1970 GTO -- Goatzilla

[Interceptor5588]

This will be the build thread on my 1970 GTO. "Goatzilla?" . . . Anyways just purchased locally in October, 20 year old repaint, no rust, "rebuilt" Pontiac 400 with a crusty-looking but working TH400. Plans are for rebuilding the 400 properly for now with a bump in compression, modern running gear and seats, and the addition of AC and a decent stereo. Car will be closer to Touring than to Pro, it won't be a high-dollar build and I have a track car to thrash (92 Formula with a 383/T56) so don't need to go all-out on the race stuff on this one.

Longterm plans include either A) an LS/T56 transplant or B) build up a turbo Pontiac or LS. My last ride (sold in the Spring) was an 11-second Turbo Buick and I do miss the power rush; we'll see what time brings.

Loaded up to come home:

[Interceptor5588]

Sold the Centerlines ASAP and rolled into the garage on stock rims.

[Interceptor5588]

Coming apart. The original owner did what we used to call an "overhaul" on a 1972 mill (original engine long gone) rather than a proper rebuild, and never fired or installed it. Cam was ridiculous for the heads, etc. I tore it down to the shortblock and checked everything, ended up polishing the crank (you should have SEEN the goop that came out of the oil passages) and changing out the new bearings cause they were already scored. New cam on the way and scored some high-compression heads from a 70. Might go with aluminum heads later but we'll see. I cant believe he put a crank back in looking like this:

[Interceptor5588]

Interior. Pulled the seats and carpets and found NO rust, I was amazed. I knew there was only surface rust underneath from many years of storage, and I knew the trunk was clean, but I thought there would be SOMETHING, somewhere, that made me go "AAARGH."

I did, however, find a big ol mouse nest under the back seat, two in the headliner, and one in the kickpanel vent with a little petrified bugger at the bottom, R.I.P.

[Interceptor5588]

Had the dash redone and installed a new cluster from Fast Lane Racing. Comes complete with gauges but you have to wire everything, it is definitely not a bolt-in. The end result is well worth it, though.

I have red leather seats on the way from a new-style GTO, and new black carpet to kill the red a little. The whole interior is red and it's just a bit much for me. A set of Year One Rally II's are also waiting at the border, that will do it for major items this winter. Found some used SC&C suspension pieces locally (thanks Gary!) and installed the front end. I was amazed at the dirt caked into the front crossmember and frame horns -- at least an inch in both, probably 20 pounds worth.

[andrewb70]

Nice project!

Andrew

[Interceptor5588]

Year One Rallys installed, 245's on 17x8 and 275's on 17x9. Car will drop another inch or so in the front (when the engine goes in) and an inch or two in the rear (didn't change to the SPC springs yet.) As it turns out I could probably have gone with 275's in the front on the 9" rims, but various sources told me they'd never fit. Anyone ever put 275's on a 17x8 rim? I could then go 275/285 staggered.

[Interceptor5588]

Seats are here. I'm finding that the pitfall with a red interior is that all reds are different, whereas black is pretty much black if you have black. I may look into some re-dying of various parts when all is said and done. I still think the red GTO seats were the best choice.

[Interceptor5588]

Seats mounted. Cut apart the rears and pushed them tight against the armrest panels, lines them up much better with the front buckets and leaves room for a custom center console of some sort. Any ideas for something that might be made to fit?

Fronts needed 8 different brackets made up as all the floor corners are different heights and shapes, and the seat tracks are 4" wider than stock. End result is perfect though -- I'm 6'1" and can sit in the seat with a helmet on. Full 8-way power seats on both sides are nice . . . Front buckets are much bulkier than the originals though, don't leave much rear legroom.

Luckily the red is not as far off as I expected. I think no matter what red interior parts I get, nothing will match the 45 year-old red existing panels well. Not uncommon with red in general I think. Funny how it changes with the camera flash, the front and back seats are identical yet show up very differently in photos. I remember my Turbo Buick had red cloth interior and it looked absolutely horrid in photos, while it wasn't bad in person.

Now just to change the outboard rear seatbelt mount position, clean it up and soundproof/carpet the floors.

[1989GTA]

Coming along pretty good. I like you wheels. I am still thinking of putting in the GTO rear seats in my 65 Skylark. I did get the attachment points for the bottom of the rear seats. I will be following along to see how it all turns out.

[Justin@EntropyRad]

The judge is dope...look into rub-n-restore if you need new leather dye, I really like that stuff

[Interceptor5588]

look into rub-n-restore if you need new leather dye, I really like that stuff

Hm, might be the answer. When the guts are all done I'll look into it. Thanks.

Your rads look great as well, will keep in mind when the time comes.

[Justin@EntropyRad]

Right on!

[Arctic_Ragtop]

Nice project. Keep the updates coming !

[Interceptor5588]

Front floors -- lucky me.

[mikes2nd]

Hah isn't Goatzilla trademarked? Pretty funny we are going to have to trademark our "cool" build names. "rolls eyes"...

Runs off to trademark office to get Goatzilla...

Back seats are hard to fit, I have seen a lot cut them back and down to make those back seats usable.

I have a set of black 2004-6 seats and I made mine into a two seater but I need some room for a roll cage. I was thinking I could put one seat but said F it, its a two seater, Maybe a little storage in the back.

[Interceptor5588]

New carpet and rear seats are in. I'm 6'1" and my head just brushes the headliner, so they're a little high. Not much to be done about that, and it's pretty common in all cars at my height anyways. The number of times I will sit back there again will be zero. Time to go start measuring fancy consoles at the junkyard for fitment. I left an extra power wire in the trunk for Ipad chargers, etc, maybe some kind of a cooler . . .

[Mr Nick]

Nice project! I'm a big fan of white muscle cars.

I'm selling a console I was going to use in my Cutlass, maybe it will work for you?

https://www.pro-touring.com/threads/90492-Semi-Custom-Center-Console-amp-A-Body-Firewall-Plate?highlight=console

[Interceptor5588]

Carpet, dash, stereo, speakers, seats, and console are all in, wired and mounted. Just a few little things left like the shifter trim etc and the interior is DONE . . . for now :-))

Time to get back to the engine . . .

[1965gp]

Car is looking good. Get some Zaino leather in a bottle for the seats and it will help ease those wrinkles. Made all the difference in the world on our 04 GTO.

You mentioned running 275's on 8" wheels. I had ordered 275 40/17 redline tires before I knew the 17 x 9's wouldn't fit our 68 LeMans. I ran the 275's on the 8" wheel and they looked fine- I little bulge but fine. I ended up having to go to 245's because the 68 fenders kept rubbing.

These are 275's on an 8" wheel all the way around:
https://static1.pt-content.com/images/pt/2013/10/f300d74e190961ea4930661076015302-1.jpg

I have 275's all the way around on my 70 GTO:
https://static1.pt-content.com/images/pt/2015/03/81451c566286ca2b249fa93b5a10c495-1.jpg

[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.

[ryeguy2006a]

Very cool swap!

[Vimes]

Sorry, don't know what the clearance on the tubular K member would be. I know they're there but have never used one. But, they are basically replacing that gigantic K-member with a 2-inch pipe, and they're designed for cars with high horsepower levels. If I were keeping my Chevelle I'd probably put one in.

[Interceptor5588]

This is what the final configuration looks like. It's amazing how tight things get in that corner of the car when you add it all up, especially when the old cars have so much room under the hood. I'm hoping heat won't be an issue, I've put heat shields everywhere. I ended up squeezing a 12x3x24 intercooler between the condenser and the rad, it actually came together quite well.

It's finally on its way to becoming Goatzilla!

[andrewb70]

Good progress! It'll be pretty quiet with those turbo mufflers.

[Interceptor5588]

Yeah it was never a loud car. May have to change that. it might be TOO quiet.

[ryeguy2006a]

That's a very clean turbo install. Nicely done.

[Way2qwk4u]

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.


How well does that console tuck up under the dash? I was looking at this and would like to do something similar in my car.

[Interceptor5588]

How well does that console tuck up under the dash? I was looking at this and would like to do something similar in my car.

Nice and tight

[Interceptor5588]

Turbo build is done. A success I would say, 550 rwhp @5800, 12 psi boost. Ended up with an Ebay billet 7875. Nice flat torque curve with boost coming on around 2500 with the 3000 stall converter. Plenty of boost for some fun at part throttle, exactly what I wanted. Passing on the freeway is awesome and effortless, should be a hoot in the mountains. Not sure how accurate the Gtech Pro is, but it showed 11.08@137mph on a test flight.

This brings new meaning to the name "Ram Air!" Now about those brakes...

[andrewb70]

Good job man!!!

Andrew

[ryeguy2006a]

Congrats! I'd say that is a very successful swap. Nice power numbers. Care to share the dyno sheet? It would be cool to see.