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#1
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Carburator questions
Hello,
For the past two months I have been periodically running my 383 just to keep things moist. It idles really rough at about 1000 rpm and it does not want to go below that. I thought that I had a pretty streetable cam so i think that i am running lean. I pulled the intake one day and noticed that on the bottom of the valley pan I was sucking oil into 6 of the intake ports. I cleaned and reinstalled the valley pan and intake and used some blue RTV under the valley pan gasket. It was too late at night so i didn't run it (Open Headers) so I waited a week and then I noticed that every time i go to start it up there is no gas in the carburator. This is after it sits for about 5-7 days. The carb is a suposed "rebuilt" big block TQ, but when I open the throttle nothing comes out. I have to turn the motor over to prime the carb. I checked all f the fittings from the tank to the carb and they are all still connected and I didn't notice any gas leaking any where. Is it time for a different carb? |
#2
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I had a similar issue on my 57 Cadillac. Didn't get run too often, but within a day after running it all the gas was gone from the carb. No signs of external leakage. I think in my case it was dumping it directly into the intake manifold, rather than siphoning it back through the lines.
Long story short, I never did find out what exactly caused it. When I swapped in another carb the issue went away! I'll be interested to find out what fixes yours. Good luck. |
#3
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Sounds familiar to the sb tq that used to be on my Duster. With mine, the vent wasn't properly hooked up or working so it would siphon back thru the lines. Just a thought ( or memory I should say)
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#4
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This is quit common and may be corrected with a fuel pump,oryou may have a leaking needle and seat since you are incountering a rough run at 1000 rpm.Looking down the primary side after you run it and turn it off do you see and fuel dripping or wetness.?Try while its running to see if it drips,also check the tighnessof the throttle shafts or spray a cleaner or wd40 while it runs to hear a change.
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#5
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1st-pull intake off,get rid of sealant.You need the 4 .015 thick intake gskts installed for the oil(also causes vacuum leak)on valley pan.You'll find them thru Fel-pro on 440-6 car.
2nd-for fuel,pull of carb top and see if float bowls empty or just accelerator pump empty(check valves go bad often)it makes a difference. 3rd-if you have any lumpy cam installed-use a Holley carb w/metering blocks pri and sec,easier to dial it in,better acc pumps,power valve better than step-up rods and springs.I used to be a Carter nut but no more,get better E.T. MPH w/Holley design. |
#6
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Hey,
Thanks for the replies guys. I think that for Chistmas santa (me) is getiing me a Holley 770cfm street avenger. They are a little pricey, but everything i read about them is awesome. Besides, I'll new to Holley's so getting the most user friendly holley is the ticket for me. Meepmeep, sealant is no good hey? Do I use the felpro gaskets with the valley pan? I take it they go on the head side of the valley pan. HOLESHOT, the feul pump is a brand new Holley HP unit so if there is one unknown in the equation it is the TQ. Ausydad, On this TQ there is no bowl vent. It is a late 70's truck TQ. The only vacumm style niples are for the PCV and the Vacum Advance. |
#7
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dry carb
You may try an old quick fix remedy for siphoning gas.Loop the inlet fuel line to carb...Like a rollar coaster...It may hold fuel in line then.
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#8
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[QUOTE]Originally posted by 71383bee
[B]Hey, Thanks for the replies guys. I think that for Chistmas santa (me) is getiing me a Holley 770cfm street avenger. They are a little pricey, but everything i read about them is awesome. Besides, I'll new to Holley's so getting the most user friendly holley is the ticket for me. Meepmeep, sealant is no good hey? Do I use the felpro gaskets with the valley pan? I take it they go on the head side of the valley pan. Use the valley pan,gaskets go 1ea on head side,1 ea on intake side.Suggest the modified intake bolts or taper ends yourself.Now we got you thinking about a Holley,consider a Demon or Barry Grant style!Really adjustable! |
#9
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Does anybody else have any remedies for leaky intakes? I have ported 906 heads and an edelbrock performer intake. I see what you mean meepmeep. You meant four (4) 0.015 thick gaskets! What are the advantages of a demon over a Holley? Mopar Muscle bolted on a Holley Street avenger in one of their dyno tests and they were so impressed with the carb they did their own little article on it. They said thet it truly was the only carb they ever bolted on that really worked right out of the box. They did not have to change jets or anything. Has anyone else had experience with these? I would like to get everyone's opinion before I go and drop 400 clams!
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#10
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Whatever you do 71383bee, don't reuse the used intake gasket. Everytime you pull the intake a new gasket should go on. They're a crush fit, like a head gasket.
Just another thought, have your heads been milled? And if so, was the intake side of the heads milled correctly (on the correct angle)? As far as the carb goes, I also have that problem where if the car sits for a few days I have to crank the engine for awhile to get the fuel to the carb, before pumping the accelerator does any good. I experience this with three Mopars. A 360 with Thermoquad, a 440 with Thermoquad, and 440 with Holley sixpack set-up. Each of these set-ups are in very good condition and have been professionally set up and dyno tuned. For awhile I ran an additional fuel pump (electric) on the 440-4 car and the 360-4 car, and of course that took care of the problem. So I know the fuel in the carb is going somewhere when the car sits. Its made me curious but hasn't been a big enough pain for me to do anything about it. I'll call the guy that does the tuning work and see what he has to say. He's been around for quite sometime and is very familiar with mopars. meepmeep, are you suggesting using four intake gaskets one on top of the other? I don't think I've heard that before. Just curious. |
#11
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Blaine,
I've thought of that myself, so I called my engine builder. He said that he only did a little resurfacing on the deck of the block and no milling on the heads and he thought that it was not enough to have the intake milled. However, sucking oil in 6 ports has got me a little worried. With the resealed intake the car did not show any sign of improvement when I last ran it, so I don't think I solved the problem. Would a compression test and a vacum test help out? I've never done a vacum test, what is involved? |
#12
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If you use the .015 paper gaskets it'll stop the leak unless the intake is warped!Re-use the old valley pan gasket w/paper gaskets or it WON'T crush and your asking for trouble.Try 800 clams for B.G. or Demon carb!Use Ultra Copper on intake front and rear rails(across block)so you don't get external oil leak.
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