Tea pot carb help

[Mike51Merc]

Manifold (below the throttle plates) vacuum drops when the throttle is opened. Venturi (above the throttle plates) vacuum increases with engine RPMS. They are kind-of opposite but not exactly.

A "normal" or "typical" vacuum advance distributor increases timing advance when the vacuum signal drops.
A load-a-matic advance increases advance when the vacuum signal increases.

So, no, you can't T them together and expect good results.

[scooder]

Also you have to understand that the loadamatic does not use a combination of manifold vacuum and ported vacuum.
It uses ported vacuum (slightly above the throttle plates) and venturi vacuum (at the venturi of the carb (the narrowest point) only loadamatic carbs have the venturi junction for vacuum. The vacuum ports are connected inside the carb. Manifold vacuum would peg the timing at full advance at idle, not good.
When all working and correct, it's a good system, that works fairly well. Problem is most are a bit stiff on the advance plate, been fiddled with on the spring tension and plain wore out. Because of this they ain't given a fair chance. Folk are to quick to heave them out and plop something else in there, oftentimes an aftermarket ignition (Mallory) that has a sbc ignition curve in it !! In this case, with a stock engine, a loadamatic in good condition would be a whole lot better than that bloody red cap of disappointment.
Martin.

[scooder]

Mike,
A "normal" vacuum advance does increase timing with increased vacuum. When the vacuum drops, it decreases timing advance.
The big difference is that the loadamatic gets its engine speed input via the venturi vacuum signal, and balances this with ported vacuum for load input. Normal stuff engine speed via the advance weights, balanced with ported or manifold vacuum for load input.
Forgot to say before, a good loadamatic gives good mpg to boot, in good fetal.
Martin.

[rotorwrench]

The later Merc 885 carbs starting in mid 1950 have a small nylon ball valve in the tube connecting the two venturi vacuum sources together. This ball check stops the flow of the throttle plate port when near full throttle in order to get max vacuum advance. At somewhere less than full throttle, the ball falls back down onto the little pedestal rod that is attached to the ball valve chamber access screw. The pedestal rod keeps the ball from sticking down at the bottom of the chamber at normal throttle opening settings and allows pressure to flow at idle. If the ball gets lost during a rebuild or gets sticky from crud while in service then the timing suffers near wide open settings.

I'm not sure if the later open top carbs have this feature or not but I would figure that they do.

[scooder]

Chopper bloke,
I like the principal behind that little ball, it does seem to make sence, a clever idea.
It apparently worked good. If you've read about the mechanics illustrated Ford (MI FORD) the 885 was used on an 8BA engine fitted with Granatelli heads (8.5:1 if I recall) dual exhaust with glass packs and a stock loadamatic ignition bar a Mallory coil and condenser, which was fitted to eliminate a miss in the ignition above 100mph. Performance was good, don't recall the numbers, and I'm away from my stuff. It was an otherwise stock 50 or 51 Ford if I recall.
Same heads, carb, ignition, exhausts them went on a 0.040 over 8BA with porting and polishing and a mild cam. Got 158 hp!
The only spec he gives for the cam is the fact you can idle along below 10mph in high with no jumping or bucking, and that low speed power wasn't apparently effected. Shows a pic of him spuddleing along window open with dog walking alongside on a leash.
Sorry for calling him him, can't remember his name or the date of the magazine.
Seems to me, that loadamatic works pretty damn nice on this car.
The article is worth a dig out for a read, it gives the mpg, mph, hp and acceleration improvements.
I'm sure it didn't have headers fitted. Even before the jump to the new engine, the Ford was faster top speed and acceleration of the fastest new US manufacturer cars, the new caddy and the olds rocket 88!
Martin.

[V8COOPMAN]

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[QUOTE=scooder;1116682]Chopper bloke,
I like the principal behind that little ball, it does seem to make sence, a clever idea.
It apparently worked good. If you've read about the mechanics illustrated Ford (MI FORD) the 885 was used on an 8BA engine fitted with Granatelli heads (8.5:1 if I recall) dual exhaust with glass packs and a stock loadamatic ignition bar a Mallory coil and condenser, which was fitted to eliminate a miss in the ignition above 100mph. Performance was good, don't recall the numbers, and I'm away from my stuff. It was an otherwise stock 50 or 51 Ford if I recall.

Shows a pic of him spuddleing along window open with dog walking alongside on a leash.
Sorry for calling him him, can't remember his name or the date of the magazine.
QUOTE]

You wouldn't be referring to Tom Mccahill and his black lab Joe, would you? DD

[scooder]

Double D,
That's the very man and his dog.
I do like his written word, good wordsmith.
Thanks for the reminder.
Martin.

[rotorwrench]

When I was a kid, I compared the performance of my hand me down 51 Merc to other cars of the 50s & early 60s and the old car would run pretty good by comparison. It was impressive how such a heavy car with only a 255 flathead would run in stock configuration. It would keep up with most larger V8s of the period. Big blocks would thump it but not too many stock small blocks or 6-bangers would walk away from it. The overdrive helped but the motor had the torque to keep up for sure. By the early 70s I was already having problems finding parts for it. Now days you can get about anything but back then just getting a carb kit for that 885 was a long affair with phone calls & snail mail through Hemmings. I kept the car and eventually my Pop gave me the title to it. I'm sure glad for the internet and all the shipping companies we have now. Getting parts in south western Kansas was near impossible back in that time frame and my uncle ran the local parts store too.
Observations from Kerby

[tjfl]

Operating principle makes perfect sense... I'm sticking with the loadamatic.

[scicala]

Scooder and rotorwrench, it's nice to hear people that understand how the Loadomatic system works.

Going back to the nylon ball in the vertical channel between the ported vacuum hole and the venturi vacuum hole, speaking for Teapot carbs only, that ball was eliminated in about mid-year of production in 1955. Still had the same ported hole and venturi hole, so not sure if they changed distributor springs when they eliminated the ball. They also had at least two different color balls. Not sure if it was a weight difference or diameter difference. This is all based on the parts lists and pictures from my Holley manual.

Sal

[scooder]

Sal,
Thanks for the nylon ball info in the teapot.
I'd think if there are different colour balls there is a difference, like the different colour speedometer gears in the post 49 stuff.
Martin.

[RalphG]

I still have a lot to learn about the Holley "teapot" on my 52 Merc so this discussion has been interesting. I find there is a very good 40 page online manual describing the operation of the carburetor here. http://www.oldcarmanualproject.com/m...901195215.html

[scicala]

Thanks Ralph. Gotta love the Old Car Manual Project.

Sal