The Old Car Blog

Frédéric wrote to us from Dijon, France about his 1936 Buick:

Here are some pictures of my Buick8 of 1936.
It is being restored, but there are very few mechanical parts in France!
It was commissioned by the French army before WW2. In 1940, the Germans would have captured this car. In 1944, the U.S. military recovered the car and given back to the French army in 1946 … !
The speedometer is in kilometers / hour and not miles / hours.
There are currently only 5 models in Europe. I am looking for sponsors to help me restore this lovely car!

It’s a fascinating bit of history on wheels.  If you would like to contact Fred, please drop us a line and we’ll pass the message along. Click on any of the pictures for a full-resolution view.

The Old Car Manual Project has the 1936 Buick brochure here and some 1936 Buick ads here.

At the risk of becoming overly repetitive, I’ll deal with another common carburetor problem.

Typical inquiry: “My Rochester 2GC runs too rich; I suspect the jets have been changed to a larger size.”

This does happen from time to time.  If your carburetor looks like it has missing pieces or has otherwise been modified, there is a good chance that someone has monkeyed with the internals.

Years ago, carb rebuilders would mostly find that 4-barrels had been messed with – QJets, Holleys and so on.

In recent years, since 2 barrel carbs have become socially acceptable, especially in the form of Tri-Powers and other multi-carb set ups, we in the carb business have found more and more “funny” Rochester 2 bbls in circulation.

What to do?

Go to our website with the Rochester carburetor manual: www.newagemetal.com

Here you can look up the specifications for your 1932-1979-ish Rocky carb.  For example, if you had a ‘71 Chevelle, you would go here: http://newagemetal.com/pages/Chevrolet/71/index.htm.

You’ll find scanned pages from the manual with part numbers listed against carb numbers.  If you want to know what jet is correct for your ‘71 Chevelle with a 7041114 carburetor, you would find (http://newagemetal.com/pages/Chevrolet/71/pages/63-69Chevy0112_jpg.htm) that the part number for the jet is 7002658.  The last two digits of the jet part number are the size in thousandths of an inch.

From the factory, the installed jets varied a bit for a variety of reasons. For the most part, 2Jet carbs should be within 1 or 2 thousandths of the size in the manual. Sometimes there were mid-year changes in calibration that weren’t recorded in the published manual, and in some cases it had to do with the nominal size and flow.

Rochester jets are calibrated against a standard jet.  In other words, there is a master jet with an orifice of exactly 58 thousandths to which every other jet is compared. The idea is that every jet labelled as ‘58′ will flow the same as the master jet.  This is why you might measure the hole in a ‘58′ jet and find that it’s smaller or larger.  The ‘58′ refers to the nominal flow, not the size.

Once in a while a jet with a different marked size would get installed in place of the nominal jet.  In other words, you might find a ‘60′ where you  expect a ‘58′ but that might be because the ‘60′ really flowed ‘58′.  Follow me?

In any case, if you have a single Rochester 2-Jet with a reasonable jet size and it runs too rich, you should check the following:

1) Ignition.  Always blame the carburetor last.  There is more on this here.

Check the timing.  If you have a Chevy engine with a harmonic balancer, be aware that the timing mark on the balancer may not be accurate.  As the rubber ring in the balancer ages, the outside hub will mover (“precess”, technically) so that setting the timing with a light gives you retarded timing. I’ve seen these be out by 20 degrees!

If you have points, check the dwell.  This should be 29-31 degrees on a V-8.  Also, check the play in the distributor shaft.  If it’s noticeable, you won’t get good ignition.

At this point, most folks these days go out and buy a new electronic distributor.  It’s not necessary, though, as all you need to do is rebuild the distributor with new bushings.

2) Vacuum.  A vacuum gauge is mandatory when working on old iron.  If your stock Chevy small block doesn’t pull close to 18″ of steady vacuum, you have a problem.  This is a subject for another long post!

3) Carburetor stuff.  If the jets are the right size and it still runs too rich there are a few more things to check on a 2G.

- float: on all carbs, a sinking float will cause flooding.  If the float is brass, shake the float to check for gas sloshing around inside.  If that’s the case, get a new one. If it’s a plastic float, replace it with a brass one.  The black plastic (nitrophyl) floats last 10-20 years and then are done.

-needle/seat: if the needle shows a scoring line where it fits into the seat, get a carb kit.

-power valve: rarely, the 2G power valve will leak.  If your power valve looks like it’s been butchered with a dull screwdriver, you may want to get a new one.  These are not part of a carb kit.  You can special order them at here.

-accelerator pump check ball: if the accelerator pump discharge check ball is missing, or if it doesn’t seat, the 2G carb will sometimes siphon fuel through the accelerator pump circuit.  This ball is under the venturi cluster.

-wrong throttle body gasket: in most 2G’s from the late 50’s to the mid 60’s the gasket between the float bowl and the throttle body should have vent slots. Without these the carb might have a hot-soak flooding condition.  Note that marine carbs never use these.

I think that pretty much covers it for single carb applications.

Tri-Powers are a different beast, however.  I’ll cover these in a later post.

At The Old Car Manual Project, we get quite a few questions about technical matters, specifications, historical information and so on.

From time to time I’ll try to answer a few of these here.

Cristobal from Chile wrote:

I have a oldsmobile omega 78′ with a V6 buick 231 engine, and a
rochester carburator 2GE model. I am trying to find the difference
between the 2GE and the 2G, 2GC and 2GV carburators, but i can’t find
it. The only difference that i could see, is that my carburetor uses a
solenoid and no automatic choke. Could you respond this doubt?

I sent you a pictures of the carburetor.

Good question!  This is the source of some confusion among Rochester owners.

The answer:

• 2G is the model of the basic Rochester Two-Jet carburetor with a manual choke (cable operated)
• 2GV is the same carb with an automatic choke when the choke coil is mounted on the manifold (a so-called remote choke)
• 2GC is this carb  with an automatic choke where the choke thermostat is attached to the carb and is heated with hot air from a tube coming from the manifold (heated by exhaust gas)
• 2GE is an automatic choke carb with the choke being heated electrically

There is more information and illustrations of the 2G family here. The complete Rochester manual up to 1979 is here.

What about the carb in the picture from Chile?  It’s hard to tell – I would guess it’s a 2GE with a missing choke housing, since there is no choke assembly visible.  In fact, in ‘78, at least in US production, GM cars used only 2GC or 2GE carbs.

The arrow in this picture is pointing to the 2GC choke housing.

In a 2GE carb, the only difference is that the housing has an electrical connector and there is no pipe fitting (for hot air) at the front.

Regarding the solenoid in the Omega carburetor above – this is an idle speed control (or idle stop solenoid), usually used to speed up the idle on air conditioned cars or for emission control purposes.  It’s not related to the operation of the choke.

In some cases, especially on smaller engines, the idle is set with the idle solenoid energized.  When the engine shuts down, the solenoid retracts allowing the throttle to close fully.  This prevents run-on when a high idle speed is required.

Back in July, the annual Lacombe Show and Shine was on and there were some really interesting vehicles as always.

This one is a 1955 Bel Air (Canadian production), equipped with a dual Fenton intake and headers.  I built a pair of Rochester model B carbs for the owner.  It took a lot of tuning to get these to run right – I think the he may still be tweaking these.

With this set up there is less manifold vacuum at part throttle, so you need to shorten the power piston springs to keep the carbs from getting into the power mixture under light load.  Also, the jets need to be on the large side because of a weaker vacuum signal (due to the larger venturi area).  As well, the carbs should be synchronized.  Finally, you have to consider that Model B carbs came with various sizes of power channel restriction – essentially a fixed jet that determines how much additional fuel flows when the power system is engaged.

Another one I really got a kick out of was the GMC COE truck.  These are getting as rare as hen’s teeth.  You sometimes see Chevrolet Cab-Over-Engine trucks, but not so many GMC’s, at least not here in the Great White North.

Notably, GMC trucks like this usually used a Zenith updraft carburetor while the Chevy versions used a Carter BB updraft.  Of course the reason for the updraft carburetor was because of clearance around the engine.  This is why these continued to use updraft carbs until 1962, while GM cars had gone downdraft by 1932.

Here’s an album of some of the other notable rides this year.

Ron Bilby, a long-time contributor to The Old Car Manual Project sent in a couple of nice shots of his ‘51 Stude (click to enlarge to full size).

Elsewhere on the site we have some print ads for the ‘51 Studebakers, both cars and trucks. Also from Ron is a 1951 Studebaker booklet with test results from Mechanix Illustrated.

I saw a nice example of the ‘76 Gran Torino in Starsky and Hutch garb at the Victoria, B.C. swap meet in late June. I remember one of these around town in the late 70’s when I was growing up there. Could this be the same one? The owner wasn’t around, so I couldn’t find out if it was an original Victoria car.

It was immaculately restored and even featured a Kojak light and police siren equipment under the dash. Note that 537 ONN is the correct license plate for the TV series car.

On the Old Car Manual Project, we have a 1976 Ford Foldout Brochure, but nothing showing the Starsky & Hutch option.  Anybody have one out there? Email me if you do!

I had hoped that this blog could be a bit of a discussion, with other old car guys commenting or asking questions related to my posts.
However, it seems that the spammers have won this round. Out of 116 comments outstanding there is but one that is real… the rest are blogspam.

Accordingly, I have disabled comments altogether.

The old “Hygrade Motor and Tune Up and Carburetor Manual” is required reading for anyone who owns or services mid-1950’s or older cars with one or two barrel carburetors.

It covers the classic ways of tuning up the cars using simple tools and delves into the details of the typical Carter, Stromberg and Zenith one and two barrel carburetors of the day.

Some of the topics include:

• How to use a vacuum gauge, including for setting ignition timing
• Use of a compression gauge
• Testing the ignition circuit

Also, it has practical advice on setting up Buick Compound Carburetion, the quirky dual two-barrel set up used on the Buick straight-eight.

Find the full text here: http://carbkitsource.com/carbs/tech/articles/TuneUp/CarburetorTuneUp01.html

The Old Car Manual Project has a new website dedicated to original ads for old cars, called oldcaradvertsing.com It’s a comprehensive collection of high resolution scans of over 12,000 ads, mostly from magazines, and covers the period 1903-1989.

I believe it’s the largest collection of classic car advertising on the web, and of course, it’s free.

Of related interest is the collection of brochures, which contains over 40,000 images, at oldcarbrochures.com

I came across this 1949 Monarch at the Lethbridge, Alberta Early Bird Swap Meet last February.

In the 1949 model year, Lincoln-Mercury dealers in Canada got the Meteor – a 114″ wheelbase Ford badged as a Mercury, but retaining the Ford 100 HP 239 V-8 – while the Ford dealers got the Monarch.

The Monarch rode on the Mercury 118″ wheelbase and used the Mercury drivetrain.  It’s easily spotted here where you can see the Holley Model 885 carburetor of the ‘49 Mercury engine, with it’s unusual rear-facing horizontal air intake.

Ford models used the Model 2100, commonly called the ‘94′ because of the venturi size in inches usually cast into the main body.

There’s more on Canadian Mercurys including the Mercury truck, with pictures,  here. 

For a thorough review of most of the special post-war Canadian Fords, there’s a detailed article here.