Some Trick Flow Spring Info

[beanhead]

This might be old news for many of you, but I never found any 'as-tested' numbers on these so I though I'd pass it along to keep FBBO hip....
The TF240 'hydraulic roller' springs on the #7802 heads I have here tested quite a bit different than the paperwork shows.
Seat pressure (TF spec) 138 @ 1.950"
(Tested spec) 170 @ 1.940"

@.600" lift (TF) 390 lbs
(Tested) 430 lbs

Coil bind checked @ 1.175"

This is why we check!

In conversations Mr. Dwayne told me this would be the case, that these springs are more like the PAC 1294, and of course they are. I can't "un-shim" these enough to be cozy with my SFT cam and not be a mile away from coil bind so I'll be switching to my Isky 8005s and shimming those for proper force, again advised by Dwayne. I never doubted him of course, I was having the heads gone through anyway and spring testing is part of my guy's standard procedure. At worst I may have to buy new locators if the TF ones don't fit the smaller I.D. of the Iskys (currently still in service). I got the heads at a good price so that wouldn't be a big deal.
So even though these heads are some of the nicest OOTB units out there for our stuff, check everything!

 

[PRHeads]

Imo, TF has missed the mark on offering those heads with what I would feel is a truly suitable spring for use with the “mid-level” SFT cams.

Taking the heads with the 1.46 spring package and shimming them to about 1.800 will work okay for a lot of combos though.

 

[ChargerST]

Has anyone tested the 1.460 springs? How do they compare to the advertised specs?

 

[PRHeads]

Those are PAC-1903’s.
They test basically right on what the PAC catalog says they are....... which is a little different(less) than what TF shows with the paperwork than comes with the heads.

The set I checked the other day were [email protected].

 

[ChargerST]

So perfect for SFT break-in and shimming afterwards.

 

[PRHeads]

The shims would go under the spring cups/seats, which requires the seals coming off first.

So, before installing the heads, I’d have the spring heights all set up to the desired height, then pull the inners for cam break in.

 

[Challenger340]

Yes I believe I saw the same thing on a set of TF270's I glanced over when they arrived ? Sheet said '138#" or so ?
but seems to me they it was waay up around 160+ at height on the seat ?

I only had time to pull two V/Springs for a quick look/measurement before getting pulled away.... and we've got a long way to go on the Block Rotating Assembly FIRST before getting back and going through the 270's so I'll have to get back here again later....
Which no matter....
as I think we're running a Street Mech Roller in that one ? so all I will be concerned with is more so if the V/Spring 'rate' will suffice ?

 

[EngineerDoug]

Gents,

I am also about to complete a 493 build using the TF 240 heads. The heads use the 1.46" springs. My cam is a solid flat tappet: lift = 0.540", duration = 242 deg @ 0.050". I would like to use the springs that came with these heads.

What would you recommend as a seat pressure with this cam? I assume I can shim the springs to suit this cam, as the seat pressure is only 110 lbs @ 1.900".

Thanks.

 

[beanhead]

Gents,

I am also about to complete a 493 build using the TF 240 heads. The heads use the 1.46" springs. My cam is a solid flat tappet: lift = 0.540", duration = 242 deg @ 0.050". I would like to use the springs that came with these heads.

What would you recommend as a seat pressure with this cam? I assume I can shim the springs to suit this cam, as the seat pressure is only 110 lbs @ 1.900".

Thanks.

I would for sure test them first, and if you found that 110 @ 1.90 was accurate, or at least very close, I would figure out the distance to shim them to get the seat load in the 130-ish range. But, you have to keep an eye on where that puts you in relation to coil bind, and what the open pressure would amount to.
Now, I could be wrong but 110 on the seat seems a little light for a cam like that? PRHeads is much more qualified to answer that than some internet circus monkey (me!)