QJet Question??
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Pro
Joined: Jan 2004
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From: oh
QJet Question??
stock 69 350/300 car starts fine when cold. when I go to start it when warm it cranks for a awhile like a floded condition. I pulled the air cleaner and started it warm and while cranking I noticed fuel coming through the air horn. Obviously it is getting too much fuel is it the float level or should I be looking at something else. Carb is new and entire fuel system is new back to factory specs (or close). The car seem to not have the power that it should under acceleration. I have adjusted the mixture screws to obtain max vacuum and my timing is set to around 36 degrees. I have checked out Lars' papers and they are very helpful. any ideas?
Jeff
Jeff
Burning Brakes
Joined: Feb 2006
Posts: 1,024
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From: AL
off the top of my head:
check the float level. use new needle and seat. make sure the "hook" on the needle is on the back side of the float arm. make sure that your float is not "gas logged". make sure the float is made of the phenolic material and not the brass. make sure that you have a full tank of "summer" formula gasoline in the tank. make sure the choke linkage is not sticking when the engine is hot.
check the float level. use new needle and seat. make sure the "hook" on the needle is on the back side of the float arm. make sure that your float is not "gas logged". make sure the float is made of the phenolic material and not the brass. make sure that you have a full tank of "summer" formula gasoline in the tank. make sure the choke linkage is not sticking when the engine is hot.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
off the top of my head:
check the float level. use new needle and seat. make sure the "hook" on the needle is on the back side of the float arm. make sure that your float is not "gas logged". make sure the float is made of the phenolic material and not the brass. make sure that you have a full tank of "summer" formula gasoline in the tank. make sure the choke linkage is not sticking when the engine is hot.
check the float level. use new needle and seat. make sure the "hook" on the needle is on the back side of the float arm. make sure that your float is not "gas logged". make sure the float is made of the phenolic material and not the brass. make sure that you have a full tank of "summer" formula gasoline in the tank. make sure the choke linkage is not sticking when the engine is hot.
And also make sure your not building tank pressure-that seems to be a problem lately.
Thread Starter
Pro
Joined: Jan 2004
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From: oh
New discovery...should there be two gaskets sandwiching the steel shim under the carb? I only have one gasket...it goes like this.. intake then gasket then metal shim then carb. Could this be the reason for my poor performance and too much fuel? I guess I want to know before I tear into the carb.
Jeff
Jeff
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
New discovery...should there be two gaskets sandwiching the steel shim under the carb? I only have one gasket...it goes like this.. intake then gasket then metal shim then carb. Could this be the reason for my poor performance and too much fuel? I guess I want to know before I tear into the carb.
Jeff
Jeff
It depends on what intake manifold you have. If you have the manifold with the "smiley-face" exhaust crossover groove that runs from side-to-side forward of the primary throttle bores, you need the 3-piece gasket with the stainless shield. All other intakes use the 3/8" gasket and nothing else.
Hope that helps.
Thread Starter
Pro
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From: oh
I have the "smiley"... so it should be: intake, gasket, shim, gasket, carb correct?
does anyone have an illustration of the gaskets so I can see the cutouts in the gaskets?
Jeff
does anyone have an illustration of the gaskets so I can see the cutouts in the gaskets?
Jeff
Last edited by 3joh; Jun 9, 2007 at 04:06 PM.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
New discovery...should there be two gaskets sandwiching the steel shim under the carb? I only have one gasket...it goes like this.. intake then gasket then metal shim then carb. Could this be the reason for my poor performance and too much fuel? I guess I want to know before I tear into the carb.
Jeff
Jeff
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Instructor
Joined: Oct 2006
Posts: 134
Likes: 17
From: Camas Wa
Same engine, same problem. Mine started after I added a choke (the car came without it installed.) It only does this when it's hot outside, like now. It'll start up ok when cold, but after I run for a while and get up to temp, when I shut down and go to start up again after several minutes it's like it's flooded. If I open the hood and take off the air cleaner, either more air or cooling helps and she fires up, but otherwise she just cranks with no light off.
I'll check the choke linkage and the float. Also seems like the gas pedal is sticking a bit (unrelated) so I need to make sure there's no binding.
There have been a couple of other threads on this recently.
I'll check the choke linkage and the float. Also seems like the gas pedal is sticking a bit (unrelated) so I need to make sure there's no binding.
There have been a couple of other threads on this recently.
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
Lars makes the gasket kit that you are talking about. PM him tho see if you can get a pic from him.
Race Director
Joined: May 2006
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From: Dayton, Ohio
So your saying there is a special gasket being made, because from the factory there was NO gasket between shim and carb?
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
http://forums.corvetteforum.com/show....php?t=1553660
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Here is a post on the subject by Lars. I have picked up couple of NOS set-ups in the past and heat shield had the gaskets attached to both sides.
http://forums.corvetteforum.com/show....php?t=1553660
http://forums.corvetteforum.com/show....php?t=1553660
Thanks for the info on the gasket set from Lars.I've never had any trouble doing it the factory way.The gasket between the carb and the steel baffle is the one I would question.That baffel was designed to be held tight against the bottom of carb to transfer lots of heat at a specific location and if it is covered on the carb side it wont do that. The baffel must be held tight against the bottom of the whole carb AND be able to transfer heat hence the cutout(smiley face).Otherwise why would they use this cutout?
Thread Starter
Pro
Joined: Jan 2004
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From: oh
pulled the carb apart, changed the float while I was in there, and set the float to the proper specs. installed the carb with the two gaskets and heat shield and it sure made a difference. I was able to adjust the carb with my vac gauge easier and also set the timing. Performs much smoother and starts right up when hot.
Thanks for the help!
Thanks for the help!
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
Sorry Smokin didnt mean to run away,a buddy just dropped by and I changed 2 tires and tubes on his titanium race chair.Pretty cool light as a feather.
Thanks for the info on the gasket set from Lars.I've never had any trouble doing it the factory way.The gasket between the carb and the steel baffle is the one I would question.That baffel was designed to be held tight against the bottom of carb to transfer lots of heat at a specific location and if it is covered on the carb side it wont do that. The baffel must be held tight against the bottom of the whole carb AND be able to transfer heat hence the cutout(smiley face).Otherwise why would they use this cutout?
Thanks for the info on the gasket set from Lars.I've never had any trouble doing it the factory way.The gasket between the carb and the steel baffle is the one I would question.That baffel was designed to be held tight against the bottom of carb to transfer lots of heat at a specific location and if it is covered on the carb side it wont do that. The baffel must be held tight against the bottom of the whole carb AND be able to transfer heat hence the cutout(smiley face).Otherwise why would they use this cutout?
pulled the carb apart, changed the float while I was in there, and set the float to the proper specs. installed the carb with the two gaskets and heat shield and it sure made a difference. I was able to adjust the carb with my vac gauge easier and also set the timing. Performs much smoother and starts right up when hot.
Thanks for the help!
Thanks for the help!
Tech Contributor
Joined: Aug 1999
Posts: 14,377
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From: At my Bar drinking and wrenching in Lafayette Colorado
You're right - the factory put the hot stainless shield against the carb to provide pre-heat to the float bowl. The factory then realized the problem of putting this much heat into the carb and discontinued the setup in favor of the thick gasket, which limits heat into the carb. The steel-against-carb setup was also prone to leaks in addition to putting a ton of heat into the float bowl. For this reason, I sell a top gasket to place on the shield. This solves the leak problems as well as eliminating some of the heat from getting into the carb. It still gets good and hot, though, so the carb is still getting some pre-heat through the thin top gasket that I provide. But it works better than the factory carb-on-steel setup.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Thanks Lars-I was always worried that the gasket on top would not hold the metal baffle tight enough against the lower gasket and exhaust would escape into the intake.I guess your gasket has all the same contact points that the carb has and doesnt leave the baffle loose at any point.
Thread Starter
Pro
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From: oh
Update...car runs ok and idles very smooth but you can tell it is still loading up especially on hot restarts. Now what do I check? Timing is right on per Lars' paper. Acceleration out of the hole seems like it should be better...no low end torque.
Jeff
Jeff