65CC heads and .600 lift cam clearance?
12-31-2017, 12:28 PM
#41
"There's battle lines being drawn, Nobody's right if everybody's wrong"
Buffalo Springfield
It doesn't matter at what point a piston to value clearance issue may occur. A measurement is made by making a full rotation for all the obvious reasons. Anyone only measuring at TDC is doing it wrong. If a valve interferes with the piston it is bad and doesn't matter at what degree it occurs.
Buffalo Springfield
It doesn't matter at what point a piston to value clearance issue may occur. A measurement is made by making a full rotation for all the obvious reasons. Anyone only measuring at TDC is doing it wrong. If a valve interferes with the piston it is bad and doesn't matter at what degree it occurs.
12-31-2017, 12:33 PM
#42
On The Tree
iTrader: (22)
Join Date: Oct 2009
Location: Merritt Island, FL
Posts: 191
Likes: 0
Received 0 Likes
on
0 Posts
Correct, not BDC but also not necessarily at TDC (0 degrees). As you pointed out the cam degree is the main factor so a rotation is necessary. A sufficient rotation to cover all the degrees of both intake and exhaust valve occurances. We are talking about the same thing.
Last edited by Duntov1967; 12-31-2017 at 12:39 PM.
12-31-2017, 12:39 PM
#43
Splitting hairs over something like tdc though is exactly why this conversation has gone the way it has. Measuring at tdc whether incidental or on purpose happens nearly every single time unless you get valve hitting piston before then. If you do, you adjust and would still likely roll through it after just to make sure of your clearance. You've gotta roll through it to check ptv on the exhaust also so its a moot point there.
12-31-2017, 12:43 PM
#44
On The Tree
iTrader: (22)
Join Date: Oct 2009
Location: Merritt Island, FL
Posts: 191
Likes: 0
Received 0 Likes
on
0 Posts
Splitting hairs over something like tdc though is exactly why this conversation has gone the way it has. Measuring at tdc whether incidental or on purpose happens nearly every single time unless you get valve hitting piston before then. If you do, you adjust and would still likely roll through it after just to make sure of your clearance. You've gotta roll through it to check ptv on the exhaust also so its a moot point there.
12-31-2017, 12:45 PM
#45
Splitting hairs again and arguing semantics doesnt fix your contradiction. Nor does it fix the fact that you cannot grasp lobe design or include ANY OTHER CAM MEASUREMENT besides lift. You fail to realize that MAXIMUM lobe lift doesnt translate to lift gained at every other duration point AND that you can have MORE lift, but the same or better PTV.
Besides you are wrong on the "one at a time please" scenario of the 0 deck block. I had the cam advanced 15 degrees on the 0 deck block. It has less PTV. You did not ask enough questions and your ignorance failed you.
So clearly you need to step back and cool your temper and learn instead of preach.
You are only showing how short tempered and short sighted you become when challenged by even the tiniest bit.
Besides you are wrong on the "one at a time please" scenario of the 0 deck block. I had the cam advanced 15 degrees on the 0 deck block. It has less PTV. You did not ask enough questions and your ignorance failed you.
So clearly you need to step back and cool your temper and learn instead of preach.
You are only showing how short tempered and short sighted you become when challenged by even the tiniest bit.
Lift vs Deck height is semantics now? There's a reason I specified "If all other variables are the same other then the pistons." Clearly they weren't. Why are you using that to try to prove something?
YOU need to learn when to shut your mouth. I'm embarassed you're a sponsor's tech person.
12-31-2017, 01:05 PM
#47
Your "i can only argue one at a time" vs your "Lift directly determines PTV, at any point in the cam's rotation, period" vs your "no one said x less ptv everywhere due to y lift" should be contradictory proof enough. And your simple math skills of .070 - .050 = .015 or less.
You should be embarrassed to claim you know more than anyone. And that your tunnel vision resorts to blanket statements with exceptions and ridiculous name calling.
You can go argue with a wall and call it names now and blast racial slurs at it and pettily demean it. Youll clearly win there.
You should be embarrassed to claim you know more than anyone. And that your tunnel vision resorts to blanket statements with exceptions and ridiculous name calling.
You can go argue with a wall and call it names now and blast racial slurs at it and pettily demean it. Youll clearly win there.
12-31-2017, 01:21 PM
#51
10 Second Club
Valve to piston clearance at TDC is called valve drop. This can be a useful number but actually doesn’t tell you your PTV clearance as your Cam specs likely don’t achieve maximum lift at TDC.
A smarter man that I can use the valve drop number and the Cam specs to tell you if you’re likely to have PTV issues.
But in the end it’s always prudent to check your PTV regardless
A smarter man that I can use the valve drop number and the Cam specs to tell you if you’re likely to have PTV issues.
But in the end it’s always prudent to check your PTV regardless
12-31-2017, 01:27 PM
#52
On The Tree
iTrader: (22)
Join Date: Oct 2009
Location: Merritt Island, FL
Posts: 191
Likes: 0
Received 0 Likes
on
0 Posts
Correct. It only shows clearance at 0 degrees. That is why using the term TDC in one's explanation to determine absolute PTV is articulated incorrectly and can be unhelpful and confusing to someone in the learning curve.
12-31-2017, 01:58 PM
#55
Its easy to be hard headed. Call a spade a spade. I can be abrasive, but most of the time text and the internet do not convey what is really meant. That should be a given in todays society by now though.
Talking to someone on the phone is often more productive and less feelings get stepped on.
Its not that i dont underatand what the other guy is trying to say and what his point is. It is that he is grossly oversimplifying it to the point where he cannot explain it clearly without resorting to belittlement and name calling.
My point of working from the bottom up is clearly the inverse operation of working from the top down and shows the hypothesis of just lift effects ptv is wrong. The same can be said if you were to recess the valves or use a different head or even flycut the pistons or even use a thicker gasket or mill the heads. The lift would be the same but the ptv would be different. Those are all other scenarios.
What he is trying to say is, if you retard or advance a cam to fix a ptv issue that you are, in excruciatingly simplest form, only combatting lift.
But if the true is the same from the top down then it is the same from the bottom up. That is clearly why you will hardly ever find exactly the same ptv measurement using the same cam in 2 separate ls1s for example. Its not just about lift.
Talking to someone on the phone is often more productive and less feelings get stepped on.
Its not that i dont underatand what the other guy is trying to say and what his point is. It is that he is grossly oversimplifying it to the point where he cannot explain it clearly without resorting to belittlement and name calling.
My point of working from the bottom up is clearly the inverse operation of working from the top down and shows the hypothesis of just lift effects ptv is wrong. The same can be said if you were to recess the valves or use a different head or even flycut the pistons or even use a thicker gasket or mill the heads. The lift would be the same but the ptv would be different. Those are all other scenarios.
What he is trying to say is, if you retard or advance a cam to fix a ptv issue that you are, in excruciatingly simplest form, only combatting lift.
But if the true is the same from the top down then it is the same from the bottom up. That is clearly why you will hardly ever find exactly the same ptv measurement using the same cam in 2 separate ls1s for example. Its not just about lift.
Last edited by tech@WS6store; 12-31-2017 at 02:11 PM.
12-31-2017, 02:07 PM
#56
On The Tree
iTrader: (22)
Join Date: Oct 2009
Location: Merritt Island, FL
Posts: 191
Likes: 0
Received 0 Likes
on
0 Posts
Its easy to be hard headed. Call a spade a spade. I can be abrasive, but most of the time text and the internet do not convey what is really meant. That should be a given in todays society by now though.
Talking to someone on the phone is often more productive and less feelings get stepped on.
Talking to someone on the phone is often more productive and less feelings get stepped on.
12-31-2017, 03:07 PM
#57
When I did my PTV measurements, my tightest clearance was at 10 degrees after top dead center with the intake valve (.040"). Even though my cam was a 112 LSA, my intake centerline measured at 105 degrees. I retarded the cam using a 4 degree sprocket which ended up actually retarding me 5 degrees. Doing this my minimum intake PTV occurred at 10 ATDC (.070"). THis tightened up my exhaust PTV (.112" at 10 BTDC from .150") but was acceptable.
Bottom line: Take the extra time to check it and then you have nithing to worry about.
Bottom line: Take the extra time to check it and then you have nithing to worry about.
12-31-2017, 03:35 PM
#59
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,452
Received 1,852 Likes
on
1,152 Posts
Originally Posted by tech@WS6store
Its easy to be hard headed. Call a spade a spade. I can be abrasive, but most of the time text and the internet do not convey what is really meant. That should be a given in todays society by now though.
Talking to someone on the phone is often more productive and less feelings get stepped on.
Its not that i dont underatand what the other guy is trying to say and what his point is. It is that he is grossly oversimplifying it to the point where he cannot explain it clearly without resorting to belittlement and name calling.
My point of working from the bottom up is clearly the inverse operation of working from the top down and shows the hypothesis of just lift effects ptv is wrong. The same can be said if you were to recess the valves or use a different head or even flycut the pistons or even use a thicker gasket or mill the heads. The lift would be the same but the ptv would be different. Those are all other scenarios.
What he is trying to say is, if you retard or advance a cam to fix a ptv issue that you are, in excruciatingly simplest form, only combatting lift.
But if the true is the same from the top down then it is the same from the bottom up. That is clearly why you will hardly ever find exactly the same ptv measurement using the same cam in 2 separate ls1s for example. Its not just about lift.
Talking to someone on the phone is often more productive and less feelings get stepped on.
Its not that i dont underatand what the other guy is trying to say and what his point is. It is that he is grossly oversimplifying it to the point where he cannot explain it clearly without resorting to belittlement and name calling.
My point of working from the bottom up is clearly the inverse operation of working from the top down and shows the hypothesis of just lift effects ptv is wrong. The same can be said if you were to recess the valves or use a different head or even flycut the pistons or even use a thicker gasket or mill the heads. The lift would be the same but the ptv would be different. Those are all other scenarios.
What he is trying to say is, if you retard or advance a cam to fix a ptv issue that you are, in excruciatingly simplest form, only combatting lift.
But if the true is the same from the top down then it is the same from the bottom up. That is clearly why you will hardly ever find exactly the same ptv measurement using the same cam in 2 separate ls1s for example. Its not just about lift.
12-31-2017, 03:37 PM
#60
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,452
Received 1,852 Likes
on
1,152 Posts
Originally Posted by Aston Tibs
When I did my PTV measurements, my tightest clearance was at 10 degrees after top dead center with the intake valve (.040"). Even though my cam was a 112 LSA, my intake centerline measured at 105 degrees. I retarded the cam using a 4 degree sprocket which ended up actually retarding me 5 degrees. Doing this my minimum intake PTV occurred at 10 ATDC (.070"). THis tightened up my exhaust PTV (.112" at 10 BTDC from .150") but was acceptable.
Bottom line: Take the extra time to check it and then you have nithing to worry about.
Bottom line: Take the extra time to check it and then you have nithing to worry about.