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1991 Volcano K5 - Family Wheeler - Fully Independent Twin Turbo BBC

Overview Gallery Discussion
I got the tailpipes done, and less than 3 quarts fit in the 241. Also added more heat shield to the fuel line next to the muffler.

Also, I have taped a nut to a wrench many times, but when a wrench won't fit, and your index finger won't fit, I guess you got to tape a nut to your pinky...


add more coolant
add transmission fluid
add Tcase fluid
plumb fuel rail exit lines
build dual 3" tailpipes
remove factory TBI wiring and ECU
reprime oil system
install distributor
install 8 coils
install dominator ECU
install relay box (6 relays for both fans, fuel pump, coils, low beams, high beams)
make new starter cables
wire EFI
wire fans
wire fuel pumps
install digital dash
write and install custom 388 DIS SBC/4L60E tune
bring engine back to life

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add more coolant
add transmission fluid
plumb fuel rail exit lines
remove factory TBI wiring and ECU
reprime oil system
install distributor
install 8 coils
mount dominator ECU
install relay box (6 relays for both fans, fuel pump, coils, low beams, high beams)
make new starter cables
wire EFI
wire fans
wire fuel pumps
install digital dash
write and install custom 388 DIS SBC/4L60E tune
bring engine back to life

wiring and ECU removed

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Once that was out of the way I figured out the dominator ECU would fit if I made a bracket for it. So I did, I can't leave it in the engine compartment, I like it better protected from the elements in the interior. TBI plastic bracket on right, my newly made .090" aluminum bracket on left...

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Not exactly easy to get the nuts on and snugged, it's also a little pain to wire it that way, but worth it to have it tucked away nicely.

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The trusty ole 68.5" 2x6....makes working on stuff behind the engine much easier....

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Started getting ready for the digital dash. This headlight switch doesn't have the little spring tab to remove it. How does the handle come off the headlight switch n the 91? Usually you just push the spring tab and slide it off, I don't see a set screw or anything. Do you remove the whole rod like the really old stuff?

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folkenheath said:
Started getting ready for the digital dash. This headlight switch doesn't have the little spring tab to remove it. How does the handle come off the headlight switch n the 91? Usually you just push the spring tab and slide it off, I don't see a set screw or anything. Do you remove the whole rod like the really old stuff?

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You're sure it doesn't have it?
It's behind the sheet metal on the side
 
is a small spring loaded button on the switch it self you need to push it in and pull knob at same time. Some time you need to wiggle the button while pushing to it to let go.
 
Thanks guys, I was looking for a little spring clip behind the knob itself like my Regal, I should of known to take the whole rod out.

BTW, is there a way to tell in the RPO codes if I have a 3.73 or 3.42? By turning the tires I estimate high 3s, like 3.73, I could just take the diff cover off and inspect, looking for a less smelly cleaner quicker method that's more accurate for my shift programming. Nothing obvious like 373 or 342 in the RPO. I found G80, we'll see if that holds up for a couple years...
 
folkenheath said:
Thanks guys, I was looking for a little spring clip behind the knob itself like my Regal, I should of known to take the whole rod out.

BTW, is there a way to tell in the RPO codes if I have a 3.73 or 3.42? By turning the tires I estimate high 3s, like 3.73, I could just take the diff cover off and inspect, looking for a less smelly cleaner quicker method that's more accurate for my shift programming. Nothing obvious like 373 or 342 in the RPO. I found G80, we'll see if that holds up for a couple years...
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The rpo codes should have it but I can tell you that generation normally got the 3.42
 
The code right ahead of the G80 is the gear ratio.
GT4 is 3:73
GU6 is 3:42

That's if my memory is working correctly this morning. My code book is at home..

I personally would think about ditching the G80 for a Truetrac ASAP. Drive it first to confirm that things are quiet, then swap out the carrier. Just my .02.
 
6872xtc said:
The code right ahead of the G80 is the gear ratio.
GT4 is 3:73
GU6 is 3:42

That's if my memory is working correctly this morning. My code book is at home..

I personally would think about ditching the G80 for a Truetrac ASAP. Drive it first to confirm that things are quiet, then swap out the carrier. Just my .02.
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G80 and 4l60e’s FTW!
 
Thanks for the info.

Although I am not spending any unnecessary money on the 1/2 ton axles when I have two aluminum 9" center sections sitting there with 4.10 gears and 35 spline pinions for the yet to be built chassis. If the diff goes out the Millermatic locker will be the repair if possible.

@longbedder , do you know if the gears are factory?
 
The more revolutions you do with the driveshaft, the more confident you become in the ratio. Tape on the tires can be used with an angle finder to get fractional rotation. Just a thought.
 
So IS there a RPO sticker in the glove box?

10 bolt Grenade Lock is on borrowed time behind your wee motor so just have fun until something goes crunch.
 
AJMBLAZER said:
So IS there a RPO sticker in the glove box?

10 bolt Grenade Lock is on borrowed time behind your wee motor so just have fun until something goes crunch.
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I feel like everything in the drivetrain is on borrowed time with the 388 even, the 4L60E, the 1/2 ton axles, the stock driveshafts...heck the only thing I thought would take it is the NP241 and that already has a slow drip from the case halves now that I filled it up. I had put new input and both output seals, but I did not separate the case halves. :doah:

So the RPO code in the glove box, is GT4 for 3.73 factory gears. I'm going to use that although the oil stains on the pumpkin suggest I should at least check the diff fluid level.

Chevy305 said:
That exhaust system looks really nice! Did you bend that up ? What headers are you using?
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Thanks, I used a Flowmaster universal build it kit, 3" aluminized mandrel bent, and cut the pieces and TIG welded any butt joints and MIG welded any lap joints. When what you want doesn't exist, you build it. :coolblue: Then I touched up all welds with silver high heat paint that darn near matches the aluminized coating perfectly, by shear luck.

The headers were off a project from a PO, I have no idea what they are. They have 1 3/4" 304 stainless tubes, and 3/8" thick mild steel header flanges. I welded on the 3/8" thick 304 stainless 3" collector flanges I had sitting there from a different project.

add more coolant
plumb fuel rail exit lines
reprime oil system
install distributor
install 8 coils
mount relay box (6 relays for both fans, both fuel pumps, both coil banks)
make new starter cables
wire EFI
wire fans
wire fuel pumps
install digital dash
write and install custom 388 DIS SBC/4L60E tune
bring engine back to life

I also realized the 91 which I knew had a modern radio, also had a kickout on the bezel, so the factory up to 87 bezels don't cover the screw holes....

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Now I am not sure what to do about the gauge bezel, the Classic Dash bezel for the Digital Dash fits the prodash perfect but leaves a large gap on the bottom right with the 91 dash. I could modify the factory bezel for the prodash by putting a layer of metal on top and cutting the back out, but it's a pretty nice factory 91 bezel to cut up. However that only solves the problem if i use an 88 - 91 bezel.

Decisions....in the meantime I will continue with wiring....

max 02 said:
I also like how you did the tail piping. Nice execution. 3” should sound tits!
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Thanks, I prefer the tailipipes out at an angle behind the rear tires because if they go straight back they can get crushed under the bumper off roading, plus I don't like them close to the fuel tank for the full length of the tank. Since I did the exhaust on the lift at full droop it was easy to make sure the leaf springs clear.
 
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