Rodchester Carb rebuild Kit question

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  #1  
Old 08-02-04, 10:43 AM
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Rodchester Carb rebuild Kit question

Hi all,
I have an older rochester quadra-jet carb that i am rebuilding. I have a question that many of the parts stores cant seem to tell me. The main reason I am looking to rebuild this is I am in need of the metering valve (power piston) seals. First question is, does anyone know if a carb rebuild kit would come with these? Second question is, does anyone know what they look like. The reason I ask this is, the carb ahs been dumping raw fuel into the intake. At a closer look when I opened it up is that the metering valve seals were never instaled from whom ever rebuilt it the first time. I just need to know if I'm looking for a rounded seal or maybe a square edged seal.
Thanks,

Brian
 
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  #2  
Old 08-02-04, 12:39 PM
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there are no "power piston seals" per se...the piston is a close machine fit and requires no additional sealing. now...as for leaking...in the main body, when the carb was manufactured the drill passages that sometimes have to be plugged from the drilled end and this is the case with the main wells that sit in the bottom of the bowl. sometimes these do leak raw fuel into the intake and require sealing. some rebuilders epoxy them and some just use the foam seal that comes in the rebuild kit. the exploded view in the kit will show the exact location of where the foam seal goes.
 
  #3  
Old 08-04-04, 05:25 AM
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Fuel leak from exhaust

Do you know of anything else I can look for that would make it leak? I have performed a full rebuild, new float had the float adjusted by ASE Pro. Cleaned everything, yet it still contiues to leak raw fuel out the exhaust. Is there anyway to check if the power piston is working correctly?
 
  #4  
Old 08-04-04, 06:29 AM
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fuel out of the exhaust

raw fuel from the exhaust is hard to believe because beyond a certain richness, gasoline won't ignite. at the very best, black smoke and rich missfire would be occurring...does it run poorly? i'm thinking that perhaps it's water coming from the exhaust...and that could smell like gasoline. water is a by-product of the catalyst and is normal.

bottom line is that depending on what year make and model car it's on determines the exact adjustment procedure for that carb (is it electromechanical?) also...the best way to verify proper adjustment and operation thru all ranges is with an exhaust gas analyzer.
 
  #5  
Old 08-04-04, 05:50 PM
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Rodchester Carb Problem

Ok, first off, it aff a boat. I tried using the boat forum but no one ever replies. I figured a carb' a carb so I would try this forum. So as far as the fuel out the exahust, it is very mcu fuel and its making lots of pretty colors. (Not so goo). I think I might have an idea but I cant seem to find an adjustment spec for it. The power piston assembly has this little adjustable stop at the bottom. I noticed when reassembing the carb that the primary metering rods just barely enetr the jet holes when the power piston is completely down. (Note, they are the right rod and there not broken). First question, how far are they suppose to enter the jet hole? Second How do you make the adjustment? I have already removed the seal cap that covers the adjuster screw but I dont know the spec for it or how to determine the spec. HELP!!
 
  #6  
Old 08-05-04, 05:25 AM
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carbs...

in my experience with carbs, if enough fuel is leaking from the carb to make it thru the exhaust as a liquid, it's not coming from a mere adjustment other than the float level. also, i can only speak from an automotive perspective and while the basic operation and theory is the same, adjustments and configuration may be very different.

you could take the metering rods out and throw them away and it wouldn't make any difference at idle...once the engine is off idle, then yes...metering rod adjustment becomes an issue. the screw you are referring to is a factory set adjustment based on airflow and fuel volume and is not supposed to be changed in the field. i guesss you can mess with it but i'd be surprised if it made any difference except during part or full throttle operation.

most leaking carbs have a crack in the bowl, a bad gasket or an improperly set float.

basic stuff, i know...but i'm not a boat guy
 
  #7  
Old 08-06-04, 07:09 AM
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Fixed

Hey all,
Thanks for all the input. I figured it out. Under 2 PSI or higher, the milling holes the factory uses to bore the jet ports were leaking. Just the primary I performed teh below fix and all of them. Probably a rare problem but all I did was epxoy cap them with fuel recommended epoxy and boom, problem solved. Hopes this helps someone else in future.
Thanks again
 
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