Stromberg BIG 97

Lawrie

Lawrie

Well-known member
Anyone using one of these,
I,m thinking of getting one for my 265 cuin 99a engine,stock cam and heads.
I currently use one 97 carb on in it. and think it may be a bit small,I have it in my 33.
Lawrie
 
I have this one.
 

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Thanks Rob, on a side issue,I just bought two sets of diff bearings at my local brg joint,all timkin and made in USA.
Lawrie
 
I can say the "BIG 97" was years in the making and has undergone serious research and development. It would be a good fit for any single carb installation such as you mentioned.
 
HI,

I noticed that these are rated at 250 CFM. Does anyone know what the original 97's CFM is rated at?
 
Velocity...the correct word Im looking for?
What would be a flatheads volumetric efficiency be 75% at best?
Just mucking around doing the calculations Lawrie you could be just over 200CFM with a 265 CI.
BUT your towing a lot, I wonder how the lager CFM might effect your bottom end?
Hey if it doesn't work you could always send to me to try on my lightweight truck
; o P
 
One thing to consider is how do the throttle openings of the big 97 match up to the carb mounting pad of a stock inlet manifold? I mention this as I know for a fact that a stock flathead intake (excluding the 8CM) don't have enough meat to open up to match a Rochester 2 gc.
Ain't worth doing if the intake is not opened up to match.
Cfm, what depression was the big 97 tested at to arrive at 250 cfm,
the normal published 150 cfm for a stock 97 is a figure that was tested at 1.5" not the usual 3" that is universal test depression for a 2 bbl carb. 1.5 is what 4bbls are tested at. So to compare flow twix 97 and Big 97 you need to test at the same depression.
Martin.
 
Martin,I haven't looked at the manifold to see if there is enough meat to open up the bores.
And as Talkwrench says ,most of the driving I do in the 33 is towing our caravan (900Kgs) at around 50 mph with the 3.78 rear gears and 17 in tyres,so about 2100 rpm,it gets reasonable gas mileage it that ,about 18 litres /100 klms.
I know the engine would make more power further up the rev range ,but it hardley ever goes above 60 towing,
If I was,t towing I think a 3.54 and bigger carb would be useful,
Lawrie
 
It's too bad they didn't standardize the carb flow depression between all companies. When I worked at Zenith carburetor in the engineering lab years ago, we flowed the carbs at a 2" hg depression. Makes it hard to compare apples to oranges unless you have you're own flow bench.

Sal
 
I have a Stromberg carb that seems to be the same as a 97, except it says "1 1/32" on the side. That would be about 1/16 bigger venturi - would that be considered a "big 97"? I don't know what the carb is from, I bought it at a garage sale.
 
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