What if your cam was 360 off?

[MadMikeyL]

The car that I am asking this about is actually a 91 cougar, but it has a 5.0HO in it, so engine-wise it is pretty much the same as a 94/95 mustang. I had it all apart and while I was there I installed GT-40 heads, a b-303 cam, 65mm TB, and a 3000 stall converter. Now the car starts and runs every day, so I have been just driving it like it is, but it doesn't get anywhere near the power that it should have from that cam/head combo. I have messed around with the timing by adjusting it then taking it for a ride and seeing if it helped or hurt, and repeating this process. It only makes 7" of vacuum at idle, is a slug off the line, will stall out if I come to a complete stop in gear, and only gets about 13mpg. I already had it apart to make sure the dots on the cam gear and crankshaft gear line up, and they do. So it occurred to me the other day, what if the cam is 360 degrees off? In other words, instead of firing 13726548, it would be firing 65481372, but the cam would be opening the valves not quite at the right time, and the injectors would be firing cyl #1 when the intake is opening on cyl #6, and cyl 3 when 5 is opening and so on. Could this be what is going on and why my motor isn't running the way it should be? Or am I way off base?

Mike

 

[Muscleford]

If it is 360 degrees off doesn't that put back where it is? Do you mean 180 degrees off? I don't think it would run off that far.

 

[MadMikeyL]

but since each valve only opens once every 720 degrees of crankshaft rotation, then the cam could be opening the wrong valves and the engine would run because it is still getting air, fuel, and spark, but the pistons wouldn't be at quite the right spot, and the fuel injectors would be firing at the wrong times, thus making the fuel not well atomized when it enters the cylinder. When I say 360 out I mean 360 degrees of crankshaft rotation, so I guess that would be 180 degrees of cam rotation. But since I timed the motor by ear and not with a timing light, theoretically I think it would run but not very well. Does this make any sense or am I just grasping at straws? It's ok to tell me if I am.

 

[HISSIN50]

i might get it to TDC on the compression stroke and check the dizzy- you sure you were not 180 off when you stabbed the dizzy in? (did not stab it in on the compression stroke).

im not sure if you dont use a timing light at all - i might get one to help with tuning it (i also dont often use a light, but after tearing a motor apart and having it not run right, i would).

good luck.

 

[Michael Yount]

I think the problem you're dealing with is simply a terrible cam selection for a 3800 lb. auto transmissioned car. That cam simply isn't gonna make much torque below 3000 rpm.

How does it run above 3500 rpm?

 

[Demented4.6]

madmikey. i think you are putting a lil too much thought into the came timing. say you line the cam up dot to dot. turn the motor over and eventually it will look as though it is 180 out with the dot on the cam at the top instead at the bottom near the crank dot. so either way you install the cam as long as the dots do line up at some time it will be fine