MrEarl

1979 Estate Wagon, AC Blower and Carburetor Problems

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23 minutes ago, JohnD1956 said:

Why not get one or two cans of carb cleaner and just blast it while its on the engine?  Inside the airhorn, primary and secondary, and see if it becomes acceptable?  Seems you'd have nothing to lose by trying.  

 

Maybe I’ll give it a try. I’ve ran a couple tanks of gas with Seafoam and have a can to run through the carb but haven’t made time to do it. 

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Seafoam in the gas is a good start.  But it misses the upper air horn and the throttle butterfly shafts.  

 

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Sorry for the short reply @JohnD1956.  Was late and I'm a bit flustrated at finding it could take 3 months to 2 years just to get a carb rebuilt by someone reputable and with good reputation and references. I'll try the carb cleaning you suggested as well as the Seafoam thru the carb I mentioned but really not anticipating much improvement. I really think it is more in the choke or choke pull off area.

 

I'm just going to walk away from it for a couple days and get on with something else. Sorry I'm not that up on all that's been discussed and the terminology used re the Quadrajet,  hence my "are we still speaking in English" comment which confused @old-tank. But hey, y'all and YouTubes old Tylers Neighborhood Garage have taught me a lot.  Thanks everybody for your help.

 

 

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I understand and feel your pain, Lamar. It's hard to walk away but sometimes it's good to take a break and regroup before your reserves are depleted. The answer is out there and it probably won't be anything major. But I know exactly how you feel and the frustration that goes with it. My tendency is to keep going even after my tank is empty, and that's when things get really broken. You're a better man than I to pause before, rather than after you've made a mistake.

 

That said, maybe take a different tack on this? My usual advice is to trust the factory engineers, but during this period of time they were pretty well handicapped by regulations and smog equipment that was well-intentioned but short of the technology needed to make it work properly. I might look at modifying the engine slightly with, say, a simpler, non-emissions carburetor, losing the rest of the emissions control equipment, and simplifying the engine somewhat. That could cut down on your diagnostics and improve performance, although admittedly it would be modifying the car and if you intend to show it (or if emissions testing is mandatory), that might be a demerit, although nobody will spot a different carb under the air cleaner and you can leave everything in place, just disconnected. By doing so, now you're just dealing with air, fuel, and spark and things might get easier at that point. Eliminate variables, so to speak. I have to assume the Trans Am guys have some work-arounds for the 403 and more performance, maybe tap that as a resource and see if there are simple things you can do to improve performance and maybe even solve the problem. I don't know, I'm just spitballin' here.

Anyway, I'm with you, brother. It'll turn out OK, that much I know.

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Thanks for the support @Matt Harwood. Hopefully Cliff's book (which should be arriving shortly) will shed some light on not only how to rebuild to stock but also what performance enhancements can be done to make the engine perform better while towing. I purposely went with this car and the 403 and towing package over a 350 with hopes it would perform well enough to tow what it is spec'd out to tow, ie 6000 lbs (I'm only at around 4,600-5,000 at the most)  I'm doing everything else to the suspension, tranny etc to give me confidence it will perform as needed but so far the engine has let me down a bit. I really think it has to be in the carb so will not give up until it is at peak performance.

 

 

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Posted (edited)

I came to this thread late.

 

I first read the then last part of the thread talking about Q-Jet rebuilders, which is when I jumped in, and recommended Cliff.

 

Just read the entire thread, and it appears towing is the major issue.

 

In 1981, my Dad bought a Winnebago with a 454 Chevrolet engine, and the 800 CFM Q-Jet. The Winnebago, when loaded and towing my van to swap meets, would gross 15,000 pounds plus.

 

Trying to use the speed control was an exercise in futility in the mountains of Pennsylvania on the way to Hershey. The engine simply did not have the power to pull the grades in high, as the cruise control would not engage the secondary except under WOT, in which case the transmission would downshift and the engine would overheat. Manual driving had the same issue and would also cause the engine to overheat. 

 

Dad and I finally got frustrated, and Dad asked me what to do? I told him the wrong style carburetor was on the engine for towing. He said, in no uncertain terms: FIX IT (there may have been some other words used, but fix it is a literal translation) ;)

 

So I ordered a different intake manifold (square bore) from Offenhauser. And "married" two genuine Carter type AFB carburetors. I took a Carter 4760s (750 CFM) as the base, and replaced the manual choke with the electric choke, throttle arm, and fast idle mechanism from a Carter 9635s.

 

At the same time, I plumbed fresh air to the snorkel on the air cleaner.

 

Result: PROBLEM SOLVED!

 

Driving the exact same route at the same cruise speed from Eldon, Missouri to Hershey. Pennsylvania the following year, the travel time decreased from 20 hours to 18 hours!

 

Fuel economy changed from 6.1 MPG to 6.9 MPG (13 percent INCREASE).

 

And the temperature gauge never moved from the center climbing the grades!

 

So why did a slightly smaller carburetor make this huge difference??

 

It is important  to understand the difference between the design of a spread-bore carburetor (the Q-Jet 800 CFM), and a square-bore carburetor (the Carter AFB 750 CFM).

 

Instead of looking at total CFM, look at the PRIMARY side CFM:  200 on the Q-Jet versus 375 on the AFB.

 

The Q-Jet is a total of 800 (200 primary plus a variable 600 secondary).

 

The AFB (the one I used) is a total of 750 (375 primary plus a variable 375 secondary).

 

The extra 175 CFM (almost double) was sufficient to feed the engine under most conditions, plus the AFB could go the WOT without the transmission downshifting.

 

If one looks at many large engined trucks, one finds that a TWO-BARREL carburetor is used, rather than a four-barrel; which is where I got my idea.

 

Just food for thought.

 

Jon.

 

 

 

 

Edited by carbking (see edit history)
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12 hours ago, MrEarl said:

 

Maybe I’ll give it a try. I’ve ran a couple tanks of gas with Seafoam and have a can to run through the carb but haven’t made time to do it. 

 

The 4GC on the 60 I removed the top. Cleaned out the garbage with carb spray.  Put in the new accelerator pump. Float level checked.  New gasket for the top and put back on the engine.  Difference between night and day when completed.  The rest of the new carb parts are still in the box.  Give it a try.   

 

 

 

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1 hour ago, carbking said:

It is important  to understand the difference between the design of a spread-bore carburetor (the Q-Jet 800 CFM), and a square-bore carburetor (the Carter AFB 750 CFM).

 

Instead of looking at total CFM, look at the PRIMARY side CFM:  200 on the Q-Jet versus 375 on the AFB.

 

The Q-Jet is a total of 800 (200 primary plus a variable 600 secondary).

 

The AFB (the one I used) is a total of 750 (375 primary plus a variable 375 secondary).

 

 

That right there is a great view into the issue--what great information! If you're towing, that Q-jet is undoubtedly getting into the secondaries, perhaps causing the bog simply because they're GIANT. I had no idea they were so large and the primaries were so small. Everything Jon says makes A LOT of sense in this situation. The bog, the unexpectedly tepid power output, and the temperature/transmission issues.

 

Jon, could you build such a carburetor for Lamar? Are those parts you mention still readily available? Or is there a different carburetor that you'd recommend, say an Edelbrock or Holley that's available off-the-shelf today?

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Matt - I am no longer building carburetors. Manufacture of carburetor rebuilding kits keeps me from fishing ;)

 

The first issue here is that installing a square-bore carburetor REQUIRES changing to a square-bore intake manifold. It cannot be successfully used with the existing manifold. Period.

 

I am unaware of what manifolds may/may not be available for the 403.

 

As to off-the-shelf new carburetors:

 

Holley carburetors seem to be a favorite with many, but for some reason, Holley carburetors don't like me. Engine fires with new muscle cars (that I bought new and never touched the carburetor) and leaky Holley carburetors on three different vehicles all within 9000 miles prove this point!

 

As to the e-clone, I cannot, in good conscience, recommend one. Period.

 

But, Buick used 625 CFM square-bore carbs on the 401, and 425 in the 1960's before the spread-bore was designed. Both the Carter AFB and the Rochester 4-Jet as used by Buick. The 625 CFM square-bore are 250 primary, variable 375 secondary. Not sure 250 would be enough for the 403 for towing. It might be.

 

There was also a 692 CFM Rochester 4-Jet, but I am only aware of two: the auto choke version was used on the 409 Chevrolet and is constructed from "verypricium". The other version (which I have, by the way) comes only with a manual choke. Conversion to an auto choke would require machine work. The 692 would be 313 primary, 375 secondary. 

 

Lots of things to consider: tire size, rear end ratio, total gross weight of both tow vehicle and towed vehicle, towing speed, and engine RPM at that speed.

 

As I have posted many times, mathematics and physics are an enthusiast's best friends.

 

Jon.

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Beginning to wonder if I should have have just gone with the '54 Roadmaster with a '56 322 and the McCullough Supercharger that's waiting patiently in the parts closet for it's day to come back alive. I think it and the Dynaflow in Low would have handled that hill better than the 403 in Low.  I'm being sarcastic here of course but I do appreciate the hp and torque of them 322's.  I plan to stick with the Quadrajet and get as much out of it as possible before seriously considering alternatives. After all the wagons name is SouthernBelle and I never planned to be climbing the Great Smoky or Rocky Mountains with the Argosy in tow but thing is you never know when you may encounter an unexpected 10+% grade local road.

Thanks for that great story of you and your dad Jon, really puts my dilemma into perspective. If your ever tire of fishing and want to experiment with how much horsepower and torque you can get out of a square bore carb on a 403, well I'm your guinea pig😄

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11 hours ago, MrEarl said:

you never know when you may encounter an unexpected 10+% grade local road.

 

 

That's a fact!  Found one in western MD while driving the 54 Special.  1st gear with the 3 speed to the top.  Was no other way.  If I had a trailer I still would be camping at the bottom of that grade figuring out how to get to the top.  :)

 

        

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The engine revin like crazy and the car and Argosy barely movin.... a real eye opener 😳

It also brought to my mind do I need a different torque converter. 

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I'm contacting the three quad rebuilders to ask turnaround times for either off the shelf or rebuild of mine. So far 9 weeks from Quadrajet Power. Will have to call Cliff as he has not allowed me access to his forum yet and there is no email address on his site and as some of you know I have a problem hearing on the phone,  so will see.

 

I am also looking at the same sites to see what is available in ordering parts ie pump and choke that I could install in conjunction with an on the engine full cleaning. 

 

 

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Posted (edited)
On ‎6‎/‎27‎/‎2019 at 9:30 AM, MrEarl said:

Sorry for the short reply @JohnD1956.

 

No apology necessary.  I understand your frustration.  I really like the 78 and 79 Estate Wagons, but in my experience, they were good for their day, but never powerhouses. 

A solid vehicle can best be enhanced by sourcing older, more potent engines.  The good news is that Oldsmobile engines have so much similarity in appearance that one would never know what lies under the 2 miles or so of vacuum hoses in that '79.  😁  But an older engine will present its own set of complications. 

 

I was just about to post the comments below when you made your last entry here. But now It sounds to me like the problem lies in your rebuilt transmission.  Anyway, for what it's worth, here is what I was going to say.  ( I guess this means I did actually say it though)  

 

Jon's comments about the disparity in the primary and secondary side on the quadrojet (for towing applications) are very interesting.  And without being an engineer I have been thinking about what he said and how this might be adjusted for in your present engine.   Here are some random thoughts:

* I remember reading that the vacuum advance unit comes into play at idle to help the engine run cooler.  I do not understand why this happens, and perhaps I read that incorrectly.

* I wonder what is  the source of vacuum for the vacuum advance on your engine.  Is it ported, or manifold?  As I understand it, ported is below the throttle plates, and manifold is above the throttle plates?

* Assuming you have some vacuum when running on the primary side alone, then, if I read the vacuum situation right, the vacuum advance is in play during highway cruising resulting in a cooler running engine.   However I imagine you have much less vacuum when the secondaries are employed with loss of any vacuum advance advantage resulting in a hotter running engine.

* If your vacuum source is ported, then I have to wonder if switching to manifold would be of some correction?  

* If not, then I also wonder if prep for a towing situation should include a timing adjustment for more advance to begin with?  Of course, too far advanced will impact how it turns over to start.  

 

And ultimately I have to wonder if this vehicle would not be best enhanced with a computer controlled fuel injection application vs a carb.  

 

Naturally I have not done any research on any of this.  It is all just random conjecture...

 

 

 

Edited by JohnD1956 (see edit history)
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Posted (edited)

I know you want to stay with the Quadrajet if possible but they do make adapter plates for Quadrajet intake manifolds if you decide to go with a Holly or Carter AFB.  In my opinion the Quadrajet is one of the most complicated carbs to rebuild.  They have metering rods inside that can be problematic to find the correct new ones and to install.  As you can see the vacuum lines going to the carb and the vacuum pots that connect to the secondaries are a nightmare to keep them routed correctly.  I would find a Holly with an electric choke that is suitable for your engine and be done with it.

 

Btw, how did you arrive at the conclusion that the Quadrajet was the problem.  This thread is so long and intertwined with the blower fan that it is hard to follow.

Edited by Ronnie (see edit history)

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17 minutes ago, Ronnie said:

I know you want to stay with the Quadrajet if possible but they do make adapter plates for Quadrajet intake manifolds if you decide to go with a Holly or Carter AFB.  In my opinion the Quadrajet is one of the most complicated carbs to rebuild.  They have metering rods inside that can be problematic to find the correct new ones and to install.  As you can see the vacuum lines going to the carb and the vacuum pots that connect to the secondaries are a nightmare to keep them routed correctly.  I would find a Holly with an electric choke that is suitable for your engine and be done with it.

 

Btw, how did you arrive at the conclusion that the Quadrajet was the problem.  This thread is so long and intertwined with the blower fan that it is hard to follow.

 

The adapter plates are wonderful inventions IF one has a strong right (or left) arm, AND a rabbit problem in one's garden ;) They also may be used for a paper-weight (most of the time, probably not in Missouri during the tornado season ;) )

 

Do the math.

 

If one has an intake designed for an 800 CFM spread-bore, and one removes this carb, and with the use of an adapter, installs a 750 CFM Holley. Question? What is the effective CFM of the system???

 

Answer - less than 575 CFM!!!!!

 

You have a maximum of 200 CFM on the primary (the manifold is the limiting factor). It is probably less due to eddy currents.

You have a maximum of 375 CFM on the secondary (the carburetor is the limiting factor). It is probably less due to eddy currents.

 

My guess would be about 180 on the primary side (less than the Q-Jet's 200), and 350 on the secondary side (less than the Holley's 375) for a total of 530 CFM.

 

I will not argue that the Q-Jets are somewhat complicated. Each individual has a favorite brand, basically from familiarity. Having worked on most brands for more than 60 years, I have my opinions, but these are not truly applicable to this thread. 

 

Both square-bore and spread-bore carbs have their place, but NEVER with a spread->square or square->spread adapter plate.

 

For the record, I have three collector cars/trucks: one totally original except for the factory high performance cam,  one modified with dual square-bore carbs, one exceptionally highly modified with a racing spread-bore.

 

Jon.

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6 minutes ago, carbking said:

The adapter plates are wonderful inventions IF one has a strong right (or left) arm, AND a rabbit problem in one's garden ;)

 

In my opinion the same could be said for Quadrajet carburetors because of the complexity but I do think that when they are in good condition they perform well. I don't think they are a good carburetor for a towing vehicle. Just my opinion...     I will go along with what you say about the adapter plates and carbs. You are the expert and if you say an adapter is a bad idea then it's bad. However, I have seen a lot of people use the four hole adapters with good success. 

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Ronnie - agree completely with you about the Q-Jet not being ideal for a tow vehicle.

 

Jon.

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Mr. Earl, since you're apparently on this "binge" of sorts, call up your Buddies at Summit and have them send you an Edelbrock Performer intake and matching Edelbrock AVS2 carb for it.  Might need some automatic trans throttle linkage adapters?

 

For a towing situation, you really need a carb with 4 holes that are somewhat the same in size.  Makes the throttle more linear in action.  Rather than going from 200cfm primary to 650cfm with very little throttle pedal movement.  Or you could let the cruise control worry about that.

 

NTX5467

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