Carburetor Rebuild Question

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tc123

Cadet
Joined
May 27, 2009
Messages
23
I have a 1987 Mercruiser 470 w/Rochester Quadrajet. The engine idle is inconsistent at times below 900 RPM(stalls ocasionally). Other than that the 470 runs great. Is it worth having the carb totally rebuilt in the off season or is there a simpler solution? One price I got from a local Marina for a rebuild is about $350.
 
86 century

86 century

Ensign
Joined
Sep 8, 2009
Messages
986
Re: Carburetor Rebuild Question

There not that tuff to do get yourself a kit and dig in.
The fine people here will help if you get stuck.
I treat carbs a lot like impellers if you need to ask the question yes it needs rebuilt.

900 rpm is to high for your idle.
You should look into the ignition as well is it points if so that would be my firts move to some type of electronic ignition.
I have had real good luck with petronix. Drop in replacement for your points you can get the kit from iboats for under $150
 
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oldjoe789

Recruit
Joined
Sep 9, 2010
Messages
3
Re: Carburetor Rebuild Question

Sounds like the primary throttle shaft bores may be worn and causing an erratic vac leak. If bore is worn, get a good bushing kit.
 
undrh2o

undrh2o

Seaman Apprentice
Joined
Nov 14, 2011
Messages
41
Re: Carburetor Rebuild Question

TC I just rebuilt my Rochester and spent about $50 in materials...go to NAPA for the kit, they have the Sierra parts you will need. I tried the other chains (autozone, advance etc) and none of their kits have the correct gaskets.

the kit was $28 and a bucket of parts cleaner was about $25...you can do the rebuild in a matter of an hour after soaking the parts for an hour or so...

if you have questions send me a pm...

Rob
 
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dan t.

Lieutenant Junior Grade
Joined
Feb 28, 2008
Messages
1,131
Re: Carburetor Rebuild Question

Just a little extra advice, plan on replacing the float and the vacuum pot on the side , I lost count of the number of q-jets I have rebuilt many years ago,but for a proper rebuild I always replace these items as they do deteriorate. I also like to seal the fuel well plugs with J B weld just for safety's sake. Good luck with your rebuild.
 
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PiratePast40

Lieutenant Commander
Joined
Mar 21, 2009
Messages
1,734
Re: Carburetor Rebuild Question

Before you remove the carb for a rebuild, check for vacuum leaks while the engine is still running. Could be a leak on the intake manifold gasket, at the carb base, or the throttle shaft. Would be time well spent to at least try to narrow down the source of the problem before tearing things apart.

Check the timing as well. Is it steady or does it bounce all over the place at low rpm?
 
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