshaft. These are promaxx heads. And yes the pockets are bigger.

I have a Bullet cam that is .731/.714 and it wants 260-275 on the seat with 625 open.

I run the PAC 1225 which is a 1.550 diameter spring. The spec is 250 seat and 765 open.

On my old heads with larger pockets I ran the Manley 221424 which is a 1.640” spring that has 250 seat and 800 open.

quote:

Originally posted by Novacaine:
Its a Strub Technology camshaft.

Didn’t strub provide the valve springs too? If so why are you questioning them now?

That said, I ran Manley’s Nextek polished dual spring #221443P on my 700+HP 468 for many years and thousands of 1/4 mile passes, whose specs are….

1.580 diameter
250psi closed
610psi open
.730 max lift

With my LSM cam

254/260 @ .050
.740/.740 gross lift
107LSA

After checking he set it up for a 496 but I told him for a 555 so there was some miscommunication somewhere. I had two projects going off the same time.

Doesn’t matter, cam is all that matters

That's right he set it up for a smaller cam.

No reason to change to a different spec spring

The springs on those heads are for a 496 smaller roller cam. They were supposed to be Springs to match a bigger cam for the 555 do Springs do not have enough Seat pressure an open pressure to run that cam.

Just wanted to know why you think the springs are too small? What is the issue?

I was having a sputter near the finish line like a weak valve spring. After checking the paper work the springs was for a 748/732 , 240 seat pressure. They was suppose to be for a 765/748 , with 275 to 290 seat pressure.

you do not need a spring with that seat pressure.

I've been running Manley’s Nextek polished dual spring #221424P on my 900+HP 522 for many years and thousands of 1/4 mile passes, whose specs are….

1.640 diameter
250psi closed
800psi open
.850 max lift

With my Comp cam

272/286 @ .050
.860/.840 gross lift
109LSA

and turning 8100 in the lights.

The spring is 240 seat and 590 open, that still gona work if I need 300 closed and 801 open? Chris said I did.

you don't need 300/800 chris don't know, he's an internet conman/salesman, not a cam grinder, not a engine builder, not a racer. Plenty of smart guys in your area, talk to them or don't.

quote:

Originally posted by Novacaine:
The spring is 240 seat and 590 open, that still gona work if I need 300 closed and 801 open? Chris said I did.

You know you need springs, why ask? If you're gonna ask someone, ask someone with engine building experience, like Straub.

You have nowhere near enough, I run more on a sbc, 730 lift, 290 - 300 on the seat.

My valve train is lighter than yours.

This message has been edited. Last edited by: Mike Rietow,

you have more than enough

Rietow brings up a point I was wondering about while reading replies. Seems nobody asking about valvetrain components. Weight of all parts combined has bigger effect on valve spring requirement than about anything. Spring only has one job keep lifter on cam at all times o that valve is doing what camshaft wants it to do.

Listening to expert on spring is big part of what cost us world championship in TA/FC. Sometimes you have to go with gut, If you feel motor is floating valves at top end add pressure.

Nobody we know has seen a Isky Tool Room spring go bad, as far as I can tell, they're permanent.

Perfect spring for ya Novacaine, these numbers are similar to my sbc.

Coil bind 1.150 on these, just enough to set up anyway you prefer.

[9999RAD] Tool Room.

quote:

Originally posted by Mike Rietow:
Nobody we know has seen a Isky Tool Room spring go bad, as far as I can tell, they're permanent.

Perfect spring for ya Novacaine, these numbers
are similar to my sbc.



Coil bind 1.150 on these, just enough to set up anyway you prefer.

[RAD9999] Tool Room.

That's more what I think I need.