Based on CB Performance's new Raised Roof, High Deck aluminum case, this motor will be a 2332cc, high compression N/A with the same CB Comp Eliminator heads we used in 2004. Most of the internal components will be either the same pieces from before or replaced with identical parts.
Starting with the case, the first thing to do was an overall visual inspection. Very nice level of fit and finish, but it is significantly heavier. There are areas inside that need to be deburred such as various sharp edges left from the factory machining. This is not unusual and should be the first step in any engine build even with stock parts. It ensures there are no small pieces that can chip off and contaminate the oil and damage the bearings and other parts. This case was also machined for the flanged 84mm Bugpack crank we are using.
After deburring, I checked the fit of the distributor drive. No problems there as there were with aluminum cases from the "Other Guys." I then tapped the oil pump discharge port in the case for a 1/4" NPT plug, tapped the discharge port for the pulley side oil pressure relief, and tapped the outlets for the oil cooler for plugs. The reason for this is the use of an external oil pressure relief valve and no oil cooler in the stock location.
I then filed bearing tang slots in the center main for the type 4 adapter bearings which is required with our crank, which has a larger type 4 center main bearing journal.
The bare case halves showing the raised deck at top and the six shuffle pins in the lower photo
Ready for Initial Mock Up
High performance engines absolutely have to be pre-assembled before anything is finalized. The reason for this is to check the fit of parts, and various clearances. To skip this step is unthinkable. First, the main bearings are snapped into the case and the bare crank with timing gears on it is laid into the case. This step lets us know that that part rotates freely with no interference anywhere. All is good. Next, the timing gear is installed onto the cam. In this build, we are re-using our steel Magnum gears and "Straight-Up" timing washers. The CB case comes ready for cam bearings with dual thrust, so filing tangs for the opposing thrust bearing is not required as it is with stock cases. Once cam is laid in, a few rotations show no interference or clearance problems with either the case or the crank.
The crank is removed and the connecting rods are installed onto it, then the assembly is laid into the case, the cam timing marks lined up, and the assembly is rotated to check rod to case, and rod to cam clearance. PLENTY of room to the case, but some clearancing of the cam was needed. A little here, and then a little there until it was clear. With that done, the case halves were bolted together and the assembly was rotated. At this point, everything fits together great.
Next, the number 1 piston is installed along with the jug. Using a deck height measuring fixture with a stop bolt, we determine where absolute top dead center is. This is done by bolting a degree wheel to the crank snout, fashioning a pointer out of stiff wire, and rotating the crank forwards till the piston contacts the stop, then back the other way till the piston contacts the stop again. Positioning the degree wheel close to the wire at TDC and going back and forth like that several times, we tweak the wire until it's the same distance on either side of TDC. Once done, we have found absolute TDC. Backing out the stop bolt, the crank is rotated to line TDC up with the wire pointer. Screwing the stop bolt in by hand till it stops will give us an exact deck height measurement by removing the fixture and measuring how far the bolt tip sticks out from the surface. We have .062" deck clearance. Too much if we want to use .040 copper head gaskets, (and we do). We'll need to have the deck surfaced .040" to achieve a .060 - .065" deck with gasket in place.
On to the valve train. First, the valve springs for number 1 are removed from the heads and replaced with "Light Checking Springs". I got these at the hardware store. I feel using light springs and a dial indicator are more accurate than the clay method others use. At any rate, it's how I've been doing it since dirt was new, so that's how I'm doing it now. The head is installed along with two pushrods and rocker arms. Suspecting a close encounter valve to piston, I rotate the motor slowly, and sure enough, I hit a stop. In this case there is no clearance. Not even close. I back the rocker adjusting screw out till the valve edge just barely makes contact, then rotate the crank back to lash checking position and find, I've got .065" lash on the exhaust, and .100" lash on the intake. This means I have MINUS .065" valve to piston clearance on the exhaust and MINUS .100" on the intake. Valve notches will have to cut into the pistons .200" deep for the intake and .165" deep for valve clearances of .100", the minimum clearance I feel comfortable with.
Removing the piston from the barrel will allow us to rotate the crank with the valve train installed and not hit anything so timing can be checked. I use the "Intake Lobe Centerline" method. I find that the cam is advanced 3 degrees, or on a 104 degree intake lobe centerline, (this means the exhaust is on a 110 degree center since this particular cam is on 107 lobe centers).
Although there are quite a few things to check, such as bearing clearances, rod side clearances, etc., for our purposes here, we are focusing primarily on the case. Now that I have determined what needs doing, I can get that done, and prep the parts for final assembly....the fun stuff. Cleaning, deburring, fitting ring gaps, y'know, FUN!
Lower end mocked up. Everything fits great at this point.
Locating Top Dead Center using a piston stop deck plate, degree wheel and wire pointer. Deck height is measured once TDC is found
The valve adjusters had to be backed out until the piston just barely touched the piston top. Lash was checked at the rocker tip to determine the NEGATIVE clearance.
The stud insert is 7/8" long and screws in to just below the deck surface
|Ready for Final Assembly
All of the parts ready for assembly after final machine work for valve notches, lifters refaced and balancing.
|Now that the pre-assembly has been completed, and
all clearances (or lack thereof) have been established, the components
were sent back to CB for the various machining operations required to
bring them into spec. Valve pockets cut in the pistons, lifters refaced
(there were a set of of the CB lite weight race lifters I bought back in
99, had around 300 runs and a bunch of street miles on), and the rotating
assembly balanced. It seems the Kennedy pressure plate I was using was
pretty far out of whack, so it makes a good case for getting new ones
balanced before use.
Since the head stud holes are open ended on four studs on each side, the studs need to have sealant on the threads, and sealant applied to the back side to keep oil from seeping past the threads. After a thorough cleaning of the case, this is the first thing we do. After that, a oil pick up tube extension is tig welded on with the tube opening 5/8" from the sump plate.
With the case handled and ready to go, the Pauter rods were assembled onto the crank (tangs down) with Clevite 77 CB610B bearings, and the main bearings snapped into the case (adapter bearing for the type 4 center main). The crank was then laid into the case, followed by the left bank lifters and cam. The cam was already dialed in, so it was simply a matter of aligning the dots on the timing gears.
Next I installed the distributor drive and ever so carefully aligned the slot so my distributor would be in the proper timing position. Wouldn't you just know it, after the case halves were together, it was bass-ackwards! With a little "finagelling" that little faux paux was corrected. A "Yamabond" type sealant was used between the case halves, and the bottom end was buttoned up. So far, this new case has assembled very easily with minimal issues.
A little sealant is applied to the open ends head studs to prevent any oil leakage.
Shortblock is assembled with distributor drive installed....backwards....again!
With the pistons, barrels and heads slid on in typical fashion, the long block is complete. The next issue with the new CB case is fitting sheet metal. But first, I dealt with a nagging problem and hopefully, this will be the final solution. The oil filter bracket, which hangs off the exhaust studs on #4 cylinder, continually work loose and are a royal pain to deal with between rounds, since the rear tin has to be removed. Normally not a big issue, but since the type 2 trans swap, this piece fights me every time it needs to be removed and reinstalled. The solution? Tig weld the bracket directly to the header flange and use normal sized lock nuts. Time will tell how that works out.
The first order of fitting the sheet metal is the pulley tin. The new case is not quite the same exact shape as the original style cases, so a fitting "tweakin" is necessary. The red circle above shows where material needed to be trimmed, and the small tab to the right of the circle needed to be bent up a little. All of the trimming operations were done with a small angle grinder with a thin cut-off blade. Makes clean work out of it!
The other side only needed a little trimming. Once a nice snug fit was achieved, it was bolted down with a dab of lock tite on the screws. The cylinder covers also needed some attention. The biggest point of interference was the 3-4 side near the bellhousing flange at the #3 cylinder base. It may not be an issue with the case with standard deck height, but because the deck goes straight to the bellhousing flange, the cylinder tin needed to be trimmed there. Some minor clearancing on the 1-2 side is necessary in the same area, but it's not nearly as tight.
That leaves only the shroud. A smidgin in the middle, just as suspected due to the raised roof design and we're done.
Filter bracket is tig welded onto the header flange to eliminate (hopefully) a constant loosening of the header flange with the regular bracket. The brass gizmo hiding underneath is the oil pressure relief valve.
A little trimming here...
A little trimming there...