Problems, problems, problems......
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
That is quite a bit of seat pressure. What is your installed valve spring height?
If it is less than 1.800, you could have 170 pounds on the seat.
If you did not measure the distance from the top of the valve sping seat to the bottom of the retainer (installed height) you need to pull one apart and do so. Also, find someone with a spring tester, and verify the spring pressure is what it is supposed to be both at the installed height, and open height.
I have a hunch you are beating your valvetrain to death with those springs. Verifying open and closed pressures will confirm or deny that.
If it is less than 1.800, you could have 170 pounds on the seat.
If you did not measure the distance from the top of the valve sping seat to the bottom of the retainer (installed height) you need to pull one apart and do so. Also, find someone with a spring tester, and verify the spring pressure is what it is supposed to be both at the installed height, and open height.
I have a hunch you are beating your valvetrain to death with those springs. Verifying open and closed pressures will confirm or deny that.
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
In my opinion, 135-145 pounds on the seat is a good amount for that cam, and 340-355 pounds open.
Those springs may be fine, but they need to be installed at the correct height to provide the correct spring rate and pressures for that cam.
If you did not verify the height, it isn't fair to blame LE. It is always the installers job to determine all parts purchased are correct, and suitable overall. If it were my car, I would stop what I am doing on the ignition, and shift my focus to valvetrain. I would hate to see the cam and lifters kill your motor while you are troubleshooting.
I see this alot. Although a cam swap is a bolt in, it is never that simple.
Everything needs to be what it is supposed to be for a direct swap in, and that rarely occurs. i.e: sping pressures, installed height, pushrod length, etc.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
In my opinion, 135-145 pounds on the seat is a good amount for that cam, and 340-355 pounds open.
Those springs may be fine, but they need to be installed at the correct height to provide the correct spring rate and pressures for that cam.
If you did not verify the height, it isn't fair to blame LE. It is always the installers job to determine all parts purchased are correct, and suitable overall. If it were my car, I would stop what I am doing on the ignition, and shift my focus to valvetrain. I would hate to see the cam and lifters kill your motor while you are troubleshooting.
I see this alot. Although a cam swap is a bolt in, it is never that simple.
Everything needs to be what it is supposed to be for a direct swap in, and that rarely occurs. i.e: sping pressures, installed height, pushrod length, etc.
Those springs may be fine, but they need to be installed at the correct height to provide the correct spring rate and pressures for that cam.
If you did not verify the height, it isn't fair to blame LE. It is always the installers job to determine all parts purchased are correct, and suitable overall. If it were my car, I would stop what I am doing on the ignition, and shift my focus to valvetrain. I would hate to see the cam and lifters kill your motor while you are troubleshooting.
I see this alot. Although a cam swap is a bolt in, it is never that simple.
Everything needs to be what it is supposed to be for a direct swap in, and that rarely occurs. i.e: sping pressures, installed height, pushrod length, etc.
Le Mans Master
Joined: Aug 2004
Posts: 5,141
Likes: 7
From: Metairie Louisiana
FWIW, I'm running the same spring kit but with a different cam.
I bought the height micrometer and the shims. Didnt need the shims.
I checked pushrod length with a trickflow adjustable checker and the magic marker method. I had to bring the length checker to a machine shop that had a digital caliper large enough to measure it. Most of the ones I found local only went up to 6".
I've had no problems since the install. Well, other than the initial intake leak I had to fix. I would get a laptop and Datamaster TTS to get it datalogged.
I bought the height micrometer and the shims. Didnt need the shims.
I checked pushrod length with a trickflow adjustable checker and the magic marker method. I had to bring the length checker to a machine shop that had a digital caliper large enough to measure it. Most of the ones I found local only went up to 6".
I've had no problems since the install. Well, other than the initial intake leak I had to fix. I would get a laptop and Datamaster TTS to get it datalogged.
Last edited by rickneworleansla; Oct 25, 2009 at 12:35 PM.
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
I think if you actually have 1.800 valve spring installed height, you may be fine. But man, in my eyes, 155 lbs on the seat is a boatload of pressure. With hydraulic rollers, my comfort level is 145 on the seat, and 350 open max.
I guess the question is 2 fold:
1) Is your height 1.800
2) Were the springs in the box correct. Misboxed happens to me often.
My last experience with misboxed was a set of .010 under rod bearings that were in a standard box, and stamped standard. Glad I checked it, or I would have been screwed.
That was on the same build as a mis boxed TPIS cam.
I guess the question is 2 fold:
1) Is your height 1.800
2) Were the springs in the box correct. Misboxed happens to me often.
My last experience with misboxed was a set of .010 under rod bearings that were in a standard box, and stamped standard. Glad I checked it, or I would have been screwed.
That was on the same build as a mis boxed TPIS cam.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
It's Much better!!!!
Ok, As I stated I installed the Autolite 104's gapped at .030. That was not the ticket. The car ran like crap. I took them out re gapped to .048 and that seemed to do the trick. Remember, I have the new PCM in now. The car runs the best it has since this install. Idle still isn't very good but I can work with that. Before, I had a very rich exhaust fume odor especially at idle and low rpm. That is gone now. I'm still going to take it (hopefully next week) for a dyno tune. That should tell the way things are for sure. So to sum things up I guess the culprit was the PCM or tune or both. I doubt the plugs had that much to do with it all along but who knows.
Thanks for all the help and support!
Thanks for all the help and support!
Le Mans Master
Joined: Feb 1999
Posts: 9,913
Likes: 37
From: South Carolina
St. Jude Donor '03 & '05
Ok, As I stated I installed the Autolite 104's gapped at .030. That was not the ticket. The car ran like crap. I took them out re gapped to .048 and that seemed to do the trick. Remember, I have the new PCM in now. The car runs the best it has since this install. Idle still isn't very good but I can work with that. Before, I had a very rich exhaust fume odor especially at idle and low rpm. That is gone now. I'm still going to take it (hopefully next week) for a dyno tune. That should tell the way things are for sure. So to sum things up I guess the culprit was the PCM or tune or both. I doubt the plugs had that much to do with it all along but who knows.
Thanks for all the help and support!
Thanks for all the help and support!
Race Director
Joined: Jan 2002
Posts: 12,261
Likes: 85
From: O'Fallon Missouri
I'm running the same springs with a 1.80 installed height. But, I have aftermarket .050 longer valves. With stock valve you will end up with a ~1.78 installed height.
You mentioned the car died right after the last dyno run, and then started later. This sounds like you could have a bad ICM. I would get it tested.
You mentioned the car died right after the last dyno run, and then started later. This sounds like you could have a bad ICM. I would get it tested.
Last edited by STL94LT1; Oct 25, 2009 at 01:50 PM.
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Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
I'm running the same springs with a 1.80 installed height. But, I have aftermarket .050 longer valves. With stock valve you will end up with a ~1.78 installed height.
You mentioned the car died right after the last dyno run, and then started later. This sounds like you could have a bad ICM. I would get it tested.
You mentioned the car died right after the last dyno run, and then started later. This sounds like you could have a bad ICM. I would get it tested.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
No improvement.......
Got another PCM with the same tune and a readjusted AFR. Went to the dyno and there was no improvement except for the AFR. It was dead on. Brian at RPM Motorsports couldn't quite pin down what the problem is but said if it was his car he would degree the cam in an then go from there.
So, where do I get a good deal on cam degree kit?
So, where do I get a good deal on cam degree kit?
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
Got another PCM with the same tune and a readjusted AFR. Went to the dyno and there was no improvement except for the AFR. It was dead on. Brian at RPM Motorsports couldn't quite pin down what the problem is but said if it was his car he would degree the cam in an then go from there.
So, where do I get a good deal on cam degree kit?
So, where do I get a good deal on cam degree kit?
It is likely degreed in. Your symptoms are consistant with too much spring pressure. Start there. It is more likely, and easier to get at. Trust me.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
Thanks Pete
Would it be a waste of time just to stick the LT4 springs I have back in just to see if that changes anything. Or should I just get another set of diffferent springs and just keep these until I get new heads?
Would it be a waste of time just to stick the LT4 springs I have back in just to see if that changes anything. Or should I just get another set of diffferent springs and just keep these until I get new heads?
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
Since you can't put the toothpaste back in the tube, you have to figure it out, or swap cam, lifters, and springs back to stock.
You need to know:
The installed height you currently have.
A valve spring mic is a handy way to measure the distance from the top of the seat, to the bottom of the retainer. Once that is determined, you can take the spring to a machine shop that has a spring tester. He can then determine closed pressure. The valve lift is then added to the equasion, and the sping is compressed that amount.
Now you can determine the open pressure.
Compress the spring an additional .060 to see if you bottom out. If you do, the spring will coil bind, and is useless.
Without the above info, you are spinning your wheels.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
Absolutely not. Valve spring set up is not a bolt in. It is a critical set up step that should never be skipped. Not enough valve spring will cause additional problems.
Since you can't put the toothpaste back in the tube, you have to figure it out, or swap cam, lifters, and springs back to stock.
You need to know:
The installed height you currently have.
A valve spring mic is a handy way to measure the distance from the top of the seat, to the bottom of the retainer. Once that is determined, you can take the spring to a machine shop that has a spring tester. He can then determine closed pressure. The valve lift is then added to the equasion, and the sping is compressed that amount.
Now you can determine the open pressure.
Compress the spring an additional .060 to see if you bottom out. If you do, the spring will coil bind, and is useless.
Without the above info, you are spinning your wheels.
Since you can't put the toothpaste back in the tube, you have to figure it out, or swap cam, lifters, and springs back to stock.
You need to know:
The installed height you currently have.
A valve spring mic is a handy way to measure the distance from the top of the seat, to the bottom of the retainer. Once that is determined, you can take the spring to a machine shop that has a spring tester. He can then determine closed pressure. The valve lift is then added to the equasion, and the sping is compressed that amount.
Now you can determine the open pressure.
Compress the spring an additional .060 to see if you bottom out. If you do, the spring will coil bind, and is useless.
Without the above info, you are spinning your wheels.
We're doing something now!
