Engine Build Pre-Assembly (Cam Degreeing)

 

The next step in my build is to degree the camshaft.  Some people may say "why not just slap it in there, it's a brand new Comp Cam".  Well, I could do that.  Chances of something being wrong with it are probably pretty small, BUT... I wasn't there when they machined it, packaged it and sent it.  So I want to verify that the cam that came to me is in fact the right one I ordered.  To verify this I have to "degree the camshaft".  Every new cam comes with a cam card that lists all the specific data about when the cam will be opening and closing the intake and exhaust valves, I will be making sure I can get these same numbers.


Below is the cam card that came with my camshaft.  I will be verifying the duration @.050" lift numbers, lobe lift, intake and exhaust centerlines and lobe separation for both the intake and exhaust cam lobes  

 

 

 

These are the tools I will be needing to degree the cam.  A dial indicator and magnetic base, a crankshaft degree wheel, crankshaft turning socket, and a wire pointer attached to the block (I used a wire coat hanger).

 

 

 

First thing to do is to find true TDC (Top dead center) of the #1 piston.  This is the exact point where the piston is at it's highest point in the cylinder.  This needs to be absolutely correct because it is the reference point that all the cam card data is based on.  I know this because during my first attempt at degreeing the cam I must have somehow knocked the degree wheel making TDC incorrect.   I was getting totally wrong numbers and scratching my head.  Finally I started over and found TDC again, after that the numbers were all correct.

 

I rotated the engine over clockwise until I got it as close to TDC by eye.  I then lined the pointer on the degree wheel up to 0(TDC).

 

I then set the dial indicator up on the top of the piston and zeroed the dial. 

The engine was turned counterclockwise until the piston was 0.100" BTDC(Before Top Dead Center).  I then rotated it back clockwise until the dial read 0.050" BTDC( I rotated it back to 0.100" BTDC and then back up to 0.050" to take the slack out of the timing chain).  With the piston at 0.050" BTDC the degree reading was taken from the wheel.

 

 

 

 

 

The engine was then turned clockwise again until the piston was reading 0.050" ATDC (After Top Dead Center).  The reading on the degree wheel was taken again.

 

TDC is the midpoint between the two numbers, so the engine is turned to that midpoint between the results.  Without moving the crank the degree wheel is then rotated so the pointer is then at "0".  The process was then repeated until the number BTDC and ATDC were the same.  At that point the "0" on the wheel should be exact TDC.

2 Lifters were then oiled and put into the lifter bores.

Making sure the lifters were both in the lowest points (valves would be closed). I set the dial indicator up on the intake lifter with a 5" pointer extension on the dial as can be seen in the picture below.  From this point on I didn't seem to take very good pictures of what I was doing.  So basically I followed the camshaft degreeing procedure included with my cam.  I will try and explain what I did.

I rotated the engine clockwise until maximum lift was achieved (dial indicator reverses direction at max lift).  The dial was zeroed at this point.  The engine was then rotated counterclockwise to 0.100" on the dial (taking slack out of timing chain), and then rotated back clockwise to 0.050" before max lift.  The reading on the degree wheel was recorded.   The engine was then rotated again past the max lift (zero on dial now) to the 0.050" mark on the closing side.  The reading on the degree wheel was recorded again.  The two numbers are added together and divided by 2.  This is the intake centerline result.  In my case was 106 degrees

To find the intake duration.  Making sure the intake lifter is on the base circle of the cam lobe (closed) the dial was zeroed.  The engine was rotated until the intake opened to 0.050".  The reading was taken off of the degree wheel.  The engine was rotated again until max lobe lift was achieved, This was also recorded.  The engine was then rotated again until 0.050" before closing ("0" on dial).  The reading was taken again off the degree wheel.  To calculate the "Intake duration @ 0.050" lift" is the first reading plus the second reading plus 180.  In my case I came up with 242.5 degrees, which is off by 0.5 degrees and close enough in my opinion.  The intake lobe lift I measured was bang on at 0.319".

To measure the exhaust lobe numbers I moved the dial indicator setup over to the exhaust lifter and repeated the same procedure.  The exhaust centerline I measured was 113 degrees.  The "exhaust duration @ 0.050" lift" was 248 degrees.  The exhaust lobe lift I measured was 0.330".

To calculate the lobe separation is calculated by adding the two centerlines together and dividing by 2.  So in my case 106+113/2= 109.5. 

It took me a few times to get the hang of this procedure, but after doing it the second time I am happy with the numbers I got and they matched the cam card numbers within 0.5 a degree.  I think I am going to go through it one more time before I finish assembling the engine just to be sure.

More Engine Parts...

 

I picked up another package from Summit Racing with some more engine parts. 

 

The Distributor I chose is the MSD Pro Billet Ready to Run.

Holley Street Avenger Carburator.  870cfm, electric choke

Edelbrock Performer RPM Air Gap Intake Manifold.  I chose the powdercoated black version, I think it'll look good with the red of the engine block.  I also picked up some intake gaskets and ARP intake bolts

Engine Build Pre-Assembly (plastigauge rods, cam and timing set install)

 

I have already determined the connecting rod oil clearances in previous posts using the dial bore gauge.  In this post I used Plastigauge to verify those results. 

 

If you look closely in the picture below you can see the small strip of Plastigauge placed on the bearing.



I used a set of vice grips to secure the crankshaft from rotating while torquing down the rod caps.  If the crankshaft were to rotate while torquing the rod bolts the Plastigauge strip on the bearing could be ruined

 



 I did the Plastigauge checks on each rod pair at a time.  The picture below shows tourqing of the #1 and #2 rod caps

 

#1 piston installed without the compression rings for now.

 



 

 

Below shows the results of the Plastigauge.  It's hard to see in the picture, but I got readings of about .002" when compared to the chart on the Plastigauge package.  All 8 rods checked in with similar results.  Which is fairly close to the dial bore gauge results within .0005", so I am happy with that.



The other rods and pistons were installed and checked too

After the Plastigauge check was done on each pair of rods.  I then wiped the Plastigauge off the crankshaft, put some assembly lube on the bearings and re-installed them and torqued down again.

The crank was then spun around a couple times to make sure everything spun freely with no interferences

 

 





After all the rods were Plastigauged, I installed the crankshaft gear using a brass punch slowly working it onto the crank.

 



 

 

Next, I pulled the camshaft out of it's box and installed the cam gear.  I installed the cam gear at this time to make sliding the cam into the block easier. 

 



The cam bearing journals were lightly lubed with motor oil at this time and the cam was slid carefully into the block.

The cam was then spun a few times to verify that it spun freely.

The cam was then pulled out and lubed liberally with some cam and lifter assembly lube.

 The timing chain is then installed.  To do this the cam gear is removed, the chain is put around the gear.  The chain is then wrapped around the crank gear.  The cam gear can then be bolted back onto the camshaft.  The Timing dots need to be lined up before the cam gear is put on.

 

The picture below show the timing dots lined up in the 6 o'clock and the 12 o'clock positions

 

I then started getting the engine ready to degree the cam, I installed the cam degree wheel, magnetic base and dial indicator and a degree pointer made from a coat hanger.  My next post will be degreeing the camshaft.  This is done to verify that the comp cams manufactured this camshaft correctly and to the specifications that are included on the cam card that came with it. 

Engine Build Pre-Assembly (piston ring gaps, piston to wall clearance)

When I got my engine block I purchased a set of piston rings to go with it.  They were the file to fit type, which they make larger so they can be filed to a specific gap.   Which in this case I was reccomended by Keith Black (manufacturer of my pistons) 0.028" for the top ring and 0.018" for the 2nd ring.  I had done the filing years ago when I originally got everything.  This week I got out all the rings that were individually packaged per cylinder and I checked all the gaps to make sure I gapped them right years ago.

 

Below is a picture of a tool used to insert the piston rings evenly down into the cylinder squarly so the gap can be checked.

 

Here is a picture of the piston ring into the cylinder.  The gap can be seen at the top if you look closely.

A feeler gauge is then used to check the gaps.  This is then done for the 2nd ring also and for all 8 cylinders.  I guess I did a good job a few years ago when gapping these rings because they all were good.  I replaced them into their labeled bags and set them aside (I won't need them until final assembly).

Next,  I had to measure the pistons.  Every piston manufacturer has a specific spot on their pistons where they are measured.   I assume this is because it is at this spot where the piston is the largest.  I went onto the Keith Black website and found the installation instructions for my pistons.  In these instuctions it tells me where to measure them.

Here is the link for the installation instruction sheet for my pistons for an example

https://www.uempistons.com/installation_instructions/kb_installation.pdf

In the picture below I am measuring the #4 piston with my 4"-5" micrometer.  I measured all 8 pistons this way.  All of the pistons measured within .0005" of each other.

I then got my dial bore gauge out again.  I set up the dial bore gauge zero to each piston measurement.  I then inserted the bore gauge into the cylinder and took the readings at the top middle and bottom of the cylinder.  Because the zero on the bore gauge was set to the piston measurement the gauge then read the piston to wall clearance.

The picture below is how I set the bore gauge to zero using my micrometer set to each specific piston size.  It's hard to take a picture of this, but I tried my best.

I checked each cylinder horizontally and vertically to double check the machining work and make sure the cylinders aren't out of round.

The picture below is showing an example of one of the cylinder piston to wall clearances I got.  Each line is 0.0005".  So this is reading .0020" clearance.

 

 

All the piston to wall clearances checked out ok from .0020" to .0025".   I once again looked at the piston installation sheet that I printed off from the KB website.  These clearances were exactly what they suggested for a street performance engine.

 

Here is my handy white board again with all my measurements recorded.