Trick Flow Heads: Conflicting Info on Mechanical Roller Spring Pressure

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Torqueflite

Torqueflite

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I could use some help making sense of necessary mechanical roller spring pressures, and therefore the parts, for my setup since I'm in the market for a set of Trick Flow heads for a circle track LA360 that will turn 7,500 RPM. The cam will have 0.640 lift after correcting for lash. The issue is that the information I'm getting from Trick Flow's advertisements and their lead parts tech over the phone isn't matching what two custom cam grinders told me, which is that I want at least 220# seat and 640# open for a 0.640" mech. roller cam.

Let me lay out the math for the two assembled head options Trick Flow recommended to me:

Trick Flow 61417802-C00
Advertised Cam: Mech. Roller
Advertised Max Lift: 0.680”
Installed: 1.90”
Diameter: 1.55”
Rate: 427#
Seat: 175#
Open at 0.640”: 448# (0.640 x 427 = 273 + 175 = 448#)
Even though the 61417802-C00 is advertised for 0.680" mech. roller, the springs will only give 175# seat (too low?) and 448# (way too low?) at 0.640" lift. Outside of shimming range.

Trick Flow 6141T784-C00
Advertised Cam: Mech. Roller
Advertised Max Lift: 0.700”
Installed: 2.00”
Diameter: 1.56”
Rate: 500#
Seat: 240#
Open at 0.640”: 560# (0.640 x 500 = 320 + 240 = 560#)
Even though the 6141T784-C00 is advertised for 0.700 mech roller, the springs will only give 240# seat (good) and 560# (too low?) at 0.640" lift. Outside of shimming range.

I also looked at 1.55" +- diameter springs for 1.90" and 2.00" installed height available on Summit, and these are the closest I found:

Comp 999 Springs
Installed 1.90”
Diameter: 1.55"
Rate: 633#
Seat: 196”
Open at 0.640”: 601# (0.640 x 633 = 405 + 196 = 601#)
These springs provide 196# seat (too low?) and 601# open at 0.640" (too low?).

PAC Racing PAC-1325 Springs
Installed: 2.00”
Diameter: 1.55"
Rate: 644#
Seat: 250#
Open at 0.640”: 662# (0.640 x 644 = 412 + 250 = 662#)

These springs seem like the correct ones at 250# seat (good) and 662# open at 0.640" (good).

I haven't explored all spring manufacturers to see what options are out there for around 1.55" diameter at either 1.90" or 2.00" installed height so I don't have to pay for the pads to be machined and so I can use the valves and retainers that come with the Trick Flow heads, but it appears I would need to buy Trick Flow 6141T784-C00 heads and swap out the springs for the PAC Racing PAC-1325 or similar. This route still looks quite a bit cheaper than buying bare heads, loading them with valves/springs/retainers, and having my machinist dial them in.

I appreciate input on this situation and if I am correct that the Trick Flow 6141T784-C00 heads are not properly set up for a 0.640" mech. roller cam and that I would need to swap out the springs to get a minimum of 220# seat, 640# open. If you know of any 1.55" +- diameter, 1.90" - 2.00" installed springs other than the PAC-1325 that will do the trick, I'd appreciate knowing of them too.
 
The heads with the 2.00” installed height 1.56” diameter springs are “designed” for SR cams.

The 1.55” spring could be suitable for a mild street roller, depending on the exact cam and application.

Measure what you actually have for installed height, and post all the cam specs.
There are numerous roller spring choices for the 1.90-1.95 range.


Edit - looks like you have a handle on the pressure vs rate situation.

The PAC 1225/1325 is pretty much what you’re looking for if you feel you need 650lbs open with .640 lift out of a 1.550 type spring.
 
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This is real simple. Go with whatever the cam manufacturer says.
 
It’s real simple. Manufacturers lie.

No way would I put any spring in there that wasn’t 240 on the seat minimum and 280 would bother me if you bought Chrysler correct lifters.

What it is over the nose as long as it’s 650 or higher.

If you do not have lifters with at least an .800 diameter wheel STOP and buy them.

A .750 wheel is too small. That’s for Chevy garbage.

Low spring load will kill parts. High spring loads won’t.

Do not buy into the lie that spring pressure hurts parts. That straight bullshit.
 
Icetech said:
Is that due to parts bouncing and slamming together due to not enough spring pressure to control it?
Click to expand...
Yes.
Somewhere here I have a bbc roller cam out of a friend's bracket car. He revved the wee out of it without enough spring. It has four divets in the flanks of the roller lobes, about an eighth of an inch deep. I can't find it right now to take a pic.
I dont know if it can be repaired and reground, but i do know it is a billet, and it was free.
 
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33IMP said:
Yes.
Somewhere here I have a bbc roller cam out of a friend's bracket car. He revved the wee out of it without enough spring. It has four divets in the flanks of the roller lobes, about an eighth of an inch deep. I can't find it right now to take a pic.
I dont know if it can be repaired and reground, but i do know it is a billet, and it was free.
Click to expand...
Eck.. didn't think it would eat stuff that bad..
 
PAC Racing 1238x set at 1.880 gave me 236 on the seat and 626 open at .668 lift. I shift at 6800. Well, my shift light is set at 6800. It'll wind way up if I'm not ready for it.

I'm looking at the actual Compu-Spring printout done on my heads. so....not guessing. MY Guru says advertised pressures are always over stated.

And Turk's right about the lifters, especially for your intended use. .800 wheel is a must! BAMM, baby!
 
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Newbomb Turk said:
It’s real simple. Manufacturers lie.

No way would I put any spring in there that wasn’t 240 on the seat minimum and 280 would bother me if you bought Chrysler correct lifters.

What it is over the nose as long as it’s 650 or higher.

If you do not have lifters with at least an .800 diameter wheel STOP and buy them.

A .750 wheel is too small. That’s for Chevy garbage.

Low spring load will kill parts. High spring loads won’t.

Do not buy into the lie that spring pressure hurts parts. That straight bullshit.
Click to expand...

I appreciate the feedback. For lifters, I'm looking at BAM #2018 with 0.815" rollers. It looks like the PAC-1325 springs are the way to go to give me 250#/662# without needing to do any machine work or get new retainers, and I'll confirm the pressures when setting up the heads.
 
Have you looked at Beehive, Conical or Dual Conical? They require less tension.
 
To the op.
Howard's told me their rule of thumb on Solid Roller cams is,
100# per .100" of lift
So that's right where your at 660#
I used the pac 1225 spring
@ 2.000" installed height
It has 250# on the seat
And 675# open
With a .660" lift cam (after .020 lash.)
After a few runs they faded between
10-15#
Still turns 7,300 rpm for miles.
( Circle track. )
 
I really like the ISKY tool room springs, part number 9935, which I believe would work just fine for your application.
, I ran these on a 698/672 roller that saw 7500 every pass at the stripe, I got cam from Porter racing, he suggested these springs as well, and they were superb.
More like 245/ 590 at your spec.
650 to me seems like more than needed.
Best machine at the time checked these springs at a freshen up( 4 years of lots of racing) and they still checked fine.
 
I think you are correct on changing the springs, the valve springs were upgraded on the Trick Flow roller cam heads on my engine, for the .660 lift Bullet roller cam.
 
The engine has run, but not at the track yet. Still working on the car, and very anxious.

17287728839475169331272853791918.jpg
 
Mopar69gts said:
To the op.
Howard's told me their rule of thumb on Solid Roller cams is,
100# per .100" of lift
So that's right where your at 660#
I used the pac 1225 spring
@ 2.000" installed height
It has 250# on the seat
And 675# open
With a .660" lift cam (after .020 lash.)
After a few runs they faded between
10-15#
Still turns 7,300 rpm for miles.
( Circle track. )
Click to expand...
Thanks for the first-hand input. The 1225 is the 1200 series equivalent of the 1325 I calced out above. The 1300 series, according to PAC, is designed/produced for circle track endurance, resulting in a higher price than the 1225. It's good to hear that in your experience the spring rate was accurate and held up well.
 
B3422w5 said:
I really like the ISKY tool room springs, part number 9935, which I believe would work just fine for your application.
, I ran these on a 698/672 roller that saw 7500 every pass at the stripe, I got cam from Porter racing, he suggested these springs as well, and they were superb.
More like 245/ 590 at your spec.
650 to me seems like more than needed.
Best machine at the time checked these springs at a freshen up( 4 years of lots of racing) and they still checked fine.
Click to expand...
Thanks. I was looking at the Isky Tool Room series after Mike Jones cams recommended them on another forum, but the 9935 is too light according to the cam grinders. At 245# seat and 490# rate, that's only 559# at 0.640".
 
Torqueflite said:
Thanks. I was looking at the Isky Tool Room series after Mike Jones cams recommended them on another forum, but the 9935 is too light according to the cam grinders. At 245# seat and 490# rate, that's only 559# at 0.640". The 9985 appears to be the only one in their catalog at 1.560" diameter that comes close with 245# seat and 600# rate, but that's 629# at 0.640, a little shy of the recommended 640#. I don't know how crucial 10# open is, but I guess that's a good question for the cam grinder.
Click to expand...

It’s 245/ 590 not 490.
Like I said, I ran them on a 699/672 lift comp roller at 7500 every pass for years. They tested good after 4 seasons on them.
 
B3422w5 said:
It’s 245/ 590 not 490.
Like I said, I ran them on a 699/672 lift comp roller at 7500 every pass for years. They tested good after 4 seasons on them.
Click to expand...
I'm not following what you mean by "it's 590 and not 490." 590# isn't the spring rate but what Isky lists as the max open pressure at coil bind. The 9935 spring rate is 490#, so 490 x 0.640 lift + 245# seat = 559# open, which is 90# less than what the cam grinders I talked to want for a .640 solid roller. For your cam at .699" lift, you have 588# open. I don't know what they'd recommend for a .699" solid roller, but I assume probably closer to 700#.

I appreciate that you had good results with running 588# open on a drag car with .699" lift, but it's not a fair comparison to my circle track demands. This circle track engine will see more hours on the valvetrain at 7,500 sustained rpm in one evening of hot laps, qualifying, heat, possible semi, and feature than an avid amateur drag racer's engine will see at that RPM in five years. A single 30-lap feature on a 3/8 mile is forty 1/4-mile passes with no rest on the parts. Now do that every two weekends for a season.
 
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