'68 Nova Pro Touring build

[NovaMC]

Hello there. I'm new to the forum and am wanting to be able to bounce ideas and ask for advice on a pretty serious build I'm doing on my 68 Nova. The picture attached is the day I got it home after buying it. This was in the summer of 2019. Shortly thereafter, the main seal went out and I decided to upgrade it from the installed 307 to a Blueprint 383 stroker. Then I wanted to upgrade the suspension and perhaps repaint it to something a little more original, as there are probably three yellow Novas in Rapid City, SD, where I live. I ordered a TCI full tube chassis and went to work dismantling the car. Unfortunately it didn't take long to find hidden rust, courtesy of the bonehead who "restored" and painted it before I bought it. After finding rust throughout the floorpan and firewall, I decided to do a full blown, off the charts (for me, anyway), restoration and modification. To go along with the chassis, I had a Supercharged 427 big block built by Wegner automotive and a cryogenically treated Tremec T56 magnum six speed from American Powertrain. It will have a Currie rearend, torque arm suspension, Wilwood six pistons up front and four piston in the back. The engine peak dyno'd at 1115hp and 1000lb torque. I am not an "autophyle" by any means, and part of my desire is to learn as this project goes along. So if you ask me a technical question, I might not know the answer off the top and I'll need to get back to you on it. One item I'm trying to work out is the gear ratio. I used Tremec's calculator and I'm thinking maybe 3.50 or 3.70's. I BELIEVE the tremec is of the "wide" variety and not the "close" type, but I'd have to go take a look at it to verify. It is with the car right now, which is at the builder's shop. I go there and help work on it most days, as he doesn't care. I'm also having Detroit Speed mini tubs put in, which is what he's working on currently. I'm debating about a roll bar and just negating the back seat. Anyone have any experience using a roll cage builder by the name of Wild Rides Race Cars? They're out of NJ and look pretty good, just going off the website and reviews. And I'm hoping to fit 315 30R19's in the back (about 26.5 inches tall) with the mini's and 18 inch wheels up front. I like that staggered tire size look.

So, for now...
1) gear ratio
2) roll bar



I'm looking forward to hearing from anyone who is willing to help me move this project along!
I don't know why the graph is rotated, but I can't seem to get it upright.

[NovaMC]

Quick update...the Tremec is the "close" variety, so 2.66-.63.

[mbheinz]

That car is going to be a beast! I have a 70 Nova and have already done the TCI, T56, Wilwoods and mini tub. Ask me any questions and I hope I can answer them.

[NovaMC]

That's kind of what I'm going for here, mbheinz....a beast! Thanks for the post. Do you have any pics of yours under construction, or after completion?

The main thing I'm trying to figure out is what gear ratio would be best with street cruising, but still be good at highway speeds, and light to light, with my engine/tranny/tire combination. Any experience with that? I don't think I really need to go taller than say a 3.08. Maybe 3.50's?

Also, what size wheels and tires are you running? I'm hoping to be able to get 315/30R19's on 19x11's in the back. 18 inch in the front, but not sure how wide. 9 inches maybe?

[Lonnies Performance]

With a 6 speed that has 2 overdrives, your gear ratio may depend on the camshaft you are running.
The larger the cam, the less use you will get out of 6th gear if the engine is not happy at low rpm.
What are your cam specs?

I have 3.54 gears with a close ratio T-56 like yours. Running 305/35-19's, it is a very good all-around gear.
The best thing about that trans is 4th-6th is close enough that you will always be able to shift to a gear the car likes.

I had 4.10's with a mild LS3 & it was nice until I added a supercharger & then it was way too much gear.
I'm happy with the 3.54 as it has enough ratio to easily drive in stop & go traffic without much effort but still cruise on the highway.
Not sure I would recommend anything under 3.40's unless you have a very small cam in the engine, which is doubtful at that power level.

The biggest issue I see is getting the power to the ground with a low profile tire.
At around 750 flywheel, I can pretty much destroy a Nitto NT05 tire in 1st & 2nd. 3rd is marginal at times also.
Not sure how you plan to drive it, but a soft compound like a NT05R or similar tire will be a lot better & the car will be less dangerous... but not last real long

[NovaMC]

With a 6 speed that has 2 overdrives, your gear ratio may depend on the camshaft you are running.
The larger the cam, the less use you will get out of 6th gear if the engine is not happy at low rpm.
What are your cam specs?

I have 3.54 gears with a close ratio T-56 like yours. Running 305/35-19's, it is a very good all-around gear.
The best thing about that trans is 4th-6th is close enough that you will always be able to shift to a gear the car likes.

I had 4.10's with a mild LS3 & it was nice until I added a supercharger & then it was way too much gear.
I'm happy with the 3.54 as it has enough ratio to easily drive in stop & go traffic without much effort but still cruise on the highway.
Not sure I would recommend anything under 3.40's unless you have a very small cam in the engine, which is doubtful at that power level.

The biggest issue I see is getting the power to the ground with a low profile tire.
At around 750 flywheel, I can pretty much destroy a Nitto NT05 tire in 1st & 2nd. 3rd is marginal at times also.
Not sure how you plan to drive it, but a soft compound like a NT05R or similar tire will be a lot better & the car will be less dangerous... but not last real long

Thanks for the post, Lonnie. The build sheet says, "Custom Wegner Grind Hydraulic Roller Supercharger Camshaft." That's the only info I have on the cam. Not sure if that tells you anything.

[mbheinz]

I don't have any pics of the car documenting the build. It was never really blown apart and built back from the shell plus I'm terrible at remembering to even take a pic. This has been a 27 to 28 year build with tons of upgrades as time went by. You should be fine with the rear tire size and the mini tub kit. I run 18 x 11 with 6.5 inch back spacing all the way around with 315/30 in the back and 295/30s in the front. I get a tiny rub in the front on the frame and sway bar in parking lots at low speed but nothing any other time. I was worried about messing up the paint and or body work with tire rub in the front, so I cut the front wheel well openings out and raised them 1 inch. I also had to widen and adjust the inner fenders to keep from rubbing. The whole front end is fiberglass so easier to work on and a lot lighter. Same with the deck lid.

For the gear ratio question Lonnie is spot on.
On the roll cage I think it's a good idea adding one. The Nova can be a flexi-flyer being unibody and with your horsepower/torque levels I'd say add the cage. The TCI subframe connectors will help a bunch but it doesn't hurt to stiffen it all up.

[NovaMC]

Sweet ride MB! It helps a lot to have info from people who have worked on the same car I'm working on. It seems something around a 3.54 like Lonnie said, is probably a good bet. And yes, I think I will go with a roll bar, not an actual full cage though.

If you're bored, feel free to watch a one minute clip of my engine on the dyno before it was shipped from Wegner to me. Just crank your speakers. Love that sound!

https://www.youtube.com/watch?v=SLUq...gnerAutomotive

[NovaMC]

MB if you put in a T56, can you tell me how much you had to notch out the trans tunnel?

[mbheinz]

MB if you put in a T56, can you tell me how much you had to notch out the trans tunnel?

I had to cut out the tunnel and raised it 2 inches to get the right transmission angle so no driveline vibration. I did it while the engine and trans were in the car during installation of the TCI front clip. Because I autocross I also made custom engine and trans mounts to move everything back and down as far as possible which wound up being where the bell housing almost touched the firewall/trans tunnel.