Is there a 318-3?

[The_Handier_Man1]

From: chip  (Original Message)
Sent: 3/14/2005 8:46 PM

i have seen a 360-3 and a 440-3 but, i have never seen a 318-3.
can anyone assure me there is such an animal? thanks.



From: jsn80
Sent: 3/14/2005 9:16 PM

Yes, that beast does exist.  I have 318-3 in my Winnie.  This is considered the Heavy Truck Motor.  I had to argue with the local Auto Zone boy that he sold me the wrong spark plugs!!!!



From: chip
Sent: 3/14/2005 9:48 PM

thanks for the info. what year is your winnie and can you post a picture where the dash 3 is cast or stamped?



From: jsn80
Sent: 3/14/2005 10:32 PM

I have a 71 Brave, I don't know if or where it would be stamped on the motor.  I'll try to find out were I saw it.  I think it was on the data plate inside the winnie.



From: chip
Sent: 3/14/2005 10:44 PM

thanks alot. a data plate would be a good indicator.



From: jsn80
Sent: 3/15/2005 9:43 PM

I couldn't take a picture of the plate yet due to dead batteries.  It does list the motor as a 318-3.  The plate is right inside the door to the left.

jsn80



From: Slantsixness
Sent: 3/16/2005 6:22 AM

It should be on the motor, too... beneath the alternator on the block, not the head.
This is not the casting number you can see along the block from the bottom, but rather a block ID number stamped on a smoothed block surface. Usually it's covered in greasy grime.

Tom



From: denison
Sent: 3/16/2005 6:50 AM

    In the Service Manual the picture of the engine i.d. stamp from a 318 is clearly shown.  Its easy to see AFTER you remove the radiator, some of the accessories, and clean the front of the engine with 3 or 4 evolutions of Gunk and oven cleaner!
    Another good reason to take the radiator out for cleaning after you buy a used motorhome!



From: chip
Sent: 3/16/2005 7:37 AM

thanks for humoring me guys. my point is/was that the -3 is, for the most part, insignificant these days. especially when considering a replacement motor or rebuild--- given hi-po parts available thru mopar and others. [anyone switch pistons right bank for left in their 318 for more power lately ? haha]
i wonder how many -3 motors are left in our old motorhomes and how many came with -3's from the factory?



From: Slantsixness
Sent: 3/16/2005 9:05 AM

Ah, but there is a sigtnificant difference in the 318-3 you can't get from a Hi perf shop, and the 360-3 doesn't have it either.

What is it?
(hint: it's inside the motor, and not an accesory)

You didn't expect to be tested, as well as humored, did you!

Slantsixness



From: chip
Sent: 3/16/2005 9:15 AM

do you mean the block or, it's components?



From: mightybooboo
Sent: 3/16/2005 9:50 AM

Could it be the crankshaft composition/build?

BooBoo



From: Slantsixness
Sent: 3/16/2005 10:25 AM

Chip,
A component in the block, along with a difference in the line boring for this component...
Which means.....

BooBoo wins!

The forged crank and journals along with the crank line bore size. Now, you CAN modify a regular 318 block by line boring it (and the bearing caps), but the Crank itself is no longer produced. Yes, Performance shops will sell you a forged crank, but it's the small journal and you'd have to use ovesized bearing casings on it, or a standard 318 "car" block.
What does it really mean? Nothing that can't be adapted or modified, but the 318-3 block is actually closer to the 318 wideblock (the old truck and car motor) than the 273-360 LA "light duty" engines, which were lightened and used cast cranks.
The 360-3 "truck motor" is actually a weaker design than the 318-3. Thin cylinder walls cause it to run hot, lack of internal balancing causes excessive main bearing wear and thrust bearing runout. And it does have more power, surely. But at a lower reliability.
An exception to this was the 340 and 360PI motors, which have the larger crank journals and usually (not always) a forged crank.

"Messing with Mopars since I was 4 years old, and lovin' every minute of it!" (well, way back then, I just handed Dad tools, but I think you get the point!)

Slantsixness (Tom)



From: chip
Sent: 3/16/2005 10:44 AM

to the best of my knowledge, all 318 cranks are cast only-- they never went thru a forging process 2658278,391,393, and 3462387 were the old mopar #'s. all had 2 1/2" main and 2 1/8" rod journals



From: Slantsixness
Sent: 3/16/2005 11:14 AM

Hmmm,
Mine's forged. and I will have to get back to you on the main cap actual size,  I don't have the books or the crank in front of me right now. But I do have the froged crank part number, for the 318-3 "commercial truck motor." Most books don't even list it.

I'll concede on the main journal size of the crank, but I beleive there is a difference in the caps and bore on the block though.



From: Slantsixness
Sent: 3/19/2005 10:23 PM

Ok, here's the scoop!

A 1972 318-3 "premium" (this is what the majority of all M300's have.)

Crankshaft LA318 (318-3)  "premium" P/N  3698269

Standard "car and "non-premium" LA 318 P/N 3698267

I was wrong as far as the bearing sizes, however, the cap castings appear different, they are the same size. (the bosses appear taller and have a  cast-in design that looks different, but even the main bolts are the same, so I assume it was just "different looking" than I'm used to....)

The crank part numbers both cross to Chip's aforementioned part numbers, and, although it'll work, the replacement for the 3698269 (2658393, and that # has been superceeded since my latest 15 year old book...) crank is not forged.

After 1973 (could be a 74 model year though) the 318-3 did not carry the "premium compnents", and was likely changed to a cast crank. I don't have any way of determining any more than that, since I don't have truck manuals until 1978, when they were all (cars too) the same, but the "318-3" designation carried on until 1991, when the block was changed to accomodate the "new" magnum engines (not like the "old" magnum engines...) and the designation is now simply the "5.2L block", only available in one configuration, and is prone to crankshaft failure (snaps in two!) in heavy duty applications.

So, yes the 318-3 "premium" Truck motor" is indeed different.

As to how different? you decide, but I wouldn't put anything but a 318-3 Premium in a motorhome. Just look at how well the 5.2L magnum engines self-destruct under a load.....

Tom
(It's my opinion, and I'm stuck with it!)



From: Slantsixness
Sent: 3/23/2005 9:56 AM

When you drive over here to the right coast and attend the NECWJ, or MACWJ wearing that hawaiian shirt!

I'll buy you a mug, if you do!

Of course, with today's gas prices (finally shot over $2 a gallon in VA) I can understand how you might not make it!

Tom