I sharpened the pointer – a piece of coat hanger attached to one of the timing cover holes in the block.
I’ve degreed cams before and it was a simple process of finding true TDC and then using the input degrees listed for the cam to do the check.
Now the manufacturer’s don’t indicate the number of degrees for the intake at .050 of lift. I tried finding it on the Melling website and elsewhere on the internet, but no real luck. What is indicated is the Lobe CTR: Int 107 and Exh 117.
I have been using this publication for bits of information to supplement the GM service manual. In it they discuss degreeing the cam. They print that there are a number of ways to degree a cam. The method they describe in the pub is the “Lobe Centre Line” method. It uses the manufacture’s specs for the Lobe Ctr. I’ll be using that to check the intake (107 degrees). My crank sprocket will allow me to retard or advance the cam by 2 degrees if necessary. I also had to watch a couple of utube videos to get comfortable with the process of LCL cam setting.
Before starting the job I decided to install the flexplate/ring gear. It will allow me to move the crank small amounts when finding TDC and the cam lobe centre line. I’m using new shake proof washers to install the plate along with a bit of blue Loctite – I’m more of a belt and braces man if you get my drift.
I’m back to using my aluminum strap for measuring piston deck height. In this shot I took the opportunity to check for true TDC (that is TDC for the piston not the crank and piston) I used that to once again check the deck height. Again using feeler gauges, I found that the deck height is actually smaller than first measured. The new measurement is .042 and using that the compression ratio rose to 8.78:1 with a quench of .057. A passable ratio and a bit better on the quench side. I’m happier with that.
This is a half-inch nut that I used as a stop for the piston. I set the degee wheel at TDC with the piston roughly in that spot using the dial gauge. I then rotated the piston back about 2 inches and then forward with the nut in place. I noted the degrees on the degree wheel when the piston contacted the nut. I then removed the nut and move the piston over TDC about 2″ and then back with the nut in place and took another measurement. The spot between the two measurements was the true TDC. I moved the crank until that spot was at the pointer and then I turned the degree wheel so that the pointer was at TDC.
This was my setup to find the #1 intake lobe centreline. I couldn’t use a pushrod since my dial gauge doesn’t have a long enough arm. So I used a short length of tube which allowed my gauge to be more or less directly above the lifter. Again set the gauge roughly at the lobe top and then I marked the degree wheel at 20 degrees on either side of the intake lobe – being careful to do the measurements with the engine going in a clockwise direction to keep the timing chain taut.
I chose to use 20 degrees rather than 50 just in case my cam’s lobes were not symmetrical – that was a recommendation made in one of the Utubes I watched.
Lots of marks on the wheel from a number of tries. The ones that count are where the degree wheel pointer sits at about 45 and the bar under 80. Those were the marks 20 degrees on either side of the cam centreline. Half way between is the cam centre line which sits at about 73. The degrees from the top dead centre mark and that point are roughly 107 degrees. That is the correct location for the cam according to Melling’s specifications (see photo up a bit). That was with the crank sprocket in the centre slot so no need to advance or retard the cam. Good as it is – hooray!
While I wait for the steel beaded Fel-Pro head gaskets and other stuff from Summit racing I’m going back to the interior to replace the cleaned carpeting.
Next: More interior progress.