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[ Crankshafts ]

* 1949 - 1964 * 1964 - 1990 * 1995 - Present

Cranks 1949 - 1964


All crankshafts of this period are forged.


Cranks 1964 - 1990


There are about seven types of cranks:

  1. Early series big block, short stroke, all forged. 400, 425's. They have an "L" or "check mark" shaped notch on the drive flange. One leg much longer than the other, one corner, one leg nearly 90' to the OD, other approaches at a gentle angle. Cast will have a thin part line, forged a very wide [1/4 to 1"] line with obvious grind marks where the flash was trimmed.

  2. Early series small block. Forged. 330's. Notch on back drive flange is "L" or "check mark" shaped like other forged cranks. One leg much longer than the other, one corner, one leg nearly 90' to the OD, other approaches at a gentle angle. Again, cast will have a thin part line, forged a very wide [1/4 to 1"] line with obvious grind marks where the flash was trimmed. This could also be the nodular (not forged) 350 crank (see next item).

  3. Nodular 350 crank. Notch on back drive flange is "L" or "check mark" shaped like other forged cranks. One leg much longer than the other, one corner, one leg nearly 90' to the OD, other approaches at a gentle angle. Check the casting parting line: wide means forged, narrow means cast. While not forged, this is a very good cast crank.

  4. Late series small block. Maybe nodular, most cast, non forged. 260, 307, 350, and 403's. Notch on back drive flange is a tall "C" or flat "U" shape. Later [sb] cranks, which are even lamer, use an even deeper C-notch, almost as deep as it is wide. Some have the "L" or "check mark" shaped notch, but they are not forged. Check the casting parting line: wide means forged, narrow means cast.

  5. Late [1968 and up] big blocks: 400, and 455's. Forged. Mystery crank - reputed to have been used in '68 Toronado, but found in a 1968 low comp. 2bbl fullsize motor. ID number 400943. Notch on back drive flange is "L" or "check mark" shaped, like other forged cranks, but is really like a "J". The notch is just like the "L" notch except for the corner will be nicely rounded where one leg meets the other. Check the casting parting line: wide means forged, narrow means cast.

  6. Late bb's, 400, and 455's, cast, Nodular iron. Casting #397363 +/- the last digit. Has a big ol' N (or smaller CN) cast onto the side of the front weight. Best 455 crank you can get, unless you count the elusive 'forged' unit mentioned above. Apparently, they came in a lot of 1968 to 1969 400's, and 1968 to 1970 455's. Maybe later engines, too. External ID: back drive flange notch is a tall "C" or wide "U" shape, like every other cast crank, big or little block. 'Course, from the outside, it looks just like...

  7. Late bb's, 455's, cast, plain iron. Same casting #397363, +/-. It has NO 'N' on the front weight, yet has the same casting #, go figure. Same tall "C" or wide "U" shaped notch cast into the back drive flange. Weaker than the Nodular crank, or so they say.

The bad new is there's no way to tell a Nodular crank from a plain Jane with the oil pan on. You have to wait and look for the big 'ole N. The good news is- A forged crank is easily id'd by the L-shaped notch in the OD of the drive flange.

With the pan off or the crank out, there are two ways to tell a forged crank:

  1. Parting line. Wide = forged. Thin = cast. If there, guarantees a forged crank.
  2. Notch in rear flywheel mounting flange. L-shaped = forged. U-shaped = cast. Caution: some 1968-69 cast small block cranks had this notch. Check parting line for sure.
[ Thanks to Chris Witt, Bob Barry for this information ]
Number   CID   Year(s)     Notes
230376   SB
390275   403   '77 - '79   Balance hole in the 1st throw, nice 1/8" or so
                           groove cut into the circumference groove on the #1
                           counterweight. Most drilled for manual trans use.
393654   350   '74         Plain iron. No 'N' on front weight. Balance hole in
                           1st throw. "C" notch ¼" deep,
                           1" wide.
397363   455   '68 - '70   Nodular iron. 'N' on front weight.
397363   455   '72 - '76   Plain iron. No 'N' on front weight.
398261   SB
400943   455   '68         Forged Steel. In fullsize, w/2bbl, w/tow package.
418882   SB
556607   350   '77         Plain iron. No 'N' on front weight. No balance hole.
                           "C" notch 5/8" deep, 1" wide.
556607   307   '85         This might be the wrong. '77 350 is positive.

One handy way to divide Olds V-8's is EARLY [pre 1968] vs. LATE [1968 and up]. One of the most notable differences in the two groups is in crankshafts. Early engines all had forged steel crankshafts, whereas late engines [almost] all had cast iron crankshafts. Furthermore, the bolt pattern on the rear face, where the flywheel or flexplate attaches, is different. The early pattern has one hole offset CCW about 5 degrees from a perfect hex pattern, whereas the late pattern has that hole, and a second hole as well, offset in the other direction about the same amount. Thus, the two are not interchangeable. Early cranks [330, E-400, 425] require an early pattern flexplate, and all other engines use the late pattern.

Quick, low-hassle ID tip: On the back of the crank, on the OD of the flange to which the flexplate or flywheel attaches, is a notch. Forged cranks [330, early 400, 425] have an L-shaped notch. Cast cranks [350, almost all 455's, late 400 engines] have a notch shaped like a tall C (or a wide U).

Early big block forged steel crankshafts carried ID #390370 or 384722. This unit, used in the 442's early 400 engines and all 425's, has a stroke of 3.975". This crank can make an early 400 engine [using a 4.000" bore E block], or a 425 [with a 4.125" bore A, D, or F block and 425 pistons and rods], or a 455 small block [with a 350 Diesel block and about $3000 worth of Mondello parts]. A 455 big block cannot be made from this crank.

For 455 use, you will almost certainly be using a cast crankshaft. These cast 455 cranks come in two kinds, unfortunately with the same casting number (397363). The better unit is made of "nodular iron" and indicates this proudly with a big N, about an inch tall, cast onto the side of the front counterweight.

Judging from where they have been found, these cranks apparently came in most 455's from inception in 1968 up until about 1972. Of course, 442/Toro/W-30 motors were more likely to have the best parts, including the Nodular crank... of these, you are more likely to find a Toronado as a cheap engine donor. [Also found in '70 Delta 88]

[ Thanks to Chris Witt for this information ]

Forged 455 Crank

The really big news is... was this crank in a Toronado engine? No. An H/O engine [as owner said rumor was]? No. This forged steel 455 crank was right out of a freshly dismantled, numbers-matching.... 1968 455 low compression, presumably 2-V engine, car possibly equipped with a tow package. This has been confirmed by another lucky person. The evidence:

VIN deriv 38M250256
Engine Unit # 8284939
Block cast on day 15 [Jan 15]
Dist'r #1111288 8A1 '68 LC 455, made Jan01
Xst mans A-T, cast on day 2-?
C heads, small valve, cast on day 3-13 or 13-13 [rusty]

Supposedly forged cranks came in every 455 produced during the first month of production for the 1968 model year. It has been found that the steel 455 crankshaft was used in all 455's during the first month of production. Check the julian date code on your motor. It was probably cast in July of '67. It is NOT found exclusively in Toro's, but are rare indeed.

Motor mounts were on the forward pair of holes, and only the rear block drain holes were drilled (as all blocks destined for full size cars were), thus negating the theory that it was an H/O motor.

400943 crank, numbers barely visible, on the rear weight. Notch in rear face is a 'rounded-L' shape, longer than say a 425's L, and the corner is smooth, not a nice right angle. Just like Mondello's tech manual shows, except he shows a sharp corner there. Forging flash removal left a very wide "part line" as per usual for a forging. The front throw has "AC" stamped in it.

[ Thanks to Chris Witt, Luke Hogan, Tony Waldner for this information ]

Pilot Bearing

The pilot bearing is a bearing [in this case a bushing- an after market quick/dirty fix] in the rear of the crankshaft, into which the [manual] trans pilot shaft fits. Serves to support the front end of the trans shaft. Only MT engines had pilot bearings. Since 90% of Olds engines were destined for AT use, most Olds cranks are not even drilled to accept a pilot bearing. So, spend another $80-100 to have the hole cut and buy the bearing if you have a manual trans.

I've used an auto crank with a stick tranny before. This is no big deal. You can have a bushing machined or buy the one Mondello sells. The bushing fits into the large recess that locates the convertor in the crank (where the torque converter hub would normally rest.).

You'll need to also do one of two thing; 1. Grind the input shaft of the manual tranny off so it is just long enough to reach the front of the "new" bushing. NOTE: If you do this the tranny will no longer work with a stick shift crank.

2. Drill a hole in the center of the crank a little larger than the input shaft to make room for the input shaft. NOTE: This hole will NOT locate the input shaft in the crank. The bushing does that.

The hole does not need to be drilled on a lathe. The recess in the crank is tapered so your starter bit will be located in the center. NOTE: make sure you drill the hole deep enough so that the input shaft will not bottom in the hole.

I've used an old bushing that was sold to convert an early 50's ch*vy 6 cyl from auto to stick. Unfortunately this bushing is no longer manufactured.

DO NOT drill the crank while it is installed in anything other than a lathe or mill. I had the crank in my car drilled at a machine shop and it is off a little. They spun the crank in the lathe with the cutter stationary. Apparently they did not get the crank located perfectly. I go through pilot bushings occasionally. I do not know about Mondello's no drill bearing, but there was another company (Super Cars Unlimited??) offering the same type of bearing set up also. This other company had you trim 3/8(?) of an inch off of the end of the input shaft of the tranny. That allows it to butt up to the end of the crank without binding. A very simple set up if you can determine the bearing you need to use. I would guess that you would have to trim the end of the input shaft to use Mondello's set up as well. I once attached a bell housing and four speed to the back of an auto type 455 and the tranny would not bolt up completely. It had a gap of about 3/8 between the tranny and bell housing because the tip of the input shaft had no place to go. I did this for storage of a non running engine in a car. It was easier to move in the car than on the floor.

Our pilot bearing adaptor allows the use of an "automatic" crankshaft with a manual transmission. Factory automatic cranks are not machined with the step required for a pilot bearing. And they lack the depth required for the manual transmissions input shaft. The adaptor bearing addresses these issues by using the torque converter ring of the crank for centering and mounting of the bearing.

A self-aligning ball bearing (Not a bushing) is encased in a hardened steel case that has a knurl on the outside that provides a VERY tight fit in the crankshaft. Installation only requires a hammer and a socket that fits the O.D. of the adaptor. As noted, the automatic crank also lacks the depth required for the manuals input shaft. To accommodate this depth, the input shaft must be shortened by approx. 1/4" to 3/8". This can be done with a hacksaw or a disc style grinder.

A common misconception with this modification is that it will somehow weaken the input shaft. Actually, it is quite the contrary. Because, the pilot bearing is now closer to the transmissions front bearing, this will reduce flex in the input shaft. Think of a piece of tubing, say, 10 feet long, supported at the ends. This will flex in the center more so than a piece of tubing 5 feet long. An alternative to cutting the end of the input shaft, is to drill the existing hole in the crank deeper, while using the adaptor to support the input shaft.

Another aspect of concern by some has been whether or not the torque converter ring on the crank provides adequate strength to support the adaptor. The example I always give is the case of race cars with a rear engine mount plate. The motor plate will space the bellhousing (scatter shield) back by the thickness of the plate. Which often requires a spacer in the crankshaft. These are very similar to our adaptor. Without sounding like I'm just trying to pimp our adaptors, I should mention that we sell a fair amount of these to "correct" pilot bearing holes that were not drilled DEAD CENTER in the crankshaft.

If you opt to have the crank drilled to accept the standard bearing or a bushing, make sure a competent shop handles the task. Performance oriented shops are your best bet. And of course, the crank will need to be out of the engine. The crank and transmission must be aligned by the pilot bearing. If this alignment is off, the results are a vibration that will lead to transmission damage. As well as main bearing damage.

[ Thanks to Chris Witt, Dave Wyatt, Dave Brode, Greg Rollin for this information ]

Late / Early Model Flex Plate Differences

Pre-68 engines [425, 330] had a different bolt pattern for the flywheel to crank attachment that the 1968 and up 350/455/etc. engines. So be sure you get a flexplate or flywheel with your engine.

However, there is NO difference between big and little block flexplates or flywheels. The bolt patterns are different for early [pre-68] and late [1968 and up] cranks, but the flexplates' weights' size and location are exactly the same for all. Rumor has it that Diesels used a thicker metal for the flexplate, thus making then heavy duty. Wouldn't doubt it. Swap to your heart's content.

OK, so we all know that these flywheels come in two flavors- early [pre-68] and late [68-up]. With the bolt pattern attaching it to the crank being different. The difference is something like the early one has one hole offset 5 degrees CCW and the later version has that hole, and another, offset 5 degrees *CW*. Why, you have got to wonder. So, I was comparing two flexplates [the AT kind] one day, and it looks to me like the weight is exactly the same chunk o' metal.

From a Toronado standpoint, all flywheels are the same from '68 to '79. Starting in '79, the Toronado, Riviera, Eldorado flywheels are a slightly smaller diameter. The rear drive cars are the same as the '68 and newer cars but are stamped "METRIC" and have additional converter holes to accommodate the newer style converters used on TH-200's beginning in 1979. They will work just fine in the older models.

[ Thanks to Chris Witt, Tony for this information ]


Cranks 1995 - Present



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