Page 1 of 2 12 LastLast
Results 1 to 20 of 26

Thread: Can timing

  1. #1

    Can timing

    I have myself the tuning school book. But from what I read where do you get you numbers from. It?s giving you a example of a stock cam. But I Have a comp270 cam with a 7 degree limiter. Where and how do I get my numbers from to plug into there spread sheet to dial in this cam. I?m lost and need some serious help. Someone teach me like I?m a 12 y/o

  2. #2
    Senior Tuner
    Join Date
    May 2015
    Posts
    1,864
    So heres how it all works...the VVT part of your tune does not care or know that you have installed a different than stock cam. The camshaft position sensor gets its reading off of the reluctor wheel that is part of the cam timing chain, which you have not changed. When your motor, or any motor, is in time and properly setup, the exhaust cam position will read 120 degrees as its centerline. From there, a stock phaser has a total of 28* of movement, 14 degrees advance and 14 degrees retard from the stock 120 degree location. In your case you installed a limiter and now only have 14 degrees of movement. Heres where it gets a little mind bendy....

    The dodge system is still a push rod, cam under head setup with ONE camshaft with both intake and exhaust "cams" on one stick, you cant move the intake side without the exhaust side moving too, its one hunk of metal. So if you tell the ECU advance the intake side 14 degrees, the exhaust side gets RETARDED by the same exact amount.

    In general, advancing the cam will provide better idle, better lower end torque. Retarding will make low end suffer but can SOMETIMES provide more upper rpm range power (past say 5500 rpms). So usually when tuning for a cam, you want max intake advance (i.e. max exhaust retard) at lower rpms and cruising areas, and then at WOT you want to retard the cam past peak torque.

    So back to the cam setup...Even the factory tune for the most part knows you should run max advance at startup, idling, and low end cruising. Max intake advance, or rather max exhaust retard, is 120 degrees plus max retard 14 degrees (your limited range), or 134 degrees. If you log your exhaust cam degree in the VCM scanner, I promise you will see 134* at idle and also if you were to just disable VVT in the tune, which results in running max advance at all times, you will see 134*.

    So now it becomes really very simple. The Exhaust Desired Angle Normal table is used for idle, cruising. With the 270 cam, you are likely going to like the car best with the entire table set to 134* across the board. I.e. max exhaust retard / max intake advance. You don't have to, but to have a "clean" tune, you would also go into the Intake Desired Angle Normal table and set this entire table to max advance. There is some math to do there, easiest is to check what the stock tune provided for Intake plus Exhaust from each table in the same cells. Likely it is 228.5* but worth checking. So if you make the entire exhaust table 134*, then the remainder of 228.5* less 134* says your entire intake table should be 94.5*.

    Same principal for the WOT tables, but here you have to interpret what is in the tune to your actual cam to understand what it is doing. Reminder, 134* is the ECU's "max retard" on the exhaust side, and therefore, using the same math of 228.5* less the exhaust, 134* and again you are at 94.5*. if you made the entire table 134* for the exhaust and 94.5* for the intake, you would be running max advance the entire time. If say you wanted to retard the cam 5 degrees, you would make the exhaust be 129* and the intake automatically becomes 99.5*. The sum of the two have to equal 228.5*. This is the logic the Tuning School spreadsheet does. You just have to start at 134* and move from there. Remember, the limiter you installed only allows 14* of total movement so you cannot move it more than that.

    Last thing to note, when you run max retard or max advance, you are going to be at "Lockpin" which then uses the VVT Lockpin timing tables. Best to make these tables and your regular timing tables the same, so as you phase the cam and move between timing tables, the ECU finds the same timing commands.
    Last edited by 06300CSRT8; 04-02-2019 at 12:35 PM.

  3. #3
    Senior Tuner
    Join Date
    May 2015
    Posts
    1,864
    Oh and once you have done all the above, you simply go back up top and fill in the Max and Min for Intake and Exhaust according to your new desired tables. For intake, most important you make the min be the lowest but you can leave the max alone (don't set both max and min to 94.5* just because the table has it). Similar for exhaust, set your max (134) but leave the stock min.

  4. #4
    Advanced Tuner
    Join Date
    Feb 2016
    Posts
    294
    The dodge system is still a push rod, cam under head setup with ONE camshaft with both intake and exhaust "cams" on one stick, you cant move the intake side without the exhaust side moving too, its one hunk of metal. So if you tell the ECU advance the intake side 14 degrees, the exhaust side gets RETARDED by the same exact amount.


    ^^
    300c is correct in that there is 1 cam...both intake and exhaust lobes are attached to this 1 stick...however if you advance the intake 5 degs, logic dictates that the exhaust advances 5 degs too.
    The confusing part is that the cam lobe centreline NUMBERS which go in opposite directions. This is because of the way this is measured relative to TDC.

    Take for example a stock 6.4L or Hellcat cam. Both have 120.5 LSA. When at 120.5 ICL, this cam is "straight up"...neither advanced or retarded, both lobes are at 120.5 CL
    Advance the cam 5 degrees, and Intake CL is now 115.5 degs, while exhaust is 125.5 degs...seems strange and takes a while to get your head around it.
    That is why at idle when it is fully advanced it will show exhaust 134ish (120.5 +14) and intake 106.5ish (120.5 -14)

    Try playing around with a cam calculator and you will see what I mean.
    When you change cams, change LSA, and change the advance ground into the cam all these numbers change.
    BUT, the PCM doesnt know that a change has been made.

    So you need to work out where the cam lobes actually ARE while being forced to retain the PCM's original number system.
    Just a matter of working backwards really...but you need to understand where both lobes are to get a good result.

    Advance down low and retard up top are kinda the principles, but it is not always as easy as that tho.
    Many other factors come into play like boost level, LSA and where you really want the intake/exhaust lobe to be.
    If you look at hellcat/demon tables, the cam is most retarded at low rpm/high load and actually is slightly more advanced as rpm increases etc...
    Last edited by Hemituna; 04-02-2019 at 10:36 PM.

  5. #5
    One other question I have is I have a jumping idle. Is it due to I went with the stock converter????

  6. #6
    Thanks for explication guys. It really helped wrap my head around. I feel like a dummy. I’ve never been much of a tuner. I’m the builder fabricator. Left that up to a friend but he’s no longer with us so I’m tryin to do all this solo these days. So any help you guys could provide would be awesome. Again thanks

  7. #7
    ve corrected -3%.hpt

    can one of you fine folks take a peak at my tune tell me what u all think...

  8. #8
    Tuner in Training
    Join Date
    Sep 2017
    Posts
    29
    So with the comp cams limiter installed you would only have 7 degs of advance or 7 degs of retard total?
    Ex . 120 icl would be 113 icl at full advance and 127 at full retard ?

  9. #9
    There we go hard numbers. Thanks

  10. #10
    Tuner in Training
    Join Date
    Sep 2017
    Posts
    29
    I'm asking a question . I'm trying to understand this too.

  11. #11
    Advanced Tuner
    Join Date
    Feb 2016
    Posts
    294
    OK, The Hemi VVT's work backwards from full advance.
    Full advance is the default/idle position and they retard from there.
    So the stock phaser can retard 14 cam degrees (28 crank degrees) and if you fit a 7deg limiter, it then limits retard to 7 cam degrees(14 crank degrees).
    Now with the stock cam we know the start position of the cam as the cam is ground with 14 degs advance and has a LSA (6.4L) of 120.5.
    So at full advance it has an ICL of 106.5 and exhaust 134.5

    Now with an aftermarket cam the LSA and cam advance are most likely now different.
    I cant remember the 270 off the top of my head but do know the 274 which is probably similiar.
    It has LSA of 116 and is ground with +3 Adv.
    So installed and at full advance this cam will have an ICL of 113....but the PCM will still use the numbers 134.5 ex and 106.5 int as it doesnt know the cam has changed.

    This cam will like to be run somewhere from 113ish to 119ish ICL so we will have to tell the PCM to keep it nearly fully advanced and retard up to max of maybe 6 degs.
    So the exhaust cam table numbers( as these are the numbers that actually control the cam not the intake numbers) will run from 134 (full adv) to 128 (6 degs retard) approx.
    This would make the intake go from 113 CL to 119 CL Actual.
    The exhaust numbers would be 119 to 113 CL Actual.

    So you can see that when swapping cams the numbers can get a little complicated.
    Hope I have explained it clearly...if not, ask away..

  12. #12
    Tuner in Training
    Join Date
    Sep 2017
    Posts
    29
    Quote Originally Posted by Hemituna View Post
    OK, The Hemi VVT's work backwards from full advance.
    Full advance is the default/idle position and they retard from there.
    So the stock phaser can retard 14 cam degrees (28 crank degrees) and if you fit a 7deg limiter, it then limits retard to 7 cam degrees(14 crank degrees).
    Now with the stock cam we know the start position of the cam as the cam is ground with 14 degs advance and has a LSA (6.4L) of 120.5.
    So at full advance it has an ICL of 106.5 and exhaust 134.5

    Now with an aftermarket cam the LSA and cam advance are most likely now different.
    I cant remember the 270 off the top of my head but do know the 274 which is probably similiar.
    It has LSA of 116 and is ground with +3 Adv.
    So installed and at full advance this cam will have an ICL of 113....but the PCM will still use the numbers 134.5 ex and 106.5 int as it doesnt know the cam has changed.

    This cam will like to be run somewhere from 113ish to 119ish ICL so we will have to tell the PCM to keep it nearly fully advanced and retard up to max of maybe 6 degs.
    So the exhaust cam table numbers( as these are the numbers that actually control the cam not the intake numbers) will run from 134 (full adv) to 128 (6 degs retard) approx.
    This would make the intake go from 113 CL to 119 CL Actual.
    The exhaust numbers would be 119 to 113 CL Actual.

    So you can see that when swapping cams the numbers can get a little complicated.
    Hope I have explained it clearly...if not, ask away..
    Good stuff very informative. I'm working with a Hellcat that I'm putting in a custom grind . It has a LSA of 123 but has 14 advance ground into it. So the installed centerline will be 109. I will be using the comp cams limiter also. . Care to elaborate on this one?

    Thanks

  13. #13
    To reply to hemituna which is a awesome screen name. The icl of the 270 is 119 degree and can be advanced 7 degree positive and negative with the cam. So I advanced full at exhaust 126 degree and 112 intake. Let me know if this is right. Also still need to find out why I jump from 900 to 1300 rpm at idle or sitting at light. I’ve adjusted the tables but still same crap. Please help??!!!!!

  14. #14
    Advanced Tuner
    Join Date
    Feb 2016
    Posts
    294
    Quote Originally Posted by Hpindy View Post
    Good stuff very informative. I'm working with a Hellcat that I'm putting in a custom grind . It has a LSA of 123 but has 14 advance ground into it. So the installed centerline will be 109. I will be using the comp cams limiter also. . Care to elaborate on this one?

    Thanks
    Fairly easy one...that is pretty much a demon cam...steal the numbers from the demon tune

    Just make the PT numbers much the same as the WOT numbers they use.

    How much bigger are the durations on this cam than demon 224/240??

  15. #15
    Advanced Tuner
    Join Date
    Feb 2016
    Posts
    294
    Quote Originally Posted by Jailhousecustoms112 View Post
    To reply to hemituna which is a awesome screen name. The icl of the 270 is 119 degree and can be advanced 7 degree positive and negative with the cam. So I advanced full at exhaust 126 degree and 112 intake. Let me know if this is right. Also still need to find out why I jump from 900 to 1300 rpm at idle or sitting at light. I’ve adjusted the tables but still same crap. Please help??!!!!!
    Do you have a pic of the cam card?

  16. #16
    I added a photo of the card
    Attached Images Attached Images

  17. #17
    Tuner in Training moparsoldier85's Avatar
    Join Date
    Mar 2018
    Posts
    33
    After reading this now I have some questions concerning if mine is even tuned correctly. I had a shop assist me tune mine and after 7 revisions being done all my cam timing is all still factory. Am I missing out here?

  18. #18
    Advanced Tuner
    Join Date
    Feb 2016
    Posts
    294
    Quote Originally Posted by moparsoldier85 View Post
    After reading this now I have some questions concerning if mine is even tuned correctly. I had a shop assist me tune mine and after 7 revisions being done all my cam timing is all still factory. Am I missing out here?
    Probably

  19. #19
    Advanced Tuner
    Join Date
    Feb 2016
    Posts
    294
    Quote Originally Posted by Jailhousecustoms112 View Post
    I added a photo of the card
    Ok, LSA is 115 with +3 adv ground into the cam.
    So with 7 (14) deg limiter, max advance puts you at 112ICL
    Max retard will be 126ICL , so as you said the mid point is 119 which is probably as far as you ever want to retard this cam.
    Now we know where the cam is, it is a matter of putting it where we want it.
    Assuming it is a 6.4, I'd start by trying 134 - 132 (0-2degs retard) in the exhaust CL table at low rpm and retard it to 129 - 128 (5-6degs retard) up top.
    Do both PT and WOT cam tables or it will be a dog at P/T.

  20. #20
    Advanced Tuner
    Join Date
    Sep 2008
    Location
    Portersville, Pa
    Posts
    282
    Quote Originally Posted by Hemituna View Post

    ...however if you advance the intake 5 degs, logic dictates that the exhaust advances 5 degs too.
    The confusing part is that the cam lobe centreline NUMBERS which go in opposite directions. This is because of the way this is measured relative to TDC.

    Take for example a stock 6.4L or Hellcat cam. Both have 120.5 LSA. When at 120.5 ICL, this cam is "straight up"...neither advanced or retarded, both lobes are at 120.5 CL
    Advance the cam 5 degrees, and Intake CL is now 115.5 degs, while exhaust is 125.5 degs...seems strange and takes a while to get your head around it.
    That is why at idle when it is fully advanced it will show exhaust 134ish (120.5 +14) and intake 106.5ish (120.5 -14)
    ..
    Important clarification and excellent explanation!
    Specializing in building and tuning 1000hp, daily driven, 9 second cars!

    www.ostdyno.com Shop Phone: 724-368-9000