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Trying to degree - need stock #'s
https://slantsix.org/forum/viewtopic.php?t=52724		 Page 2 of 2
Author:  DusterIdiot [ Tue Jul 16, 2013 5:22 pm ]
Post subject:  Lol...
Quote:
DI I think you got some things incorrect there.ie Intake open ABDC? you also did not take the 11* from 180* as IO was ATDC.
That was supposed to be intake close not IO

Like I said in the disclaimer I typically do this in front of me 'hands on' so I can check the events as I roll the engine (so far I've seen some wobbles in Erson's lobes so the cam card numbers are off and sometimes OCG is a little short on one number or another, so I don't 100% trust the cam card), I knew something would be off, thus i asked for the backup. :lol:

-D.Idiot
Author:  robertob [ Tue Jul 16, 2013 5:32 pm ]
Post subject: 
Yes, I fixed it. Bad math. You and I both have the same numbers.

Quote:
Robertob

you posted
Quote:
Intake duration at .050 = 187 deg (180-11+2Cool
I think that should be 180-11+28 not a cool smiley!!

which is 197* !! 8)
Author:  Eatkinson [ Tue Jul 16, 2013 6:10 pm ]
Post subject: 
Quote:
So your intake lobe center line is:
IO at .050" =197*
197* /2 =98.5* will give the intake lobe center line.
Now your IO @ .050" at 11* ATDC
so add 98.5* to 11* =109.5*
Your intake lobe center line is 109.5 * ATDC.
....

Do your exhaust lobe the same way(remember the #1 exhaust lobe is at the end of bump stick)
Just measured #1 exhaust lobe. Wouldn't have, but I apparently I'm off stock figures, so I've got to figure this out.

#1 exhaust opening event: 146° ATDC (or 34° BBDC).
#1 exhaust closing event: 14° BTDC.

Are you just giving me a courtesy reminder that #1 exhaust is at the end of the cam, or is there another reason you mentioned that?

Thanks for helping me work this out, all of you.
Author:  slantsik [ Tue Jul 16, 2013 6:38 pm ]
Post subject: 
Quote:
Are you just giving me a courtesy reminder that #1 exhaust is at the end of the cam
yes.

Ok exhaust .
Assuming at .050"
EO = 34* BBDC
EC = 14 *BTDC
So 34* + 166*(180 * -14* = 166*) = 200*
Ex duration at .050 = 200*
Now find exhaust Centerline.
200* /2 =100* from either the opening or closing event working toward lobe peak.

So if we go from 34*BBDC + 100* toward TDC is 100* -34* = 66* ABDC
or 114* BTDC is the exhaust lobe centerline.
To check if correct just go another 100* toward TDC and you will end up at 14* BTDC!

So we now know
Intake duration at .050" is 197*
Exhaust Duration at .050" is 200*
remember these are not figures at the valves due to rocker ratio and other things.
We also know:
Intake centerline is 109.5* ATDC
Exhaut Centerline is 114*BTDC

OK?
Once you are ok with the above we can find the cam grind center line and compare that to TDC
Author:  Eatkinson [ Tue Jul 16, 2013 9:08 pm ]
Post subject: 
I "think" I have it. I'm following you so far. Now what?
Author:  slantsik [ Tue Jul 16, 2013 9:22 pm ]
Post subject: 
Ok now there are two TDC on a four stroke engine.
One TDC on the compression /power strokes (both valves closed)
One TDC at the end of the exhaust stroke/beginning of intake stroke.( both valves slightly open.
It is the second of these TDC's that the camshaft is ground in relation to.
So we need to find out where the cam center line is.
Image

sorry about the small pic. Try this link for a better look.(click my name at the bottom to see more pics of AP5 valiant repairs:
http://www.flickr.com/photos/brendans_pics/8449149339

The cam center line is the vertical line through the center of the cam ,at the top of the line is printed TDC.
It is this line that determines if your cam is advanced or retarded.
to find the line do this.
add Intake center line to exhaust center line
ie 109.5 +114 =223.5*
This is your Lobe Seperation Angle (LSA)
Divide the angle by 2
So 223.5 / 2 = 111.75* this is the cam center line in degrees from each lobe center line.
Now go 111.75 degrees from either lobe center line toward TDC.
Where the line ends up is where the cam is degreed to.
So if you work from the I center line at 109.5* and count toward TDC 111.75* you end up 2.25 degrees to the right of TDC.
Thus your cam is 2,25 degrees advanced.
Check back 111.75* toward TDC from the exhaust center line and you should end up at the same conclusion!
Sorry I hit the submit button earlier by accident.
Another easier way to find the cam center line is to do this:
The difference between 109.5* and 114* is 4.5*
half this is 2.25*
We can see from your lobe centerline numbers that the cam is advanced.

Brendan

Brendan
Author:  robertob [ Tue Jul 16, 2013 9:27 pm ]
Post subject: 
LSA is intake center + exhaust center / 2 or 109.5+114/2=111.75 (rounded to 112)

So the cam is designed with a 112 LSA and ground 3 degrees advanced.

Personally I would leave it right where it is. It's not a 'normal' slant cam, but it should work fine.
Author:  slantsik [ Wed Jul 17, 2013 12:02 am ]
Post subject: 
I am going to drive mine with about 2* advance ground in.
Then if I feel it needs to have more low down torque i will play with the cam timing.
I put grease on one side of my timing cover gasket ,so hopefully I can remove it easily.
I may even purchase a GTech device and play around.(GPS (10 Hz)powered dyno device.

Here is a video of the older model. the g tech is within 2 hp of mustang dyno.
http://www.youtube.com/watch?v=2Tyozgkc7dE

I will see if I can find a clip of the newer model.
Brendan
Author:  DusterIdiot [ Wed Jul 17, 2013 12:25 am ]
Post subject:  GPS unit might be better...but...
Quote:
Here is a video of the older model. the g tech is within 2 hp of mustang dyno.
I have one of those SS Gtechs and unless the pull is done on a completely level surface (kind of hard in the US as all roads are poured with a crown to allow water run off in the gutters and ditches), it won't read correctly. There was a couple of patch upgrades to the firmware and the last one required a complete recalibration of the accelerometers.

I suspect the GPS unit would would work better without the worry of road conditions. Another issue is finding a place to use it, I luckily have country roads to do speed testing at my own peril, most local authorities frown on it (speed tests conducted in my locality are now fined $5000 and they repo the car)and if they suspect the item suction cupped to the window is a fuzz buster it goes south in a hurry...make sure to check the local laws before conducting your own highway dyno test.

That cam would make a better turbo cam than an NA cam, at least it will have a smooth idle...
Author:  Eatkinson [ Wed Jul 17, 2013 12:59 am ]
Post subject: 
Wow. Thank you all for helping out. I couldn't have figured this out on my own, for sure. But that's interesting that I ended up with a 2-3° advance. Wonder how that happened? Does the cam grinder sometimes try to grind advance in, purposefully? Might my grinder have done this?

On with the build!!
Author:  slantsik [ Wed Jul 17, 2013 2:55 am ]
Post subject: 
Quote:
Does the cam grinder sometimes try to grind advance in, purposefully
Yep.
The sooner the Intake valve opens the more air/fuel is pushed in early in the intake stroke,which means the cylinder fills better at lower RPM = more torque at lower rpm.Your grinder may have put some advance in ,or It was there stock?!

One other thing you should do is put the head back on with the #1 cylinder valve train working.
Take some measurements off the valve spring retainers .
Take the lash out of the Rockers.
Do say .002" .050" highest lift .050" and .002"
then you can use the Intake valve closing point(.002") to determine your Dynamic Compression Ratio.
Skim a bit off the head to bring the compression right up :twisted:

DI
I am lucky here. I am surrounded by sugar cane fields which are flat and have 100Kph speed limits.(62Mph)
Also a freeway not far away which is 110Kph
I believe the new model can do curves for any speeds you desire, say 60-100Kph
The GPS model calculates every 1/10th of a second so should be fairly accurate but more important it should be consistent.I cant see road camber affecting it at all.
If it works as it seems ,it would be a great tuning tool.
About $200 + post to find out.
My first experiment would be to remove the air filter and should see about a couple Hp difference.
I believe It was you who informed me of the device in another thread a while ago?

Brendan
Author:  DusterIdiot [ Wed Jul 17, 2013 8:40 am ]
Post subject:  Yep...
Quote:
I believe It was you who informed me of the device in another thread a while ago?
Quite a few years ago the first gen ones were on e-bay for $80, i think Lou and couple others bought them and tryed them out. I had plunked for the pro version that allowed a download of the run so you could watch the curve and see the shift points and modify driving style. It worked OK, but as always you have to find a good road without interference or slope. The GPS version should be able to compensate for it and give a much more accurate reading without the need to recalibrate the unit.

-D.Idiot
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