The Stovebolt Site Forums The Shop Area Engine Shop Why The Glass Bowl On Top?

All my tractors had the glass bowl on the bottom. Made it much less messy to remove and dump the water/fuel/dirt.

Why are the Chevy versions on the top of the fuel pump?

Contrary to popular belief, the glass bowl on top of the Chevy fuel pump is not a sediment bowl. It is a clear cover to allow you to see if the filter screen in the pump is clogged or whatever.

The AC glass bowl inline fuel filters with the replaceable paper element are also not sediment bowls. Many people install them with the glass bowl on the bottom under the mistaken belief that they are sediment bowls.

They are not. The turbulence created by the fuel when it enters the filter bowl is such that no sediment will settle at the bottom. Debris is trapped in the folds of the paper element. Chevrolet and Cadillac refer to the glass bowl in literature as the fuel pump cover or fuel filter cover, never as a sediment bowl.

Cadillac may be the only GM maker that installed the AC filter "right side up" with the glass bowl on top.

On some early Ford engines they were installed bottom down and were indeed sediment bowls. Those were also hard to keep sealed at the top of the clear bowl. You would see gas dripping out when they pulled in to a gas station...always unnerving. Then sometime in the mid or late 50s Ford changed the design of the pump and the bowls had to be mounted facing up when the fuel pump was replaced (or you had to do some clever re-routing of the fuel line). As I recall the new pump design put the bowl too close to the exhaust manifold (especially on sixes) and caused vapor lock.

Cool question and great informative answers!

Cadillac and possibly Oldsmobile (?) engineers had a "rectal-cranial inversion" when they deciced to put the fuel pump on top of the engine. Not only was it up there where the engine compartment was the hottest, but fuel pumps push gasoline a lot better than they lift it. Cadillacs in particular were bad about vapor lock and/or low pump volume, especially when somebody installed an AC pump instead of a Carter. There was something like a 14 inch lift between the gas tank and the pump. Flathead Fords had the same kind of issues with the pump mounted right over the valve valley.
Jerry

My 4010 JD diesel has the glass bowl on top of the pump just like my old Chevy truck.

I've been told before about the 331/365/390 propensity for vapor lock but in the 23 years and 150,000+ miles that I've driven the Bismark, I've fortunately never suffered from it. That includes hot summers in Atlanta and regular trips to Tampa, Florida in it.

D you happen to know if the Cadillac 390 shares a bellhousing bolt pattern with any of the other GM engines- - - - -possibly Buick/Olds/Pontiac? I'm thinking about trying to mate up a 390 with some variation of a turbo 350 or 400, possibly. Currently, it's got a Controlled Coupling Hydramatic on it.
Jerry

There are two Cadillac 390s. The original postwar overhead cam V8 331/365/390 will not mate with a TH350 or TH400. They used the Hydramatic transmissions.

This engine's successor was a completely different 390 - the precursor of the hated Cadillac 429. It was introduced in 1963, whereas the TH400 debuted in 1964. The '63 390 still utilized the old Hydramatic transmission - Jetaway on Oldsmobiles.

The 1964 Cadillac 429 utilized the TH400.

I'm not aware of any adapters available to mount a TH350 or TH400 on an engine originally equipped with a Hydramatic.

This one's a 61- - - -one of the last of the Kettering-designed Cadillac engines. Looks like I might have to design my own adapter plate. I've got a spare Hydramatic bell housing stashed away to use as a pattern. The engine is headed for an Excalibur fiberglass roadster body, with a Toyota Supra independent suspension rear end and probably some sort of M-II IFS with rack & pinion steering. It will have a slight resemblance to the old Cadillac-powered Allard sports car from the early 1950s.

dobsonmotorsport.com/car/1950-cadillac-allard-j2/

Jerry

Good luck. Many have wished to convert their Cadillacs to TH400 but the task isn't as straightforward as one might think. Of course most people aren't machinists, like you so you may succeed where others have failed.

Gentlemen, we’re starting to stray too much, please keep this thread on the subject.

Leakage at the glass bowl generally was caused by a shrunk gasket, or someone using an aftermarket paper gasket.

If you have this issue, check your FLAPS and ask for a 1/8 inch thick sheet of rubberized cork gasket material, and cut your own gasket.

Jon