Piston to Valve Clearance

[g8_795]

So I have my car all ready to fire up but I am chicken since I don't believe I have enough PTV clearance. Can some of you engine builders chime in here?

Here is my concern:
I have a much weaker spring on my number one cylinder right now to try to measure the PTV. The spring is strong enough to keep the valve closed, but to weak to load the lifter. With NO load on the lifter, I get a collision between the valve and the piston. If I put a little load on the lifter with my finger pushing down on the top of the rocker arm, I can clear the piston with no problem.

Is this the way this is suppose to work?

I have tried two different push rod lengths and here is what I am measuring:
PR #1
length: 7.425
Measured preload: 0.100
Turns to torque from no lash: 1-3/8

PR #2:
length: 7.375
Measured preload: 0.054
Turns to torque from no lash: 0-15/16

Will the lifter ever get "longer" then what is on the preload?

Any insight will help.

I WANT TO FIRE THIS THING UP!!!!!

I have searched online every where and it seems like the PTV clearances should be measured unloaded. I did find on a FORD site that the lifter SHOULD be loaded. I chalked that up as just being a FORD site.....

Thanks,
Robert

[Andy@Livernois]

Sorry I didn't get back to you through email... For some reason its been acting up all day. I have been talking to Tim in the shop and he said something seems off. We have never had a PTV issue with this camshaft, and we generally verify with a checking spring as well (no load on lifter) my initial reaction is it's not safe enough clearance off of everything we have checked, but it should be enough off of everything we have done in house...

[g8_795]

I am already bumping this.

I want to fire it up tonight without :poof:

Thanks.

[g8_795]

Here is the Cobra link regarding PTV clearance.
http://www.cobraclub.com/forum/engine-tech-tips-questions/28263-valve-clearance.html

I think I am going to fire it up.

Thoughts?

[todds87ss]

Did you have success?

[G8GT721]

any more help for this guy before he fires it up?

[g8_795]

I am going to take a few more measurements in a few minutes. I was talking with Andy over at Livernois a bit this morning.

I think the whole question boils down to whether you need the 0.080/0.100 minimum clearance with or without the load on the lifter.

Any last thoughts would be beneficial.

Thanks.

[g8_795]

Going to top off the fluids and fire this thing up.

Wish me luck.

[GRRRR8]

Going to top off the fluids and fire this thing up.

Wish me luck.

Good Luck!!

[Blackrider]

Good Luck!

[G8GT721]

good luck

[Blackrider]

Why are you making us wait this long???? You best be out enjoying it!! lol

[Mike@NewEra]

If the lifter is not loaded, you can not establish PTV clearance. In other words, you can not do this with a stock hydraulic lifter, if you are really trying to check PTV clearnace, you have to use a solid lifter with the preload figured in. Your preload on the lifter is most likely .07-.12, I'm guessing here because I don't know the exact geometry on your camshaft lobe base circle and if your heads are milled or you are using a thinner gasket. So, without the lifter getting preloaded, unless you have a ton of PTV, you will most likely hit the valve on the piston with most aftermarket camshafts trying to test it the way you are doing it.
The load will most likely not move much at all once the oil pressure is up, maybe +/- .005 at most so this should not be an issue.
One last thing to check, if you feel something might be wrong, I know it sounds crazy, but take the front apart and check your timing chain to make sure the dots are lined up if you are still using the stock set up there, so many people have made that mistake, you would be real surprised how many times I have had a car brought to me to tune clattering and this is the case. Hope these things help you out a bit!

[Blackrider]

If the lifter is not loaded, you can not establish PTV clearance. In other words, you can not do this with a stock hydraulic lifter, if you are really trying to check PTV clearnace, you have to use a solid lifter with the preload figured in. Your preload on the lifter is most likely .07-.12, I'm guessing here because I don't know the exact geometry on your camshaft lobe base circle and if your heads are milled or you are using a thinner gasket. So, without the lifter getting preloaded, unless you have a ton of PTV, you will most likely hit the valve on the piston with most aftermarket camshafts trying to test it the way you are doing it.
The load will most likely not move much at all once the oil pressure is up, maybe +/- .005 at most so this should not be an issue.
One last thing to check, if you feel something might be wrong, I know it sounds crazy, but take the front apart and check your timing chain to make sure the dots are lined up if you are still using the stock set up there, so many people have made that mistake, you would be real surprised how many times I have had a car brought to me to tune clattering and this is the case. Hope these things help you out a bit!

From the pictures in his thread the dots are lined up perfect, unless he changed something.

[Mike@NewEra]

I was just throwing that out there, it doesn't hurt to double check.
BlackBerry9530/4.7.0.75 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105

[GRRRR8]

I was just throwing that out there, it doesn't hurt to double check.
BlackBerry9530/4.7.0.75 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105

No it doesnt. I PMd him the same question earlier.

[Blackrider]

I was just throwing that out there, it doesn't hurt to double check.
BlackBerry9530/4.7.0.75 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105
Yeup, the phrase "Mesure twice, cut once" comes to mind.

"Check sprocket alignment twice, start engine once"
:)

[g8_795]

It's RUNNING!!!!

[Blackrider]

It's RUNNING!!!!

Awsome dude, good job!

[GRRRR8]

:woohoo:

[Mike@NewEra]

I had a feeling it would be soon!
BlackBerry9530/4.7.0.75 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105

[g8_795]

If the lifter is not loaded, you can not establish PTV clearance. In other words, you can not do this with a stock hydraulic lifter, if you are really trying to check PTV clearnace, you have to use a solid lifter with the preload figured in. Your preload on the lifter is most likely .07-.12, I'm guessing here because I don't know the exact geometry on your camshaft lobe base circle and if your heads are milled or you are using a thinner gasket. So, without the lifter getting preloaded, unless you have a ton of PTV, you will most likely hit the valve on the piston with most aftermarket camshafts trying to test it the way you are doing it.
The load will most likely not move much at all once the oil pressure is up, maybe +/- .005 at most so this should not be an issue.
One last thing to check, if you feel something might be wrong, I know it sounds crazy, but take the front apart and check your timing chain to make sure the dots are lined up if you are still using the stock set up there, so many people have made that mistake, you would be real surprised how many times I have had a car brought to me to tune clattering and this is the case. Hope these things help you out a bit!

Excellent. Thanks for chiming in here Mike. This is what I thought about the load. If you look all over the internet they say to run the PTV test with NO load. But that is crazy. My preload is at ~0.055. Do you think I should run with a long rod and get more preload? Without load I was ~-.007 on the exhaust.

[Mike@NewEra]

No, I wouldn't reccomend more preload, I think you will be fine with what you have. More reload will not change pts really
BlackBerry9530/4.7.0.75 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105

[-Ray-]

It's RUNNING!!!!

Awesome to here! :woohoo: