AKHeathen

okay, i have to step in and stand up for engnbldr..... it appers most of you guys are not experienced in aggressive cam tuning. turn your idle up and the missfire should go away would be the easy answer. what you are experiencing is the increased overlap to give you more power at like 1200rpm+ is dependent on constant flow inertia.... so at idle speeds there is too much overlap, and the intake charge can escape to the exhaust and result in less stuffing. cylinder one recieves the most cooling and so suffers the most lower dynamic compression, which equates to more misfires, plug cooling, and loading.

more or less, this is more a lesson on people thinking that better cams are basically free bolt-on power, than the unnecisarry bashing thread it turned into. think about it: have you ever heard a big engine drag car pull up to the lanes and purr like a kitten? no, it chops and lopes because it has a huge cam in it making power at off-idle rpms, and the idle is high because of that. you have to tune to the cam, period. when the description says "decent idle" it just means you can tune it not to die on you most of the time, not that it will run like a stock engine.

Odin

It is a lot of pages to read through.. he only had a problem with one cylinder.

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Runner4Luke

I wouldn't call this an englbdr bashing thread. You actually read all of it? Engbldr really only came up a couple times, this was really a technical discussion.

Something happened with the machining of a couple, possibly more, of his cams. I don't believe he cuts them either, as his "cam guy" checkout out and found the issue with this cam. Don't know more about it then that.
˟˟˟˟˟ happens and this was a really obscure, unexpected issue which unfortunately cost a lot of time and money to track down.
That being said, I would still purchase engbldr parts in the future. I built my 87 with all his parts and am completely satisfied. I don't doubt the quality of his parts because of it. ˟˟˟˟˟ happens, no one is perfect 100% of the time.

And for the record, the 268 is mild cam, which should hardly, if at all, effect idle. Those are Tods words.
I agree, aggressive cams are different story.
Also, that missire remained at high idle rpms. Didn't go away until the engine was loaded. It was manifold pressure, not RPM that really stopped the issue. (but you read all that right?)

AKHeathen

no, i had not read the whole thing till now, my bad. i just followed it from another thread on my way to bed and fighting firefox which kept freezing.

nordicwargod

Very interesting read! I learned a lot from this thread. I had not heard of a running compression test till now. I may just try it for the fun of it. Quite intriguing.
I too bought a engine kit and cam from Tod and I can't say how much help he was. His Dad returned a few emails quickly and answered all my stupid questions. They are the best people to deal with!!!!
Question: Did you degree the cam when you installed it? I've never done this before. All the previous times I put engines together I simply lined up the dots and called it good. I got a degree wheel, found true tdc [it was two degrees after the timing mark] and then with a dial gauge compared where the cam opened at .050 and closed at .050 for both the intake and exhaust. I also measured lift and the center line of each lobe. I then compared to the cam card supplied and was surprised that there was quite a bit of difference. My duration was ten degrees less than claimed and the opening and closing points were off too by a few degrees. And this was at 0 lash. I don't have the specs in front of me now but I do remember the over all center line and lift to be accurate. I bought the .261 crawler cam. You mentioned the valve lash with yours! Something I'll keep in mind. Tod told me 009 on exhaust and .006 in intake. Exhaust seems tight compared to the service manual.
I talked to Tod about my degree results and he told me about the math for finding actual lift and because of variations of each engine that getting the same numbers was impossible.
I'm putting the rest of the engine together and will soon have it installed. The truck has been sitting for seven years and I'm sure that before I get it running there will be lots of other little things to address.
Again, great write up !