[TRADERMIKE 2012]

When we removed the Heads, we found that the Exhaust Valves, at the center of each Head, where the two Exhausts Valves are adjacent to one another, were sunk /recessed into their un- hardened factory Seats by about 1/32", possibly adding 1/16". The O/A Valve slap/noise, in an overly heated area. Duly noted, we removed the Heads, to be machined with new hardened Exhaust seats. After learning both about the Pontiac Block and 421 Head cooling mods., over this PY forum, it is just as well that I drill the Heads between the two center Exhaust cooling ports, for better cooling in that area, that is, when I get them back.

Of course, we have already drilled and plugged three holes on each Deck that the Head rests on plus, tapped and plugged them, with stainless plugs. We also drilled the 421-mod. holes between the center Exhausts ports into the Block, on both Head Decks. Thís should help in "not" allowing this overheated area from ever getting that hot.

We used a Dial indicator over the Piston and Degree wheel to find the TDC, using a stop, that we made from flat aluminum added 2 Bolt holes to lock it down to the Deck. By drilling a smaller hole in the center of the flat stock, we tapped a bolt through that hole, to measure depth along with a feeler gauge, over cylinder # 1 using the intake Valve on the compression stroke.

To find the actual ICL, we placed the Dial indicator over the edge of the Intake Valves Hydraulic Lifter and measured the duration of the Cam @ .050" on both sides of the Valve duration Ramps by passing the .050" mark on the Dial Indicator first then moving toward the .100" mark first then rotating back to exactly 050", where we took our readings off the Degree wheel # and recorded that number, adding those numbers and dividing by two equals 112 degrees for the Intake c/l and 115 degrees for the Exhaust c/l, then to obtain the lobe separation angle we added these two numbers and divided by two equals 113.5 degrees.

We advanced the Valve Timing from 113.5 to 109.5 by using the Comp Cam four-way Crank Gear, each notch is two degrees according to their directions, thus the fourth notch equals 8 degrees at the Crank and that means 4 degrees at the Cam. Because the Crank rotates twice, 720 degrees and the Cam rotates once 360 degrees. 360 degrees at the Crank equals 180 degrees on the cam, the Crank spins 2x the Cams one. Half a turn at the Cam is equal to one rotation of the Crank.

We were told by Butler Performance that Melling added 1.5 degrees to my "041" Cam and that I should install the Cam straight - up, in the Pontiac case, that is orientate the dot mark at 12 o'clock on both the Cam and Crank gears @ TDC on the compression stroke.

On my 1979 Pontiac T/A we point the Rotor within the Distributor cap toward #1 in the firing order, toward my steering wheel, where my timing order starts and rotates CCW within the Dist.

Because there is little room remaining between the 428 ci Engine and the Fire wall, under the windshield and the MSD large Distributor Cap, we orientate the Vacuum Advance canister vacuum port toward my Steering Wheel.

Currently the Rotor is pointing @ number 6 in the firing order within the Dist. Cap and we are on TDC on number one Piston cylinder, because #1 and #6 are companion cylinders plus one must consider the constant changing Valve opening and closing events.

We spent a lot of time proving that the Valve opening and closing events were happening at both 050" and .006", according to our self-made Timing card numbers that we made from information obtained over the Internet and the Melling Cam site. These numbers were exact.

The Intake and Exhaust Cam lift is .313" each measured off their respective Lifters.

The Lobe separation angle (LSA) is 113.5 degrees as well. Intake c/l is 112 and Exhaust c/l is 115 for the "041" Melling Cam and we are using 1.5 Rocker arms. Total lift is .469" on each Valve and the Cam is asymmetrical in Pontiac design as all their Cams were in the day or so I read. You take 115 - 112 = 3 divided by 2 = 1.5 degrees. I believe this is how Butler Performance had Melling build advance into my Cam by adding Intake 112 c/l to 1.5 obtained above = 113.5 LSA = new Intake c/l advanced, this is done to asymmetrical Cams.

I installed the "041" Cam straight-up initially for degreeing purposes, plus to find TDC. Then I went back into the Timing cover to advance the Cam Timing by 4 degrees, for a total of 109.5 race ready performance purposes.

The Cracked Hub is the "Vibration smoking gun", issue along with the 2 Exhaust Valves slapping away in their worn-out Exhaust seats, I am sure of that, this is my Theory and add in the fact that the Exhaust cross over plugs were not doing their jobs. is like adding the candle on top of the cake so to speak. Now through in the Valve guides only needing remanufacturing back to factory spec. no more no less, they still contributed to excessive Vibrations. Of all the emphasis put on the Pistons, I disagree to agree it matters. But it is not my problem, it is yours who experienced it firsthand. I have a lot of **** to fix and I don't want to fix anything that is not broken at this very moment. I learned much in this discussion and found out even more as I disassembled the Engine. In conclusion, I will not have to rebuild the bottom end today, I am saving for a rainy day when there is nothing else to do.

As far as the Hub is concerned, I am glad that I asked the question whether or not to buy a used or new one. Here is my related story, once on my 1981 Camaro Z-28 I changed the Harmonic Balancer only to have the Timing Gears and Chain fail one year later, causing me to sell it, as is. The fact is I loved that red luxury interior, that it possessed. Not to mention that it had T-tops, plus factory air induction, electric windows, tilt steering, rally gauges, add on AC with automatic Trans. with a center console, air induction that actually opens and closes when I smash the peddle down to the floor. So, what I am leading to is: "This is where I want to spend my money, at this time that makes a big difference, let's talk about spending Mikes money on a Hub or complete Dampener that will be strong, one that will save this poor tired Engine, so I can squeeze the existing life/miles out of the Crank and Pistons and rings that are waiting to be driven yet.