New to Avanti IIs

[Klaus]

Hi all,

New to Avantis and this forum.

Purchased a beautiful 1976 well-optioned sunroof car. The car looks like it never even saw rain. Paint buffs out nicely with a couple small nicks from decades of garage storage. As luck would have it, the Avanti is the same color as our survivor GT Hawk.

Relevant history:

The Avanti is a jigsaw puzzle. The prior owner purchased in 92. He drove it for a couple summers and then removed the engine for a rebuild. Engine rebuild was done by a reputable shop. Engine never reinstalled and the long block sits on a stand. He is now elderly and decided it was time to sell the car to somebody who will complete it.  Nice folks and we look forward to taking them out in in when completed.

We have been doing our research in anticipation of a spring challenge. Some questions linger as we research and assemble parts. Accordingly, some questions for the collective Avanti knowledge of this forum:

Cam:  the engine was rebuild to stock. Rebuild receipt and boroscope confirm dished pistons and stock cam. There are many cam recommendations on various forums. This is a light car with a torque abundant engine.

            What cam have you installed with a stock valvetrain that wakes this engine up a bit more than stock?

Exhaust: anybody install ramhorns? Want to remove the ugly 1976 manifolds.

Carb: Purchased an aluminum dual plane intake.

          What carbs are you running on the 400 with success?

          Have Edelbrocks on my GT Hawk and 390 Thunderbird. They are easy to tune and responsive. 

Ignition: Do you ditch the stock GM HEI? What aftermarket electronic ignitions work.

Front Brakes:  Ditch the Lark setup in favor of a Jim Turner kit?

            Have a Turner front disk/dual master on the GT HAwk. Simple and straightforward install. Have a Minnesota company kit on the Tbird. Horrible to install.

Aluminum Radiator:  Any consensus or suggestions?

Your insight is appreciated. Looking forward to putting Humpty Dumpty back together and driving it.

Thank

[Gunslinger]

First…welcome to world of Avantis…one of the most strikingly beautiful cars ever…and can also be one of the most frustrating at times.   This is great bunch here with lots of real world experience with these cars.  By experience I mean that’s what you get when don’t get what you want.  By that definition we’re very experienced here.
 

Before anything else…upgrade brakes…pads…calipers…hoses…metal lines.  Safety is paramount.  If the car won’t stop safely nothing else you do will matter.

The Turner brake kit is the way to go.  It’s far more cost effective than rebuilding the original system.  You can sell the old parts to offset the costs as well as they have value.  

On the ‘70 Avanti I had I had a set of Sanderson block hugger headers installed and a 2.5” exhaust system to let the engine breathe. 

I had a GM Performance 350/330hp crate engine installed with Edelbrock fuel injection…that’s not where you seem to be going but Edelbrock carbs are excellent.  

There’s nothing wrong with the GM HEI…it may need tweaking by a carb tech as it’s set up for smog reduction…not performance.  There are good hi-po distributors marketed if you want one.

For information on camshafts…give a call to Summit Racing’s tech line.  They will ask you specific questions about what you want out of the car and will give you solid recommendations.  I’m kinda partial to Lunati VooDoo cams…they have asymmetric lobe profiles that can give power without a loping idle…but there’s lots of good cams and profiles to choose from.

As far as a radiator…aluminum is fine…anything that helps take some weight off the front end is a plus.  I would suggest whichever way to go…aluminum or brass…get one with a core that has more fins per inch than stock…it increases swept area and aids cooling.  Electric fans are an advantage as well.

[mfg]

Every ‘66 -‘85 Avanti that I’ve seen had Chevy ‘Rams horn’ exhaust manifolds from the factory… your’s doesn’t?

I like the Edelbrock carb and stock HEI ignition idea!

I installed an Edelbrock Performer intake on my small block ‘400’.

Best of luck with your ‘new’ Avanti!!

[John D]

my 79 350 came with a single plane Torker (mt-1) manifold and an older AFB without a choke. The Torker was likely used for hood clearance purposes. After rebuilding and tweaking it the AFB worked okay but still not great at normal loafing speeds. Great above 2500 RPM but the car rarely sees that. Engine has a Mallory HEI Style distributor, I don't know much about internals but it does have .010 over TRW pistons (seen from below) and .010 under main bearings (seen during rear seal change).

After some research I pulled the trigger on a new Performer EPS manifold, which really woke the car up at lower RPM. it's~3/8" taller but I was able to get enough clearance by tweaking the air cleaner. I was able to virtually eliminate soot deposits around the exhaust pipes with a little more tuning. 

I was tired of no choke, and the AFB had some wear, so when I found a deal on a Holley 4150 series carb I grabbed it. I haven't spent much time dialing it in but it drives pretty great right out of the box (only a couple short test drives so far). I suspect a new Edelbrock would too, but I always wanted to try a Holley. 

Thought about EFI but that's $2k+ vs $350 for the new 4150. Plus O2 sensors and hp fuel pump installation etc. Hope this helps.

 

[John D]

[Klaus]

Thanks John. Much appreciated. I am new to Chevy engines, so all insight is appreciated. 

That intake sounds like a good idea. Especially if it improves low end. 

[Gunslinger]

The Edelbrock Torker is designed for higher rpm driving...the Performer EPS is optimized for better all around performance.  The EPS is optimized for the Edelbrock Performer carbs but the Holley will work just fine.  

[Klaus]

Thanks folks.

Insight much appreciated. Looking forward to tackling this project in spring. 

One of the first projects will be to open the filler door without destroying anything - no filler key came with car. 

 

[Gunslinger]

Not trying to get you to spend money unnecessarily…but let a locksmith open the fuel door…he can probably pick it quickly with no damage and cut you keys for it.

[Klaus]

So much for my hammer drill idea......

Because the engine is out, I am going to remove the transmission too and take it for a rebuild.Do the U joints then too. 

Do not know if it needs a transmission rebuild, but do not care. I has been sitting, unused for thirty years.  Would rather do it now, than have it malfunction after the engine is installed.

A frame question:

On Hawks, with a frame simlar to the Lark frame under the Avanti, there is often a need to install a fishplate near the pillar base. On the GT Hawk, the frame was allegedly heavier gauge and the problem mostly alleviated. (even though we beat on our GT Hawk, there has been no frame fatigue issue)

Is frame fatigue an Avanti II issue? The 400 has an abundance of torque. Does it make the Lark frame a bit too twisty in your experience?  ALthough my car led a pampered life, I will upgrade the frame to ensure continued pampering if it is recommended..

[Zedman]

On 2/8/2025 at 3:57 PM, Klaus said:

So much for my hammer drill idea......

Because the engine is out, I am going to remove the transmission too and take it for a rebuild.Do the U joints then too. 

Do not know if it needs a transmission rebuild, but do not care. I has been sitting, unused for thirty years.  Would rather do it now, than have it malfunction after the engine is installed.

A frame question:

On Hawks, with a frame simlar to the Lark frame under the Avanti, there is often a need to install a fishplate near the pillar base. On the GT Hawk, the frame was allegedly heavier gauge and the problem mostly alleviated. (even though we beat on our GT Hawk, there has been no frame fatigue issue)

Is frame fatigue an Avanti II issue? The 400 has an abundance of torque. Does it make the Lark frame a bit too twisty in your experience?  ALthough my car led a pampered life, I will upgrade the frame to ensure continued pampering if it is recommended..

Hi Klaus-I have a really nice '81 Avanti II with a 305 V8 and TH350C transmission (with lockup TC) with only 67,000 original miles  (but rotted out Frame and non existent HT's !).  It has been untouched since new and largely laid up for 17 years before I bought it and imported it into Australia.  Like  yourself, I felt that I should rebuild and renew knowing what old transmission seals look like given time  (I have a Blog here... http://studebakerflightomatic.blogspot.com ).  The engine had a worn out camshaft and I really didn't need to rebuild the whole thing but I did.  I completely disassembled the TH350 and rebuilt it (even paid for a dyno test to make sure I hadn't buggered it up).  I learned an awful lot about this Transmission the hard way and now have the benefit of knowledge.  However...  as I started to go through the parts, I found that despite its age, it was absolutely perfectly serviceable and was a waste of time. Oh yes , I did find the lockup solenoid faulty and the Speedometer drive will need to be re sealed, but the rest- perfect, Friction Discs/Clutch Plates perfect, with nice soft O rings everywhere.  I know I seem to contradict myself, but if your tranny is going to cost you big dough, if it is functional, maybe leave a sleeping dog lie and spend it elsewhere? Best of luck- you are gunna love that car !

Edited February 18 by Zedman