Early Cadillac V8s

[scott12180]

Hi All -- Does anyone out there own or have experience with a pre-1923 Cadillac V8, the models with the single-plane crankshaft?

I've read that these engines produced a significant vibration at 2000 rpm, which is between 40-50 mph depending on the gearing.

Practically, however, what are these like to drive? Are you really limited to speeds below 40 mph (for, say, an enclosed car) ? Is the vibration that bad?

What I've read suggests that these cars are very limited in their driveability because of that, but would Henry Leland have designed a car that was so bad that it couldn't be driven over 40 mph when the 1914 Cadillac 4-cylinder could do almost 60 mph? I'd like to hear about your experiences.

Thanks -- Scott

[Ivan Saxton]

They did have periods that the split plane counterbalanced V63 and later Cadillacs did not, but this only became really important when big closed bodies became much more popular, bcause the resonance with a big sedan body was annoying. It appears the first effort to reduce the vibration was by increasing journal size, but while Earnest Seagrave was absent in Europe, Charles Kettering in consultation with a mathematician at General Motors called Hutchinson did the conversion to the split plane crank with a different firing order, and when Seagrave returne it was fait acomplis and much improved. Apparentlty a similar conversion had been done previously at Wright Field on a big Hispano Suiza V8 aero engine. Just watch your conrods and bolts with those fork and blade rod Cadillacs that there are no cracks. Leland changed the angle between the blocks on the V8 Lincoln to cotrol the problem. Some big expensive V8 cars like the Cunningham and Daniels had the single plane cranks , so it can not have been too much problem. Just drive though the vibration period as quickly as possible. This is hardr in a heavy car.

[Rusty_OToole]

They had the same type crankshaft as a straight 4 and a vibration period to match.

This is characteristic of 4 cylinder engines. Their primary balance is good but there is a secondary vibration that cannot be avoided.

Today, 4 cylinder engines over 2 liters (134 cubic inches) are usually equipped with balance shafts to kill this vibration.

Smaller engines do without, because the vibration is not so obtrusive that it can't be controlled by rubber mounts.

The point of all this palaver is that the vibration is not dangerous to the engine or the car. It is an unavoidable characteristic of early V8 and 4 cylinder engines.

It simply means the early V8s are not as smooth as a good straight six, or a straight eight or V8 of after 1923.

The V8 should actually be somewhat smoother than the earlier 4 cylinder because the individual parts are smaller. But it will have a similar vibration at higher speeds. If you don't find it offensive in the 4 cylinder it will not bother you in the V8.

The significance of 1923 is, that is the year V8s and straight eights started using the 90 degree crankshaft. That is, a crankshaft with alternate throws at 90 degrees to each other, instead of 180 degrees as formerly.

Such a crankshaft eliminates the secondary vibration problem.

You simply have to accept that the pre 1923 engine is not as smooth as a newer car. Consider it part of the character.

Now if the engine rattles, knocks and tries to shake the car to pieces that is a completely different matter. That indicates a worn out engine.

Edited February 7, 2010 by Rusty_OToole (see edit history)

[Rusty_OToole]

When they were new the Cadillacs were good performing cars capable of much more than 40 MPH. 70 would have been within the reach of even the closed models, open cars with higher gearing 80-90.

Due to road conditions cruising speeds of 40 to 50 were most common.

The engine vibration was hardly noticable except in comparison to the best 6 cylinder luxury cars.