What did you do with your Thunderbird Today?

[XR7-4.6]

Ok, so just for those of us whose mechanical acumen never stretches beyond our (my) current project at hand, what exactly makes a cam  killer?

I mean I can picture a cam shaft, I understand what it does, I know I only have one deep inside the V of my engine...but I don't know what makes one shaft better than the other shaft. Shaft shaft. Beautiful word. Talking about cam shafts.

Longer duration, slightly more valve lift and more overlap. That means more time and volume of air/fuel allowed into the cylinders and with the overlap (and soon headers) more scavenging… overlap means for a few degrees the intake and exhaust valves are open at the same time and the exhaust pulses actually help pull more air/fuel into the cylinder than otherwise possible with just the suction of the piston going down on the intake stroke.

It also sounds really cool idling, though I’m not sure what to expect with where I degreed them.

Killer in this context is high lift, high duration (,and high price,) lol.
Buying cams for a 4v hurts. Which is why we hunt cobra cams.

Want to buy my Cobra cams to slightly offset the pain I’ve endured?

 

[1997ThunderbirdLXV6]

When you say you "degreed" them, is that the cams relative to the crank? Or also the cams relative to each other? (Not sure if the cams relative to each other is essentially pre-determined by their design).

Sounds like A LOT of variables to consider, and I imagine the PCM tune is a lengthy trial and error process?

 

[XR7-4.6]

When you say you "degreed" them, is that the cams relative to the crank? Or also the cams relative to each other? (Not sure if the cams relative to each other is essential pre-determined by their design).

Sounds like A LOT of variables to consider, and I imagine the PCM tune is a lengthy trial and error process?

With a DOHC it’s both relative to the crank and to each other as the intake cams are driven off of the exhaust cams. Yes it’s lengthy trial and error, hence this in my head being a weekend job… two weeks ago

Tuning will probably be a thing which I’m not looking forward to, lots of dashpot/idle tweaks which have never been my forte.

 

[theterminator93]

PCM tuning is some trial and error, but only for certain functions. Many of the things you tune for have an exact science to them - you have the program, you observe the result, and modify the program by the difference in what it does vs. what you want. Verify behavior, and done. An example is the MAF transfer function (perhaps the most important single table in the entire program); use a wideband to observe the actual AFR, log the commanded AFR, and adjust the MAF transfer by looking at the differences across the range to make sure it always matches.

For idle, I really only needed to log ISC_INTEGRATOR PID to adjust and the idle airflow tables - I didn't need to fidget with the timing at all.

Though on occasion, it will die out when cold and in open loop when I go from P/N to R/D. Mitch Black PM'd me a few times thinking he had a fix but I never got it, and never followed up.

 

[Grog6]

Matt, pm me what you'd want for the cobra cams, but I'm still trying to get the cash f8r the spoiler,lol.