Stromberg 97

T

Tanglfoot

Member
I am looking for some advice when fitting a Stromberg 97 carb to my warmed up A Roadster.
IE: jet sizes etc. I am not using a fuel pump as it seems to be going ok with gravity and near empty tank. However it just spits and farts when going through the gears. Does anyone have experience with the 97/ MA combination?
Cheers, Ross in sunny NZ.

The older we get the better we were.
 
Thank you ps/sr you may be correct I am trying to do it without a pump as I had a 94 without pump and it worked ok at low level tank, just thought the 97 would be better as the inlet is 35mm/1 1/4 lower than the 94.
cheers
 
I tried using Mr Gravity, but he just didn't work so well. Fuel pump fixed that bigtime.
 
I recently completed some dynamometer testing on two engines. In both cases we tried to gravity feed a single Stromberg 97 carb and found we could not develop power under a heavy load. When we added a fuel pump to raise the fuel line pressure to 2.5#, the problem ceased.
On one of the engines, we also tried a pair of 48's and a pair of 94's. They were a bit more forgiving. I did not try the 94 as a single but did test a single 48 and when doing so, it had the same loss of power under heavy loading.
Hope you find your solution.
Good Day!
 
Rule of thumb for single 97 carb, flathead banger

Main Jets #45 for 0 - 5000' elevation
jet down 2 sizes for 5000' - 10000'
jet down 2 more sizes for 10000' +

Based on information from the English Stromberg manufacturer and my experiences.
 
I have a single 97 with a 3/8 fuel line, its ok on gravity until I try to stay at 60mph and over. At a lower constant speed its ok, I would suggest that if you go with the pump, always keep an extra line of fuel hose in the car if ever the pump or regulator fails
 
I like the Carter P60504. It's a 12v pump but produces about 2 psi if you run it on 6v

Cheapest I've found is at Rockauto for about $30

Fits neatly in the frame rail and is almost silent
 
My 97 works great on gravity feed,I made my own float valve and it will make full power up a hill with a nearly empty tank.
Will post some pics if you want,a very easy thing to do,and so far trouble free,(20,000 kms)
Lawrie
 
I have a 97 on my 30 Tudor , started out with no pump and had similar problems . The needle / float valve needed some pressure to open . I modified the valve , but still wasn't 100 per cent , so gave up and fitted a pump , no more problems . Lawrie may have the remedy with his valve.
 
Tanglfoot,

I think you need to do like Lawrie did. Modify the fuel valve on the carb by opening up the orifice size a little at a time. Stake it lightly with a solid steel fuel valve needle after drilling to ensure a good seal. You're issue isn't because the jets are too small. With the head pressure from the fuel tank, you probably only have around 1 PSI max. (1/2 PSI for every foot of head pressure). You're problem is that you can't get fuel in the carb fast enough without a fuel pump with a standard small orifice in the fuel valve.

Sal
 
What I did was to open up the inlet hole slightly,but the main thing was to fit a little gizmo to pull the valve off its seat when the float drops.
I used the spring loaded pin assy from an old 97 power valve,drilled a hole in the end of the needle valve, drilled a small hole in the float part that pushed onto the needle valve,fit the pin and spring through and pressed the pin and spring assy into it the needle valve,this has been on my A for 8 or 10 years.
Lawrie
 

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Thank you again to all you very clever people, SBcarb,34 fordor,scicala,juggler.1929 and Lawrie. I will try Lawrys method first.
Cheers
Rosco
.
 
I can see you undertaking the suggestion from Lawrie as a very interesting challenge given your approach to such things Ross. I had similar issues with the Weber on my Roadster - ok till hills or acceleration were required. The Carter pump solved the problem. Happy New Year from Great barrier Island.
 
Ya know, with my experiences using 97s I would say yes, but the metering might be a wee bit different depending on how you have them fueled.

Oh, ya know, now that I think about how he did it, I would say they could be done the same to each and it should work because it is depending on float height to close off the orifice.

Sure, should work.

My 2¢ worth
 
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