What is this?? 318 stroker??

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BadAss71

BadAss71

Let's Go Brandon
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I need to ask my fellow mopar brothers a question.....or two lol. I recently acquired a 318 magnum motor with a car I bought. Its been freshly gone thru and everything is brand new. I'm just trying to figure out what exactly I have here. I ran the casting numbers on the crank and rods and pistons. Here's what I know.

Block:
10/91 casting 318
360 crank
360 rods
360 sealed power standard bore pistons
Oiling mod

Heads:
Magnum heads mild port job
Behive springs
1.94?? Intake valves
1.6?? Exhaust valves
1.7 rockers

I just pulled the timing cover and discovered they installed a gear drive also. I havent pulled the cam yet so I am not sure exactly what the specs are. My questions for you guys are:

What size is this thing cubes wise??
Any idea what compression ratio??
What are the reasons for doing this kind of thing? Torque?
I am contemplating on installing this thing in my dart, but I want to know if it's really worth doing. Any help is much appreciated!! I will post some pictures tomorrow.
 
Sure the block wasn't miss-stamped? I have a hard time finding a 318 block fitting a 360 rotating assembly.
 
I'm going to venture and say it's a 360 with an incorrect cast number on the block?

If it's got 360 4.000" pistons, it could likely just be a re-ring magnum, which is common, considering how clean most of them look when they come apart, due to fuel injection.

If it's really a 318 and someone punched it out to a 360 stock bore, you've got a piston that is sitting in a .090" overbore, which is highly unlikely, unless it's been sleeved or something.
 
True enough to it's math, it is a 360.

Sneaky as hell, if it says 318.

Earns cool points.
 
Thanks for the quick responses! Well it is definitely a 318 block for sure. From what I have read on the web, folks would take a 360 crank and turn down the main journals to fit in the 318. Then bore the 318 out to fit standard bore 360 slugs. With the 360 rods in the 318 it would then make it a stroker right?? But what would you really gain going this route??
 
Magnums don't like going over .060" ,as a general rule. Pictures,and a piston pulled & micrometer'ed,would belp....
 
Well I did a quick mic on the bore and its 4.00 on the money. I havent pulled pistons as of yet. Here are the numbers on the pistons, rods, and crank.

Crank 4027169
Rods 3418645
Pistons HC55CP
 
Without over thinking it,
If it has a stock 360 crank, stock 360 pistons, and stock 360 rods, it works out to just about......

360.....
 
Revhendo said:
Without over thinking it,
If it has a stock 360 crank, stock 360 pistons, and stock 360 rods, it works out to just about......

360.....
Click to expand...

Well that's what I tbought too lol. But why would someone go thru all of the machine work to put a 360 crank in a 318 when he could have just started with a 360 to begin with?? There has to be some reason for it!
 
The fact that someone built it that way, and added a gear drive, makes me really curious as to what cam was used :D. Was this engine previously run as a carbed engine?
 
The 10/91 tells me 92 Magnum. In late model circles,July ,August,was the start ,for domestic year. Japanese, June/July...
 
OldmanRick said:
The fact that someone built it that way, and added a gear drive, makes me really curious as to what cam was used :D. Was this engine previously run as a carbed engine?
Click to expand...

Hmmm what are you thinkin lol?? Never has been run since the rebuild. I did get an M1 intake along with it.
 
BadAss71 said:
Well that's what I tbought too lol. But why would someone go thru all of the machine work to put a 360 crank in a 318 when he could have just started with a 360 to begin with?? There has to be some reason for it!
Click to expand...

I know, right?

Maybe it was for some sanctioned racing that required a "stock" 318.
LOL. Would be interesting to hear the story behind this one.....
 
Pull one of the main caps off and measure the the diameter of the main journal. You will then know what you actually have.
360-2.81
318-2.50

edit... dirty white boy beat me to it
 
skrews said:
Pull one of the main caps off and measure the the diameter of the main journal. You will then know what you actually have.
360-2.81
318-2.50

edit... dirty white boy beat me to it
Click to expand...
I plan on pulling the motor totally apart. I will get that measurement posted asap. Being its a 360 crank in a 318 block i'm putting money on the 2.5 main.
Abodybomber said:
Pictures, lol...
Click to expand...

Check back tomorrow lol. I will post a few pics for sure.
 
OldmanRick said:
The fact that someone built it that way, and added a gear drive, makes me really curious as to what cam was used :D. Was this engine previously run as a carbed engine?
Click to expand...

BadAss71 said:
Hmmm what are you thinkin lol?? Never has been run since the rebuild. I did get an M1 intake along with it.
Click to expand...

I just think if you can determine something close to the specs, that we all could understand better where they were going with this combo. Maybe some numbers stamped on the cam will give a clue?

I love treasure hunt's :D. You may have gotten something special.....I sure hope so. :thumbrig:
 
OldmanRick said:
I just think if you can determine something close to the specs, that we all could understand better where they were going with this combo. Maybe some numbers stamped on the cam will give a clue?

I love treasure hunt's :D. You may have gotten something special.....I sure hope so. :thumbrig:
Click to expand...

I'm with you. Cam specs will tell a lot. I plan on pulling the motor completely apart tomorrow night. I'm curious as hell to know now!
 
:D Tongue in cheek here, but my first thought was that someone was putting together a combo to "skirt" the rules somewhere. This could be a fun find you have obtained. Not that it will work for you, but it would be cool. If that cam has a low/moderate lift along with some big duration, i think you've found something...lol.

Seriously though, I hope this works out as a good usable engine for you. Can't wait to see what you find.
 
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