Bottom End Assembly
The bottom end assembly was pretty much Bruce Greer's department. The first move was to check all the bearing clearances to see that they fell within tolerances. Normally, this would have been done with an extremely high-dollar internal micrometer (there is no such thing as a cheap one) but, in an effort to keep this in the realm of reality so the average hot rodder can follow the same path, plasti-gage was used. The bearings were the Calico-coated ones. Sure, they are more expensive, but over the last few years they have more than proved themselves in extreme situations. The target clearances for our 482 big-block were 2 thousandths for the big ends and 2.5 for the mains. Judging plasti-gage closer than a couple of tenths of a thousandth does take a sharp eye, but with an eye glass and patience, it can be done. What was seen was a very acceptable 2.4 to 2.8 for the mains and between 1.9 and 2.3 for the big ends. Whether that was precisely so would still take a $600 mic, but the plasti-gage did tell us that our clearances were well within a working range.
Cam Timing
At this point, we were ready to assemble the bottom end, but an oversight on my part meant that the Total Seal rings were still a couple of days away from arriving. Still, that did not preclude us from installing the cam. The cam's valve opening and closing points were established based on a computer modeling of our engine and then using Cam Master to predict the required events. Just for the record, this program is extremely accurate and for all practical purposes eliminates having to dyno test to get the best cam for the job. [You can also buy a copy of CamQuest6 from COMP Cams for $10. It runs on any Windows PC and allows you to spec several cams--showing you simulated dyno pulls--just by plugging in your other engine specs.--ed.] Using our Cam Master generated a COMP Cams Xtreme Street roller cam with an advertised 292 degrees on the intake and 298 on the exhaust. This was ground on a 107 LCA at four degrees advanced. Although we may be giving away a few hp to more aggressive profiles, these Xtreme street roller profiles have characteristics conducive toward long life. With the valvesprings selected (these were COMP's latest beehives intended primarily for big-block applications such as ours), we can now accommodate about 685 thousandths lift max. With 1.7 ratio rockers, the cam will deliver, after being lashed, just shy of 650 thousandths.
A point of interest is that the more accurately a cam is spec'd, the more important it is to time it in correctly. To facilitate this, a COMP Cams adjustable timing set (PN 8110) was used. This is infinitely adjustable over a range from +6 to -6 degrees. To establish where TDC was, the number one piston/rod assembly, less rings, was temporarily installed. Next, the cam and roller lifters, (PN 819-16) were installed and COMP's cam timing tools were ready to do the job. It took just one degree of adjustment to get the cam's intake centerline to the required 103 degrees. The last job to do was to install the nylon end thrust button, and the lower part of the 482's valvetrain was done. The next job would be selecting the pushrod lengths and that would come later in the build.
Piston and Rod Assembly
After establishing which way they go on the pistons, the pistons were mated to the now full-floating-pin rods. A generous coating of high-pressure build lube is advisable to cover the time it takes for the engine oil to work its way into the pin/rod clearance space. Bruce Greer then gapped the Total Seal rings exactly as per the instructions contained in the box, and assembled them onto the pistons. The installation of the piston/rod assembly into the block was the next step. Here it is always advisable, especially when using Total Seal rings, to use a tapered installer. Usually, these are a fixed size and can only be used on one bore size, but Total Seal has adjustable ones that will cover over 1/8-inch adjustment.
After all the short-block components were in, the assembly was tested for turning torque. Typically, a big-block falls into the 30-35 lb-ft range. This one turned over at 16 lb-ft. [You may remember our winning big-block Chevy from the Engine Masters Challenge turned at 12 lb-ft, proof that low friction does matter. --ed.]That is a testament to the fine bore preparation done by T&L and to the care taken by the students to make sure everything was right on the money. The last item of importance on the bottom end was the crank damper. Here, a cost-effective unit from Professional Products was used. It got the job done without costing an arm and a leg.
Next month, we'll show you how to make big flow numbers with some cost-effective Dart Iron Eagle heads; we'll assemble everything, and put the Street Beast on the dyno.
The selection of lightweight pistons, plus the rod lightening, meant having to take quite a lot off the counterweights to achieve a fully balanced rotating assembly. |
The final balance on the rotating assembly was to T&L's strict Busch Car engine accuracy. |
For our bearing requirements, we used the Busch car tested and proven bearings from Calico coating. |
You may not be able to afford a $600 internal micrometer to test bearing clearances, but you can afford Plasti-gage. It is not quite as accurate, but it will determine if the clearance is out of tolerance. |
This double-roller timing set from COMP Cams is infinitely adjustable over a +/- 6 degree range and reduces cam timing hassles to an absolute minimum. |
Want to avoid nicking those freshly installed cam bearings as you load the cam into the block? If so, you need this simple installation handle from COMP Cams. |
The solid rollers we used were the latest heavy-duty spec big-block items from COMP, PN 810-16. |
Our 286 x 286 Xtreme solid street roller was timed in to a 103-degree intake centerline. The optimum valve events for the engine were computed using a UNCC copy of the highly accurate Cam Master program. |
Roller cams need end float control. Here we used a nylon thrust button to do the job. |
A considerable reduction was made in reciprocating mass. Firstly, the rods were reworked, bringing about a weight reduction of 90 grams. Next, a lightweight Ross piston was selected which brought about a similar drop in mass. |
When installing pistons with Total Seal rings, the chances of inadvertent damage are increased because of the thin rings involved. The best move to avoid problems is to use a tapered ring installer. |
For damping out any crank-destroying torsional vibrations, a highly affordable Professional Products damper was used. |
Here is our finished block and rotating assembly. Turning torque was a scant 16 lb-ft. |