[TRADERMIKE 2012]

I just joined the forum. I've received good information here in the past, thank you .

I own a 1979 Pontiac Trans Am with a 1967 Pontiac 428HO tripower engine, TH400 transmission and Gear Vendors overdrive, B&M shifter, working air induction, Herb Adams suspension, posi-traction with 4 wheel disc brakes, roll bar throughout the cab, trunk and motor compartment, never raced. There is more, but that should be enough to give people an idea what I have so they may help me with this decision.

The question is, I pulled out the worn used cam but I liked the way it worked. Not knowing better I put in the Melling #8 (or Pontiac 041) cam. The vehicle has top end performance in the upper range. I would like to bring the power range back where it is useful as a weekend driver. The original cam number is 524886, and even though this cam was worn out and I was bending a push rod at 130 mph because the rocker bolt was split and I had just got this second hand project in a non running form, I liked the way it would get up to say 90 mph and launch to 120 mph and then slowly get to 130 mph. It is the perfect cam. The secondaries, kick down, cam and converter all worked as Pontiac invented it.

Back to the 041 cam. I had delusions of grandeur that I wanted to have the upper end speed over and above 130 mph. I then learned the Cooper GT tires are only rated to 80 mph, so over a four year period, running at times up to 130 mph the tires one by one would separate from the misuse I inflicted on them. I am now back to earth and grounded in the fact that this air conditioned vehicle is never going to race on the salt flats. I now have the 041 cam installed and broken in, and I am trying a Comp Cams timing chain set that is adjustable at the crank. I installed the 041 cam a few years ago straight up as Melling said to, and it runs as it should.

I have the option to advance the cam timing 8 degrees at the crank and at the cam it will be 4 degrees. Please keep in mind I took this project on 7 or 8 years ago, and it's been 3 steps forward and 2 steps back. In my reading I've learned that one can bring the high end power range within a cam back from the top end to the lower end to launch the vehicle as if I were racing. Each advance degree would be equal to about 500 rpm of the power range, so 4 degrees will be moving the power range back 2000 rpm in average terms (500 rpm x 4 degrees at the cam).

Please don't quote me on this, because I am depending on memory of what people write. I am trying to discern who is telling the truth compared to who is knowledgeable or not, and who is speculating. First and foremost, before I start this motor with the cam advanced as much as I stated, I must know if it is safe and that I will not hurt the motor? Secondly, I am figuring that the intake has 230 degrees duration at 0.050" and the power range is from 2500 rpm to 6000 rpm. The exhaust is 240 degrees duration and the power range is between 3000 and 6500 rpm. The intake peaks at 3500 rpm and the exhaust peaks at 4000 rpm.

This is what I learned over the net: the 041 cam in my 4000 lb vehicle moves in a steady acceleration from stand still to top end and just goes like it will pass 130 mph, but there is no jaw dropping fun with the. the original 524886 cam could not exceed 120 mph, as it fell on its face after throwing me back in my seat between 90 mph and 120 mph. I thought about replacing the 041 cam with one that has the same specs as the original. I like the duration of the 014 cam, plus the lift is 0.470 using 1.5 rocker ratio. Since the 428ci engine can handle the 041 better than a 400ci engine, I might as well try the advance trick.

This new Comp Cam timing chain set can be set to 1-2-3-4-degrees at the cam and that's 2-4-6-8- degrees at the crank. Presently i am at 4 degrees at the cam. Will I be overdoing the cam timing or can I hurt the engine by over-advancing the timing chain using 4 degrees advance without installing a set of 1.6 rockers? Is that as far as I can go without doing some modification at the base of the dual springs?

Keep in mind this is a stock engine with a new timing chain and gears. The lifters went in around 7000 miles ago, with new chrome molly HD pushrods that were installed with the cam along with new Johnson hydraulic lifters. Also at that time I installed a new oil pump, and stronger rocker arm studs/nuts/washers for adjustable factory settings for lash. The engine has a strong bottom end and no head leaks. There are the original splash shields under the valve covers.

The 1966 GTO tripower intake and Rochester carbs have new rebuild kits with new power pistons, jets, inner screens, discharge tubes, anti-perculation aerators (they have the holes in brass to break down fuel molecules for better atomization.) The ram air pan is sealed to the bottom of the hood so all you get is cool outside air to the motor. This keeps the fuel with alcohol from percolating and causing a vapor lock. I installed a HD temperature clutch fan and a extra side kick fan. I then installed an electric pusher fan out front of the radiator, and a special thermostat with 3 by pass holes. The head crossovers for the choke are covered so no heat gets under the center carb.

i pulled the intake off and put phenolic over the valley pan and under the intake, to help block engine heat from the bottom of the carbs. I followed instructions on line to modify the water pump to lower the clearance. When I installed the a/c, the engine temperature went up 30 degrees, so I wrapped the fuel bowls with insulation and added phenolics under the bowls to keep excess heat from getting to the fuel bowls. The metal lines to each carburetor are also wrapped with heat wrap.

I have 4 remote oil coolers. Two of them are using 3/4 " copper pipe a few feet long, along with two transmission coolers, plus I just added a remote oil filter. There is also a power steering cooler and filter. I’m running an MSD box and a super coil. The only option I don't have installed is the cruise control although I do have all the parts.

Recently, I broke the torque converter, so I bought a 12” HD monster that will move a large RV. I just installed a B&M transmission kit, and cleaned out all the valves in the valve body. I added a new vacuum modulator and cleaned the governor.

The car is lowered 2" with Belltech drop spindles in the front and Herb Adams leaf springs in the rear. It has larger diameter anti sway bars and Koni shocks. I only use fuel without alcohol so the boiling point of the unleaded is higher than alcohol fuel by 10 degrees to avoid percolation.

Over the years i have done the wrong fixes first and learned what the major fixes are toward the middle and toward the end. This is my first build. Hopefully you have enough information to help me make the best decision for this project.

Thanks
Michael