BUILD THREAD my 1980 Grand Prix w/BBC 454 build thread

[Texas82GP]

For the curious: my next fill-up netted 12.35 mpg, but the one after that dropped to 10.9 mpg (no highway driving on that tank).

I am planning out my next move. I am debating between installing the EFI (which would require a new gas tank & pump assembly), upgrading the front brakes (they are down to the wear indicators, and the RWD 2nd-gen Blazer setup bolts on), or addressing the rear axle (installing c-clip eliminators and new axle shafts). Decisions, decisions.

Oh! I did do something a few weeks ago, and it is well worth mentioning here. Ever since getting the car running with the V8, I have had a bizarre variety of intermittent electrical issues. For example, my 4-pack of secondary gauges would sometimes wiggle all their needles in unison... but since my primary gauges didn't do the same thing, I figured it had to do with a poor connection in their wiring (the 4-pack is wired completely independent from the primary gauges). I would also notice the volt gauge indicated the alternator would struggle to get past 12v any time I was at idle, and even at moderate RPM seemingly small loads would cause the gauge to drop significantly. The real kicker was nighttime driving: the car's entire lighting system would randomly dim sharply for no apparent reason, as if the entire lighting system was shorting out or something. Replacing the alternator didn't make a lick of difference. It was weird.

Then one day Mike and I stopped by O'Reilly. Eric was telling us about his '64 El Camino which he just got running, and out of the blue he shared a fascinating tale. "Man, when I started driving the car it kept having electrical problems. I'd be going along and it was like the entire car would suddenly short out--the headlights would go dark, the engine would sputter, the gauges went nuts, etc. Someone asked me about ground straps, so I went home and dug up a plain old GM engine-to-firewall strap. I attached it to the back of the intake manifold and the firewall. Suddenly all of my electrical problems were fixed."

I started thinking about the GP. I couldn't recall hooking up any sort of ground wire like this. Furthermore, the car's negative battery cable has a beefy wire going to the engine block, but does not have a smaller wire going to the body. Hmm. Could my solution really be so simple? As soon as I got home, I went looking through my garage for a ground strap. I didn't have a GM one, but I did have a couple from FWD turbo Mopars. I figured the electrons wouldn't mind the brand mismatch, so I installed one between the back of the intake manifold and the firewall.

Bam! Just like that, all of my electrical gremlins disappeared. Gauge needles stopped flickering, alternator charges properly, my voltage doesn't drop, my headlights stay bright, etc etc etc.

Ground straps, people! Ground straps!

Nice work. My vote is front brakes, since it needs them already.

 

[pontiacgp]

For the curious: my next fill-up netted 12.35 mpg, but the one after that dropped to 10.9 mpg (no highway driving on that tank).

I am planning out my next move. I am debating between installing the EFI (which would require a new gas tank & pump assembly),

If you are considering the EFI to better the fuel mileage I would install an Air/Fuel mixture gauge to see if the carb is set up right. It doesn't take much to be off the 14.7 to waste gas.

 

[motorheadmike]

Never under estimate the power of good grounds. See what I did there?

I have two large ground straps on both sides of the block going to the frame, one off the battery and one stand alone. It is also paramount that the connections are clean and tight.

 

[454GrandPrix]

As it happens, my backyard-engineered TPS setup has been giving me occasional fits.

Some days, it works fine. Other days, it sends a signal >100%, which causes the TCU to freak out and go into limp mode. I can't wait to install the FiTech EFI, as I plan to tap into its internal sensor and send that signal to the TCU... but I needed to do something else for the time being to improve the situation. I didn't want to spend any money if I didn't need to, since this new setup will just be temporary. What to do?

I was venting about this to Mike a few weeks ago, and he told me he had a cable system for a remote TPS just sitting around in his RV (which he stores at a lot 20 miles away). It took a while, but he finally had a reason to drive down there... so I went with him. Sure enough, he had this fancy cable thingy which looked like exactly what I needed. He let me borrow it, as promised, and I went home to see what I could do with it.

The carburetor end could not have been easier--it simply clicked into the bracket I was already using:

I routed the cable around the firewall and over to the left inner fender, then screwed it into place. The mildly tricky part was determining exactly how to attach the sensor to the fender so that I could use its entire sweep range and yet not go so far as to trigger the TCU's panic mode. But after a bit of testing and experimentation, I decided mounting the sensor at this angle would be perfect:

I've been driving it this way for a couple weeks now, and I've been sure to make frequent full-throttle stabs at the gas pedal--you know, in the name of science--to test and see if it will work as intended. It has been flawless thus far. Victory!


In other news, I ran through a tank of fuel almost entirely on the freeway. For one of those freeway trips, my mother was visiting from out of state and I was driving her home from the airport. For all you gas hogs out there, I offer this pro tip: if you want good gas mileage, just take your mother with you wherever you go. Not wanting to scare the poor woman, I drove very gently while she was on board... and that tank earned me 14.56 mpg. 😀


And in other other news, I went hiking through the local Pick-N-Pull today. I passed an early 90s Grand Am and its fender badges caught my eye... so I liberated them. I stuck one on my car just to take this photo:

I'm wondering what kind of reactions I will get if I stick them on there for good.

 

[454GrandPrix]

My schedule was open yesterday evening, so I decided another modification of the Grand Prix was in order. Time to install those Trans Am hood vents! Reciting the 'measure twice, cut once' mantra over and over to myself, I began at my kitchen table by making a heavy paper template for the holes. Once I was convinced it was exactly the perfect shape, I went out to the driveway and went bonkers with my tape measure. I measured, took notes, re-measured, updated my notes by a sixteenth of an inch here or there, then re-measured again, re-checked my notes, etc until the design was perfect. I then taped the template in place, measured it carefully to ensure it was where I wanted it, and then used a Sharpie to draw its shape on my hood. I removed the template, flipped it over, and began measuring to put it in its proper place on the other side. It took a number of minute adjustments until it was exactly symmetrical with the first outline, but once it was finally perfect I taped it in place and marked the second outline on the hood.

I was now ready to have my neighbor help me remove the hood. I set it on my front lawn, then propped it up against an old chair I keep in my garage. I grabbed my trusty Makita cordless angle grinder, installed the cutting wheel, and began carving like a Thanksgiving turkey. It didn't take long before I crossed the point of no return.

Hmm, there was a support rib which was annoyingly in my way. I laid the hood upside down on the grass and cut off that rib, plus its symmetrical twin since it would soon be in my way, too. Then I propped it back up against the chair and proceeded to cut the second hole. As I was making a vertical cut, through the first hole I was surprised to see a column of smoke apparently coming from the backside of the hood. What's going on??? I shut of the tool and peeked around the hood. I think I found out where my trail of heavy sparks had been going:

Oops.

Thankfully, it didn't quite erupt in flames. But even if it had, I was prepared: before I began cutting, I had filled a large bucket with water and had it sitting next to me all the while. You can't be too safe when it comes to fire, even if you're on your front lawn.

With the holes completed, I switched to the grinder wheel and smoothed off the edges as best I could. I laid down some black paint to help prevent rust, then had my neighbor help me reinstall the hood. For the first time, I could stand back and admire my handiwork. (Dusk was setting in, so these two potato pix look worse than normal.)

These particular vents are held in place via four thread-cutting nuts (two per vent)... and I had none. I drove to AutoZone and bought their only package of random assorted thread-cutting nuts, and it had three of the size I needed. By the time I returned home the sun had set, so I didn't get any more photos then. However, I quickly realized I need to slightly grind one of my cuts--it prevents the passenger-side vent from sitting flush against the hood. Nevertheless, I installed them both as best I could for the time being. This morning at work, I took a couple more photos in the sunlight:

Perhaps after I get the passenger side vent to sit flush, I'll update with another photo. Oh, and I'll probably fog the vents black at some point. But for now, I think they fit the image of the car just fine.

 

[TURNA]

HAHA that is awesome!!!!!!!

Nice!!!!!!!!!

 

[MrSony]

coolio

 

[Bar50]

You need to add T/A vents at the back, they are like 6 or 7 inches long, about 2 inches wide, have them accent the hood body line.

 

[454GrandPrix]

Brave man that I am, while driving home last night I finally decided it was time to try some sort of burnout in this car. I detoured slightly to the edge of town, where I could find a quiet back country road away from residential areas and with some roadside trees for cover. No powerbraking was involved; I simply came to a stop, then nailed the throttle. I was of course greeted by instant wheelspin, which continued throughout first gear and into second. My slight bit of tree cover was ending, so I lifted before the transmission shifted into third and thus ended the smoke show. I drove around the 'block' (which meant a couple miles all together), then made a second trip down the road to check out my pavement signature.

That's when I saw only one tire had spun. 😡

Hmm. Maybe I need to install that TrueTrac diff sooner than later. I sedately continued the rest of the way home. I parked in the driveway, shut down, and got out as usual. As I was walking around the car, I could smell a very strong odor of burning rubber. Really? Still??? So I took a peek at the car, trying to figure out why. It didn't take long to figure it out:

Oh. 🙂

 

[454GrandPrix]

Leaving work last night, I noticed there was a small water puddle in the aisle. Hmm, perhaps I could use it as a water box for the left tire, and then they might both spin. I pulled through it slowly, then nailed the gas for just a few seconds. There was a ton of smoke, which made me happy because I figured both tires must have spun.

As I arrived at work this morning, I saw that apparently only one and a half tires spun:

(sigh)