91RSCamaroSteve

iTrader: (1)

Hey Everyone,

I am looking to get some advice/confirmation on the max lift of the Trickflow 205 (TFS-3051T001-C00) head. I will start out by saying I did email requesting confirmation but the answer lacked detail, did not really line up with my understanding and appeared to primarily reference the product sale page that does not line up with the installation instructions and specs. But more in that below with pictures and details.

The engine is a 2004 5.3L iron block with dished pistons and the cam is 222/226 0.596/0.598 LSA 113+2. The cam springs are TFS-16306-16 with the following specs according to head installation instructions: Install Height: 1.820", Coil Bind: 1.100", Max Lift: 0.650" and Spring Rate: 463 lbs/inch. The spreadsheet for all the TFS valve springs has slighlty different numbers but very similar, pictures attached. Based on my understanding of calculating max lift of valve springs is the installed height minus the coil bind and you want around 0.050" before coil bind (usually you shim until about 0.050" to my understanding) Based on this it would be 1.820-1.100-0.050=0.670". Understanding that often the installed height is 1.800" that would put max lift at 0.650". With the max lift of my cam, that would put me around the sweet spot at 0.054" and 0.052" before coil bind. Additionally, based on my research other spring rates for valve springs rates for similar lift is less than or equal to the spring rate of these springs so based on all that I should be good to go. Part of the reponse to my email was that "This spring is rated to .600 valve lift. This cam will be running the spring close to max lift. I would swap them out for something with a stiffer spring rate."

Am I missing something in my research or should I be good to use the springs that come with this head? As a side note, i believe the head and cam package for their i believe 235cc version of the head has 0.595" intake and exhaust lift, with the same springs and the max lift on the product page also says 0.600" lift. So I am wondering if the max lift advertised on the product pages takes into account the 0.050" before coil bind.

As a side question, i will of course be claying my pistons to verify piston to valve clearance, but based on these heads and the cam profile, does anyone expect I will have piston to valve clearance issues?

Thank you all for the assistance. The below are pictures for reference.





This is a picture from the TFS valve spring spec spreadsheet.


This is a screenshot from the Trickflow webpage showing the 0.600" max lift.


This is a screenshot from the Trickflow Installation Instructions that contain the valve spring spes.

TurboBuick6

iTrader: (2)

The springs on your head will handle .650" lift safely at 1.800" installed height. Do not put a stiffer spring in unless you plan on going with a heavy aftermarket rocker arm.

91RSCamaroSteve

iTrader: (1)

Awesome, thanks for the info. That is what I was thinking but wanted to throw it out there to make sure I was not missingsomething. Yes I thought the spring rate was on the higher end so I plan on getting the Yella Terra YT 6727 rockers with a max open spring rate of 480lbs. This should be more than the max rate at about 0.600" lift.

99 Black Bird T/A

iTrader: (4)

What lifters are you planning to run?

TurboBuick6

iTrader: (2)

If you will be using the YT rockers, throw a -0.050" offset lock in there. That will get you 175 seat and 445 open. You will need that 175 on the seat for the rockers. This is assuming you stick with 0.600" lift. If you go higher, you will need a spring change like the PAC-1222X (drop in for the TFS spring hardware)

91RSCamaroSteve

iTrader: (1)

I will be sticking with 0.600 lift for the foreseeable future.

The main reason I was/am contemplating the yella terra rockers is due to the recommendation for a roller rockers. They do recommended the Harland Sharps but those seem to have less positive reviews in comparison.

These do have the powered metal valve seals and not the bronze ones so they should be more robust. I am currently running stock rockers with upgraded trunions which would be the cheaper option. However with the combination of the different valve angle (13.5 vice 15), the recommendation and my lack of understanding of the effects of valve angle changes, higher than stock lift, etc... on sweep pattern and valve side load makes me persue the roller rockers.

I am not sure if you have any recommendations with regards to which rockers I should look to use. Otherwise I will look to get offset locks like you suggested.

91RSCamaroSteve

iTrader: (1)

I haven't decided what lifters I am going to run yet. If you have any recommendations I would be happy to take them. I am planning to reach out to someone like Comp Cams to see what they recommend. But I was hoping to avoid the requirement for adjustable rockers with low preload lifters but I haven't done a deep dive researching lifters yet. But I do plan in replacing them when I do the heads.

91RSCamaroSteve

iTrader: (1)

Well I have looked into it a bit and in retrospect, I think I will take a serious look at pursuing short travel/low preload hydraulic roller lifters and adjustable rockers. Reading a bit about lifter longevity of LS7 style lifters (because the open spring pressure will be higher than 400lbs) and potential "pump up issues" (can't say I fully understand it yet but seems to be a potential issue), I am leaning more towards a different option than I originally thought.

I am not planning to put the head on until spring so I have a bit of time to get educated and read the forums and I have already reached out to some cam companies for recommendations. I would rather spend a bit more and get the right stuff the first time then have to replace parts or destroy somthing because I was trying to cut costs. (Not including the usual preventive maintenance and normal wear and tear)