Hi i am new to this site so hi to everyone out there…I have just got hold of a 1947 buick special and have been doing some cleaning up under the hood. but have noticed that the engine seems to lean back towards the fire wall, i thought that the engine should be level in the bay … could any one please let me know it the engine has been mounted correctly thank you all
Some are straight and some lean. You may need to just crawl under it and take a look at the engine and transmission mounts to make sure they look ok and are there, @triedag is an expert on the late 40’s cars but he’s in bed right now I assume.
Congrats on the car.
The tip off will be the carb. They design the carb to be level, so if the carb mount has a slight tilt relative to the plane of the intake, the engine mounts are designed to tilt the engine until the carb mount is level. This applies to down draft carbs only. Side draft carbs are a bit more complicated, but the bowl of the carb should still be level.
We had a 1947 Roadmaster (roadmonster to some) and the straight 8 defintely leaned back,. as did many engines, mostly straight 6s, of that era. I think the rational was that this car had a torque tube drive and it benefited from as straight a line between the engine crankshaft and the rear differential.
Engines are suppost to tilt back on a rear wheel drive vehicle. This not only allows the oil that gets pumped up to the top of head to drain back into the oil pan, but it also causes the transmission tip down keeping it out of phase with the driveshaft. If the driveshaft and transmission were perfectly aligned with each other it can cause a vibration in the driveline.
" but he’s in bed right now I assume".
@Bing–you just woke me up, but a 1947 Buick is a worthy cause. I think tester is correct. When you have problems with a rear wheel drive car is when the motor leans forward. By the way, the Special for the 1946 through early 1949 models is rather rare. After WW II, all automobile manufacturers could sell anything they could produce. Buick pushed the Super and Roadmaster models which had front fenders that extended through the doors to the rear fenders. However, the Special was different and sales were around 10,000 a year. The Special had the GM B body while the senior Buicks had the GM C body. The design of your 1947 Special carried through to mid 1949 model year. It was then replaced by a really revolutionary design which some called the late 1949 Buick Special and others called the 1950 model. The senior Buicks then picked up the design for the 1950 models. This redesigned Special then made the Special the best selling Buick model.
I did like that fastback design of the Buick Specials of the 1946 to early 1949 vintage. I had a 1947 Pontiac with the fastback GM B body. It’s appearance was very similar to the 1947 Buick Special. Be sure to put a pair of outside rear view mirrors on your Buick–they weren’t standard equipment. The rear window of these fastbacks was more like a skylight.
Now, if Bing will let me, I’ll resume my nap.
Tester, h you said “If the driveshaft and transmission were perfectly aligned with each other it can cause a vibration in the driveline”. Are you serious??
Not only is Tester serious he’s also dead on correct.
You can just do a google on a 47 buick special and you’ll see a picture of the engine. Definitely tilted back.
I got the thinking about how the rear of your car could have a torque tube but still compensate for the change of drive shaft length as the rear axle moves up and down without a drive shaft and a torque tube slip joint
I am wondering if your 1947 has coil springs or leaf springs on the rear suspension? If it has leaf springs, are there shackles on both ends of each leaf spring i.e. front and rear on the right side and the same for the left side?
@Researcher–I am almost certain that the 1947 Buick had coil springs in the rear. I believe that the shock absorbers were of the “lever action” type and could be filled. I know this is the set-up my 1954 Buick had and it was a carry-over from earlier models.
I’ve been thinking about the question posed by Researcher about the use of a torque tube drive and the type of rear springs used. The Buicks did have the torque tube drive through the 1960 models and had coil springs. The Nash cars and later the senior Ramblers had torque tube drive and coil springs. However, Chevrolets through 1954 had torque tube drive, but I believe they had leaf springs in the back. My 1950 Chevrolet truck had torque tube and leaf springs in the rear so there must have been shackles on both ends of each spring.
@Bing -I know the engine is tilted back, I just have a hard time beleiving that if it is lined up straight with the driveshaft that it would cause a vibration in the driveline. BTW I had a '48 Super and a '50 special, NEW
That was a '53 Special, not a '50.
Our Buick had coil springs in the rear and the torque tube shaft had a flex joint right at the end of the transmission. The actual drive shaft was inside the tube and had one universal joint. Since the engine sits relatively high up copared to the differential, the engine has to be tilted back somewhat to reduce the angle in the drive train. Also the hump inside the car would be huge if the engine sat straight. In those days, the front seat was meant for 3 passengers.
The belief that lining the engine centerline up with the differential by tilting the crankshaft centerline would cause vibration is pure fiction. The less bending the better. It’s true that these long stroke straight 8s suffered from some “crankshaft whip”, but this was caused by the lack of crankshaft journal overlap (which would give stiffness) which is found in todays short stroke and over-square engines.
@EllyEllis–I really liked the Buicks of that vintage. The only Buick I ever owned waa a 1954 Special. By that time, the Special had the OHV V-8 engine. I had an Aunt that owned a 1948 Buick convertible. I was a teenager at the time and I really enjoyed driving that car.
I’m a ‘post torque tube’ kid, never remember seeing one at the garage ('70-'76). What was the reason for them? To avoid 2 universal joints? As I remember, with 2 u-joints the goal was to have the engine/trans. and the differential input axes be parallel to maximize u-joint life.
@EllyEllis Here’s a link that explains driveline angles. http://www.hotrodhotline.com/md/html/drive_shaft_harmonics.php
@texases The Buicks had coil springs which had little lateral stability. So the rigid torque tube acted as a stabilizer-locater for the rear axle together with the shocks. It was not a great arrangement since the car was partially pushed by the driveshaft rather than but the rear springs and rear spring linkages, as in a modern rear coil spring setup.
It also made for a rather wallowing ride. The long coil springs made up for the required play in a normal 2 U-joint drive shaft’s sliding joint.
The coil springs wandered fore & aft to allow the arc? Man, that must have been a wallowing ride!
Of course, it’s highly unfair to judge a 1947 design by today’s standards.