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Edelbrock Q Jet Model #1901 Carb...need Help

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Randy 71

Guest
Vetters, I finally bought one and put it on. I am having some difficulty. this was my first carb replacement I followed the instruction closely. Everything connected just fine. I heard that it was basically a bolt on and go. Not in this case. Here are the problems as I see it.

1. Secondaries are not opening. Here is what I have observed. It appears that the throttle is not traveling far enough to engage the secondaries. Does not appear that the length of the metal rod can be adjusted so that it engages the secondary metal (thing) that pushes open the secondaries. I have noticed that were the secondary linkage/rod
recoil spring is located that it might allow for an adjustment. Is this true? If so, how do I reduce the travel of the throttle to allow the secondaries to kick in?

2. Related to #1, I think. The diaphragm on the choke side does not appear to functioning properly. I believe this is also preventing the secondary butterfly valve from opening which is not allowing the secondaries to open. Any thoughts. I have notices that the vacuum to the diaphragm is content at all RPM's. I thought that as the RPM increased the vacuum decreased and this would cause the diaphragm to open and in turn open the butterfly valve to the secondaries. Does this sound correct? If so, what are your thoughts to correct this.

3. Though I have checked the choke for proper operation. Open when engine is cold then hit the throttle, then it closes. Problem is that is does not keep the idle up to the engine warms up. As soon as I give it throttle it kicks down and does not idle very well, and will die on occasion. Does it sound like I need a choke adjustment? If so, how?

4. What is the proper way to adjust the Fast Idle Solenoid. Mine pops out when the key is turn. Is this normal. I thought it only engaged when the AC or a heavy load was put on the engine.

Sorry for so many question. Believe it or not these type of adjustments are not covered in the instructions provided with the carb. $417.00 for the Carb, I have to say I am disappointed so far. I heard so many good things about it.

Thanks in advance
Randy
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Randy,

I wish I could really help you here. People seem to either love or hate the Edelbrock carbs. Once in a while you get lucky, bolt it on and go. That has never happened to me. My friend is good with them and has adjusted them on everything from mild daily drivers to a supercharged small block.

Outside of just getting it set on the car (which sounds like your problem right now), there are several other adjustments that either require drilling holes in the counter weights, changing springs, jets, and rods. All this while making the proper external adjustments. My hat is off to anybody that can get these things to perfectly match the characteristics of the motor they are feeding.

You can go online to Edelbrock and review the trouble shooting chart. You can call the Mon-Fri tech line for help.

I can't help but wonder if you don't have the throttle cable on the best possible stud location. You must have something binding or bent in the linkage. I have never had the problem you are asking about here. Now, when you start driving and it boggs pulling the secondaries, gets very poor fuel economy, or pings like crazy, post back to me and I will try to help.
 
Joined
Nov 4, 2000
Messages
947
Location
Scottsville, Kentucky
Corvette
08 Jetstream Blue Z51 coupe
Randy,

I believe that the carb you are reffering to is a copy of the original Q-jet. There are several manuals including Haynes that have a step by step adjustment menu. Your carb should have come with an owners manual from Edelbrock with adjustment instructions also. Yes the choke locks out the secondaries, yes the cold idle can be set higher or lower, and no when set properly it should not stall. Without the manual in front of me, I would not be too much help with hands on adjustments. There may be another member who has more "hands on" than me that could do it from memory. Another option is to call Edelbrock, their customer support is pretty good, I converted my 81 to a 1407 square bore and used the tech line a couple of times.
 
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Doug78

Guest
You may have the wrong vaccum source connected to the control for the secondaries. Make sure you have manifold vacuum connected to the linkage you are reffering to. If you have a vacuum gauge connect it to that line it should drop near zero when you open the throttle. I had similar problems with my stock Q-Jet, that and the choke didn't work worth a sh*t! I bought the #1904 with the electric choke on the reccomendation of an Edelbrock rep. It works great, get in hit the gas ONCE and fire it up, choke shuts off on its own to without having to keep tapping the throttle.
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Tech Line

Don't be surprised if you don't get anywhere the first time you call the tech line. I remember calling for help on making some adjustments. The tech rep needed to know my compression on each cylinder, vacuum, gap and color of spark plugs, type of gas, and total degrees of timing. They want to rule out everything else before tweaking the carb.

I agree with the last post. Also, if he is right, you need to let it warm up to operating temperature before making your final idle adjustment.

I think the solenoid does kick a little when the key is turned on. It should then kick all the way when the a/c comes on.

Good luck. Make sure to post your final solution for all those that eventually follow in your footsteps.
 
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Randy 71

Guest
UPDATE:
I am not very please with the 1901 so far. Found out today, when I called the Edlebrock TECH support line that I have to send the carb back. I notice a chip and some rough spot inside the carb (not sure what its called) the flaired single tube that sticks straight up in the center from each primary. Anyway the flaired portion had the metal
bent and rough spots. I say this before I installed it but they were so small I didnt think much about it. The TECH said, that it need to be smooth like the other one. He said send it back and we would start fresh. Very helpful. Just a pain to take it off, take it back, what for the new one. No what I mean?

I am almost tempted to go with a Holley instead. I was looking at the 4150 or the 4175. Anyone have suggestions on a Holley replacement?

Thanks for all the previous comments helping with the 1901.

Randy
 
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Franky Mize

Guest
I am glad you mentioned the Holley,when i first read the post, i cringed!!! i understand if you are trying to keep that factory look by going with a q-jet replacement, but in my circle of hot rod buddies here in Tennessee, we refer to those carbs as a "quadra-junk"!!!. I am sure I may catch some slack about that comment, but hey, if the shoe fits wear it!!! I am also sure that there are many people out there who swear by a q-jet, and can probably tune and set one up in an hour or two,but I cant!!! but for all around ease of tunability and setup, i would go for the Holley!!! check out Holleys new line of carbs called the "Street Avenger" series carb, their specially made for those of us who are not carb guru's!! they only make 3 carbs, and they are straight forward in their setup and tuning procedures. Holley claims that they are foolproof!!! i will be adding one of these carbs to a ZZ4 crate motor for my 81 vette!! good luck on getting your setup dialed in!! if you can not get any info on these carbs, let me know and I will be glad to mail you one!!!:cool if you tell me how much hp you have, i can get you a part #
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
I went from a Q-jet to a Holley 600 or 650 (can't remember) vacuum secondaries, single feed, with the spread bore design on my old 74. The car was a 350, four speed, 3.7 rear gear. It was amazing the difference in performance. It only took me about two hours to tweak and tune to a point I was happy. It would break the back wheels loose in first, and second by simply pumping the throttle to open the secondaries. The Q-jet was not crisp enough to do that.

Just think, that was an old Holley from about 12 years ago. Imagine how much better the new ones are.
I did have a little trouble gettting the stock air cleaner to fit over the carb. The new ones may be different. The 74 had the cowl induction air cleaner. I was able to modify the bottom housing to get it to squeeze over.
 
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Randy 71

Guest
Tom, Its a stock 350/270HP with an open air filter. Maybe a little over 270 hp. Maybe 290-300hp.

Randy
 
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Doug78

Guest
Personally I would prefer fuel injection over any carb. Because I live in the Portland Metro area (Oregon) I have to deal with smog laws. The only carb I could legally run was another Quadra-junk. The 23-year-old stock Q-junk was giving me 8 MPH and no choke, the change to the Edelbrock Q-junk #1904 gave me an electric choke and 12 MPG. Thats not bad considering the vette has over 100K on it. As far as performance goes it will spin the tires off the line and gives a firm bark grabbing second, L-82 w/ auto and 3.55 gears. If I find someone that knows how tune a Q-junk it might do even better.

Am I saying its better than a Holley? Heck no! I don't know, the only other carburated vehicles I've driven were a 75 Chevy pickup with 250 straight six and an 87 Chevette. I just like Edelbrock parts and don't have any complaints about my Quadra- jet
 
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Franky Mize

Guest
Randy, your horsepower level is an in between carb situation!! i am quoting this info from the latest summit racing catalog,and here are their recomendations!
part #HLY-0-80570...570 cfm, stock-300 hp....$349.95
part #HLY-0-80670...670 cfm, 300-400 hp......$359.95
part #HLY-0-80770...770 cfm, 400+ hp...........$379.95
so, if you plan on pretty much leaving stock,i would go for the 570 cfm,you will have great low to mid throttle response,but slighty less cfm for wide open throttle,on the other hand with the 670 cfm,you will have pretty good low to mid throttle response and alot better high end breathing ability!! the choice is yours! its just a matter of how you drive your car!!! i will agree with doug78, fuel injection is far superior to a carb,my problem is adapting a tuned port setup to the vortech style heads found on the ZZ4!! I am sure i can find a LT1 fuel injection somewhere, but i already have a polished tuned port setup waiting to go on something!! I think it would be cool to pop the hood on my '81 and see a newer polished tuned port setup under the hood!!

Franky
 

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