Well I need some help and opinions on my head/cam install. Cam is installed on 110 degree centerline per the cam card. We even measured valve lift at the rockers and it came in just under .600 like it should. Heads are new TFS 215's milled by TEA to 61cc. For the mock up we bolted down my old GM MLS gasket. Problem is that we are checking PTV with a dial indicator and getting .040. (indicator is counting backwards)

Below are the pictures and I need some HELP and ideas!!!

Cam card



Degree wheel position



Tightest intake valve clearance point



PTV measured




Any ideas on what may be wrong? Everyone said PTV with this setup should be fine!!!

 

First, since you are set up, double check your 0.050" opening and closing on the cam (at 6 and 46 degrees per the card).

Also, what pushrods are you using, it should be the adjustable on a solid lifter with zero lash.

Also, double check with clay. One thing you will find is clay will give you a slightly larger number. The dial indicator method, due to the very light springs, tends to be very conservative.

 

Bob, thanks for the help! Checked with clay and got .085 but using old lifters - not sure if the checking springs will compress them. Pushrods used are the stock ones - I don't have the new ones yet till I measure!

 

Verne,

If the rocker/pushrod is not at zero lash, you may be holding the valve open some and getting a false reading (not enough clearance). If using check springs, use the adjustable pushrod and adjust to zero lash on base circle, then re-check. Don't be surprised if you come up a little tighter than the clay is giving you.

 

Id like to check out your car sometime if i ever make it over that direction!

 

Checked the intake valve events at .050 and we are ok there. I am pretty confident in the cam install. We even degreed it a few times to be sure! I don't see how the pushrods could be affecting it. They don't appear to be holding the valve up at all. Is it possible that the rockers even though 1.7 ratio are opening the valve too quick at the start? Or, could my heads be milled more than reported? I will be making some calls to Jesel & TEA on Monday and hope to get some ideas!!!

 

your heads will have a number stamped on them...i gave my number to TEA and they pulled my work order...indeed they were 61cc .015-.018 mill
try and get a solid lifter in there....and/or cc the head your self
i didnt check mine...i only calculated it via head specs (intake and exhaust valve drop)
piston out of the hole, gasket thickness and cam lift.
PatG and myself calculated this, also calculated with Geoff at engine power systems (geoff cofounder of thunder racing), as well as gave the spec to TEA to confirm PTV clearance...got me worried now

 

When I ran into problems I thought of you.
Didn't want you to have problems with your new cam!
I could be messed up somewhere but so far everything checks out. We checked the the cam events with a cam checking tool and a dial indicator.

Comp Cam #4925 checking tool pictures:

 

Are you using a solid lifter? The lifter will hold the valve open if you are not at zero lash on the cam base circle. I am not convinced you have an issue with the setup.

 

No, I don't have a solid lifter for checking PTV. I guess I can try and make one on Monday using an old lifter if needed. It sure didn't seem like the valve moved or was being held open. May try and get a piece of plexiglass when I run to the airport in a few minutes and rough check head cc later tonight.

FYI - when we degreed the cam with the hex adjust it ended up that we had to retard the bushing by 1/2-1 degree or so.

 

Using a hydraulic lifter and a standard pushrod may be the problem. If you don't have a solid lifter, then use the adjustable and set to zero and re-measure. Just gently lift the rocker at the pushrod side each time to make sure the plunger isn't depressing and skewing the measurement.

 

The lifters/pushrods are NOT holding the valve open. We verified this repeatedly by removing/reinstalling the rocker arm with zero movement of the valve (when on the base circle with the valve closed). We were testing this with his stock pushrods, which if anything, are about .100" short for the TFS heads. And if we were preloading the lifter (doubtful with the checker springs), that would mean the actual p/v would be even tighter than what we were seeing, no?

The clearance at TDC is fine. We verified the .050" IVO lobe check @ about 6* BTDC which agrees with the cam card.

The clearance is tightest at about 10* ATDC, as the intake valve is chasing the piston down. It is at that point we can only get about .040" of valve drop before it contacts the piston. We tried this setup a few times, tryed the clay, and tried this setup again, and the results are repeatable every time. The clay did give us a little better indicated clearance, but just looking at the imprint, it still seems way tighter than it should be.

As I left today, I advised Verne to try the same test with his stock LS6 heads, just to see how different the results are. If it gets noticeably better, then we can look at the heads as suspect. If not, then it would point to the cam...but we verified the degree and correct ICL numerous times today....we were getting good, accurate, and repeated readings.

The other thought is maybe the rockers...can also try the same with the stock, and YT rockers to see if there's any variance in how quickly the rockers open the valve off the seat.

Those are about the only variables I can see left that could cause this.

 

side note...just comparing to my cam card...my duration at .006 lift is the same split as it is at .050 lift...yours is 4 degrees at .050 and 8 degrees at .006
what lobes are those? xer intake and xe exhaust?
also on my row that says Grind numbers at the end mine says 111+3....yours just says HR113
not sure what im getting at but every cam ive had that had advance ground in had it listed there...now on down i see it says to be installed at 110...i am cam stupid but maybe your cam doesnt have the advance built in and youre advancing it (degreeing it in at 110 if say it was ground on a 113...which i think would lessen your PTV clearance...heres my cam card...notice splits are the same at .006 and .050....again just pointing this out...i have no clue what it affects...but if someone knows i'd like to know why this is
also look at my grind number it shows +3
where'd you buy your cam?

 

Intake lobes are XER and exhaust are Cheater HR. Bought my cam from TEA with the heads and they had it dropped shipped directly from Comp Cams. I will be asking TEA for help tomorrow along with trying to make a solid lifter I guess. Why doesn't someone just make an inexpensive one for LS engines?

 

Well decided to rough check heads cc to eliminate a gross error there. Heads are supposed to be milled to 61cc.
Here is my setup:




Filled medical syringe to exactly 60cc (didn't have any food coloring!)



Almost filled




All done with 60cc emptied from the syringe




The heads were level and the chamber was filled till it started to just barely seep a little under the edges of the plexiglass. My conclusion is the heads are close to 60cc but no less than that. I could not get another 1 cc into the chamber - I tried with a 10 cc syring and it started to come out of the hole! Looks like the heads are close to spec....maybe a hair under at worst!

 

Yes, that's why I mentioned it. Depending on the lifter being used it can happen. When my Morels were new out of the box, the plunger was very easy to depress and were very hard to "feel" when I was adjusting my fully adjustable rockers and the check springs would compress the plunger as well. I was actually very surprised how easily they depressed.

Mine was slightly before that, but my ICL is different than this cam. I did see a difference between the clay and the dial indicator but the two numbers were not as far apart (unless they are closer than 0.040" and 0.085" as Verne mentioned in earlier posts).


Yes, not sure how quickly the Jesel's come off the seat. If they are like Crane that may be a contributor, not sure how much.

How was the exhaust side?

Other option would be to retard the cam a couple of degrees and see how that affects clearance but the ICL won't be as designed.

 

The first time we clayed it, we did it on the # 3 cyl with the normal dual valve springs. Like Verne said, we got a pretty light imprint and generous reading from the clay. I also told him, because of the springs, at that point the lifter would compress and would definitely alter the readings. That is where you really need the solid lifter to give you a true reading.

Then, as I thought about it more...the springs shouldn't matter for the purpose of the clay check, so we then clayed the #1 cyl with the checker springs., and the clay imprint was noticeably deeper and clay thinner than what we saw on #3...proving that yes, we did compress the lifter when subjected to full spring pressure clay test, and two, that our dial-indicated valve drop readings were of some merit. The clean clay imprint we got on the #1 cyl was what I considered still too close, just by looking at it.

Getting a good measurement off the clay imprint is so difficult, because the valve hits at such an angle, you're basically trying to measure the thickness of a tapered point....But it doesn't take much of a trained eye to simply see the difference between .040" and .080" thickness.

It was much easier to measure the clay when I did mine, because I flycut, and the valve was landing in the pocket that was cut at the same angle, which left the imprint thickness parallel and easy to mic.


Exhaust side seems plenty fine (by feel)...but we haven't put the indicator on it yet. Kinda been focused on the disappearing clearance on the intake side so far.

 

I guess I should add to that statement by explaining how we were doing this.

Verne was slowly spinning the crank over, while I was constantly depressing the rockers down to see where the valve hit while it was going through it's normal cycle. On both sides, there is a very narrow window where clearance goes from huge to little....on the exhaust side, at any given point, I don't think I "felt" less than .100" of travel at any degree of engine rotation.

The intake side is obviously getting tight. At 10* ATDC, the intake valve is naturally partially open, but pushing the rocker (and valve) down to the piston at that point is like almost nothing...The piston is right there, .040" away.

 

I'm not surprised you have to cut the pistons?Just did a close setup with 60cc TFS,stock gasket and a higher lift 230/236 on 113 +2 and it had about .090 which is borderline.So a slower ramp 232 installed on a 110 would definitely get the intake reliefs cut.
On a side note we have run as close as .040 on the intake valves before but the springs can not float.

 

I hate to say this, but it seems you're making it way more complicated than is needed. My older TFS heads require a 7.9" PR, and the newer ones use a 7.5" IIRC. I'm not ****, but cautious, and as per instructions over @ LS1tech, from lots of guys that've done this, I just installed the cam dot-to-dot. No problems after many times @ 6900. I believe you're just worrying about nothing.