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General Tech Carbs Flooding While Car Sits
- Thread starter KVH
- Start date
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I swap out some needles that were supposed to lean out the mixture and they did work very well. I went back to the standard set up. I got the extra needles from one of the big 3 not a carb specialist. I did this to help me with a rich running problem, but no luck. I think people have swap out needles only and not changed the jet, but IMHO the needle and the jet need to come as a pair because of the fine adjustment perhaps that might be some of your problem.
steve
steve
charleyf
Luke Skywalker
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That is a new one I have never heard before. If the needles and jets are worn then change them both. But if they are fresh you should be able to change needles and not the jets.
Charley
CJD
Yoda
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Normally gas is good for a year. The vapor lock issue can be caused by good gas, but the improper mix at the refinery for the weather being experienced. In winter they blend gas with a lower flash point so it will start easier in cold weather. The same, low flash point, gas in hot weather will boil at a lower temperature and can cause problems if used in the summer.
Well what I did was purchase some new needles from Moss (this was many years ago, like 1985) to play around with the carb mix. One of the needles would not go into the jet all the way, and I cannot remember for sure what the other needle did, but I think that needle was smaller and fell right into the jet. I had not thought about the needles for years, but still I would feel better about installing a smaller jet and needle, but I am not sure if my case was different. I remember John changed out the needles only in his tr2 and was happy with the results.
Anyways, KVH said the only other thing he did was change needles, so I thought I would mention what I did.
The jets come with I think .01 or .1 for standard and the needle sm. If it was me trying fix a problem, I would start out stock.
steve
Anyways, KVH said the only other thing he did was change needles, so I thought I would mention what I did.
The jets come with I think .01 or .1 for standard and the needle sm. If it was me trying fix a problem, I would start out stock.
steve
OP
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I'm back to hard starting after it sits. Looking down the jets, here's what I see. Carb 1, the front one, has fuel right to the top and likely spilling a little bit down the throat of the manifold. Fuel in Carb 2 is lower. I see fuel over 1/8 inch down the jet. A bit too far. Is any of this material enough to cause my starting issue? Based on weather changes and the behavior of the car, I'm disinclined to suspect a vapor lock. My pump looks fine and my fuel line is insulated all the way, plus I have a heat shield.
OP
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I finally pulled the float lids and checked the needles and floats. Both needles are viton tipped. Not sure I like those, but they're there. Gas level was about 1/3 of the bowl on each carb. One float was, itself, defective and half full of gas. So, I put in new floats and adjusted to HS6 clearance, and cleaned and reinstalled the needles. I'll report if that fixes my issue.
OP
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Guys, I still need help.
I can't seem to resolve this issue of hard starting after a stop. From cold the car runs great. And it runs great on the road. It's just an issue after it sits.
I took a video, and while the car runs there's a constant stream of gas and bubbles, lots of air, heading into carb no. 1. After the car is hot, and after shut-down, the bubbles continue. In fact, if I use the manual finger pump on the fuel pump, the "squirt" is really sort of pathetic, obviously part gas and part air. And the gas reeks. The ethanol just about takes my nose off my face.
I've checked for leaks. I'm certain there are none. All relatively new lines and hoses.
One item I can't imagine is an issue is that my fuel line from the pump to the carbs has a slight negative slope, downward along the engine before heading across the engine in front of the water pump to the carbs. I saw a post from one guy saying a slope like that can cause trapped air, but I can't see that would cause all this since all I'm getting is gas and lots of air anyway.
My floats and jets seem OK, but I'm going to adjust one float because it's too high after the modification I made just yesterday.
So, I'm beginning to feel defeated here. I need to ask: Is this just a bad fuel pump all along? I'm not sure but I thought I'd swapped it out when this all manifested itself two years ago.
I'll await some sage advice. But, just FYI, I have another TR, with the same HS6s (and the same servicing mechanic
), and no problems at all. And the lines and hoses are all about the same. Isn't it just that fuel pump after all? Where's all the air coming from? Or is the air not the problem?
Thx all.
I think I recall years ago that a good pump sends a solid stream of gas to the carbs, not some wimpy air-filled splash. But that wouldn't seem to make total sense since my car runs great after it's been started. So, where's that air coming from, and why does the finger lever on the pump also send so much air?
I can't seem to resolve this issue of hard starting after a stop. From cold the car runs great. And it runs great on the road. It's just an issue after it sits.
I took a video, and while the car runs there's a constant stream of gas and bubbles, lots of air, heading into carb no. 1. After the car is hot, and after shut-down, the bubbles continue. In fact, if I use the manual finger pump on the fuel pump, the "squirt" is really sort of pathetic, obviously part gas and part air. And the gas reeks. The ethanol just about takes my nose off my face.
I've checked for leaks. I'm certain there are none. All relatively new lines and hoses.
One item I can't imagine is an issue is that my fuel line from the pump to the carbs has a slight negative slope, downward along the engine before heading across the engine in front of the water pump to the carbs. I saw a post from one guy saying a slope like that can cause trapped air, but I can't see that would cause all this since all I'm getting is gas and lots of air anyway.
My floats and jets seem OK, but I'm going to adjust one float because it's too high after the modification I made just yesterday.
So, I'm beginning to feel defeated here. I need to ask: Is this just a bad fuel pump all along? I'm not sure but I thought I'd swapped it out when this all manifested itself two years ago.
I'll await some sage advice. But, just FYI, I have another TR, with the same HS6s (and the same servicing mechanic
), and no problems at all. And the lines and hoses are all about the same. Isn't it just that fuel pump after all? Where's all the air coming from? Or is the air not the problem?Thx all.
I think I recall years ago that a good pump sends a solid stream of gas to the carbs, not some wimpy air-filled splash. But that wouldn't seem to make total sense since my car runs great after it's been started. So, where's that air coming from, and why does the finger lever on the pump also send so much air?
Hi KVH,
I think that I know what your problem may be as I had EXACTLY the same symptoms in a straight 6 Triumph that I owned many years ago.
The formation of the vapour lock is a result of heat, hence the car is fine on cold start but lets you down when you try to restart when hot. Excessive heat getting to the carbs obviously comes from the engine. I tried to isolate the heat by adding thick teflon spacers between the carbs and the manifold but that was insufficient. Eventually, I removed the head and found that one of the exhaust valves had developed a small crack and so hot exhaust gases from the point of ignition could escape (much hotter than the exhaust gases after the power stroke is complete). I fixed the valve and never had the problem again.
So I think you are looking in the wrong direction in terms of the fuel pump, float chamber setting, etc.
Tony
I think that I know what your problem may be as I had EXACTLY the same symptoms in a straight 6 Triumph that I owned many years ago.
The formation of the vapour lock is a result of heat, hence the car is fine on cold start but lets you down when you try to restart when hot. Excessive heat getting to the carbs obviously comes from the engine. I tried to isolate the heat by adding thick teflon spacers between the carbs and the manifold but that was insufficient. Eventually, I removed the head and found that one of the exhaust valves had developed a small crack and so hot exhaust gases from the point of ignition could escape (much hotter than the exhaust gases after the power stroke is complete). I fixed the valve and never had the problem again.
So I think you are looking in the wrong direction in terms of the fuel pump, float chamber setting, etc.
Tony
Offline
The dirty little secret of the SU crabs is that there are dozens of different jet combinations. Each one
Likes unique engine set-ups (cams ,compression ,displacement, porting, ect). Getting the initial combination
is a matter for an experienced tuner. New jets? , what profile?? Which needles?? These pros use tools and sensors
to get into the correct range of "tunability" ,then set the mixture and idle.
If your engine is modified(most are) it may well need a particular jet/needle combo to work well.
Mad dog
Likes unique engine set-ups (cams ,compression ,displacement, porting, ect). Getting the initial combination
is a matter for an experienced tuner. New jets? , what profile?? Which needles?? These pros use tools and sensors
to get into the correct range of "tunability" ,then set the mixture and idle.
If your engine is modified(most are) it may well need a particular jet/needle combo to work well.
Mad dog
Two things helped shorten the time before being able to restart my balky TR3-B was bringing up the revs while turning off the ignition. This sucked lots of cool air through the engine before it stopped rotating. Opening the hood to keep the temp from building up while stopped also helped.
OP
Offline
I must admit; my problem started after I messed with new needles; but I still can't figure out what I did wrong, or how to get back to where I was before my frolicking,
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Back in the bad old days the tuner used an exhaust gas "sniffer" that let you read unburned
gas at RPM's. If your needle was rich in mid range you selected a needle with a better profile.
After a few hours you would zero in on a profile that allowed you to "dial in the flats"
Then you would NEVER muck about with it again.
On the motor in my 59 , we wound up sanding down the needles a bit ,since there was no
profile that was quite right(big cam/port work/header). Dyno at the crank just shy of 160HP (pump gas)
6800 rpm. I call it my bad boy motor.
Mad dog
gas at RPM's. If your needle was rich in mid range you selected a needle with a better profile.
After a few hours you would zero in on a profile that allowed you to "dial in the flats"
Then you would NEVER muck about with it again.
On the motor in my 59 , we wound up sanding down the needles a bit ,since there was no
profile that was quite right(big cam/port work/header). Dyno at the crank just shy of 160HP (pump gas)
6800 rpm. I call it my bad boy motor.
Mad dog