Timing chain marks! WTF?

[First Fox]

Let me preface this by saying that I am not new at engine repair. I am not being coy and trying to say that I do this for a living or have assembled a thousand engines, but probably like many of you I have honestly bolted together dozens of them since my youth. Some of them were actually "built" with aftermarket components and measured properly, others were bread and butter rebuilds that were only checked using plastigauge. Either way, I am very familiar with the workings of most common piston engines and I pay attention to the details when I have them apart. I have never had a catastrophic engine failure due to any mistake of mine.

With that being said, I just stumbled across an article written about a rebuild of one of our beloved little sixes and wanted to pass it along as I believe it contains either a terrible typo, or the solution to a valve timing problem that myself and a few other here have encountered. It could also be of no consequence, just looking for another opinion or knowledge from someone that knows about this for certain. So please don't just google this to verify and then leave a comment like " Well, yeah dummy, of course that's how it works."

This article states in a sidebar that the marks on the timing sets for these engines are actually NOT supposed to align at the common 12 and 6 o'clock positions, but rather at 2 and 8 o'clock!!!! Without actually having an example in front of me, it is difficult for me to to discern where that would place the marks as they approach the 12 and 6 positions. Could this be why myself and a few others had the cam timing so far off on our sixes?

Am I just somehow out of the loop and is this common knowledge here? Even when doing timing belts on DOHC engines in the past in which the timing marks are more complicated, it has always been pretty clearly marked, or at least the set came with instructions that explained the markings.

It is noted on the sidebar with the photo showing the timing set installed on the engine:

http://www.mustangmonthly.com/techartic ... ewall.html

 

[100_2023]

I think they are looking at it from the perspective of the top of the block. The camshaft key would be at the 8 o'clock position, and the crankshaft key would be at the 2 o'clock position with respect to the top of the block.

If you look at the perspective of just the camshaft and crankshaft gears with a centerline drawn through them, they would still be at 6 o'clock & 12 o'clock positions.

I believe they make it more confusing when referring to them with respect to the top of the block. Just my $ .02.

Darrell

 

[rbohm]

8) darrell is right. on most cam in block engines, the cam is directly above the crank, and thus the timing marks are at 6 and 12 respectively. in the case of inline sixes the cam is offset to one side, and thus the 8 and 2 locations for the timing marks. if it confuses anyone, and you have your engine on an engine stand, rotate the engine until the cam is directly above the crank and line up the timing marks as if it were a V8.

 

[First Fox]

Oh, I gotcha. I guess the author was merely describing it in a retarded way to make the article more interesting. He could have easily have said "...the gears are exactly like an average V8 in that the marks point directly toward one another between the crank and cam gear..." but I guess the way it was written made the build seem more difficult or unconventional or something.

I really don't know why, but from his description I was picturing the marks being on opposite sides of the gears with the CRANK gear mark @ 8 o'clock, and the CAM Gear mark @ 2 o'clock, and the marks coming around and meeting just a tooth off or so at 12 and 6 which would explain some of the goofy cam timing stories I have seen on here. I recently had my Comp 260 installation (it was Darrell's actually 8) ) come in at 10 degrees advanced on my 200 and it being my first build of a small six, I was dumbfounded. I have still to make any sense of why it was so far off. I have never seen it more than a couple of degrees off with any previous V8 builds and I thought it had something to do with a stock type timing set I used being advanced or something along those lines.

But hey, this is exactly why we degree cams in the first place right?