Degreed My Cam

[Shelby]

this wheel i have found to be easier to read

 

http://www.26liter.us/gallery/albums/userpics/10009/degree_whl.jpg

[Shelby]

for cpmpairsion heres a 292 F card

 

http://www.26liter.us/gallery/albums/userpics/10009/292_cam_card.jpg

[Shelby]

befor you can read any numbers on your cam the degree wheel must agree 100% with the oem TDC marks on the pully and timeing cover if the pully and timeing cover are install'd , if cover is not on you must make absolutely sure the tdc point on the degree wheel is acurate

 

also keep it in mind the cam card is as view'd from behind not looking at it from the frt

and when adding up total duration you take the number BTDC 30 if 0 lift and 3 if useing the .050 point add it to 180 (1/2) wheel and add to that the number after BDC in this case 74 if useing 0 lift point or 47 if useing the .050 lift point

total duration is diff if useing .050" from 0 lash lift point but both should match the card specs for point of lift use'd

Edited November 16, 2008 by Shelby

[Shelby]

let me add here that i am far from an expert at degreeing cam shafts , what i write is what little i have learn'd on my own from doing several cams over the years,,

like most things this and most every thing else can be done in more then one way,,if you have a simpler or better way by all means use your way, and share it with the rest of us , no one is gona hurt my feelings by offering a better way or correcting me when i state some thing that don't work or is simply wrong

[psu_Crash]

I do get exactly 230 duration at .050 cam lift. So that is encouraging.

At .050 cam lift I should be at 1 degree BTDC right?

I am assuming that is what the right picture is for.

I just realized that is probably what it is telling me.

I will check it out tomorrow morning again.

I have to tell you I had no idea how much of a PITA this was going to be.

Words cannot express how helpful you have been Shelby!

 

I will let you know how it goes

[Edde]

Measuring at .50 is only for finding centerline, not confirming duration. Your duration should be 284 right? This means your OPEN point and CLOSE point must be exactly 284 degrees apart on the wheel.

 

It's all very precise.

[Shelby]

it's all very precise for sure but NOT HARD

it's much easier to understand once you see the card is showing the wrong side of the valve open curve and you have "0" lash

and once you understand the timeing does NOT have to be EXACTLY at the state'd number, say the card says the intake valve opens @ 25btdc , if you find yours does great but if it's off by 1 or 2 degrees NO BIG deal

 

you find the exact open and close points to verify you cam card and your findings ,

normaly your real world findings will always be later then the card state'd numbers ,by 1-2 or as much as 5 degrees , in truth it takes aprox 5 degree of cam movement to actualy notice a diff in the power curve , what you want is to check the timeing to begin with so you will have a better idea where it will be in 10 or 20 k miles of engine wear on the timeing chains and gears , because starting from day one the cam will slowly start to retard , this not much of a problem with a drag engine as in it's life time it'l never see 1000 miles but with a daily driver that may see 10-15k a yr it can be a problem if your looking for top performance

 

side note you will want to check the crank absolute TDC against the oem mark, and make a mark on the adj cam gear where "0" advance is and where you end up seting the timeing,, for later referance , you should keep your cam card in a safe place and have the actual timeing you did mark'd on the card

 

as to center line if the card has it mark'd and your open and closeing numbers match the card so does the center line figure given on the card , you can move the center line simply by moveing the open and close points , any movement to any number effects all other numbers, advanceing the open valve number advances the close point and the center line

 

seting the cam to the state'd points will give you a center line to check performance against befor you go moveing it in any direction , like an advance of 2 degrees will shorly bring the cam timeing into the number state'd on the card, with in a 1000 miles or so , seting it dead on will cause it to move slightly late as the chain system wears in

 

also if your useing the stock dist any change in the cam timeing will effect the position the dist sets in when the 10 btdc timeing is set , for a DIS system the cam change will not effect the ign timeing at all , it's referance'd from the crank not the cam

[psu_Crash]

Thanks a TON guys!

Yeah finally realizing that the card looks at the cam from the other side REALLY made things click.

I think I got it now and I am reading 284 duration, with the intake opening 2 degrees early.

And yep the mark on my crank pulley lines right up with the timing marks on the engine perfectly when i am at TDC from the positive stop calculations.

 

On a bad note I broke the part off my TB where the throttle cable attatches. Oops .. must have leaned on it or hit it with something in the process of changing the head gasket. O well new one is on the way.

Edited November 19, 2008 by psu_Crash

[Shelby]

if you said i don't recall but what cam gear did you use , an adjustable one i hope , if so what one ,, and i hope you scribe'd a mark on it for final timeing,, and tighten'd the lock down bolts properly,, or it can slip

 

no paint'd marks has to be actual mark in the metal

[psu_Crash]

It's an ajustable gear from Pagemo. Lock tighted every bolt on the cam gear and the timing mark on the pulley lines up very well.

Advanced the opening by 2 degrees on the final setup becaus i don't plan to do this again in the near future and from what you have said it will wear in.

Now I have to wait to start it up ... and find out if Edis is working. Edis is only connected to MS for an RPM input at the moment with the stock dizzy and MSD controling ignition.