Logo
FULL SITE MENU

Rotation direction of Chrysler Marine LM318BW

D

Doug Brooke

Guest
" I have a 1968 210 HP Chrysle

" I have a 1968 210 HP Chrysler Marine engine #LM318BW that rotates opposite of automotive rotation. Should the pistons be installed backwards? That is, should the notch in the piston top face the rear of the engine rather than the front?
Thank you "
 
"Jeez, why are all the good qu

"Jeez, why are all the good questions about Chryslers?? Just kidding. Assuming the notches indicate wrist pin offset in this engine, I'll vote yes - you should reverse the pistons. Read this knowing that although I've rebuilt a number of marine V8's, none were reverse rotation. But, I think we can reason through this.......

Wrist pin offset is related to rotation. The offset is designed to direct the angular resistance of the rod on the power stroke more closely to the center of the piston as the rod moves through the stroke. If the rod angle is reversed on the power stroke, as it would be in a reverse rotation engine, it makes sense that the offset also needs to be reversed.

This is all done in an effort to minimize piston slap, with the price being slightly increased friction. But it's a small price, considering that most engines would destroy themselves after only a few hours of running, not to mention the gawdawful racket of rattling pistons.

Reversing wrist pin offset in a standard rotation engine is an old racer's trick to get a little more power, but only for engines expected to last a few laps around the track - not what we want in reliable marine engines.

"
 
" I disagree, according to the

" I disagree, according to the chrysler service manual they do not make any changes in piston orientation I am putting the motor together at this time and after researching this question I am going to put the notches on the piston towards the front of the engine as specified by chrysler. I would recommend getting the service manual if you do not have one, it is invaluable not only for assembling the motor but also has specs and rebuild info for all components on the engine. Good Luck I hope everything goes well. "
 
" Im sure you dont have to cha

" Im sure you dont have to change the direction.The force on the piston is the same regardless,of the direction. "
 
I WOULD LIKE TO KNOW WHAT SIZ

I WOULD LIKE TO KNOW WHAT SIZE PROPELLER WOULD BE CORRECT FOR A 1972 LUHRS 320 WITH 2 CHRYSLER 318 ENGINES.
 
"I just got a 1985 Supra Sunsp

"I just got a 1985 Supra Sunsport. It only had 44 hours on it before being repoed, so I got it for a great deal. I need to go through the motor, as it has been sitting for over 10 years. Could anyone tell me anything about my boat, it's motor (a 351), or what rotation it is (specifically, what direction is standard or reversed rotation). I'm clueless!!!"
 
"John: WAIT! The piston DO g

"John: WAIT! The piston DO go in the other way around, and here's why:

The wrist pins in an engine are deliberately offset by about a 1/16 inch to keep the piston from slamming against the wall of the cylinder (due to the angle of the con rod as the piston comes up). This is a 'fact of life' in all reciprocating engines, and when they are set up to turn backwards, the pistons MUST go in backwards as well. Failure to do it this way DOUBLES the amount of piston slap and will shorten engine life.

Jeff

PS: Not sure why the manual would say otherwise; perhaps it's a misprint?"
 
could you please advise the ti

could you please advise the timing and firing order of chrysler 318 engine and point settings etc
 
"On a reverse rotation engine,

"On a reverse rotation engine, does the cylinder number change? In Otherwords, does 1,3,5,7 become 2,4,6,8? I just blew up a 454 reverse rotation engine, and have no clue why, 3 months old and less than 50 hours. #1 (or #2) piston is discentagrated, and the wrist pin wore a hole through the water jacket (the width of the wrist pin, and from the bottom to the top of the stroke. Any help is greatly appreciated. Just an FYI, My engine has all the pistons installed with the notch facing the rear. 1987 Lurhs SportFisher with Dual 454 inboards."
 
Back
Top