Stromberg BIG 97

[av8coupe]

I think that would be a Stromberg 48. Dave

[Tim Brown]

Running this back up to see if anyone is running a Single Big 97 and what jets and power valves are working. They ship out with #56 jets in them.

[Russ/40]

If someone wouldn't mind, i'd like a tutorial on 2" hg depression. What is the "depression" concept.

[deuce_roadster]

Maybe Lincoln Jim in Wisconsin?

[Pete]

Recently I furnished the valve train for a 304 that is running 3 big 97's.
It could use a 4th because it is pulling about 2 inches of vacuum.
Knowing the owner though, he may opt for electronic Hilborn's instead.

[scicala]

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Originally Posted by Russ/40

If someone wouldn't mind, i'd like a tutorial on 2" hg depression. What is the "depression" concept.

The 2"hg depression being talked about is how a flow stand is set up to measure total CFM air flow capacity at a manufacturer's facility or other business. 2"hg is the same as 2" of manifold vacuum (mercury = hg).


When flowing a carburetor, after mounting the carburetor on a flow stand, you open the carburetor to wide open throttle (WOT) and adjust the vacuum pump for 2"hg or any other amount you want. When I worked at Zenith Carburetor in Detroit we used 2"hg as the standard. Then when at WOT at 2"hg, the air flow going through the carb was measured (CFM). The higher the depression, the higher the air flow.


Holley measures two barrel carbs at 3"hg depression and four barrel carbs at 1 1/2 or 2" depression. That is why they say a two barrel Holley carb with the same size venturi's and throttle bores flows more air than a four barrel carb (just two of the barrels) with the same size venturi's and throttle bores.
To me this just makes things confusing and comparing apples to oranges sometimes.


Sal

[Tim Ayers]

Originally Posted by Pete

Recently I furnished the valve train for a 304 that is running 3 big 97's.
It could use a 4th because it is pulling about 2 inches of vacuum.
Knowing the owner though, he may opt for electronic Hilborn's instead.

Hey Pete:

Wondering if you could provide more details about valve train work you did?

I'm starting to think two "regular" 97's won't be enough on my 296.

Thanks,

[Pete]

Originally Posted by Tim Ayers

Hey Pete:

Wondering if you could provide more details about valve train work you did?

I'm starting to think two "regular" 97's won't be enough on my 296.

Thanks,

404A cam. Drilled radius lifters. Bronze guides. Titanium 1.7 dia. valves. 4 turn springs with dampers. Titanium retainers.

2 regular 97's will work fine for mild street driving and parades.

[Tim Ayers]

Originally Posted by Pete

404A cam. Drilled radius lifters. Bronze guides. Titanium 1.7 dia. valves. 4 turn springs with dampers. Titanium retainers.

2 regular 97's will work fine for mild street driving and parades.

Haha. Yeah, I'm no where near that beast you built. 1.6" valves, full porting and relief work.

[Russ/40]

Sal, thank you for the explanation, much appreciated.

[swanwaco32]

I have installed them on a 383 small block chevy after having tripower with Rochester's and they do flow a lot more than the 2g Rochester's..!! Not sure the flathead would take it??

[Bored&Stroked]

Originally Posted by Pete

404A cam. Drilled radius lifters. Bronze guides. Titanium 1.7 dia. valves. 4 turn springs with dampers. Titanium retainers.

2 regular 97's will work fine for mild street driving and parades.

Well that type of driving DOES NOT include me! LOL Hope all is well with you Pete - haven't chatted in awhile, I think we need too. I have two 48's on my 284 CI engine, is far too little. I'm sticking with this manifold for now (due to the build period, but it is NOT optimal).

I'm going to port another "spare" Eddie Meyer top and first try two Holley 2110's (on an engine dyno - want to see if the flow helps), then I'd like to try two Big 97's. Would be a fun experiment.

Take care my ole' friend.
D

[tubman]

Originally Posted by swanwaco32

I have installed them on a 383 small block chevy after having tripower with Rochester's and they do flow a lot more than the 2g Rochester's..!! Not sure the flathead would take it??

How do you arrive at this conclusion? As far as I have ever known, a small base 2G flows about 275 cfm, while these are rated at 250 cfm.

While these may be alright to use on an SBC manifold, I believe that there may be problems on standard, 3-bolt Ford manifolds. I am very partial to 2G's on a street flathead in a car with a hood. I have found that, while the Mercury manifolds have enough "meat" in them to permit them to be bored all the way down to 2GC size, most Ford manifolds won't take it. I suppose this may not be a problem with "racing" manifolds without provision for exhaust heat, but I would not want to "roll the dice" on a heated Ford manifold. Just one more thing to consider. Unless you bore the manifold to match the throttle bores on the carburetor all the way (and possibly radius the corners like I do), you will not get full benefit of the larger carburetors.

[revkev6]

Originally Posted by Bored&Stroked

Well that type of driving DOES NOT include me! LOL Hope all is well with you Pete - haven't chatted in awhile, I think we need too. I have two 48's on my 284 CI engine, is far too little. I'm sticking with this manifold for now (due to the build period, but it is NOT optimal).

I'm going to port another "spare" Eddie Meyer top and first try two Holley 2110's (on an engine dyno - want to see if the flow helps), then I'd like to try two Big 97's. Would be a fun experiment.

Take care my ole' friend.
D

Interesting that you are trying this dale. I'm building a blower setup and want to stick with 2x2 on it because three looks too crowded on the Eaton m112. I picked up a really nice 2110 that I need to find a match for. 1 5/32 venturis. Manual choke with plugged valve factory. Havent seen another like it. Basically looks like a big bore replacement for a 94

[Tim Ayers]

Originally Posted by revkev6

Interesting that you are trying this dale. I'm building a blower setup and want to stick with 2x2 on it because three looks too crowded on the Eaton m112. I picked up a really nice 2110 that I need to find a match for. 1 5/32 venturis. Manual choke with plugged valve factory. Havent seen another like it. Basically looks like a big bore replacement for a 94

I wonder if this is a what was called the Bug Spray carb? Bug Sprays were used on VW's when putting a performance 2bbl. set up on the car.

[revkev6]

Originally Posted by Tim Ayers

I wonder if this is a what was called the Bug Spray carb? Bug Sprays were used on VW's when putting a performance 2bbl. set up on the car.

i looked up the number and it wasn't a bugspray carb. pretty sure it was an oem ford unit or replacement from the 50's. the bugspray units have electric choke if I'm not mistaken.

[Ol' Ron]

Does amybody have any idea what the two 2GC carbs floe. The make the small onr that bolts to the Merc intake and a larger one. I've never seen any data on them, Or forgot??

[revkev6]

Tubman said the small base is 275 a couple posts up

[Tim Ayers]

Originally Posted by revkev6

i looked up the number and it wasn't a bugspray carb. pretty sure it was an oem ford unit or replacement from the 50's. the bugspray units have electric choke if I'm not mistaken.

Hmmm. I had what I thought was a Bug Spray on my VW and it had a manual choke. You are probably right. I was a dumb kid when I owed it. Haha.

[scicala]

Originally Posted by revkev6

Tubman said the small base is 275 a couple posts up

I think there were also different venturi sized small base 2 GC's, since they went on a lot of different size engines on GM and marine engines.
So probably the 2GC's from larger engines flowed 275 CFM.


Sal