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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: mcintyrederek on August 03, 2015, 06:43:31 pm
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Hi,
I am running a 350 engine with a stock iron intake that came off something else (has some blue and orange paint underneath someone else's crappy black paint job. Anyway, I have been running a non-ECM Rochester Q-jet carb since I got it and it's been fine. I had some ignition issues, and have resolved them, now the carb pours gas out all over the intake and won't idle. I had to keep the throttle open pretty big just to get it fired up and back home.
I am certain the Q-jet needs a rebuild but for the time being I am looking for a new carb.
I have NOT been using the electric choke on the Q-jet, or the fast idle. I have converted to manual choke a good while back just because that's what I like. I have always had trouble with the idle mixture on this carb. I can back the screws all the way out until they are nearly ready to fall out and I can't get a good peak on idle speed or vacuum. In other words, I can't seem to get the mixture rich enough, or "too rich" backing them out. I have been told that I need to drill out the idle port holes but I'm not really into doing that.
I have been looking at an Edelbrock 1405. I am guessing that purchasing the spreadbore to squarebore adapter plate will obviously be necessary for the conversion.
Is anyone else running the 1405 manual choke carb and do you like it? Is there anything else I need to examine before making the purchase? This is my daily driver, NOT a hot rod. Just a regular old 350 with a lazy cam, TH400 and 2.73.
Thanks for any advice on the Edelbrock 1405.
Mack.
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Pics of my existing manifold and what I think I need to purchase to make the Edelbrock 1405 fit onto it. I am also guessing I need an external fuel filter and the proper fittings to adapt to the 1405.
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i came across this video yesterday while i was furiously searching for something else related to my problem(s):
https://www.youtube.com/watch?v=2eX0mZy4iB8&index=3&list=PLyJdUbaA5z26Cegn7GYJW8X93R2W7UMVM
Also, can i ask where your choke cable is passing thru the firewall?
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Here's another one. Very detailed:
https://www.youtube.com/watch?v=-P7-ZFNHgnE
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many of us on here will tell you theres nothing wrong with a quad. you may need to rebuild it and it will last for years not to mention it will be a lot cheaper than a new carb. if you do get a new carb 500 will be just fine in cfms. but i will strongly suggest rebuilding your old carb its not hard and you can find plenty of videos
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I have fought with old, pre-owned Edelbrocks, I have fought with brand new Holleys, I have also seen on original to the truck Q-jet run better than both of those. If I was still carburated, I would be running a Q-jet.
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There's atleast one guy on here who runs one on his drag truck
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I've been running a 1406 (same as 1405 but elec choke and jetted about 2% leaner) for several years now. I took off my Q-jet, used the adapter like you posted, plumbed in an external fuel filter, FPR, and set the idle. I've had no problems with mine. It's a daily driver on a 350, stock intake manifold.
The FPR (Fuel Pressure Regulator) is necessary. The Q-jets like 8-12PSI, a stock mechanical fuel pump puts off around 10PSI. But the edelbrock should only have 4-6PSI. I have a Holley FPR set at 5PSI for mine.
I live at 4700ft so had to lean out the idle a little (edelbrock actually suggests re-jetting for my altitude but it's been fine)
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The choke cable is routed through a grommet that was already there and looks factory. It's a large grommet just to the upper right of the brake pedal and there's only one wire going through it, a single 16 gauge orange wire that goes to the downshift solenoid on the trans. The grommet was plenty big enough to route a choke cable through, along with an external temp/oil pressure gauge lines.
The choke pull mounted just fine under the head light switch. I couldn't find a bracket I was satisfied with mounting it to the carb, so I just used a cable clamp and a piece of bent aluminum and mounted it to the valve cover.
Please ignore the starter wire and wire nut, I don't leave stuff like this permanently.
Mack.
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Thanks for the info on Q-jet. I have an '85 Monte Carlo with a Q-jet that looks similar only it has a wiring harness on it (?) I'm old school so I don't like wires going to my carb. unless it's electric choke (don't like that much either). I've heard that the wires go to a mixing solenoid that changes the fuel mixture depending on what the ECM says but that's another subject.
My current Q-jet on the C10 looks incredibly rough. ALL of the fast idle cam is missing (someone else's fault) and the electric choke was GONE. I put the manual choke on there just so it would start in the winter.
I've looked at vids online and rebuilt kit manuals and it doesn't seem that difficult. However, I have 305 that's going into another project car with a stock iron Q-jet manifold so I might rebuild the Q-jet for that one.
Thanks for the info on the pressure regulator for the Edelbrock, I had no idea.
Mack.
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Looks like if I use the Edelbrock then I'll need to buy a 3/8" inline filter and regulator. I am guessing it would be best to put the filter BEFORE the regulator?
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I have my filter before the regulator, you'll also need some extra fuel line. I'll snap a picture of mine and uploaded once I'm off work
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OK, thanks. I'd appreciate any pics. I was thinking that the filter before the regulator would be best as to keep any trash out of the regulator also.
Mack.
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I carefully took the Q-jet apart and it was extremely nasty. The needles were corroded almost to where they are pitted. Most components as you can see are covered in a black nasty coating. Furthermore, spraying any kind of carb cleaner on the chassis makes a gray film run off almost like gray paint (?) There is also quite a bit of chalky stuff under the float. The float feels like it's disintegrated and the bottom two caps that have some sort of epoxy covering them, they epoxy looks like it has eroded off for some reason.
Overall it looks very corroded and dirty. The truck had been sitting in the woods abandoned for many years. I am surprised I was able to drive it at all in this condition.
Mack.
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Here's how I have mine
factory line goes to rubber hose, inline filter, into the FPR which is bolted to the firewall, out of the FPR through a pressure guage, then into the carb. Could be done a lot cleaner looking, but this works for me.
(http://i2.photobucket.com/albums/y48/timthescarred/IMG_20150804_164302.jpg)
(http://i2.photobucket.com/albums/y48/timthescarred/IMG_20150804_164324.jpg)
(http://i2.photobucket.com/albums/y48/timthescarred/IMG_20150804_164348.jpg)
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I am also happy with my 1406. Had it for about 5 years. I disagree on the fuel pressure regulator. Never needed one and seen an awful lot of sbc setups without one on stock mechanical fuel pump.
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That's a good idea, I never thought about moving the regulator to the firewall. I was wondering where to put it.
I have read several other places where some people don't use a regulator and others do. I'm not sure what my stock mechanical pump is pushing out but I do have a gauge and I'm sure I could readily check. Edelbrock's on-line manual for the 1405 says 5 PSI.. I don't think 7 or 8 would hurt anything but I am wondering if something higher would do damage to the needle valve seats over time.
I'm going to put a gauge on my pump anyway just to see, when and if I get it all running again.
Thanks for the pics and replies.
Mack.
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Here's something to think about:
Different pumps put out different pressures based on the application; The pump, which had a return line, i used for the 350 was putting out close to 7lbs. The service manual for my 83 called for 5 to 7.5 lbs if the pump has a return line and 7.5 to 9 lbs if no return line!
Then when i switched to the 305 which came out of a 78 malibu, the pumps for 78 malibus didn't have a return line (rochester 2G) was it putting out 9lbs in this case? i'm pretty sure it wasn't.