Main Bearing Cap Bolts

[Matt Wilson]

I noticed the main bearing cap bolts on my 251 are not the same as those on my 230.  See the attached images.  The view of the tops of the bolt heads shows the 251 bolts marked with an "S" and they also have the lines you expect to see on Grade 8 bolts from the hardware store, while the 230 bolts have no lines, but they all say "NC."

 

From the side, it can be seen that the 251 bolt heads are a little thinner and the threaded portion is a little longer than on the 230 bolts.

 

Does either of these bolts look correct?

 

The 251 came out of a '63 Power Wagon and I'm certain it was never rebuilt.  The 230 was rebuilt (by me) nearly 20 years ago, and at least one time before, back in the 50s, according to a tag that was on the engine.

 

As a side question, do you all use lock washers on your main caps?  The 251 had no washers.  I can't recall if the 230 had washers when I disassembled it, but it sure did afterward, as you can see in the photo.  Those look like hardware store Grade 8 washers, and I imagine I they were my doing (whether I was replacing existing washers or not, I do not recall).

[JBNeal]

I dunno about that lock washer, but the bolts might have been supplied by a different vendors over the years.

[Dodgeb4ya]

#120384 lock washers on the main cap bolts were used on most all flathead  engines thru 1954. This after looking at four different MoPar car and truck parts books.

Main cap bolts #864118 was used on most all the 1941-54 flathead six engines also.

[Matt Wilson]

On 11/25/2021 at 11:45 AM, JBNeal said:

I dunno about that lock washer, but the bolts might have been supplied by a different vendors over the years.

Yeah, I thought that might be the case, but I guess I just mainly didn't expect the bolts from the 251 to look like hardware store Grade 8 bolts.  I suppose they're fine, though.

[Matt Wilson]

On 11/25/2021 at 3:54 PM, Dodgeb4ya said:

#120384 lock washers on the main cap bolts were used on most all flathead  engines thru 1954. This after looking at four different MoPar car and truck parts books.

Main cap bolts #864118 was used on most all the 1941-54 flathead six engines also.

Thanks for the info.  I guess the 230 was correct with its washers and the 251 was correct without washers. 

[Dodgeb4ya]

All of my engines used the 1/2" lock washers # 120384 on the main bolts as shown in all my MoPar parts books.

I carefully checked this in 1946-1955 truck and car parts books.

These being..218/230

                     ..251/265

                     ..323 Straight Eights

                     ..306/413 Moly Block Six

I just rebuilt the 413 six using sixteen 1/2" lock washers on the main caps as assembled from the factory.

Even the 331/354 Hemi's show the same #120384 ten lock washers as being used.

So the 251 uses them too.

I rebuilt a 251 in my 1948 DT 2-1/2 I'm sure used washers.

I don't know though if it would matter much other than galling the main cap.?

 

 

Edited November 28, 2021 by Dodgeb4ya

[Matt Wilson]

15 hours ago, Dodgeb4ya said:

All of my engines used the 1/2" lock washers # 120384 on the main bolts as shown in all my MoPar parts books.

I carefully checked this in 1946-1955 truck and car parts books.

These being..218/230

                     ..251/265

                     ..323 Straight Eights

                     ..306/413 Moly Block Six

I just rebuilt the 413 six using sixteen 1/2" lock washers on the main caps as assembled from the factory.

Even the 331/354 Hemi's show the same #120384 ten lock washers as being used.

So the 251 uses them too.

I rebuilt a 251 in my 1948 DT 2-1/2 I'm sure used washers.

I don't know though if it would matter much other than galling the main cap.?

 

 

Good info.  The 251 came out of a 1963 Power Wagon, and perhaps they didn't use lock washers on the main cap bolts by that time.  The rod cap bolts also did not use lock washers, unlike the 230, which came out of an earlier Power Wagon.  And the rod nuts were not lock nuts either, contrary to what someone posted on another website forum.

[Dodgeb4ya]

You are probably right.

I have seem a lot of later engines that use just plain hardened washers or none at all.

I'm really only into 1946-54 MoPar cars and trucks.

I know those pretty well.

Edited November 30, 2021 by Dodgeb4ya
Spelling error

[Matt Wilson]

1 hour ago, Dodgeb4ya said:

You are probably right.

I have seem a lot of lster wngines that use just plain hardened washers or none at all.

I'm really only into 1946-54 MoPar cars and trucks.

I know those pretty well.

Yeah, that '63 251 didn't have any washers at all on the main or rod caps.

[Dodgeb4ya]

I forgot I do have 60's MoPar parts books in another bldg. I'm going to check to see if they show the lock washers just to see.

I'll post the results tomorrow.

[Matt Wilson]

20 hours ago, Dodgeb4ya said:

I forgot I do have 60's MoPar parts books in another bldg. I'm going to check to see if they show the lock washers just to see.

I'll post the results tomorrow.

That would be great, thanks.

[Dodgeb4ya]

***I looked at the 1954-56 C-Series truck parts book...

***The L and K Series 1957-58

***1959, 60 and to 1963 trucks.

***1965-70 truck book skipped the flathead 251.

What I found was through the 1956 C-3 series trucks all flat heads used the lock washers on the main cap bolts.

A # 120384 lock washer was used.

But starting in the 1957 "K" models that main bolt lock washer was discontinued up thru at least 1963 as shown in the posted pictures.  

The 1963 truck parts book exploded engine view is showing the main bolts with out washers. 

The 1955 parts list shows the the main bolt lock washers .

The 1963 parts list sheet only shows the main cap bolts...no lock washers as also shown in the exploded engine view.

No rod lock washers used either.

Hope this helps!

Edited November 30, 2021 by Dodgeb4ya

[Matt Wilson]

On 11/29/2021 at 11:13 PM, Dodgeb4ya said:

***I looked at the 1954-56 C-Series truck parts book...

***The L and K Series 1957-58

***1959, 60 and to 1963 trucks.

***1965-70 truck book skipped the flathead 251.

What I found was through the 1956 C-3 series trucks all flat heads used the lock washers on the main cap bolts.

A # 120384 lock washer was used.

But starting in the 1957 "K" models that main bolt lock washer was discontinued up thru at least 1963 as shown in the posted pictures.  

The 1963 truck parts book exploded engine view is showing the main bolts with out washers. 

The 1955 parts list shows the the main bolt lock washers .

The 1963 parts list sheet only shows the main cap bolts...no lock washers as also shown in the exploded engine view.

No rod lock washers used either.

Hope this helps!

That is great info!  Thanks so much!  Looks like that confirms my findings in both engines.  In talking with one of the machine shops I used for the 251 work (actually, I'm turning the 251 into a 265 with the appropriate crankshaft and rods), it seems that nearly all engines of any make for at least the last 50+ years have not used lock washers, or any type of washers, on the rods.  Presumably that's the same as for the main caps too, although we didn't get into that discussion. 

 

The 265 rods had recesses for lock washers, but I had those machined down to eliminate the need for washers.  This was at the recommendation of Vintage Power Wagons, who said something about a Chrysler Technical Bulletin that indicated it was better to go without the washers, but they didn't have a copy they could send me.  I'm sure it would have been fine if I had left the washers in place, as most folks have done, but I decided to remove the need for them, especially since those washers are difficult to come by in unused condition, which is what I would have strongly preferred. 

 

By the way, the 265 and 251 rods are nearly identical in every respect except for length, bolt head configuration (and rod features related to the bolt heads), and possibly the thickness of the beam section.  I measured and compared these two types of rods in every detail I could possibly cover, and they seem to be identical except for what I mentioned.  In fact, the beam thickness may be the same as well, but I just can't quite recall.  Based on this, I felt comfortable in removing the lock washer recesses from the 265 rods, since the caps would then be identical to those of the 251 rods.  The nuts and threaded portions of the bolts for those two rod configurations also appeared to be identical to each other.

Edited December 1, 2021 by Matt Wilson

[John-T-53]

I recall hearing somewhere (probably from an old machinist) that back in the old days, there was "fear" that the rotating assembly fasteners would come loose and cause catastrophic failure, thus the lock washers. Some engines also had wire ties going through the nuts, and some were fastened dry. Somewhere along the line (as indicated above) this concern had dissipated, now the standard operating procedure is to liberally lube up the fasteners before torqueing them down. 

 

My main caps were quite chewed up from the lock washers. This warranted a little machining to create a clean base for the few fasteners.

Edited December 3, 2021 by John-T-53

[Matt Wilson]

6 hours ago, John-T-53 said:

I recall hearing somewhere (probably from an old machinist) that back in the old days, there was "fear" that the rotating assembly fasteners would come loose and cause catastrophic failure, thus the lock washers. Some engines also had wire ties going through the nuts, and some were fastened dry. Somewhere along the line (as indicated above) this concern had dissipated, now the standard operating procedure is to liberally lube up the fasteners before torqueing them down. 

 

My main caps were quite chewed up from the lock washers. This warranted a little machining to create a clean base for the few fasteners.

Right, I spoke to George Asche a couple of years ago,and he said he puts a light coating of engine oil on the bolt threads and torques the rod bolts to 45 ft-lbs.  Presumably the same would be done for the main cap bolts.