Technical Crankshafts ? Are they all oriented the same.......

Had a thought buzzing around in my head and thought maybe some of you guys might pull some old cranks off the shelf and answer my question. I looked at two different crankshafts I have. One is a Cadillac and the other is an unmentionable on the Hamb Chevy. Hey, it's all I had handy Anyway the Cad has a 15634278 firing order while the Chevy has a 18736542 firing order. A normal small block Chevy is 18426573. I don't have one of those cranks available to compare.
Now I understand that different manufacturers number their cylinders differently and that affects what the stated firing order will be.
It seems logical that manufacturers index their crank throws to create the best balance condition. Looking at both crankshafts from what would be the front of the engine, they both are indexed the same. With the first crank throw at the twelve o'clock position, the second throw is at 3 o'clock. The 3rd throw is directly opposite which puts it at 9 o'clock. Then the 4th throw is at 6 o'clock.....opposite number 1 throw. It seems logical that manufacturers may have determined that this is the optimal orientation in most/all engines and then they decide what firing order works best within these mechanical allowances. I know that camshafts can be made to alter the order that cylinders fire......I understand that. What I would like to know is if generally all cranks are manufactured with this same orientation.......or not?

 

You got a couple numbers wrong on the Chevrolet firing order. 1-8-4-3-6-5-7-2 is the normal firing order. 1-8-7-3-6-5-4-2 is commonly called a 4-7 swap, and requires a different camshaft with that profile ground on it. The crankshaft is unchanged in the 4-7 swap deal.

You also asked "What I would like to know is if generally all cranks are manufactured with this same orientation.......or not?"

Virtually all production V8's use this configuration, with the four rod journals spaced at 90 degree increments. The configuration is called a cross-plane crankshaft. There are engines built specifically for high revving that use what is called a flat-plane crankshaft, where two sets of journals are spaced at 180 degree intervals. I'll let you search for the pros and cons of each.

Some 4-7 swap reading for you here.....
https://www.enginelabs.com/engine-tech/engine/firing-order-swaps-whats-best-for-your-engine/#:~:text=Calming down the crankshaft,in certain applications, like NASCAR.

To hell with it, I'll make it easy. Here's some cross-plane vs flat-plane info.
https://www.onallcylinders.com/2015/01/15/cross-plane-vs-flat-plane-crankshafts/

 

I would expect that you'd either find what you did, or possibly the two 'inside' journals could be swapped; 12, then 9, then 3, then 6. There is different harmonics involved.

I'd be just as curious as to just how many different firing orders there are. As noted, how the manufacturers assign numbers to the cylinders varies so naturally affects the numbering in the firing order. So if you used a 'standard' cylinder numbering system for all then 'translated' the 'old' numbers to the new 'standard' numbers how many different firing orders would you really have? I suspect no more than four; two for the 12/3/9/6 crank and two for the 12/9/3/6 crank. All this assumes a 90 degree V8; change the 'V' angle and/or the number of cylinders and now you have a new set of harmonic issues.

 

Ok, I went and satisfied my curiosity....

Chevy and Chrysler used the same cylinder numbering designations, so you find that they both use the same firing order with the exception of the Chevy LS motors. Non-LS Chev and all Chrysler is 1-8-4-3-6-5-7-2. The LS swaps 4-3 and 7-2 for 1-8-7-2-6-5-4-3.

Ford numbered their cylinders differently, but after 'translation' you have the exact same orders; Fords use the same order as the Chevys and Chryslers except for the late 302 and all 351/400 (Windsor/Cleveland/M) which as it turns out uses the same order as the LS. I guess Ford figured out whatever advantage this offered before Chevy did as Ford started using this in '69.

Knowing this, I'd bet that crankshafts across brands would be laid out the same too.

I didn't check the 'other' GM V8s, but I'd be surprised if you found anything different.

 

At risk of getting kicked in the potatoes, a few different kind of cranks are:
flat plane cranks, crank type used in radial engines, crank types used in rotary engines, and the type used in Harley Davidson's just to name a few.

I realize that helps not at all for your question, and to be honest, I've never mixed the numbers around to see if they are same as ford or dodge as above posts indicate. Interesting.

 

I realized some time ago , that all 90 degree V8 engines fire the same no matter the camshaft or cylinder numbering. They fire the outer 4, then the inner 4. Sometimes number 1 is at the end or middle of the outer 4 firing order but it is outer 4, inner 4. Just draw a picture of a V8 cylinder arrangement and follow it out. Try various cylinder numbering systems like Ford or GM, but it will always be out 4, inner 4. My students would argue with me until we would lay it out on the blackboard.

 

I have never thought about it nor even had two cranks, say Ford and Dodge, side by side to even take a look.

Interesting topic.

 

I’ll throw a fact in that twists my sense of right and wrong...
I say the farthest forward cylinder on any engine should be considered #1, and the rear most cylinder should be #8. Engines that don’t follow this arrangement make me ttwittcch.

 

But left or right for number one, odd or even down each bank?

Okay, take a happy pill, it’ll be okay

 

OK, I want to thank Ebbspeed for the articles he posted. Very interesting reading and it points out the fact that many firing orders are actually the same, just obfuscated by cylinder numbering. I knew that the late model version (LS) of Chevys smallblock had changed the firing order from 18436572 to 18726543, but wondered if a crankshaft change was involved or just a camshaft change. So the crank stays the same and apparently the general theme is that most cranks follow the same pattern. Some change slightly with which cylinder in an engine is farthest forward.....the left bank or the right bank.......but basically its mostly just how the manufacturer labels the cylinders. Its the same, just different.
The flat plane cranks are used in aero engines and Corvairs. I have rebuilt a handful of aero engines and have seen the flat plane cranks firsthand. Aero engines are known for their vibration. Corvairs are popular with homebuilt/experimental airplane builders and I have some of them in my shed. I was driving the wifes SUV into town a couple weeks ago and a Ferrari came by me on the X-way. I'm not a fan of sports cars, but I have to admit it had a nice sound.

Based on an engine configuration of a 90-degree V8 block spinning a cross-plane crankshaft, there are only eight possible firing-order combinations. Actually, there are 16 because GM and Chrysler engines are left-bank forward and the automakers number their cylinders differently than Ford, which is right-bank forward. With a little math and comparison mapping, we can find the common ground for the eight firing orders (see chart below) available to the manufacturers


The chart shows the eight possible firing orders for a GM V8 engine, with the exception of a Cadillac Northstar–which is right-bank forward for packaging reasons and has a different firing order. The firing order with the asterisk is the one used most often when attempting a bank-to-bank configuration

Interesting huh!

 

It doesn't matter what the firing order is...I'll inevitably get it wrong and cross a couple of wires when putting wires on an engine.

 

First V8 engines had a flat, 4 cylinder type crankshaft - one up, two down, one up - and a secondary vibration to match. Starting in 1923 they went to a new type crankshaft with throws at 90 degrees. This eliminated the secondary vibration, and was used in V8 and straight eight engines.
Straight six cylinder engines have crank throws at 120 degrees. All this is worked out mathematically for smoothness. The vibration from one cylinder cancels out the vibration from the next. A straight six has the smallest number of cylinders giving perfect primary and secondary balance and overlapping power impulses. This makes it inherently smooth which is why so many European luxury cars stuck with the six cylinder engine for so long.
In the thirties some companies experimented with a straight nine. Like a six with 3 extra cylinders and crank throws at 120 degrees, it was extremely smooth and powerful but never made production as they figured the public wouldn't go for it. I believe Studebaker and Pierce Arrow tried this configuration.

 

Two other thoughts come to mind. One, I can hear you GM and Mopar guys thinking 'Why did Ford screw up their numbering?'. Ford adopted that in 1932 with the introduction of the flathead (the first mass-produced V8) and never changed it. GM and Chrysler were late to that party, they decided to be 'different'. Two, Ford used the what is now referred to as the '4-7 swap' firing order from the beginning all the way through the Y-block, finally changing it with the introduction of the FE in '58. Again begging the question, did Ford figure this out way back then?

 

You’re Crazy Steve.
It’s like any other “first of” product. The inventor gets a good idea, and someone comes along, fixes the rough edges, and refines it.
GM had some people walk off of the ranch too.. Pontiacs have the first cylinder on the passenger side, and call it #2!

 

Pretty tough to 'refine' a firing order... LOL

 

Well, ok. Lets call it redefined

 

In 1914 Cadillac sold over 13,000 automobiles with a V8 engine. I'm not sure what quantity is required to qualify as mass-produced vs not mass-produced, but I'm going with 13,000 as a mass-produced number. Cadillac was building V8's for 18 years before the Ford variant hit the streets.

Cadillac’s firing order was 1L-2R-3L-1R-4L-3R-2L-4R as viewed from the rear and each bank was numbered one through four from the front. In todays world that would be a firing order of 1-4-5-2-7-6-3-8.

 

Not on a Pontiac v8 the right bank is like a Ford it is the farthest forward but they number like a Chevy so the front rod on the crank is #2. Now a 302 Ford you have 2 firing orders with a cam change. A Yblock and 302 crank throws are indexed the same and have yet another firing order For you guys that like the sound of a y block with the right cam grind you could get it with other engines to sound that way..

 

Years ago my son bought a gutless OT Mustang. Idled smooth but every other cylinder was dead. After trying for over an hour to find out why one side of the carb wasn't working, went back and looked at the firing order again, paying attention to the direction of rotation this time. If you run the Hi-po 302/351 order backwards every other cylinder is right for the standard 302 firing order.

 

My totally off-topic pickup truck has a 5 cylinder engine, can’t get my head wrapped around how that crankshaft works........

 

Please elaborate. I'm not a Ford engine guy but I believe one of the following would be the firing order:

1-3-7-2-6-5-4-8? Only cylinders #1 and #6 would fire correctly if the wires were in reverse order.
1-5-4-2-6-3-7-8? Only cylinders #1 and #6 would fire correctly if the wires were in reverse order.

 

Ford changed the firing order in the 80's to " reduce crankshaft loads". 40 years later chevy followed

 

The index and firing orders are changed which changes the harmonics loads on the crankshaft. It is the harmonics that control - strength,ware, fatigue and where it will break. Very complex analysis 36fordguy

 

I agree with that. Thats why Chevy changed the firing order on the new version of its smallblock. I think the idea is that there is probably one sequence of firing which works best as far as reducing harmonic vibrations. Are most manufacturers using that sequence but concealing it by numbering their cylinders differently? Yes, some engines have their left bank ahead and some have the right bank ahead.

I agree! I wonder if you switched numbers side to side what the order would look like.

 

Draw a circle and mark 8 spots around it. Starting at one with each firing order run one clockwise and the other counterclockwise.

 

I believe the reason Ford changed the 302 firing order on the late motors is because they lightened the crankshaft by a considerable amount (7 lbs?). Less weight, freer revving. Or if you have space constraints in the crankcase, the different firing order may allow smaller counterweights. It can't be a huge deal because when Ford came out with the 351W you couldn't buy a performance cam with that firing order, you had to 'convert' back the standard order.

 

Chevy used a 5 cyl in the Trailblazer? Know nothing about it. Is yours online or V engine?

 

Ah, standard 302 vs HO 302 firing orders. I missed that in your post. That would make for a gutless runner.

They were inline engines used in the Chevy Colorado and GMC Canyon pickups.

 

Ford did it in 69 with the 351 and a 351 W cam will work in a 302

 

Didn't Colorados get the 5 and trailblazers get the 6