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Post Info TOPIC: carburetion problem....I'm stumped!


Canadian Poncho Superstar!

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carburetion problem....I'm stumped!


194 ci   I6. So James car had a bit of a flat spot on acceleration...just on part throttle taking off. It would stumble and sometimes almost stall at part throttle, so I told him to punch it when leaving from a stop to get the accelerator pump to dump in fuel. Seemed to be getting worse so I ordered a reman carb. That one back fired through the intake and exhaust! Found that the accel pump wasn't working,went to dads and grabbed one off his shelf....would idle fine but same problem on acceleration....would fall flat on it's face once under load. Both mine and dads rev up/accel fine in "p" but once under load(driving) they both cut out(no power). 3 bad carbs?? Ran fine when we first put it on the road a week ago other than the one small flat spot. Now it seems after 1/3 throttle is all flat until you back of and let it climb slowly? Stumped

Vacuum 17"

checked vac adv for leak in diaphram

checked trans act for leak in diaphram

checked timing

fuel pump press 2.5-3 lbs



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A Poncho Legend!

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Silly question but it's not a case of old stale fuel is it?

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Carl Stevenson wrote:

Silly question but it's not a case of old stale fuel is it?


 That's what I thought so I put in another 5 gal of fresh fuel last night. Car had 1/8 tank when we put it on the road. threw in $30 and then $40 plus the 5 gal last night? Ran fine after the first $30???



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A Poncho Legend!

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In line fuel filter or do the carbs have those inlet filters? If in line perhaps change it - might have been some crap in the fuel tank now in the filter.


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Poncho Master!

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Fuel pressure seems a little low. What kind of volume is it pumping maybe a restriction somewhere? Try running off a can of gas under the hood.

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Poncho Master!

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Those Rochester BVs actually have a piece of leather in them for accelerator pump action that needs to be soaked in fuel. If it has been sitting dry a long time perhaps the leather is cracked. it should be included in a proper rebuild kit

I know, leather. confuse  That is because the B-series carbs date back to 1931, gaining a coil type automatic choke in 1954, switching to a vacuum choke for 1963. Last year of use was 1967 (some say '68 but I can't imagine where. Medium trucks with manual choke maybe?)

The factory filter is actually one of those sintered "rock" type where the fuel inlet is in the carb body.

 

Beside old fuel or crap in the fuel line (2 most likely scenarios), if you are running a points type ignition it may be time for a tune up. My 250 had a bit of a stumble, but once it was tuned it was so smooth & quiet I could sneak up & bump someone on the back of the legs.



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A Poncho Legend!

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I was also thinking about the common issue of a worn bushing/shaft in the distributor. I have no personal experience with it so don't know how they behave but over the years I've heard of a number of cases on 194/230/250 having a very sloppy shaft.

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as Carl stated, worn didtributor housings were very common. don't be quick to condemn the carb, flat spot/backfire is prob a timing issue. chk the ignition system, dwell, base timing, vac advance etc 



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Poncho Master!

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Also a weak coil acts like fuel.

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Thanks for the suggestions guys....will check them out,also going to pick up a new fuel pump and pump out of a jerrycan and see if that helps.

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A Poncho Legend!

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Is the heat stove in place? When I had my 70 Biscayne with a 250/6 getting that system working made a HUGE difference!

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Does distributor have points and what shape are they just another shot in the dark



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Update...fixed!! smile Tried pump and jerrycan fuel...same problem! . So..seems there were a couple of problems. On a whim I thought I would check the intake bolts(rebuilt engine..not by me) one bolt was only hanging on by a thread ,went to tighten and just spun ,so longer bolt fixed that problem. Lept her to the brother inlaws shop. Have HEI Dist and was hooked up to stock 16 gauge wire,put in a relay and ran 10 gauge to dizzy,helped but still a lag. Took a couple of buds for a ride and we all thought the same thing, fuel problem. Used to pull out the metering rod in the old timer racing class...sooo that's what we did. More fuel runs great,idles smooth. Must be under carb'd or too small of jets? Brought her home and James took her for a drive and luvs it! Maybe he can take it to school next week. If this rain doesn't stop I'll put paddle wheels on it!!!! Thanks for all the suggestions it helped to narrow it down!



-- Edited by hawkeye5766 on Saturday 7th of April 2018 01:51:50 AM

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Canadian Poncho Superstar!

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Canadian Poncho wrote:

Is the heat stove in place? When I had my 70 Biscayne with a 250/6 getting that system working made a HUGE difference!


 Funny,James has the heat stove and it works perfect!! Brother inlaw always seems to get the carb'd cars,hot rodded ones(the go too guy) but they all have headers!Hes old school and hasn't seen one for a decade!

 

 



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A Poncho Legend!

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hawkeye5766 wrote:

Update...fixed!! smile Took a couple of buds for a ride and we all thought the same thing, fuel problem.





First time I ever heard of a couple of beers helping to diagnose car problems. I didn't think beers were that smart!

I know, I know, you're gonna say a couple of buds, or coors or whatever often help solve car problems!

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