buick standard six marvel carbaretor alternative

[Guest nmcawley]

I'm considering reversing my inlet manifold and changing to an su. Can anyone recommend what size to use and what needle size to use? Are there better alternatives i should consider?

[MCHinson]

nmcawley,

Welcome to the AACA Discussion Forum. I have moved your post to the Buick Pre-War Forum. Hopefully someone will be able to help you here.

[Guest nmcawley]

Many thanks

[Mark Shaw]

I never did well with the SU carbs on my old MG. I didn't have the tools to get them synchronized.

Before you give up check out this article... The Marvelous Marvel Updraft Carburetor</SPAN>

One of the most condemned and abused components in Buicks from the teens to the early thirties is the infamous Marvel Carburetor. Many Buick owners have plugged their exhaust heat systems and either replaced their original Marvel Carburetor with a Zenith, Carter BB1, or some other updraft carburetor. Some just gave up and flipped their intake manifold to install a more fuel efficient downdraft carburetor to improve both performance and mileage in their cars. </SPAN></SPAN>

I still run original Marvel carbs in most of my Buicks. I use full choke from a cold start & usually need to keep the choke out 1/3 to 1/2 until the engine warms up. This seems to be normal for Buicks with or without working exhaust heat systems. Mileage & performance is not as good as downdraft carburetors, but I believe that keeping these old girls going with their original equipment is part of the pleasure in driving and maintaining these old cars.

The most common cause of Marvel carburetor problems seems to be the need to replace the 70-80 year old cork float. I know that many prewar Buick owners will struggle to get their Marvel carburetor to work properly with these old dried up cork floats. It would be rare for such old cork floats to work reliably, so they must be either be replaced or coated to prevent saturation. </SPAN></SPAN>

The purpose of the float is not just to start and stop fuel flow to the engine; it also continuously maintains the correct fuel level at the jets. The jets are carefully sized to atomize and supply the correct volume fuel & air to the engine at all operating speeds. If the fuel level is too high or too low, the jets will either starve or flood the engine. Sound familiar? </SPAN></SPAN>

I have several old books and manuals that troubleshoot and/or explain the various designs and theories of how all kinds carburetors work. I also have Harold Sharon’s book “Understanding Your Brass Car” that explains how any do-it-yourself amateur can replace the cork in an updraft carburetor to drastically improve performance. Harold explains in simple terms how you can use “Crazy Glue” & wine corks to make a replacement cork float to fit in almost any carburetor. He also states that coating the cork is not necessary. I expect that gasoline additives & ethanol in modern gasoline would probably dissolve any of the old recommended shellac coatings and gum up everything anyway. But, I know that model airplane dope or Crazy Glue can be used to seal cork floats.

Another relatively common problem with Marvel Carburetors is with the main jets that develop small cracks. These cracks can easily be soldered to solve the problem. Just run a drill bit with the same inside diameter through the jet after soldering to make sure excess solder does not restrict flow.

The ultimate alternative is to flip the intake manifold and bolt on a Rochester carb from a "stovebolt six" GM engine. There are several models of this carb...with and without automatic choke. My son is considering doing this on his 29 Buick. If you keep all the original parts, this modification can easily be reversed if you or the next owner prefers to show the car. </SPAN>

[FLYER15015]

I'm considering reversing my inlet manifold and changing to an su. Can anyone recommend what size to use and what needle size to use? Are there better alternatives i should consider?

Though I have installed several Jag S.U.'s on old Harly's, I have to go with Mark on this one. When you flip the manifold, there are several GM carbs at your disposal, OR you could try a Stromberg 94 or 97 if you really want to "get out there", but a carter or rochester is probably your best bet, subject to the mounting bolt pattern.

Mike in Colorado

[Old26Buick]

I have flipped the intake on both my 26 Standard and my 27 Standard Woodie Wagon and used a one barrel Stromberg Carb. They both run super. never even have to use the choke. I used an electric fuel pump by tank and a pressure reg on the firewall. But not be stock but sure runs nice. Good Luck

=FLYER15015;1171751]Though I have installed several Jag S.U.'s on old Harly's, I have to go with Mark on this one. When you flip the manifold, there are several GM carbs at your disposal, OR you could try a Stromberg 94 or 97 if you really want to "get out there", but a carter or rochester is probably your best bet, subject to the mounting bolt pattern.

Mike in Colorado

[Dwight Romberger]

Old26Buick,

May I ask which Stromberg you used?

Thanks,

Dwight

[carbking]

The Rochesters from the stovebolt Chevrolet six are readily available and quite cheap! The reason: many of the stovebolt six owners got tired of the problems with the Rochesters, and replaced them with Carters.

Jon.