Crusader 270 Misfire/Rough Idle

rybad

Petty Officer 1st Class
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May 20, 2004
Messages
215
I have 1987 Carver Mariner 3297 twin Crusader 270. Port side was sounding and feeling a little off, then blew head gasket (in 5-6' swells in the middle of Lake Erie of course!). Pulled heads, had heads re-done, cleaned out block, reinstalled everything, new plugs, wires, points, cond. cap & roter, fuel filter and timed 10* BTDC at 7500 RPM (RH rotation). Engine still rough idle. Vac guage reads about 17-19 psi and stumbles every few seconds. Tested fuel pump and came back 6 psi which should be good.

The ONLY way I can get this engine to idle smooth is to pull the mix pins completely out of the carb (Rochester Quadrajet). Once removed, I can time perfectly and she runs much better (still not 100% but about 99%)

I sprayed the carb with carb cleaner and even sprayed carb cleaner into the mix pin sockets. Nothing helps. As soon as I even put the pin back over the hole, is starts to disrupt the idle again. Seems to be that the engine is wanting more gas (or more air). Not sure what else to look for at this point. In troubleshooting I have swapped plugs, wires and coil from starboard engine (stb runs fine).

I'm not opposed to buying a rebuilt carb and putting that in, but just dont want to throw money at it unless I get other opinions to support a carb problem first.

I have not yet checked anti-sipon valves, only because the fuel pump tested good... I also did a compression test. Lowest was 142, highest was 146, very consistient across all cylinders. I believe 140's is good.

Any suggestions? (keep in mind, engine was acting up prior to head gasket blowing.. I assumed that was why it was acting up, but apparently now).

Thanks!!
 

alldodge

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Mar 8, 2009
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40,581
You need to remove and rebuild the carb. Spraying cleaner in and around will not work.
 

Bondo

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Apr 17, 2002
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70,464
Ayuh,.... Ditto what AD says,.... Rebuild the carb ya got,....
 

rybad

Petty Officer 1st Class
Joined
May 20, 2004
Messages
215
So, I would rather buy a carb already rebuilt, so I can just drop it in (presumable). What are the objections to that? Is it just a cost issue to rebuild it, or is there some other significant reason to rebuild as opposed to replace?
 

alldodge

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Just the cost and most here like to work on there stuff
 

rybad

Petty Officer 1st Class
Joined
May 20, 2004
Messages
215
OK.. My plan is to buy a rebuilt, then rebuild mine to have a spare.
 
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