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Carb vs fuel injection on nailheads


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Originality aside...

I'm watching people pay 1k for 4bbl manifolds for some nailheads.  What is the benefit of a 4bbl manifold and carb over the stock 2bbl manifold with a holley EFI unit capable to 350hp?  Again without considering originality...

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1 minute ago, Ben Bruce aka First Born said:

Bragging rights?   Surely not performance.

 

  Ben

I guess I wonder if the 2 holes in the manifold become the issue.  The full sniper kit for 1200 looks good when compared to a pricey manifold. Especially for cold starting and ethanol fuels.

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I put a 1966 Spreadbore (Quadrajet) manifold on mine. My fuel economy improved over the 2 barrel. That is when I drive conservatively. I'm in to the whole swap for about $500-$600. I don't think EFI would make it any more "driveable". That said, I store the car in Winter. Also, I haven't seen a true off the shelf EFI for a nailhead. The Holey snipers are Throttle body injection which is effectively an electronically controlled carb. 

 

The Quadrajet is a fantastic carb. It's complicated and kind of intimidating at first, but there is a wealth of knowledge and you can get them dialed I pretty darned good. 

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13 hours ago, drhach said:

I put a 1966 Spreadbore (Quadrajet) manifold on mine. My fuel economy improved over the 2 barrel. That is when I drive conservatively. I'm in to the whole swap for about $500-$600. I don't think EFI would make it any more "driveable". That said, I store the car in Winter. Also, I haven't seen a true off the shelf EFI for a nailhead. The Holey snipers are Throttle body injection which is effectively an electronically controlled carb. 

 

The Quadrajet is a fantastic carb. It's complicated and kind of intimidating at first, but there is a wealth of knowledge and you can get them dialed I pretty darned good. 

Wow.  I just dumped the Qjet off my caddie for a holley.

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On 9/4/2020 at 5:17 PM, drhach said:

The Quadrajet is a fantastic carb. It's complicated and kind of intimidating at first, but there is a wealth of knowledge and you can get them dialed I pretty darned good. 

 

X2 on that. I purchased a rebuilt Quadrajet for my Wagon that when installed ran worse than my old never rebuilt unit. Seller swapped it out and that one was almost as bad as the first.   Finally had my original one rebuilt by a local shop I've been using for ever and could not believe the difference, woke that 402 UP!!! 

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I bought Cliff Ruggles Quadrajet book. I also joined the forum on his website and ended up talking to him over the phone a  couple of times. I ended up ditching the 1966 Quadrajet in favor of a late 70's unit. He helped me dial it in for my 401. It really is an amazing design. The later models are 800 CFM, but only flow to what the engine needs. So the carb is always right sized CFM-wise to the engine. You tailor the fuel needs to our design and the carb does the rest. The ting starts instantly, has no stumble and is just all around great. 

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1 hour ago, drhach said:

I bought Cliff Ruggles Quadrajet book. I also joined the forum on his website and ended up talking to him over the phone a  couple of times. I ended up ditching the 1966 Quadrajet in favor of a late 70's unit. He helped me dial it in for my 401. It really is an amazing design. The later models are 800 CFM, but only flow to what the engine needs. So the carb is always right sized CFM-wise to the engine. You tailor the fuel needs to our design and the carb does the rest. The ting starts instantly, has no stumble and is just all around great. 

 

Sometime when you are conversing with Cliff, ask him about the dyno test of his Pontiac 455? It was tested with a Q-Jet, and got some really nice figures. Then the operator made a comment to the effect "let's see what this engine will do with a REAL carburetor" and dropped on an 880 Holley. Lost several pounds-feet, and a few ponies. Operator was flabergasted!  ;)

 

The Q-Jet is in my top three of street carburetors.

 

Jon.

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21 hours ago, drhach said:

I bought Cliff Ruggles Quadrajet book. I also joined the forum on his website and ended up talking to him over the phone a  couple of times. I ended up ditching the 1966 Quadrajet in favor of a late 70's unit. He helped me dial it in for my 401. It really is an amazing design. The later models are 800 CFM, but only flow to what the engine needs. So the carb is always right sized CFM-wise to the engine. You tailor the fuel needs to our design and the carb does the rest. The ting starts instantly, has no stumble and is just all around great. 

 I too bought Cliff's book when we got my wife's Wildcat with a 455, and the Q-jet was messed up on a number of fronts. Followed it closely, and it is a sweet running 455 now. I have done a number of carbs over the years, but never a Q-jet, so I figured I should educate myself.

 

 Re, Earl's comment. I think it was in Cliff's book I read that many rebuilders generalize the rebuilds, so that a given carb part number will fit a number of different models, instead of building each for that specific engine, so perhaps that's what happened. Then with a proper rebuild of the correct original carb you got the performance it was designed to give.

 

 Just my few cent's worth.

 Keith

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Well said. Given that they were used across so many models you can't interchange them easily. I think that's what puts so many people off of them. With a few small changes an Edelbrock will cross over pretty easily. Not so with Q-Jets

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On 9/9/2020 at 12:58 PM, Buicknutty said:

Re, Earl's comment. I think it was in Cliff's book I read that many rebuilders generalize the rebuilds, so that a given carb part number will fit a number of different models, instead of building each for that specific engine, so perhaps that's what happened. Then with a proper rebuild of the correct original carb you got the performance it was designed to give.

 

I think you hit the nail square on the head there Keith. That's exactly what my re-builder had to say too. I researched Q-Jet rebuilds, even read most of Cliff's book and if I had it all to do over again would have just sent it to him for a rebuild. The shop who rebuilt mine also removed as much of the smog lines etc as possible so am sure that improved performance some also.  

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On 9/10/2020 at 11:42 AM, drhach said:

Well said. Given that they were used across so many models you can't interchange them easily. I think that's what puts so many people off of them. With a few small changes an Edelbrock will cross over pretty easily. Not so with Q-Jets

 

Very few carburetors cross over EASILY, and still give excellent performance!

 

I don't know (and frankly, don't care) how many e-clones are being made; however, Carter built 505 different AFB carburetors. They did not make so many different simply to spend money that would otherwise be awarded to investors, for R and D instead. And these, for the most part, do NOT cross over easily. If one has decades of experience, and a boat load of parts, they will cross over to a certain degree. Read the third line in my signature block ;)

 

Cliff has specialized in the Q-Jet for decades. I doubt there is anyone alive as knowledgeable about the Q-Jet as Cliff.

 

A plug here: I have read hundreds, probably over a thousand carburetor books since 1959 when I did my first Holley carburetor. Cliff's book is absolutely at the head of the group in being "user-friendly" (one does not need an advanced degree in mathematics to use the book) to use the current vernacular; and would easily be in the top 4 or 5 for overall best. Anyone considering rebuilding a Q-Jet should first read the book. Lots of really sharp technical people are unable to convey their knowledge to others. Cliff can, and does.

 

And to keep those interested from having to ask, "Weber Carburetors", by John Passini would be my favorite for best, but I had to dust off my college calculus books to understand it! ;) 

 

Jon.

Edited by carbking (see edit history)
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In 1971 I bought a '68 Riviera with a 430-4 Q-Jet. I thought I was going to make the world all bright and cheery when the Holley Spreadbore came out. That is when i really started learning about carburetors.

I live in Rochester and one of my friends was a QC guy at Rochester Products so I got good training. In the early 1990's I got to spend the better part of a day with Tom Toal, one of the applications and design engineers of the Q-Jet. We were working on a 4GC that had an untenable problem. I had gone my limit and we found Tom's that day. At one point he accused me of be part of a set up his friends were using to play a joke on him. At the end of the day he told me I was a pretty good carb mechanic. We worked together and still couldn't fix it.

Tom said he had learned that carburation was an art as opposed to a science. Air/fuel combinations have too many variables. He sited the 1976 Cadillac FI as the classic example of trying to do too much with too much data and too many parts. He said they overkilled it with engineering. He pointed to a shelf that had a few "gold" carburetors. Those were the ones the divisions had field tested for the best all around performance and economy. They sprayed them with gold paint, sent them back to Rochester, and said "Put this on that model." Calculations were rough guesses. The empirical application was the only sure way. And what I have used with pretty good success for almost 3 decades.

 

As always, my hardest task seems to be the transition from the low speed to high speed circuits. I usually order two gasket sets. And they may get a gasket or two reused. Even on the most modern with DFI and 3,000 PSIG fuel pressure, I will read the O2 sensor values and still keep the image of the Gold carb in the back of my mind. But today the artwork is in the interpretation. A little too much flair (not flare) and the science will throw a code.

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  • 3 weeks later...

So I got my 4bbl intake for my 57 special in the mail.  What carb should I use and what space do I need? I know I need to block the little exhaust channel. 

My caddy has a Holley but centerville auto seems to prefer edelbrock....

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What size engine???

 

In 1957, Buick used the Carter AFB number 2507s on the 364 CID.

 

The 1957 AFB's (first year) were not the best AFB's Carter ever made (still head and shoulders above the modern imitation AFB's). By 1959, Carter had updated the accelerator pump check valve, and the 1959 and newer carbs were great carbs.

 

The factory replacement carburetor for the 2507s was the Carter 2982s (1960 carb). If you have a 364 CID, that would be my suggestion. Unless you have heavily modified the engine for racing, the factory carburetor is generally the way to go. To quote a friend who posts on a different forum: "Engineers do things for a reason".

 

Jon.

Edited by carbking (see edit history)
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7 minutes ago, carbking said:

What size engine???

 

In 1957, Buick used the Carter AFB number 2507s on the 364 CID.

 

The 1957 AFB's (first year) were not the best AFB's Carter ever made (still head and shoulders above the modern imitation AFB's). By 1959, Carter had updated the accelerator pump check valve, and the 1959 and newer carbs were great carbs.

 

The factory replacement carburetor for the 2507s was the Carter 2982s (1960 carb). If you have a 364 CID, that would be my suggestion. Unless you have heavily modified the engine for racing, the factory carburetor is generally the way to go. To quote a friend who posts on a different forum: "Engineers do things for a reason".

 

Jon.

Thanks.  You know how it is today though we're all obsessed with thinking that we made things better and adapting that to old things.

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16 minutes ago, carbking said:

What size engine???

 

In 1957, Buick used the Carter AFB number 2507s on the 364 CID.

 

The 1957 AFB's (first year) were not the best AFB's Carter ever made (still head and shoulders above the modern imitation AFB's). By 1959, Carter had updated the accelerator pump check valve, and the 1959 and newer carbs were great carbs.

 

The factory replacement carburetor for the 2507s was the Carter 2982s (1960 carb). If you have a 364 CID, that would be my suggestion. Unless you have heavily modified the engine for racing, the factory carburetor is generally the way to go. To quote a friend who posts on a different forum: "Engineers do things for a reason".

 

Jon.

 Funny because after thinking about it not even sure why I really want the 4 bbl other than that is what car culture drills into your head

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9 minutes ago, NC-car-guy said:

Thanks.  You know how it is today though we're all obsessed with thinking that we made things better and adapting that to old things.

 

Changes can be made.

 

Three things can happen: (1) there is an improvement, (2) there is no measurable change, (3) things get worse.

 

I am reminded of a quote attributed to Coach Royal when he was a "ground-pounder" at Texas:

 

"When you pass the ball, three things can happen; two of them are bad" ;)

 

Jon. 

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14 hours ago, carbking said:

What size engine???

 

In 1957, Buick used the Carter AFB number 2507s on the 364 CID.

 

The 1957 AFB's (first year) were not the best AFB's Carter ever made (still head and shoulders above the modern imitation AFB's). By 1959, Carter had updated the accelerator pump check valve, and the 1959 and newer carbs were great carbs.

 

The factory replacement carburetor for the 2507s was the Carter 2982s (1960 carb). If you have a 364 CID, that would be my suggestion. Unless you have heavily modified the engine for racing, the factory carburetor is generally the way to go. To quote a friend who posts on a different forum: "Engineers do things for a reason".

 

Jon.

Wow! The only 2982 carbs currently on the market are $699 for a rebuilt one or a non-working core for $200.  That's just absurd. @Ben Bruce aka First Born might be onto something with the fuel injection.  I can sell both my 4bbl manifolds and my 2507 and just about buy the Holley sniper TBI kit.

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12 minutes ago, NC-car-guy said:

Wow! The only 2982 carbs currently on the market are $699 for a rebuilt one or a non-working core for $200.  That's just absurd. @Ben Bruce aka First Born might be onto something with the fuel injection.  I can sell both my 4bbl manifolds and my 2507 and just about buy the Holley sniper TBI kit.

Or just keep my 2bbl lol

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The two-barrel will work well.

 

A properly selected/tuned four-barrel will deliver more power at WOT, and should raise the maximum RPM of the engine slightly (maybe a good thing, maybe not); and, depending on the driving habits of the operator, SHOULD give somewhat better fuel economy.

 

I can honestly state that, while some others like fuel injection, I personally do not live in an area that requires it. I can see no easier starting (it regularly gets below zero in Missouri winters), driveability, or performance with fuel injection compared to my carburetor vehicles (however, I may have a wee bit more experience in tuning carburetors than some ;) ) I will grant that the vehicles I start/drive in the winter ALL have manual chokes.

 

We have more trouble with electronic ignitions than anything else, even on modern vehicles. I will grant that while (so far) we have had no trouble with the 2014 Ford, average mean time to failure on factory electonic ignitions on everything else has been about 35,000 miles. My 1979 Ford Mustang that I special ordered in 1979, now has 55,000 miles, is always, has never seen snow, and rain only once, is currently on its FOURTH electronic ignition! Dad had two different vans (1988, 2008) that both had major fuel injection reliability issues. (And fixing efi AFTER it goes out of warranty is NOT inexpensive!). Other than those, 1997 van had efi problems at 80k.

 

If I lived in an area such as Colorado, and regularly drove from about 2500' to 12,000', I would certainly consider fuel injection. While I can make my Carters work well at all of those altitudes, I would have to change metering rods (a 3-minute task). Fuel injection certainly handles major altitude changes easier than carburetors. 

 

The above just my personal experience. Those that prefer efi, or electronic ignitions, go for it! Just please don't try to convince me they are overall superior to carburetors, points, and condenser (well, condensers made in the USA ;) ).

 

Jon.

Edited by carbking (see edit history)
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3 hours ago, NC-car-guy said:

Wow! The only 2982 carbs currently on the market are $699 for a rebuilt one or a non-working core for $200.  That's just absurd. @Ben Bruce aka First Born might be onto something with the fuel injection.  I can sell both my 4bbl manifolds and my 2507 and just about buy the Holley sniper TBI kit.

 

 LOL. Try it, you will like it.

  Feel free to contact me.

 

  Ben.

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