[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

['ol Pinion head]

What is effective gear ratio in top gear with GV OD?

Rhoads lifters w the 041 is where many of us would start. Otherwise... Good luck going to a smaller "cam of the month", as unless it's setting on a shelf somewhere, going to be some time til one can be machined.

[1968GTO421]

Originally Posted by 'ol Pinion head

What is effective gear ratio in top gear with GV OD?

Rhoads lifters w the 041 is where many of us would start. Otherwise... Good luck going to a smaller "cam of the month" as unless it's setting on a shelf somewhere, going to be some time til one can be machined.

That is the truth. Cams are harder to find than winning lottery tickets. 041 with Rhoads would be a good setup. I was lucky and found my Voodoo on eBay but haven't seen a Pontiac one since.

[Vid]

Originally Posted by 'ol Pinion head

Otherwise... Gluck going to a smaller "cam of the month" as unless it's setting on a shelf somewhere, going to be some time til one can be machined.

Bullet/Ultradyne custom ground my cam to order and I was surprised that the entire process from initial phone call to delivery at my door only took a little over a month. In this day and age, that’s downright FAST! Mad props to those guys for great service.


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['ol Pinion head]

Originally Posted by Vid

Bullet/Ultradyne custom ground my cam to order and I was surprised that the entire process from initial phone call to delivery at my door only took a little over a month. In this day and age, that’s downright FAST! Mad props to those guys for great service.


Sent from my iPhone using Tapatalk

Great to hear. I had planned a Bullet cam, & need to finalize cam specs on a near future build. THANK YOU.

[Cardo]

Hopefully the cam blanks are starting to show up... I ordered a Lunati Voodoo HFT cam on July 22 and got it on August 17.... Pretty quick considering the current situation.

[TRADERMIKE 2012]

I have 3.23 gears. In overdrive, I get the less than 1:1 ratio that one gets in third gear of the TH400 transmission. I think Gear Vendors allows the overdrive in the .75 range, but don't quote me. I am at 80 mph in overdrive tops at 3000 rpm now. I have heard of the Rhoads lifters and going to 1.6 rockers, not sure if i need all that but in the future maybe if someone can explain why i should go that way.

As for today, I have a timing gear and chain from Comp Cams installed 8 crank degrees advanced and that is 4 degrees advanced at the cam, but I have not run the engine yet this way. If I understand anything I have read over the years, I will be bringing the power range toward the starting line as a race car would like. Question is, before i start the engine with this advanced setting, am I safe and will not hurt the engine at all? Once I feel safe to run the car in this advanced condition, then I will test and tune and curve the distributor to match the advanced cam.

I originally installed this cam straight up per Mellings advice, but after running it for a few years I found the power range is higher than it needs to be. So, I want to bring the power range toward the launch of the vehicle off the line for street purposes only. By advancing the the cam 4 degrees, am I doing the correct thing or not? If I like the way the vehicle moves off the line for street use, then I will have the distributor advance re-curved.

[Tom Vaught]

I have a 744 high lift Wolverine "Blue Racer" camshaft that has the lift of the RA-IV camshaft but less duration than the RA-IV that has worked well on several engines like the engine you want to do.

Just a thought, no sales pitch.

Tom V.

[TRADERMIKE 2012]

I don't want to go down to a smaller cam, this is the reason that i am sticking with this 041 cam. More duration and higher lift works well with my up jetted tripower carbs.

This YK code 1967 428HO is one of 1,024 made in 1967 with special equipment. Is it special in that it uses the 524886, cam or is it because of the Y-branch manifolds? I have the partial vin on the block number but have yet to learn from PS what vehicle it was in. All I know is a moonshiner in the Carolinas used it and it was pulled out of a truck. The man who sold me this 1979 TA has passed away, and that is his story.

This motor has d-port heads and 10.75 compression. The 1966 tripower intake and carbs belong to 389 or 421 motor. My engine YK code is automatic and 4 barrel carb, so how did this motor get the tri power set up? is that what makes it special equipment? It was produced early in 1967 and Pontiac had stopped installing tripower in 1966, could my motor be one that was on the shelf prior to the gm tripower ban? The 524886 cam is #6 1956-62 tri power cam, 283 112 .407 60 293 116 .407, it’s between the 067 and 068 cams but i found it is the only cam designated for tripower out of the entire list. That is why in my own personal trial that it works perfectly in sync with the kick down, torque converter and tri power secondaries. At the time i had one inch phenolics under each carb.

[TRADERMIKE 2012]

tom, i must stay with all things factory build , this project scope is thus , i have a 1979 pontiac ta with a 1976 front and rear clip. a 1976 formula hood with the snorkels and a ta reverse scoop facing the windshield for actual running
cold air induction. i use the ram air pan under the tri power carbs.

[padgett]

Just my opinion but have a 744 cam in my 4-speed/AC 400. For more cubes I'd go to a 041.

[TRADERMIKE 2012]

padgett are you running tri power also?. and i have red that your set up works well . keep in mind i don"t race and i am running 3.23 gears at this time . nice judge or t-37 or tempest .

[Tom Vaught]

524886 camshaft specs:

1956-62 3/2bbl 6 283 112 .407" .447" 60 293 116 .407" .447" 524886
The .447 lift is with 1.65 Rocker Arms. .407 with stock 1.5 rocker arms.

1966-69 RA H 301 113 .407" .447" 76 313 118 .407" .447" 9785744

My camshaft I proposed (same as the 1966-69 RA H Camshaft as far as duration but more lift vs the stock .407 lift. It has .469 lift.)

That cam is one step below the RA-IV camshaft you want to remove. Lift does not affect driveability as much as duration does.

Your 524886 cams is smaller that even the stock RA-III camshaft for specs.

But your decision.

Tom V.

[padgett]

Right now I have an 800 CFM QJ on mine. At various times I have had dual quad AFBs and 66 tripowers. Secret to decent MPG is in the progressive linkage & tripower is best with a single large oval air cleaner as used on B-bodies. Little A93C pots are terrible.

[Stan Weiss]

From H-O

Stan

[74Grandville]

are you stuck on the 041 cam? maybe step down to a smaller cam to move the torque curve where you want it.

what are the specs of the rest of the engine.

[74Grandville]

in my opinion you're going about this a in a way that will not give you the results you want. sounds like you were happy with the old, much smaller cam. your gearing is also not ideal, let alone having a gear vendor unit. your engine will be cruising at an RPM range it will not be happy with. I think most say to install a RAIV around 110 degrees ICL for best results. You would use the advance/retard settings in the chain to put the cam where it should be using a degree wheel.

for example, even if you advanced the 041 to 105 ICL (8 degrees). it will be down in power everywhere compared to a high lift 744 (summit 2802). especially low end torque!

[TRADERMIKE 2012]

ok for now i am stuck with this cam and i have the option to set the cam at 2-4-6-8- degrees at the crank . what should i set it at or should i just put it back straight up as it was before?

[tooski]

As yet I have not seen a comment on degreeing the cam. The cam card will state where the intake center line should be. Just picking an amount to advance the cam is not proper. Hopefully one of the various engine builders will better assist you.

[lust4speed]

Don't worry about what the timing is at the cam. Conversation should only be about what the degree wheel reads, and that is crank degrees. The eight degrees would be crank degrees. With high lifts you could have valve piston interference advancing the cam that far. Regardless, adding that much advance is going to at least make all ranges of the RPM range suck. For many of us, an 041 cam is a tame grind and it really shouldn't be that bad if installed correctly. Only thing that jumps out at me is the 12" torque converter that would really be more at home on a truck turning low revs.

My advice would be to actually degree in the cam and set it where the cam card specifies it should be, or at least no more than two degrees advanced. If you want more low end power, then grab a set of the Rhoads lifters that were recommended above.