Don Terrill’s Speed-Talk

383, old brodix heads, (maybe 190cc's, doesn't matter) dual plane intake, rev limited to 6000.

Going to use a GM 212 222 P/N24502476 HFT cam.

Head and valves only accommodate a 1.70" installed height without going to plus retainers and plus locks.

So in theory I can run a standard SBC valve spring with 80 odd lbs of seat pressure, in the past I always would have run a Z28 LT1 valve spring on these low lift deals.

I don't like the high pound inch spring rate of the LT1 spring but the extra seat pressure I do like.

Do I run a stock spring, an LT1 spring, or is there a better option these days ?

I also used to run low spring rate bigger diameter springs for the higher seat pressure low nose pressure on these sort of builds.

Beehives. Comp #26986 or similar.

T. Willie's advice was don't use larger than the 1.25" diameter spring on under .500 lift. The standard spring will be fine. The old 346 and 151 cams turned well over 6000 with them for thousands of miles. All more pressure will give you is more friction and less power.

Chevrolet used the same standard SBC spring on low performance 327-350 cams and higher RPM cams by using a retainer with shorter installed height for more seat pressure with the HP cams.

Geoff2 wrote: ↑Sat Feb 04, 2023 12:22 am Beehives. Comp #26986 or similar.

Like it, gotta add a 100 thou, 11/32 pus 100 beehive retainers should be available.

Tuner wrote: ↑Sat Feb 04, 2023 12:35 am T. Willie's advice was don't use larger than the 1.25" diameter spring on under .500 lift. The standard spring will be fine. The old 346 and 151 cams turned well over 6000 with them for thousands of miles. All more pressure will give you is more friction and less power.

Chevrolet used the same standard SBC spring on low performance 327-350 cams and higher RPM cams by using a retainer with shorter installed height for more seat pressure with the HP cams.

That's sort of what I'm thinking, standard springs, at least to run the cam in, go stiffer if it pumps the lifters up.

Only thing that stops me is I have a 327 with LT1 springs and a 210 210 cam, and I manage to pump the lifters up on that from time to time, no rev limiter or tacho though, so no idea at what revs they pump up, just when the scream turns to a gurgle.

Go local Tom.

Crow Cams 4931-16 or 4828-16

Anyone inclined to do the math can run the springs across Hooke's Law and understand why T. Willy said to not use larger than 1.25" diameter spring with under .500 lift. The larger spring will enter a surge condition at lower RPM because the larger spring has a lower natural frequency.

Tuner wrote: ↑Sat Feb 04, 2023 1:24 am Anyone inclined to do the math can run the springs across Hooke's Law and understand why T. Willy said to not use larger than 1.25" diameter spring with under .500 lift. The larger spring will enter a surge condition at lower RPM because the larger spring has a lower natural frequency.

I've done a lot of spring math over the years, what formula do you have for that ?

Like the bumble bee, down tell the Cleveland V8 engineers that, or all those Clevelands will have never flown.

In the suspension world, larger diameter springs are more stable, less prone to buckling and the associated rate loss.

Tom68 wrote: ↑Sat Feb 04, 2023 1:58 am

Tuner wrote: ↑Sat Feb 04, 2023 1:24 am Anyone inclined to do the math can run the springs across Hooke's Law and understand why T. Willy said to not use larger than 1.25" diameter spring with under .500 lift. The larger spring will enter a surge condition at lower RPM because the larger spring has a lower natural frequency.

I've done a lot of spring math over the years, what formula do you have for that ?

Like the bumble bee, down tell the Cleveland V8 engineers that, or all those Clevelands will have never flown.

In the suspension world, larger diameter springs are more stable, less prone to buckling and the associated rate loss.

Don't conflate low frequency suspension spring requirements with high frequency valve spring applications.

I think it is the Goodman diagram that explains it. The spring needs to be stressed enough the surge frequency is above maximum engine speed. Obviously, we understand there is a range of stress the spring needs to be within in the circumstances it is installed and run. Although for different reasons, too little is as wrong as too much.

At the same seat pressure the larger spring is stressed less, so the frequency at which it will begin to surge is lower and can be within the engine's operating speed range. The smaller spring is stressed higher so the surge frequency is higher, like a tighter guitar string, and is above engine speed. Valve float occurs when the spring enters the surge condition.

With low lift, under .500", the spring larger than 1.25" isn't stressed enough to avoid surge.

20 years ago the 305 Chevy for SCCA A/S was limited to .480" lift. This was a problem for the CompCamTards who insisted on using the 1.437" spring with their special spec rule cam, but even with 175 on the seat the CC hot mess still floated at less than 6000 RPM. The T. Willy setup with a 1.25" spring with 110 on the seat would turn 7500 with no float.

I noticed in a post recently somebody was trying to source a spring with minimal clearance between coils at full lift, guess they were going for a high stress situation.

A quick note....

Maybe the PAC Racing 1201???

/awaiting the wrath of the elders.

I have all kinds of those small diameter valve springs I use on a lot of low lift cams. Never had much trouble with them until you float the things at 7K.

This is all you need with that cam.

https://www.racingsprings.com/index.php ... 11373.html

Hi, Mike,

I trust your recommendations, so trying to learn something here. I've been going to beehives whenever possible and have usually found about another 300-500 RPM over same seat pressure cylindrical. Why would we choose the old school cylindrical over the beehive?

Tuner wrote: ↑Sat Feb 04, 2023 12:35 am T. Willie's advice was don't use larger than the 1.25" diameter spring on under .500 lift. The standard spring will be fine. The old 346 and 151 cams turned well over 6000 with them for thousands of miles. All more pressure will give you is more friction and less power.

Chevrolet used the same standard SBC spring on low performance 327-350 cams and higher RPM cams by using a retainer with shorter installed height for more seat pressure with the HP cams.

Cool you knew/know T. Willie. What a character, love that guy

The GM "Blue" beehive spring would be great(12499224)...just not sure where you will find an 11/32 retainer for it on the cheap.

I've used plenty of the sets Mike suggested, they are pretty awesome too.