Rotation

[DRW1000]

Forgive me if the answer is in this froum but I did search and did not find it.

This is a very basic question I am sure and something I am surprised I do not know.

I have been doing some research on cranckshafts and have mapped out the position of each piston at various rotational positions of a chevy V8 small block and Ford Windsor V8s.

Do the Chevys rotate counter clockwise and the Fords Clockwise? For some strange reason I always assumed all engines rotated the same way but now I am unsure.

Thanks

[curtis73]

All engines rotate clockwise as you look at them from the front. As you are sitting in the driver's seat, they would rotate counter clockwise.

There may be some rare exotic exceptions, but not in the mainstream. Someone suggested that Mazda's Wankel Rotary spun opposite, but since they used the same transmission, alternator, and rear axle, I highly doubt it... Unless the car had five reverse speeds and one forward

Its possible that some obscure car like the Dhadkhema or Pritchett had opposite running engines, but doubtful since they sourced some of their parts like trannys and axles from other makes.

[DRW1000]

Good point Curtis. I was referring to standing in front of the car.

Thanks for your answer. I suppose I did something incorrect when I mapped out the Chevs.

At least I got the Fords right.

While we are on the topic of basic questions I will ask another if no one minds:

I have been researching Chevy small blocks in particular 283, 302, 305, 307 ,327 and 350 and the interchangeability of cranks and pistons....

I have seen a lot of photos and the one thing I cant figure out is the following:

The cranks have 4 bearing lobes (for lack of the proper name) for the 8 connecting rods and obviously the front two cylinders (1 and 2) are on the same lobe. as are 3 and 4 .... As far as I know the cylinders are not staggered and the connecting rods connect to the centre of the pin on the piston and not to one side or another. I also noted that the connecting rods seem symetrical with no offsets. would that not require them to both be connected to the same place on the crankshaft (which of course is not possible) rather than side by side?

I am obviously missing something here.

[curtis73]

Take a gander at this photo of a Chevy lower end viewed from the bottom... You are incorrect in one of your assumptions... that the cylinders are not offset. They are in fact offset by about an inch.




Notice how each rod journal (that's the word you're looking for) holds two rods. The first thing you see on the left is the front of the engine, the crank snout. Then you see the oil pan rail in light grey, then you see the first main cap. This is what holds the crank to the block via the main journals. The next thing you see is the first counterweight on the crank. This particular chevy has been balanced by drilling material out of the counterweight. Take a look at the two rods just to the right of the second main cap. The left rod on this journal goes to the far bank, and the right rod on this journal goes to the near bank.

The reason they don't need to be offset is because the cylinders are offset in the block. I tried to find a representative photo of an engine block, but none showed the proper angle. Take a look at this intake from Edelbrock. It gives you an idea of how the two banks of cylinders are offset by how the intake ports are offset.




The driver's side bank of cylinders (the odd numbers on most cars) are always set forward by about an inch or inch-and-a-half. That is how the rods can share journals without being offset.

[DRW1000]

Hey Curtis73,

Thank you so much for your explaination. The photos are helpful aids too. Although you did not manage to find a photo to illustrate the offset in the cylinders I think the manifold clearly shows me what I need to see and your description was quite thorough.

I know so much more today than I did yesterday.

[Moppie]

Originally Posted by curtis73

All engines rotate clockwise as you look at them from the front..............
There may be some rare exotic exceptions,

I didn't know Honda's were considered an exotic exception
Every pre K series Honda engine I can think of spins anti-clockwise.
There are other less common, but certianly not rare exceptions, I just can't think of them off the top of my head.

[sierrap615]

Originally Posted by Moppie

I didn't know Honda's were considered an exotic exception
Every pre K series Honda engine I can think of spins anti-clockwise.
There are other less common, but certianly not rare exceptions, I just can't think of them off the top of my head.

i think a few oddball desiel and marine engines turn CCW