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Discussion Starter #1 (Edited)
Hello all!

It has been a while, but looking for your thoughts on the situation. My wife and I recently swapped a stock block from a 6k mile 07 Lincoln towncar, has TFS 38cc heads and stage 3 cms cams; as well as almost every bolt-on available. Was hoping for 350/350, and after fixing issues with fuel pump, car made 341 hp, 348 tq on the final pull. Before this head/cam combo, car was 287hp/302 tq with old setup.

Here's the situation (s)

1st, power curve drops completely flat at around 6k. The tuner, Jake Lamotta (Lamotta performance Longwood) says that the power curve should come down gradually, but instead looks like it drops off a cliff (I'll try to upload a pic soon). He is wondering if maybe the 90lb springs in the tfs heads aren't strong enough. TFS says the 90lb springs are good for .600 lift, and CMS stage 3 na says lift is .580 I believe.

Main concern NOW is that after the dyno, we went for a ride and the car wasn't running right. He hooked up his PC and it showed that cylinder 7 had almost no compression in it. He suspected maybe the valve was bent, or the rocker fell off. He took out the spark plug and use a borescope, and was expecting to see PTV contact, but there was NONE. We took the valve cover off, and the rockers were in place, but he says the valve is definitely NOT seating fully now. Says this could be a bad valve guide or valve seat.

Needless to say, we are going to have the car towed back to our house because I can't afford his labor to drop the engine and pull the head etc. Any input is appreciated on any of these issues:

Dyno power curve falling straight down @ 6k
valve seating/guide issues
90 lb spring not good enough for CMS stage 3 cam etc

thanks in advance for your input!
 

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Thats a tough situation, if you are running flat on the top... That sounds like valve float to me. When you go back through the cylinder head to figure out the compression problem, i would change the springs to some heavier duty ones.
 

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Discussion Starter #3
Thats a tough situation, if you are running flat on the top... That sounds like valve float to me. When you go back through the cylinder head to figure out the compression problem, i would change the springs to some heavier duty ones.
I appreciate it. Any particular spring "rate" or LB, or brand? The last thing we DONT want to do is pull the motor, fix everything and hit 6k again and the same issue happen.

Sorry for the "noob"ness, but valve float happens at high rpm and the valves stay open because the springs aren't strong enough to keep up with the cam lift and speed etc?
 

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^^Correct. Valve float is due to weak springs not pushing the valve back up fast enough before the lobe from cam starts to press back down on the valve.

Definitely get that all worked out. Sounds like you answered your questions. Brian Tooley is a reputable valve spring. I don’t know what the Comp beehive springs are rated at but worth a shot to look at.

I’m assuming you got the cams ground from CMS specifically for the TFS heads? Due to the relocated intake valve TFS heads need specifically ground cams and you should not use cams ground for PI/NPI heads.
 
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Discussion Starter #5
I appreciate all the responses. I had messaged Jim @ CMS regarding the order to make sure these were the right grind. In regards to valve springs, I need to find out if I need a TFS specific spring or what, IDK. When I ordered the heads, I was advised that the 90LB spring should be fine since its rated for .600 lift, and the cams were less than that, but it doesn't sound like it.

From the gathered responses, I'm concluding that the stronger spring would help with the power not dropping off flat. I checked out the Brian Tooley springs and retainers. says springs are rated at 130lbs. This should do the trick im guessing.

Just got to take the head off and see if there is damage to the valve seats/guides etc
 

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I appreciate it. Any particular spring "rate" or LB, or brand? The last thing we DONT want to do is pull the motor, fix everything and hit 6k again and the same issue happen.



Sorry for the "noob"ness, but valve float happens at high rpm and the valves stay open because the springs aren't strong enough to keep up with the cam lift and speed etc?


I have CMS blower cams and Cushman recommended PAC stage 2 racing springs. They are beefy.


Sent from my iPhone using Tapatalk Pro
 

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Discussion Starter #7
awesome thank you, I will check those out right now
 

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I have the btr .600 lift springs. The seat pressure is usually only an issue with boosted applications. It does sound like valve float........but what does everything else look like? Voltage up top? Fuel pressure up top? Are you getting spark blowout? What do the plugs look like?

It could be so many different things.
 

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Discussion Starter #9
I have the btr .600 lift springs. The seat pressure is usually only an issue with boosted applications. It does sound like valve float........but what does everything else look like? Voltage up top? Fuel pressure up top? Are you getting spark blowout? What do the plugs look like?

It could be so many different things.
Thanks for the response, I am probably going to get the BTR springs. I had Lamotta check everything else out, voltage/fuel pressure is good, plugs are not blowing out. He did a compression test and #7 was way down after the dyno run.

All was good for about 6-8 pulls/tuning etc. He wanted to adjust a couple things in the tune and run one more time before finishing up. That's when he said it "sounds" like somethings wrong. Hooked up his PC while the car was idling to show "power balance" on the graph, and #7 was way down.

Initially he thought valve float, PTV contact, and maybe a rocker got pushed off. Using his borescope, there's no PTV, and the rockers are in place. That's when he did the compression test, and there was air coming out of the exhaust pipe.

His guess now is a bad valve guide or seat, but this might have been prevented by having better springs.

Do we know if the BTR springs fit the TFS heads? on their site, it says PI heads, but I just want to make sure.
 

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Sorry for your troubles I have certainly been there myself many times..

These guy definitely are bringing up some good points and it could be many things.

what valve springs do you have now?

Who timed the engine?

Do a leak down test on that cylinder and the others while your at it so you can eliminate any valve issues.
 
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Discussion Starter #11
Thank you SSG Pate for your service and your response. The springs that are in it are the 90LB springs that came with the TFS. I had verified the timing events at the point of install. Before leaving the shop last night, the leakdown test was performed and concluded that a valve was stuck open. Since there was no PTV contact, he thinks the seat or guide might be bad
 
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Discussion Starter #13
Thank you, the BTR looks like the way to go. going to have the car back home tomorrow and start tearing into it over the next week or so. After reading and losing sleep, it makes sense about the valve float and not making ANY power up top. Just sux because my lady has been wanting to get back into the racing scene--car was finally together, and now going to be down again for a little bit.

I will continue to gladly receive any feedback while going through this journey. Thank you all!
 
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