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Originally Posted by TRADERMIKE 2012
Here is Mikes car:
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Mike here to revisit this post, see: TH 400 Pontiac Transmission Build or not to Build Myself? In this other post of mine I am linking it to this one for an update on my progress, it turns out that my passing gear kick-down switch was inoperable, thus there is no need to change my Cam back to the original one after all. I admit I have more to learn and that is how I discovered that the reason my vehicle ran like a raped ape and then stopped is because the wire to the high-end passing detent downshift was cut.
My 428 ci HO Tri-power engine in my 1979 Pontiac T/A used to go from 70 mph and step down hard on the accelerator and the detent solenoid would engage at 70 percent opened throttle and then the secondaries would open and dump the fuel at about 90 percent open throttle. This amounted to say 70 mph the vehicle took off into second gear and when I hit 90 mph the secondaries opened up and threw me back into the seat and went to 120 mph very fast. Then it dropped off and increased slowly from 120 mph to 130 mph max. My tires were not speed rated for those types of speeds and over the years playing around in the high-speed range, the tires were fatigued and were ruined, so that in four years, I had to replace one tire at a time about one per year. I am now aware that tires have speed ratings and a letter associated with those speeds, one can look up their specs online.
I don't spend any time up in that high-speed range anymore because I now know the limits are 130 mph opened up. Originally, I thought that when the vehicle did not perform as it used to that I had changed to a different cam in between and that might be the reason, but I was wrong. Too bad no one on the forum picked up on this and told me that the detent solenoid was the culprit. I did not figure it out until I took the trans. apart and we disassembled the detent solenoid and noticed the split wire., plus the switch in line with the linkage needed modification as well.
We installed an LED light bulb in series, so that when we adjust the switch, we can reliably see when the actual switch was in the opened position, this led to a more accurate adjustment and proof we were getting power to the switch, at all times. So, update this post, I don't need to change my Cam from the 041 that is in the 428 ci Pontiac engine back to a #588 type of cam which is like the 067-068 Tri-power cams. It turns out that the 041 cam is a good and recommended cam for a 428-455 ci blocks, I do not need the Roads variable lifters in my case either since I don't race my vehicle. I advanced the adjustable timing to race performance as well, if you read this entire post, if not please do so, there is allot of good information from forum members.