[punkin]

Hello all,

Maybe I'm making too much out of this but I'm putting together a new IA2 motor with a 4L80e. I'm replacing the motor mounts with interlocking poly type and having to add an an aftermarket transmission cross-member for the longer transmission.

With all these new parts should I be concerned with the motor and trans being in straight, level, positioned correctly in the car? If this is something worth checking, what would I search for?

Thanks for taking a moment to consider my questions.

[Chief of the 60's]

Drivetrains are never in straight.

Tilted down in the back, to the right a tad, to the left a tad, every make and model is different. There are formulas out there when starting with a new chassis. The only one I recall is down about 3 degrees in the back.

Most of the formulas are to combat torque and vibration.

[lust4speed]

True, all over the map even between the same year and model cars in our club. If your old engine/trans is still in place simply put the angle gauge across the air cleaner lid and then match the new assembly after it is installed. Even just changing out the transmission mount with a different brand will have the trans at a different height. If rear is too low some large fender washers under the mount will bring it up.

Can't back it up, but I suspect that Pontiac angled the stock intake manifold base plate for the carburetor to sit level with the proper engine/trans tilt. Some aftermarket manifolds have the same tilt but others sit parallel with the heads.

[Half-Inch Stud]

PMD may have angled the Intake & Carb base to clear sloping hoods.

[steve25]

PMD and many others angled the intake towards the front to compensate for the engines front to rear tilt back so as to get the Carb back to being level, not due to the hood line!

This started with the first V8 in 1955 when you could
Just about fit another half a car under the darn hood, lol!

[Formulajones]

I've found the most important thing to check Punkin is to put an angle finder on the output shaft of the transmission with everything bolted in, to make sure it has a slight downward angle. No more than 3-4 degrees is necessary.

From there you can make sure your driveline angles are proper for the driveshaft so you don't induce drivetrain vibrations.

["QUICK-SILVER"]

Don't know why, but engines in first gen birds looks worse than other body styles, to me, when it comes to the engine being off-center to the passengers side.

Clay

[Formulajones]

Originally Posted by "QUICK-SILVER"

Don't know why, but engines in first gen birds looks worse than other body styles, to me, when it comes to the engine being off-center to the passengers side.

Clay

They were in fact set to the passenger side slightly, for more steering box clearance on the BBC first gen camaros.

Chevrolet camaro's especially had different frame mounts for BBC and SBC, to shift the engine to the right.
It's a big reason why over the years you hear so many stories about people not being able to fit headers on their BB camaro without bashing in the tubes to clear the steering box. It's because the car started life as a SBC, swapped in a BBC and didn't bother to install the proper frame mounts. The headers were designed around having the correct mounts in place.


It would not surprise me if this was also done on the 1st gen firebirds too for better fitment of the Pontiac engines.

[Chief of the 60's]

The MoPars of the late 60's - early 70's were the worst at moving the engine far right.

[punkin]

Originally Posted by Formulajones

I've found the most important thing to check Punkin is to put an angle finder on the output shaft of the transmission with everything bolted in, to make sure it has a slight downward angle. No more than 3-4 degrees is necessary.

From there you can make sure your driveline angles are proper for the driveshaft so you don't induce drivetrain vibrations.

Thanks VERY much. It so happens that the rear is coming out this spring too. Thanks!