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Thread: Valve Spring Recommendation
05-29-2019, 04:59 PM #1
Valve Spring Recommendation
I running a built 4.6 with a Vortech @ 15psi. When I built the engine I installed the Trick Flow FMOD Track Heat Spring Upgrade Kit TFS-2500525. The instructions state that they support up to .580” of lift and have a seat pressure of 15psi. They also state to install the supplied .030” shim under the spring when installing in PI heads instead of Trick Flow heads.
I installed upgraded camshafts from Comp Cams XE270AH with .550 lift to MHS Stage 2 Blower Cams with .575” lift and ran into a problem. I think the valve springs are binding with the increased lift. I suspect with the shim the max lift the is actually .550” (.580 - .030).
I'm going to either remove the shim under the TFS springs or install new valve springs. I tried multiple times calling and emailing trick flow and have yet to reach anyone. Hopefully someone here can help out.
05-30-2019, 05:03 AM #2
The TrickFlow spec sheet for your springs shows the seat pressure to be 125 lbs at a 1.570 installed height, see below;
That spring is made for TrickFlow by PAC. Pac offers a similar spring as their part # PAC 1214, see below;
The only other upgrade I see for you is the PAC part # PAC 1312 which would need to be installed w/o any shims. The seat pressure at a 1.670 installed height would be approximately 178 lbs. They would also require new retainers.
Some of the other attractive attributes in addition to the higher seat pressure, would be the increased increased valve lift (0.700") along with the increased spring rate (400 lbs/in). These springs would raise the engine's valve float speeds well in excess of anything you would want to run the engine at.
05-30-2019, 09:07 AM #3
Ed, Thank you for the reply. In your opinion is the .030" shim reducing the max lift and causing coil bind and would removing the shim a provide the required valve lift? Are there any issues with the valve spring seating against the aluminum head without a shim of some sort? I really think these are Trick Flow questions, but they are unreachable.
I guess if I can't get a satifactory answer, I'll just buy a new set of springs from someone that can answer those questions. I'd rather spend the $200 than take the engine apart again.
05-30-2019, 09:49 AM #4
I do not / have not built two valve or three valve heads so I am unfamiliar with how Ford addresses this problem. On the 4V head Ford built the protective shim into the valve stem oil seal so the installation of the oil seals for each of the valves automatically brought with it a protective spring seating surface. I would not be surprised to find that Ford may have done something similar with the 2V heads. Bottom line you need cylinder head protection from the springs when the heads are made of cast aluminum.
There is also a third problem you need to be attentive to which you seem to be already aware of — coil bind or stacking of the spring coils before the valve reaches max lift. This is an engine and a head killer. When the cam lobe begins lifting the valve, if the valve springs coil bind before the valve reaches max lift you will break cam caps or cylinder head castings. In a best case scenario you will break a timing chain and bend the valves that are still open as the piston cycles up and down in the cylinder.
If you think the springs are in coil bind or near coil bind I would not start the engine anymore until I fixed the problem. It is always the responsibility of the engine / cylinder head builder to check for coil bind before assembling the springs to the head or the heads to the engine. If this was not done you should not start that motor for any reason until you have determined, with absolute certainty, whether or not those springs and that cam have a coil bind problem.
05-30-2019, 10:28 AM #5
Thanks you Ed. I have not run the engine since it seemed way to hard to turn over by hand. Failing any answer from TFS (I'm on 3 emails and 3 phone calls over 3 days now), I'll just purchase new springs that I know will work for my application rather than damaging the engine.
05-30-2019, 01:26 PM #6
I have attached three pages in pdf format from Ford's internal use Terminator Engine Assembly Manual, at the bottom of this post. The manual covers both the Terminator and Ford's two valve Natural Gas Vehicle (NVG) 4.6L engine. Although fueled by natural gas the mechanicals are the same as your engine. The difference is in the fueling and ECU calibration strategy code.
Page 2 of the pdf shows the same oil seals the 4V engine uses and they have the integrated shim steel spring seat. Sooo, as long as the person who rebuilt the heads used original Ford oil seals or identical aftermarket equivalents you should already have a protective barrier between the spring base and the head.
Towards the bottom of page 2 of the pdf, you will see the installed height specifications for the springs. The dimensions are in millimeters. They are 39.7mm minimum and 40.3mm maximum. That is the window you should be setting your spring heights to. You can convert to inches by dividing by 25.4. You will need a valve spring height micrometer to measure this dimension. If you don't already have one you can find them at Jegs and Summit.
Heads seem simple. They are deceivingly sophisticated. Take the time to do the job right — it can mean the difference between life and death for your engine.
p.s. With Ford's installed height dimensions we can now make a more accurate assessment of valve spring pressures at Ford's recommended install height upper limit. Ford's 40.3mm maximum height spec translates to 1.587 inches. Pac's seat pressure spec for the spring is 100 lbs at 1.640 inches. If you compress the spring an additional 0.053" to the Ford 1.587" upper limit you will increase seat pressure by approximately 15 lbs to 115 lbs.
Last edited by eschaider; 05-30-2019 at 01:40 PM. Reason: Added Postscript
05-30-2019, 03:50 PM #7
Thank you for the information. I finally spoke to a tech at Trick Flow. He initially said their spring should work with the .030 shim in my application with .575" lift, but when I stated that I actually had the combination assembled and it clearly seemed like it was binding, he recanted and said he'd talk to another tech to confirm. I think the bottom line is that they may not know, so barring a definative answer, I'm buying new springs and Ford valve seals. I agree that valvetrains are deceptively simple and it doesn't sound like manufactures always know the correct answer. The TFS tech was going to send me off to assemble the engine with this combo until I told him it didn't work.
05-30-2019, 06:47 PM #8
You need to be careful when you are dealing with vendor support personnel. It is not uncommon to discover that two weeks, or perhaps even two months months ago your support person was bagging groceries at Safeway grocery store and today he is your tech support counselor. Even worse sometimes the individual has never built a performance engine let alone turned a wrench on anything like what you have — and you are going to take his advice on your expensive motor pieces?
There is no substitute for personal knowledge and personal experience. You want to be self-sufficient as soon as possible. Pay attention to the guys who make it happen without blowing up pieces. The moment you hear things like, "How fast do you want to go? How much money day have?" or the always insightful, "That's Drag Racing" comment after you have wounded your pieces you are talking to one of the grocery store refugees masquerading as some type of knowledge source.
Remember Reagans famous words about nuclear disarmament, "Trust but verify!"
06-03-2019, 11:16 AM #9
I got an answer back from TFS on Friday afternoon. The tech was stright forward with his answer. He just didn't know. He said that at an installed height of 1.6" the max lift is .580. I assume the with the PI head installed height of 1.587 the max lift will be .567. He also thought that spec was with the .030 shim installed. He didn't know if removing the shim would work.
I think the TFS spring, the PAC #1214 spring, and the recommended PAC spring offered by MHS (who ground the cams ) are all the same spring. TFS just specs the .030 shim to increase seat pressure from 100lb/in to 125lb/in.
Last edited by Bullitt5566; 06-03-2019 at 11:21 AM.
06-03-2019, 12:28 PM #10
I could believe all of that, Scott.
In the end there are only about three spring manufacturers, of any significance, that service the performance industry. One is Associated, one is PAC and the other I forgot. Virtually all springs can be traced back to one of those three manufacturers which is why I suspect your suspicion is correct.