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Chrysler LM318BXRX-036

76F26express

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Can anyone tell me what the letters xrx (lm318bxrx-036) in my engine model number represent? Also my engine has a black box behind the distributor that says 5.2ltr 240hp but i have not seen this on any other engine as 240 hp only 225hp. What makes my engine have 240 hp verses 225hp on all the others ive seen?
 
Possible bigger carb, 4 barrel as opposed to 2 barrel,different cam,pistons, different compression ratio,cylinder head configuration
 
Possible bigger carb, 4 barrel as opposed to 2 barrel,different cam,pistons, different compression ratio,cylinder head configuration

Ok I figured it was not a simple answer. Thx
also, I am not getting full rpm at wot, only getting 34 to 3600 rpm, it should be around 44/4600 rpm. I'm sure the correct prop is on it for different reasons, so I'm hoping with a good tuneup and a carburetor cleaning I'll get those RPMs back outside of that any suggestions. The turnup would be including plugs wires cap rotor and carburetor cleaning.
 
Check throttle linkage to see if throttle plates are opening fully,also check to see if timing is advancing properly
 
Check throttle linkage to see if throttle plates are opening fully,also check to see if timing is advancing properly

Ok will do on the linkage. I did adjust the timing. I'm hoping I did it correctly. The little tab that lines up with the timing mark on the harmonic balancer only had one center hole and no other degrees marked on it so at idle in gear around 650 to 700 rpm's I set it directly on the mark. As I increased the RPMs the timing Did advance. So unless I didn't set It properly that should be complete. I also just found out from the previous owner that the boat never really went anywhere for 10 years that he owned it he put the boat in the water and it stayed at the dock all year and never went anywhere for the last 10 years. So I don't know if that would play a part in anything at all.
 
IIRC the 240 HP 318 is the later 85 and newer engine with the center rise exhaust manifolds. The Exhaust manifolds are actually the biggest contributor to the increased HP.


 
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Thx for the info. My engine has the log style exhaust manifolds but the engine tad serial number matches a 1986. So guess the engine was rebuilt or replaced and they used the old manifolds.
 
Has carb been cleaned,rebuilt,,you said boat sat around 10 years going nowhere,could possibly be gummed up,ethanol?? Is fuel new,old ,untreated? You mentioned carb cleaning in thread#3, It must be thoroughly taken apart,soaked overnight,scrubbed.high pressure water blown threw everything,followed by dry compressed air. Reassembled and installed. All components from tank to carb. should be addressed,lines, filters,separator ,fuel pump. Check fuel pressure
 
Has carb been cleaned,rebuilt,,you said boat sat around 10 years going nowhere,could possibly be gummed up,ethanol?? Is fuel new,old ,untreated? You mentioned carb cleaning in thread#3, It must be thoroughly taken apart,soaked overnight,scrubbed.high pressure water blown threw everything,followed by dry compressed air. Reassembled and installed. All components from tank to carb. should be addressed,lines, filters,separator ,fuel pump. Check fuel pressure

You are right about the carb. I was saying earlier that and a tune up was needed. The boat was just put in in October after sitting for over a year and a half. Runs good except at wot.
 
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