davejake

3 is company too!
I need a little coaching (or link to where this is all explained). I am building a "hot street" 1500FI engine. High Compression pistons and 242deg cam from MWB. JonLogan@MW-124 built my head to perfection! I'll be running this with a Megasquirt ECU using the Ford EDIS ignition and crankshaft sensor.

Now, to get it all dialed in:

I found TDC. I've mapped the camshaft and know its TDC and centerline. Now my question is -- what do I advance it on the variable camshaft gear? I'm not exactly sure how to measure where it's at and where it should be.

Can someone talk me through this (meaning, what do I adjust the camshaft gear to?)

IMG_8644.jpg


I'm noticing that while the Cam is definitely set for TDC, the marking on the gear is off -- do I need to adjust and make that line up?
IMG_8646.jpg
 
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I am a neophyte around this and since someone smarter hasn’t posted I will get you started and a more knowledgeable person can follow up with Karl really is an idiot no one should be listening to.

Did you shave the head as well or is the compression increase only in the HC pistons?

You likely need to reposition the timing belt on the cam wheel. It is likely possible you will have the cam wheel location indicator not on TDC perhaps slightly ahead of the TDC position once all is said and done. Almost guaranteed if you have a shaved head and cam box.

At TDC for the crank you want the cam to also be at TDC, not the just wheel but the peak of the cam lobe. So your dial indicator will tell you where the peak is on the cam lobe. You will loosen the cam wheel allen bolts, set the wheel at the TDC position with the crank also at TDC, keep it there and then rotate the cam relative to the wheel so both the wheel and the cam lobes are at their “TDC”and lock them together.
 
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Timing the cam to the makers specs is quite easy, the only thing you really need to be aware of is the dwell at full cam lift. So just the same as the positive stop method for finding TDC where you find a point either side of true tdc (to negate the dwell at tdc) and then split the difference to find true TDC for the crank/piston. you need to find a point either side of full cam lift, and then split the difference to determine the lobe centreline as you once again negate the dwell period around full cam lift.

Dave Vizard just a few weeks ago put up one of his vids on using precisely this method


I know he's difficult to watch (he had brain surgery I think to remove tumor a couple of years back, and hasn't really been the same since) but persevere and watch his method.

So with your dial gauge you will need to find points (say 0.5mm down from full lift) either side of full lift and then split the difference to find the "true" full lift lobe centreline, and this is where the big diameter degree wheel comes into it's own for accuracy.

SteveC
 
I know where the cam's TDC is as Jon Logan marked it for me. He did tell me last night that the "dot" on the cam gear can be disregarded as he has already timed it.

So, for now, I think I'm set. Just need to finish building the fuel and ignition system and get it on the test stand!
 
Jake, it sounds like what John did was mark the cam gear so that the pointer for the cam gear points at his mark on the cam gear when the crankshaft is at TDC for cylinders #1 and #4. I'm sure he degreed the cam for you before he marked the cam gear. He may have advanced the cam a bit, that would rock the power curve to a little more HP at higher RPM. Or he may have retarded the timing a bit to rock the power curve to a little more HP at lower RPMs. Or, he may have split the difference and installed it "split" between the two. He probably gave you the information on how the cam was degreed in the build sheet. In any case I'm sure that if John did it, it is set right.
 
Ooops, I got the above wrong. Advancing the cam improves low RPM power while retarding it does the opposite. Sorry for the confusion!
 
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