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MG MGB GT V8 Factory Originals Technical - Ford V8 install driveline angles

Hello everyone. I'm fitting a 289 Ford to my 1970 MGB convertible. I've chosen to go the route of setting the engine WAY back and have the firewall, tunnel etc. modified to allow it to fit. I'm using the T5 5 speed transmission. I'm right at the point now of installing the engine and tranny mounts. Here's where my confusion is starting to build:

I was reading in the archives where someone's advice was to get the engine level front to back and side to side using the carburetor mounting surface on the intake as a reference point, making sure the car is level. Here's the problem. When front to back level is achived using this method, the front face of the crank pulley, and of course the transmission output shaft, are not level. So it seems the carburetor mounting surface on the stock 2 barrel intake is not parallel to the crankshaft. So do I abandon the intake manifold for a front to back reference? Oh BTW, what is a reference for level on the car? The tops of the doors? With my car "level" on jackstands the door tops are perfectly level.
So then I crawl underneath and start checking my stock driveshaft pinion flange on the rear end in reference to the car. It's not level either. If you drew an imaginary line from the center of the differential flange forward to infinity, it would probably pass high through the radiator opening. Is this about right? Does the input angle of the differential change under different vertical loads on the rear suspension? Or does it stay close to the same angle? Does the stock mounting boss of the T5 end up being parallel to the the bottom of the rear crossmember? Can somebody with some real world experience help me sort this out before I permanently install my mounts. I want to get this as right as I possibly can.

Thanks in advance.

Scott
Scott Wooley

The carb flange or mounting base should be close to level front to back, side to side. This allows the carb floats to be close to level most of the time, which is a good thing.

With the carb base level, the motor will slant down towards the back. This varies from engine to engine but is around 3-7'.

Idealy, the rear of the engine will be parallel to the pinion on the differential, but not in line with it. In order for the U-joints to rotate, they need to be at an angle to the drive shaft, somewhere between 2-6'.

It is not necessary for the engine to be exactly parallel to the drive shaft, and the engine can be offset slightly to the rear end, but it is important for the U-joint angle to the drive shaft to be in the 2-6' range. Here is where smaller is better. Angle.
Jim Stuart

Scott,

Download the January 2002 issue of the British V8 newsletter for a short article entitled "Pinion Angle" on what Jim just said, with diagrams, at http://www.britishv8.org/jan2002.pdf
Dan Masters

YUp, Jim and Dan have it right. That is the metode I used to set mine in. What makes the difference is the intake used, some have a steeper slant to them than others.

One limiting factor I found was the fixed trans crossmember. My trans ende right over the top of it and limits how low I could set the trans and thus the engine to get a proper angle. If for whatever reason you can only get the engine and trans to be parralel to the ground, then you may need to get some wedges to put under your leaf springs to tilt the axle and get beck within the 3* margin that is recommended.
Larry Embrey

The first thing in any engine swap is to locate the engine in the bay. Second, is to set the angle on the drive line 3 degrees is the prefer # but 6 shold be max. The starter base is the best place to read the angle with an angle meter, as describe above the two lines should be paralell to each other meaning between the diferential and the engine.
Third, set the engine level from side to side. the front and rear level is set by the angle of the drive line.
Bill Guzman

All good information so far. What's a good way to find the pinion angle on the differential to match with the angle found at the starter mounting surface? Given my far setback, the end of the T5 is behind the solid rear crossmember. I had to notch it to allow the webbing on the bottom of the tranny to pass through. I cut a piece of pipe in half lenghthwise and welded this down through the top center of the crossmember so that now the top has a small dip in the top. It looks like I'm close to parallel with the pinion by eyeball method, but I'm hoping for a more accurate method of measuring this.

Thanks for all your comments.

Scott
Scott Wooley

Pinion angle is not the easiest thing to measure mostly because of lack of clearance to see the gauge. I use a magnetic base angle gauge across the flats of the pinion yolk. There are some digital gauges which I believe will allow you to take a reading and lock it in so that you can check it with the gauge out of the car. Make sure that the car is supported on the axles as pinion angle can change slightly as the suspension moves through it's range. It's worth the time to make sure the angles match, as driveline vibrations and short u-joint life will likely plague you if you don't.
Bill Young

One of Scott's original questions was how do you check if the car is level, the top of the doors, the sills, the floor oor what?
Regards
Tony
Tony Bates

Scott,
Regarding leveling the actual car, it's not necessary to have the car level in order to match the pinion angles. The angle at the differential flange and the transmission flange are measured relative to vertical, and if this changes by a few degrees due to the car being slightly angled front to back, it won't matter, as the angles are still the same relative to each other. Like Bill, I used a magnetic angle gauge; not the easiest to read while lying under the car, but with patience, it can be done. I used a shop light and a magnifying glass to read the gauge. If you can get ahold of one of those electronic gauges, it sounds like the ticket, but the way stated above will work if you take your time.
Yes, the angle may change slightly as you load the suspension, but the final setting can be made at the rear end, using wedges available at spring and suspension shops. After the motor mounts settle, you may be making adjustments there at a later date.
As the other Bill states, the engine fore and aft angle is dictated by the need to match the rearend pinion angle.

Best, Joe
Joe Ullman

Tony,
The car does not have to be level and it doesn't matter that the chosen reference surface isn't zero degrees. Whatever datum surface is chosen, all measured angles should be referenced to this datum. i.e. if one chooses the chrome side strip as the "level" datum, the engine angle, diff angle and driveshaft angle should all be in reference to this...just have to do the math, or as Bill says, there are digital angle finders available that lock the reference surface as "zero" and this not only eliminates the math, but they also allow locking the measurement to be viewed outside of an awkward measuring location.
I, fortunately, have access to an Anglemaster brand digital inclinometer, supplied by Dana Spicer Corp. Check out the following site for a picture/application.
http://www.drivetrain.com/driveline_angle_problem.html
Graham Creswick

Good advice as always guys. My original question about "Where is level?" for the car stemmed from the fact that I was trying to get the engine level for carburetor float reasons while my car was on jackstands. Since the car is partially stripped down and the weight of the engine is hanging on the engine crane, it's not practical to actually sit the car on the ground under a normal load to to know what "level" actually is. What if my rear jack stands are actually 2 inches higher off the ground than the front and I set the engine to be level at the carburetor mounting pad? And what if at the same time the tops of my doors just happened to be level? Do you see what I'm getting at?
I understand now the relation between the pinion angle and the driveline angle, and that they don't change relative to any "level" reference I have chosen. But if my first job is to get the engine level, and then set the driveline and pinion angle, it pays to get the "level" part of the problem solved first right? It's probably not "that" critical anyway, but I want to get as close as I can manage.

Thanks again for all the very useful information.

Scott
Scott Wooley

When I did mine, I just made a datum for the centre of the front crankshaft pulley (on the original engine) both up and down and side to side. I ended up with two pieces of wire crossing at right angles which I then marked on the radiator support. Did the same at the rear drive flange centre from the output shaft. All you have to do then is install the new motor and gearbox so you end up with the front crank pulley centre and g'box output pulley centres in the same planes. This should mean the driveline is now the same as before. The angles change as the rear axle moves up and down in any event but I think you should avoid any angles over 3 degrees static if you can. The trick is to have all this right and avoid other items colliding at the same time! Good luck, Bob
Bob Elwin

This thread was discussed between 10/10/2004 and 12/10/2004

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