318 tear down... it’s about time.

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Iv seen that 400hp build several times pop up on my search engine while searching for 318 building tips. I remember reading one years and years ago in a mopar muscle mag using a stock bottom end I dont recall the hp. I'm curious why a 273 crank it's the stroke as a 318?
 
Treblig said:
I thought that in order to "stroke" an engine you either had to increase or decrease the stroke of the original motor???
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Yes you are correct but if he uses a 273 wouldn't be destroking he is just staying the same.
 
el5dart said:
im guessing it took a number 2 in cyl number 2 is why it was running so rough. my numbers matching motor looks like it was 6 inches deep in the dirt on an angle for 10 years so i am hoping that i can do what you are going to do to yours to mine.
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Isnt that the #4 cylinder?
 
j par said:
It wouldn't make it a 390 as some suggestions...
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Depending on the over bore still a 318! Imo over bore dont count lol a 318 .030 over is still a 318!! But that's just me call it what you want.
 
dartfreak75 said:
Iv seen that 400hp build several times pop up on my search engine while searching for 318 building tips. I remember reading one years and years ago in a mopar muscle mag using a stock bottom end I dont recall the hp. I'm curious why a 273 crank it's the stroke as a 318?
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My guess on the 273 crank, is to get a forged crank. Still the same stroke though.
 
Personally, I always liked the way a 4"x3 1/4" motor ran and 318s and 340s are pretty darn close to that. In my dream world I would probably use a 383/400 B block in my Dart if I were to go the big block route that is. Same bore to stroke ratio, within a few .001s. JMO after a quadruple espresso :lol:
 
If you install a 273 crank, with 340 rods, and hypers, you are gonna incur the cost of a rebalance.
Late teener rods have the same casting numbers as 340s, and early 360s; the difference being bushed or pressed pins.Otherwise they appear identical.
On the street, I wouldn't lose any sleep over using a cast crank. My 360 crank has been to 7000rpm probably thousands of times over it's life. It was balanced with bushed teener rods and KB107s, and runs a flywheel. The assembly has over 100,000 miles on it
 
AJ/FormS said:
If you install a 273 crank, with 340 rods, and hypers, you are gonna incur the cost of a rebalance.
Late teener rods have the same casting numbers as 340s, and early 360s; the difference being bushed or pressed pins.Otherwise they appear identical.
On the street, I wouldn't lose any sleep over using a cast crank. My 360 crank has been to 7000rpm probably thousands of times over it's life. It was balanced with bushed teener rods and KB107s, and runs a flywheel. The assembly has over 100,000 miles on it
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Hey AJ which 318 rods had bushed pins? Like what years? truck? Pass car? Police? Just curious
 
Chryslerkid said:
I’m sure you’re correct about the strength.
I am copying the exact blueprint from a previous build. Not trying to reinvent the wheel. I know this engine makes 400hp with pump gas and zero fab work other than engine block machining. I don’t have the expertise to know if 340 rods would change the stroke or force me to use a different parts from that list.
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All small block rods are the same length 6.123" from center to center...

The 340 rods are a little beefier/heavier...

However, the 273 crank is balanced for the lighter 318 rods... The 273 crank and 318 rods will work together without any modifications needed...
 
dartfreak75 said:
Iv seen that 400hp build several times pop up on my search engine while searching for 318 building tips. I remember reading one years and years ago in a mopar muscle mag using a stock bottom end I dont recall the hp. I'm curious why a 273 crank it's the stroke as a 318?
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273 cranks are forged...
 
Forged cranks flex less at high rpm's and are easier on the main bearings, less wear, last longer.

The 273 engines were designed for going 3,000-4,000 rpms on the freeways and lasting 100,000 miles. They had solid lifters too, very mild cams but the was always upgrade cams available.

Then came the oil shock of 1973 and slower speed limits, so then cast cranks work just fine. Today, few people run 4.10 gears and no OD and drive 75 mph min on the expressways and if they do its not everyday for long distances
 
dartfreak75 said:
Hey AJ which 318 rods had bushed pins? Like what years? truck? Pass car? Police? Just curious
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My data says
the 1618699 lightweight floating pin 273 rods were also installed in........ 318s up to 1971.
the 2899496 rods were all floating and were installed in all 340s, and in.. 318s from 72 to 73.
the 3418645s were pressed pins and cam in 360s from 71 to 86, and in 318s from 74 to 86 also.
And yes the 496 rods are quite a bit beefier than the 699s; I think the weight difference in them might be up to 100grams. IIRC, my pressed pin 360 rods looked like bushed 340 rods except for the bushings of course. I had lots of bushed teener rods so that is what went into my engine.
 
AJ/FormS said:
And yes the 496 rods are quite a bit beefier than the 699s; I think the weight difference in them might be up to 100grams.
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758 grams versus 726 grams. Weight is mostly in the beams, from what I recall (I have compared sets of both). The bushed 273/318 rods also were under a 2406782 PN.
 
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'73red-duster said:
Not positive, but I believe, with the exception of some truck motors, 318's had cast cranks.
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Maybe some of them, years ago I got given a 318 short block out of a 71 D600, it was a cast crank, still have it in my "Mean Teen".........being cast didn't hurt my feelings a bit.......
 
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