valve lash q's

[396_WAYS_TO_SPIT]

I know that its EO/IC to set them. My question is that say if you pull all the rockers off and start from scratch. Where do you start with the polylocks? Do you put them on hand tight? How do you get an accurate setting to know when they are about to open or close. to set them?
Also, when you set them cold how much will that affect the actual setting when they heat up? I have heard that your supposed to set them 3-4 thousandths under to compensate for heat. And last but not least, If your valves are loose, how will that affect the way the motor performs? Will it hurt low end,top end or all of it......

[Fiat48]

What are we here..solid..roller..hydraulic?

[WannabeRacing]

We will need to know what the cam is. Hydraulic, roller, solid?
But the engine will grow depending on the engine. The deck height, aluminum block, aluminum heads? ETc.
A standard iron headed 9.8 deck height will grow about 3 to 4 thou.
Aluminum heads will grow more. Maybe 5 to 7 thou
Cast aluminum block in a 10.2 will grow with aluminum heads over 10 thou.
Billet blocks grow about half of the standard cast blocks.
So, there is some basic and general info on growth of blocks from dead cold to running temp.
The rest, We have to know what cam you are running.

[GofastRacer]

I know that its EO/IC to set them. My question is that say if you pull all the rockers off and start from scratch. Where do you start with the polylocks? Do you put them on hand tight? How do you get an accurate setting to know when they are about to open or close. to set them?
Also, when you set them cold how much will that affect the actual setting when they heat up? I have heard that your supposed to set them 3-4 thousandths under to compensate for heat. And last but not least, If your valves are loose, how will that affect the way the motor performs? Will it hurt low end,top end or all of it......
All I do is rotate the motor and watch the pushrods drop and when they quit moving I run the polyloc by hand to zero and back off a hair, then I'll go ahead and do the adjustments(same applies for solid or hydraulic)!....
With Iron heads I just set them according to the timing ticket or whatever seems to work best for my application. With aluminum heads I go by the MFG's recomondation usually subtract .004!..
As far as performance with lash goes, the tighter the lash the more lift and duration and vice versa. The MFG gives you a general setting but there are a lot of variables in the motor that dictates the best lash for a particular application!..

[Fiat48]

That is not an acceptable answer. Surely you can make this more difficult or at least act like it is a pro stock secret.

[Cheap Thrills]

I know that its EO/IC to set them. My question is that say if you pull all the rockers off and start from scratch. Where do you start with the polylocks? Do you put them on hand tight? How do you get an accurate setting to know when they are about to open or close. to set them?
Also, when you set them cold how much will that affect the actual setting when they heat up? I have heard that your supposed to set them 3-4 thousandths under to compensate for heat. And last but not least, If your valves are loose, how will that affect the way the motor performs? Will it hurt low end,top end or all of it......
As usuall there is more than one way to skin a cat but the cat isn't going to be happy with any of them. :D
I set the polylocks as tight as they would be for final adjustment. If you just set them hand tight with the correct clearances chances are the clearance will change when you tighten them up to final tourque.
If I'm setting valves from scratch I rotate the engine until the intake closes at the beginning of the compression stroke and then set the exhaust. Then rotate the engine until the exhaust just starts to open and adjust the intake side.
Like the other post stated the composition of the heads/block has alot to do with the clearance differences cold Vs. hot.
I am of the opinion that if the valves are set loose will have an affect on overall performance. compression is lowered due to the valves closing sooner and opening later and may distort the valve stem and rocker due to hammering instead of pushing.
Not the Gospel just my nickle's worth.
C.T. :wink:

[GofastRacer]

That is not an acceptable answer. Surely you can make this more difficult or at least act like it is a pro stock secret.
LMAO, yes I could but I don't want to be accused of causing severe brain damage at a later date!.. :D :D

[396_WAYS_TO_SPIT]

Ok here's a few specs.....
454/30 over/ 12.5-1 comp/solid flat tappet 258@.050,108 lobe,.615 lift
block has been decked/ slugs are .005 in the hole(almost "0" decked)
Heads milled 108cc closed chambered "old school" irons
I am just trying to get a better understanding on valve lash. My motor ran good all year last year(thanks to alot of people in here;)) I am getting ready to fine tune it and want to try to get as accurate as possible. Im all ready for info;) Lets hear it fellas.......

[396_WAYS_TO_SPIT]

All I do is rotate the motor and watch the pushrods drop and when they quit moving I run the polyloc by hand to zero and back off a hair, then I'll go ahead and do the adjustments(same applies for solid or hydraulic)!....
Ok thats one answer that I was looking for;)
With Iron heads I just set them according to the timing ticket or whatever seems to work best for my application. With aluminum heads I go by the MFG's recomondation usually subtract .004!
So the lash doesnt change when an iron headed mill gets how???:confused: Just trying to understand. A few people have told me that iron will "grow/change". When I set my lash cold, I have noticed that when I check them they are usually .002-.004 looser after the motor has been run. Then again this number comes after the motor is cool.
As far as performance with lash goes, the tighter the lash the more lift and duration and vice versa. The MFG gives you a general setting but there are a lot of variables in the motor that dictates the best lash for a particular application!..
I would love to hear some of the variables. Im not trying to be a smartass. I really just want to learn and hopefully teach someone else in the futrue thats in my shoes:cool: Thanks again for taking the time to answer some of my stupid q's fellas;);)
396

[GofastRacer]

So the lash doesnt change when an iron headed mill gets how???:confused: Just trying to understand. A few people have told me that iron will "grow/change". When I set my lash cold, I have noticed that when I check them they are usually .002-.004 looser after the motor has been run. Then again this number comes after the motor is cool.
Everything grows when hot, irons included but aluminum grows even more and the lash will end up way off from the initial settings, not to mention things could get tight!..If you set the lash cold and run the motor and check the lash after the motor is cold, it should be the same, unless it's a brand new flat tappet and that's after break in, sometimes it will change!.
I would love to hear some of the variables. Im not trying to be a smartass. I really just want to learn and hopefully teach someone else in the futrue thats in my shoes:cool: Thanks again for taking the time to answer some of my stupid q's fellas;);)
396
Well to make this simple, anytime you change lash or advance or retard cam timing, the timing events change from what your timing ticket says, and when you change timing events you move the power and torque around. Where the ultimate comes in can depend on head flow induction and the vehicle itself, where do you need the power and torque, low, mid or upper rpm range!.. An example, same motor no changes, I took it out of a lightweight boat and put in a heavy boat, with some playing around found out that the motor liked the cam 2 degrees advanced and .002 tighter lash on the intake. Now that I got injectors on it I plan on doing some tweaking and see if it likes something different!.. Hope this all made sense, I could get more technical but I have a hard time tranferring it to the fkn keyboard!..

[Fiat48]

I will add.
Playing with lash is good for testing...but getting tighter than .020 or looser than .035 is not good for prolonged running. I am talking roller here.
During a camshaft development deal I was doing it was necessary to have an intake lash at .010 for a run for some data. We got the data but cost a broken lifter bore in the block.
On moving camshaft phasing I found 2 degrees really not enough to feel. 4 degrees you could feel. 6 degrees and general performance all over fell off for the given camshaft.
And many cam grinders..especially Crane are prone to put advance in the camshaft. They do this because people tend to buy too big a cam in the first place and low end performance suffers.
That's why most cam grinders tend to suggest a smaller cam than your buddies do.

[GofastRacer]

Wow .035, I don't even like .010 LOL!...
I talked to a "tech" at Crane a while back and he told me they put advance in to componsate for chain stretch, since I run a gear drive guess 2 degrees would make a difference!.. Makes sence on people buying too big a cam though!..

[Fiat48]

3 roller grinds I know of and have used have 5 degrees advance in them.
Why I ran the lash where I did you will understand when you get that loaner spool back.

[396_WAYS_TO_SPIT]

Now its making more sense to me. When I called claysmith about this cam he told to run it straight up. That was after I gave him all of my info. Now Im still stuck to where I should run the lash. The cam card states .024 whould it be ok to run it at .022??

[GofastRacer]

3 roller grinds I know of and have used have 5 degrees advance in them.
Why I ran the lash where I did you will understand when you get that loaner spool back.
At the time I didn't ask about a roller, this flat I had they said 2 degrees???...
I'll be watching for it!..

[GofastRacer]

No its making more sense to me. When I called claysmith about this cam he told to run it straight up. That was after I gave him all of my info. Now Im still stuck to where I should run the lash. The cam card states .024 whould it be ok to run it at .022??
That's where the fun comes in, try it and see what happens. Mine said .026 across, I tried different settings and .024 and .026 seems to work the best!..

[396_WAYS_TO_SPIT]

That's where the fun comes in, try it and see what happens. Mine said .026 across, I tried different settings and .024 and .026 seems to work the best!..
What did you notice when you set them like that?? Low,mid or top end? More rpm???

[esabataj]

Sup 396
Long time no talk to buddy.
When I set my motor up and had a custom grind Solid flat tappet done for my 521, we specked it out for running the bottle. Adj specs on this tight clearance cam was .014 to .016. Fine tuning showed that running with out the bottle, the motor likes it best at .022-.024. Backed up by GPS numbers. My conclusion is that by shedding a little duration by opening up the lash, the motor makes more power. We added duration on the exhaust profile for when running the bottle and it's probally a little too much when N/A. Been playing with this all summer and notice no adverse affects from the extra clearance.

[WannabeRacing]

We have to look at the acutal happenings inside the engine. First of all, and most important on this deal, the valve does not just close. They bounce shut. (Thank spintrons and high quality video cameras for this info.) With medium spring pressures on a steel valve BBC at 2.25, they bounce seven times before they are shut for good on that cycle. The bounces just get smaller until it is closed. Now, when the lash is too tight, the valve will bounce back open (especially the first bounce) and crash the rocker arm and through the pushrod, lifter and cam. Not only does this create harmonics that WILL rob power, but this is hard on parts. (Can even blow out a lifter bore when the pressure comes down and crashes the cam. Energy has got to go somewhere.) Then you look at the other end of things. When the lash is too large, you get a bigger running start on the lift from the cam to slam against your parts when they engage. This is hard on parts.
Yes, tightening up the cam will make it that touch bigger, and loosening will make it smaller, but only to a point. Do not run less than .022 if you have steel valves. Preferably .024. (There is a reason the cam companies give you numbers in the .024-.028) And I cannot see a reason to run more than about .032.
Now, timing a cam will make some differences. WOW!!!

[396_WAYS_TO_SPIT]

We have to look at the acutal happenings inside the engine. First of all, and most important on this deal, the valve does not just close. They bounce shut. (Thank spintrons and high quality video cameras for this info.) With medium spring pressures on a steel valve BBC at 2.25, they bounce seven times before they are shut for good on that cycle. The bounces just get smaller until it is closed. Now, when the lash is too tight, the valve will bounce back open (especially the first bounce) and crash the rocker arm and through the pushrod, lifter and cam. Not only does this create harmonics that WILL rob power, but this is hard on parts. (Can even blow out a lifter bore when the pressure comes down and crashes the cam. Energy has got to go somewhere.) Then you look at the other end of things. When the lash is too large, you get a bigger running start on the lift from the cam to slam against your parts when they engage. This is hard on parts.
Yes, tightening up the cam will make it that touch bigger, and loosening will make it smaller, but only to a point. Do not run less than .022 if you have steel valves. Preferably .024. (There is a reason the cam companies give you numbers in the .024-.028) And I cannot see a reason to run more than about .032.
Now, timing a cam will make some differences. WOW!!!
That makes perfect sense! My cam card doesnt give a variable. It only states .024, so I called clay smith and he is at lunch. I am waiting for him to return to get a better answer.I will post what the actual cam grinder says;) This is some great info fellas. I really appreciate the time you guys are taking to post;)
396

[WannabeRacing]

All numbers will be at operating temperatures. That is standard.
So if you engine grows 3 thou, set them at .021 cold.

[GofastRacer]

What did you notice when you set them like that?? Low,mid or top end? More rpm???
In my application it helped the torque curve all the way thru the rpm range, but that has nothing to do with your application, you need to experiment!..

[GofastRacer]

My cam card doesnt give a variable.
Cam cards never give variables because it don't know anything about your motor or application. Specs on a card is a general,(mostly for liability) install it according to the specs and it will run without problems, even the specs on spring pressures(on flat tappets)are low, final tuning is up to the owner!..