Anybody dealt with "Quadrajet Power"?

[wallaby]

I looked over their site, and they seem competent. Pricing isn't too bad, after all, these carbs are getting rare.

I'm not happy with the Holley my builder recommended, and want to try a good Q-jet...plus I hope it has that SOUND

[MC1of80]

Ummmm, whose site did you look at? Why are you not happy with the holley?

[wallaby]

Sorry, I typed the wrong name on the subject line; It has been corrected.

My builder set me up with a Holley street avenger, a Performer RPM intake, and peanut port heads.

It works ok, but is a pig on fuel. I still have my old q-jet intakes, and thought I'd go that direction with a fresh Q-jet to see if that works any better.

[MC1of80]

Are you sure you have peanut port heads? What cubic inch is the engine?

  I was not aware the RPM intake was made for peanut ports. Only oval or square/rectangle port. If you have an oval port intake on a peanut port head the transition between the two could be your issue. Fuel puddling between  the head and intake. 

What size holley avenger did your engine guy recommend? What's your timing set at? Cam specs? Converter size? Gear ratio? 

[1970mcss]

When I bought my car it had the original Quadrajet on it and it ran like doodoo. I bought a rebuild kit and had a mechanic friend of mine rebuild it and no it runs great. 

[wallaby]

Yes, they are just as you describe. Oval port intake feeding tiny peanut port heads. 

To be fair, the heads were ported and give good flow numbers, but there was no effort that I can see to deal with the transition issue. The engine has good dyno numbers, and it feels strong on the street, but it starts laying down at about 4500 so it's not good at the dragstrip. It tends to get around by using its cubic inches and torque. Dyno sheet gives 530hp/ 600tq @ 3000 rpm.

I'm trying to figure out how to maximize the combo without having to swap out the heads. I figured that going back to my stock intake and a Q-jet might boost the bottom end even more and give some better fuel efficiency. It's an easy swap and I have the parts already. My question about the Quadrajet power guys was just me looking into the future. I had this engine built and tried to let the builder do what he does. I specified the cam be a roller, but let him choose. I have been running the engine as it is, and it's ok...but it feels kind of labored.  Even at cruise, it doesn't sound happy...it sounds a bit like it's running under water. On the street It feels strong, but you wouldn't use the word brutal. I would like it to come alive when I open it up, but instead it simply accelerates strong and without drama.

The engine was expensive. I bought it complete, with carb, distributor, and all. I have been hesitant to take it apart and start changing stuff at additional expense. I am in denial, as I think it should be as good as the dyno sheet would indicate.

Here are the numbers you asked for: Engine is now 468 cubic inch.  Holley 750 avenger, Not sure about the timing...it likes a lot, it seems. I want to say 19 initial. (might be wrong with that number). I set the timing at 3000 rpm and simply dialed in the smoothest sound and locked it down. The camshaft is an Isky roller; unknown specs..it has good idle, with a hint of lope. Converter is a Coan with 2500 stall. 3.31 gears.

[MC1of80]

Thanks for the info. Is this a vortec pro engine? The numbers are good but normal for a peanut port big block. Meaning alot of torque and out of steam at lower rpm. 

With a normal size oval port head and a 468 cube big block 5500 rpm should be no problem. That being said and what you said I would first try bringing in the timing curve down to 2000 ish. 

What distributor are you running? 

Any quadrajet roughly is 750-800 cfm. Depending how far the secondaries open. I would see if anyone you know has a 650DP holley you can try. From your description it sounds like it is drowning on itself. 

Have a friend that just installed a vortec pro 468 into his Monte. Dynoed at the same numbers as yours only with oval port heads and a 650 quick fuel holley style carb.

He says it's better on gas than the 355 small block he removed. 

He is running a th400, 2500 stall and a 3.73 gear and can smoke the tires at will. 

Edit: do you have the dyno sheets? Why did you change the timing? Before anything, reset the timing to the dyno specs and go from there. You may have too much timing and that's why the engine is flat. 530hp and 600 ftlbs should be fun to drive! 

[wallaby]

Hmm. Yes, its a vortec pro engine. Throttle response is kinda lacking now that I think about it.

You think a smaller carb might work better? I have a new AVS2 on my small block, maybe a quick try-out with that will give me some answers. It's pretty tiny, though...I think its like 500 cfm.

The distributor is a billet HEI.

I have to dig out my dyno sheet and see about the timing. I think he had a spec with a number, then noted it was locked with no advance and no vacuum. I figured that was a spec for best dyno performance, but wasn't going to be street friendly. Again, I have to verify that.

[MC1of80]

What carb was the engine dynoed with? Put the timing back to his specs and try from there. You will probably be happy with the results. 

He had it set for best engine performance and power. When you reset it, those dyno figures went out the window. 

[wallaby]

I have the dyno results in my hand. He provided two. One is labeled "4 hole 1 inch 35 degrees". I assume this is referring to a spacer under the carb, and the total timing.

The other sheet provided is labeled "770 no spacer 35 degrees". The 770 I assume is my carb cfm. The two sheets are very close regarding output. The spacer gave about 4 hp and 5 lbft, but I don't have room under the hood for that.

For the  results without the spacer, the dyno starts recording at 4000 rpm. It is at 448hp and 589lbft at that point. This is where my max recorded torque happens. As the rpms go up my torque falls off, but HP grows. The rev limit is 5800 rpm, and at that point is shows 560 hp, with 507 lbft.

The setup sheet has fields that are then filled in by hand: he specifies the oil, then the spark plugs, ignition timing, and thermostat temp.

It is all as he specified, except for the ignition timing. The engine was supposed to be dyno'd with MY carb and distributor, but they were packaged seperately. 

His specs call for timing of 35 degrees total and NO distributor vacuum advance. I have never run a street motor without vacuum advance. Isn't my mileage going to suffer from that change alone? I will have to get in there and check what my total advance is ...it might be well above that. I am currently running manifold vacuum to my distributor so advance falls off as throttle is applied. I am getting full centrifugal and full vacuum at cruise. His dyno sheet also shows an A/F ratio as rich as 13.35, and as lean as 15.03. My A/F gauge shows I'm in the 12's all the time except at highway cruise when I show I'm in the high 13's. I have never heard a hint of pre-igniton or ping, even with regular grade fuel. Thoughts?

[MC1of80]

Ok. Thank you for that info. Put the engine back to the dyno sheet specs. Total of 35 degrees of timing, the 770 carb and NO vacuum advance. 

Your timing is probably off the chart advanced making the car a pig. 

Set everything back and I can almost guarantee a totally different car! For the better! 

[wallaby]

Ok, I got in there today and checked it out with a real timing light.  Honestly, I thought your scenario was unlikely.. I didn't expect the timing to be so far off it would cause the issue I was having. I have to give credit where credit is due, and admit I was wrong. Somehow I had the timing way advanced. I unhooked the vacuum, then idled it down to 500 or so RPM so the centrifugal wasn't in play and took a look. I was at about 35-40 initial!

Now came the hard part....retarding the timing in hope of more power. I twisted the distributor a lot. lol.  I set the initial at 15, because the centrifugal adds 20, giving me the total of 35 specified on my dyno sheet. After a carb adjustment (raising the idle and leaning the mixture) my idle was good and my A/F gauge showed I was out of the 12's and into the 13's.. Otherwise it seemed the engine was the same as before.

Then came the test drive. I was stunned. The engine seemed much more responsive and the car felt 1,000 lbs lighter. Still no ping (never did) and it breaks the  tires loose going into 3rd. At cruise the A/F gauge shows low 13's, but have to take a long drive yet to see if mileage improved. Even if the MPG is the same I am getting much more power to the ground, and have been rejuvenated in my love for the car.

Happy guy right now!

[MC1of80]

YAYAYAY! Sweet! Glad that was the issue!! Always happy to help. That's what we are here for. 

[zucchi]

I bought one of their Quadrajet custom built and tuned for your engine, SKU:QB1c; nothing but problems.

On April 3, 2020, I received one of these. It was flooding. Please follow the sequence of events below that lead me to this diagnosis. 

• Mid-July, new engine was finally ready.
• I installed new engine into car. NOTE: engine has stock style mechanical fuel pump installed.
• Early September, on initial startup of new engine with new carb, allowed cam to break-in for 30 minutes. Checked for leaks, adjusted timing, mixture, fast idle and curb idle. Drove car for about 20 minutes. Re-checked all settings and adjustments. Ran engine a few more minutes. In all, engine was run for about an hour then shut off.
• Next morning, engine started right up with no problems. did more checks for leaks, etc. Engine ran for about 30 minutes. Shut engine off. Waited about 5-minutes to re-start engine; it started right up.
• The next time I drove the car, started engine and allowed it to warm up for about one-minute. Put it in gear and engine stalled. Could not restart engine; it behaved as though it were flooded and the aroma of gasoline was heavy in the air. I figured the car needed more time to warm up and some adjustments. I let it sit overnight.
• Next day, engine started right up and allowed to fully warm-up (about four-minutes) before driving. Performance was sluggish in such a way that it was consistent with flooding but dismissed flooding as cause since carb was new. Explored vacuum leaks or ignition issues instead.
• After accumulating about 12-hours of engine running time, I readjusted the rocker arms. I hooked up a remote starter switch in order to turn the engine (without starting it) as part of the rocker adjustment process. I began on the driver's side. Three rockers into this process, I smelled gasoline. Considering I am working inside my garage with the air cleaner removed from the carburetor, I didn't think much of it until I saw a drop of liquid fall from the outside of the carb onto the intake manifold. I discovered fuel was seeping out between the air horn and main body, the part of that gasket which is exposed outside the carb was completely soaked with gasoline.

Seeing that, with the carb not being touched and the stock style mechanical fuel pump operating at cranking speed, there's fuel leaking from between the carb body and air horn, I can only conclude that the carburetor is flooding due to a bad needle/seat, mis-adjusted float, or bad float. I've been banging my head against the wall for weeks trying to figure out why my engine was manifesting the symptoms mentioned above, never taking into account the possibility of a professionally built carburetor being defective.   

Considering what I paid for this carburetor, to say that I am disappointed would be an understatement. I expect shoddy work from today's repair shops where they hire inept monkeys who can't wipe off [censored] after taking a dump unless they're plugged into a computer that told them where to find their own [censored], which is why I do all automotive work on my cars myself. Each time I become the victim of incompetence, I say to myself that I can [censored] this up myself for free and learn something along the way rather than pay someone to [censored] it up for me with nothing to show for it. I've rebuilt several Q-j's for my own cars myself. The first one (back in the early 1980's) turned out a bit crappy. After learning from my mistakes, I got better and the last few were flawless. The only reason I didn't rebuild my original carb, against my better judgment, was, now that I'm in my later years, I wanted to save myself the time and inconvenience of doing all that work; I had plenty to do with the engine install and all the details that go with it. The bench work to do the carburetor is no issue for me, it's going through the calculations for jets, rods, etc., so as to optimally dial in my application that's tedious. After researching performance Q-j builders, these guys appealed to me the most, so I elected to engage them for this task. Not only did my experience with their end product leave me thoroughly dissatisfied, it made me even more resolute in my resolve that if you want something done right, do it yourself.

I am so utterly disillusioned by this whole thing that I would have preferred to simply return this carb for a full refund and be done. However, being that I am a realist, I am aware that "All sales are final. No refunds for carburetor purchase...". Furthermore, despite its being in operation for only two-months (this past September to mid-November), unfortunately, I did not discover this issue until seven-months after receiving the carb which puts it just over one month outside the time frame for return for service: "Contact QP within 6 months of original purchase if your QP built carburetor has issues that cannot be tuned out with enclosed tuning guide". This is the area where they earned the one star. They offered to examine/inspect/repair the carb, catch is I had to pay for shipping the defective carb back to the shop. They never told me what was causing the problem, only that: “It was disassembled. Changed the needle/seat. Set float changed the air horn gasket and assembled. Tested and needle/seat holds pressure. Also changed the fuel filter for you.”

I got the carb back on 12/10/2020. I had no occasion to open the package and inspect it until 01/30/2021. Upon simple checking of operation (throttle valves and choke valve open/close) the choke valve was jammed. In, what I can only surmise as a bonehead rookie mistake, one of the linkage rods was not installed correctly which caused the choke mechanism to bind. Albeit was a three-minute fix, it should not have been necessary to fix the “fixed” carb in the first place. How many inspections/hands did this carb pass through before sending it back to the customer? None of them noticed the choke valve was jammed? Where’s the pride in workmanship? What’s their standard for quality control? I now wonder what else is wrong with this “professionally built and repaired” carb? I am beyond disillusioned, disappointed, and dissatisfied, I am downright disgusted.

My experience of being sent a defective carburetor twice may be an isolated anomaly but it’s a cautionary tale nevertheless.

[Dtret]

All I can say is WOW. I agree

[rsorg]

 i had put a holley carb on my car 30 plus years ago, thank gosh i kept my original quad, although the holley did good ,i was going thru the gas ,,i had an old time mechanic, do a vacuum test ,while the car running he took a propane torch unlit of course and waved it over the throttle base, rpm s, went up leading to the worn out brass throttle plate bushings had the carb rebuilt with new bushes , etc. car runs like new, roger