My 400i Auto is a stone

Using the auto trans the way you do with todays tiptronic auto cars makes the car ALOT more fun to drive. I usually start out from a stop with it in 2nd gear, and manually upshift to 3rd. Much better keeping it in 2nd for stuff below 50mph or so.

My two cents is try driving it like that (if you havent already) and see if it makes your driving experience better.

And probably do the tune-up.

 

They all are.
That's gonna be really expensive and I suspect disappointing as well. A two ton plus car with long gearing is going to need a BUNCH more torque or suitable gear ratios to feel very lively under 90 MPH.
That 396 would do the trick though.

 

If you want to throw a lot of money at it, do a full rebuild with modern pistons and rings, EFI and twin turbo. Cams to suit.

 

Have a look at Mark's site:
gemellocattivo.com to see what he has done with TR heads on a bored and stroked 400 block in a 308 - 900hp!

John

 

A 456 transplant, maybe? It would still be cheaper than a 400 rebuild

 

No dyno figures yet, he set fire to his workshop during a startup so a new garage is being built..

 

The stretched chain will make a surprising difference to the (cam timing) and hence power. If you do a compression test and you'll find one bank ( drviers side) of the engine has lower compression than the other.
Run a new chain through it, time the cams and then sync the airflow between both throttles using a manometer - you'll be surprised at the difference it makes.
I know you have a 400, however I've driven both a friends 412 auto and my manual 412's and the auto is surprisingly quick in traffic etc. The torque convertor helps get get the car off the mark quite briskly and works quite well with a relatively low torque, high revving engine.

The chain is particularly important in the 412 with electronic ignition, the distributor housings are fixed to the head and the distributor rotors are directly driven by the camshafts so if the cam chain is worn, the rotor is also slightly out of aligment with the distributor cap, affecting spark timing and quality. Because the distributor housing ( and hence the cap ) is fixed, it's not possible to adjust for this.
With everything set up as it should be these things pull like a train...
M

 

Paul, stupid question but since the engine or at least bellhousing is already configured for GM, would a late model GM box fit and unlock more of the engine's character and abilities? I know someone else sort of asked the same, but I just looked up the specs for a base '18 Camaro and see it has an 8-speed (!) A/T. Granted that would be a bit silly, maybe the General offered 5-speed units in the recent past? I realize that doesn't solve for the power shortfall, but surely five ratios would make better use of what you already have? But if you could find a newer, bigger, stronger F-car drivetrain, as you have for Boxers, then................Best, John

 

Completely stock 400 with fresh timing chain, crank up the volume

 

New timing chain makes a difference! Only driven on Sundays.

 

With the engine in a proper state of tune, and utilizing the GM three speed gearbox manually, these cars are pretty darn quick and do in fact pull very hard.

 

Thats funny!

 

The cost of converting to a 456 or 550 engine would far exceed the cost of a rebuild. And you would have a much longer technical exercise to sort everything out to work reliably.

Aside from the cost of a 456 or 550 V12 in good condition, you would have to have all new mounts custom fabricated, alternator mountings and all accessory drive pieces custom fabricated, hoses and pipes, coolers, all new electrical work for the motor and to work with the engine management system, custom bellhousings (or an entirely new custom driveline if you went with a 456 or 550 trans, which would also require body / trans tunnel and frame modifications, custom driveshaft, etc...).

This would be a huge project at great expense. Though very cool!

 

Is there no more adjustment left on your chain tensioner that you are assuming it is stretched to the point of degrading timing and power?

 

https://www.forza-mag.com/issues/150/articles/competition-conversion?page=1#.Wz4dvYopChA

Obviously a much more extreme example of the concept, but note engine bay and transmission work.

 

I wouldnt do a chain as i’m guessing you dont need one. But you should check the tensioner. Its real easy to adjust. Search this section for a how-to. It can start wearing alot of other things and cause bigger issues long term, so worth taking a few minutes to give it a look.

 

https://www.ferrarichat.com/forum/threads/1984-400i-timing-chain-tensioner.96775/

 

Perhaps worth to mention that the page B41 of the workshop manual had a mis-translation of the original Italian text into the English version (and the French version too). This was picked up by a member of the Ferrari Club 400.

The Italian text says:

"...ruotare la vite 5 fino a quando la catena non diviene rumurosa, a questo punto tornare indietro di un quarto di giro..."

This can be translated as follows:

...rotate the screw number 5 until the chain stops being noisy, then go back a quarter of a turn...

 

I'm a hot rodder by birth, so bear with me...

Assuming the 400i uses an IRS system, converting to an open driveline should be too difficult. Bracketry and custom drive axles should do the trick without too much cost.

As for the transmission, how big is the tunnel? Most modern GM transmissions are pretty big. Still, a 4L80E should fit as it's not much bigger than a 400. But if you have the room, a 6L80E would be great, and would give you the option of paddles. A rear mount should be employed, but that shouldn't be too difficult, and perhaps a larger cooler as the new transmissions tend to run a bit hotter.

The only other issue is, of course, bolting the transmission to the engine. The fexplate for the Turbo 400 should work (if I recall correctly). How is the T-400 adapted to the engine? If it's an adapter plate of some sort, the 4l60E and 6L80E should bolt to it.