1970 GTO -- Goatzilla

[Interceptor5588]

Current stance, no engine. How much should I expect the front end to drop when the engine goes in (6-700 lbs) with the SPC springs? I think they are rated at 535-550 lbs/in, does that mean it should drop about 1.3"?

[Interceptor5588]

Update: Finally have it more or less on the road. Ended up rebuilding the Pontiac 400, took a few extra months. Now the REAL work starts -- ironing out the little electrical and mechanical bugs . . .

[TerryD]

Man that's a great looking GTO!

[Interceptor5588]

Thanks! Once on the road I didn't do anything to it, just drove it every chance I got for break-in. When snowfall finally hit for good I changed up to the dual valvesprings, getting things together for the overdrive swap.

I did find 2 (!) black interior 2006 Impalas (one SS, one LTZ) at the local boneyard and scammed the center consoles out of both. The original consoles were spectacular in 1970 but nowadays they suck, with no armrests, no cupholders, no lighter/chargers, so . . .

Haven't decided whether to create a full-length console out of the 2 or just chop off the back one in front of the cupholders. Opinions? For the full-length version I would need to find something to fill the spot where the shifter was. Anyone know of a slim-profile cooler I could slip in there?

[0065]

I've been wanting a gto myself lately. Seeing you're gto didn't help my situation......looks great love the wheels too

[Interceptor5588]

So I've been hard at the interior for the winter and have the consoles almost done. The front is complete, waiting for the filler between the back seats to finish up the rear.



Also just about finished swapping in a TH200-R4, no pics of that but the car definitely needed it.

[F-Body International]

I'm a fan of this one...way cool!

[Interceptor5588]

I can tell you that the modern seats, console, suspension, & transmission were the best things to ever happen to the old GTO. Totally changes the feel of the car and the driving experience from a rickety old A-body to a comfy cruiser ready to drive anywhere. I can't believe guys still drive around at 4000 rpm on the freeway with 70 series tires, flat seats, and no cupholders!

Air conditioning will be the next major investment.

[Motown 454]

I like the console idea, that's slick!

[Interceptor5588]

Darned if I can upload photos though, not sure what's up with that

[TerryD]

That looks great! Amazed how OEM it looks.
Great job.

[Interceptor5588]

My goal is always to make the installation look OEM but perform better!

Need to find/fab a storage bin for the rear console to match the curve of the console. Future plans are for AC custom serpentine drive, rear control arms, big brakes, and fuel injection for the Pontiac 406; I've rediscovered that I don't like carburetors ...

[Interceptor5588]

So after messing with the Pontiac 400 for a couple of years I decided to give up. Just too many issues and not enough power for the effort. Certainly not the reliability that I need for cross-country touring. Since I have a background in Buick turbocars and I miss the rush, I figured the best route would be to work my way back into turbo power. Car is up and running now, I'll spend the summer working out little bugs and then set up a single turbo this winter.

I chose an aluminum 5.3 for weight savings and thicker cylinder walls, and a 4L80e after hearing all the stories of failed 4L60's. Summit Ghost Cam, gapped rings, MLS headgaskets, TBSS intake and a 3000 stall converter are about it for mods. Holley pan and mounts fit pretty well and a March serp setup with AC looks great. Added Classic Auto AC as well.

The converter is a little loose for my liking -- no more puttering around at 1200 RPM like the Pontiac V8. Once on the roll it provides the familiar slingshot feeling of my couple of Buick T-types. The converter masks any bottom end power the 5.3 might have so I can't really compare with the 400, but with any serious throttle it seems to pull harder than the Pontiac did at all RPM's over 3000. Main difference is it feels turbine-smooth all the way through, while even with the Pontiac motor balanced it was as if you could feel every cylinder firing.

Overall happy with the swap. I figure if Buick could take a 140hp V6 and make it that much fun, starting with a 400hp V8 should make it more so. A single 76-78mm turbo should get me 6-700hp, should be enough to entertain me til the next phase...

[Interceptor5588]

Before installing the LS I mocked up a pair of twin-turbo ebay headers, look pretty sexy but I dont know if they will work in the end or not due to the AC lines etc. Oh well, makes for cool photos anyways!

[andrewb70]

Good to have so much room under the hood!

[Interceptor5588]

Good to have so much room under the hood!

One would think. In mocking up the turbo system I've found that there's not as much as it seems.

I've completed the 5.3/4L80e swap and driven it around for the year. Driveability is great, power feels similar to that of the Pontiac, a little more up top and a little less down low. Dyno'd at 340 rwhp/320tq. Took it on a 2000-mile roadtrip and never had to lid the hood once. Overall I'm happy with it but needs another 2-300hp.

I've started mocking up the turbo and found that those sexy twin turbo headers wont fit around my AC without serious mods. Also, the outlets place v-band mounted twins right into the rad, unless you elbow them. Thirdly, the flanges don't quite fit the bolt holes in the heads ...

Any kits available (CX Racing etc) are the same with regards to the AC, all require mods. I see no sense in spending $1000 on a kit and then have to mod it, so I'm building my own. I'm going with a single billet 7875, using forward and down truck manifolds with a crossover under the crank pulley. All tight but looking good so far.

[Vimes]

Forward and down? I thought using stock manifolds was supposed to be forward and up, although I'm certainly no expert.

On the AC problem, you could use a GMT800 truck AC bracket which mounts the compressor at the bottom passenger side of the engine. You can notch and box the K-member to make room for the back of the compressor, or install an aftermarket tubular member which will free up quite a bit of room down there. I've seen them for Chevelles, should fit a GTO as well since they're both A-bodies. Once it's all installed you can run new AC lines to clear everything. It would probably be best to use a shop that can make lines for this one since the routing would be a one-off job and making AC lines is really best left to a shop unless you have experience with it.

A nifty alternative from the hypermiling world - an ice box. Over there they just dump a bag of ice into the fresh air intake, but that adds humidity into the cabin. Build a box that will hold 10lbs of ice along with a heater core in the trunk, with a drain. Clean the AC evaporator out, then pipe it back to the ice box. Put a circulating pump inline and add a water/antifreeze mix. 10lbs in an insulated box should last all day, and if it doesn't ice can be had at any grocery store. You'd have AC without the compressor, and without the engine load. This will also keep the dehumidification ability of the AC, although this would require ice in the winter.

[andrewb70]

Why not use the Holley single log with the crossover under the trans?

Andrew

[Interceptor5588]

MIGHT work. Real good holiday pricing on them right now I see too... What's the ground clearance like under that crossover? To go under a 4L80 converter cover it would have to be below the crossmember, or would need to remove the cover. I like the cover in place for a real street car that actually encounters the occasional gravel road. In photos the Hooker turbo v-band outlet appears to be too far forward (seemed to be around the front heater hose port) to bring the discharge pipe up where the turbo would fit on an A-body, again requiring modification to a $700 part, or mounting the turbo farther forward requiring bracing off the frame. I know guys do it but I can't see it being a good idea.

My electric fan setup is about 2" off the March AC compressor so not a lot of extra space out front. No doubt the AC is what makes this challenging, but that's the fun part! Worst case scenario, I've wasted a a couple of hundred bucks on manifolds, v-bands and mandrel bends and I have to admit defeat and go with the Hooker setup. We will see...

[andrewb70]

You'd have to build a pipe from the exit so that you position the turbo where you want. I don't know about the ground clearance.