Stromberg Big 97 on a stock manifold?

[SoCalCoupe]

Don't see any posts on this topic in the past couple of years. I'm considering a Big 97 (that flows 250 cfm and has 1.175 in. venturis) on a stock 1941 manifold.


1. Anyone tried this?
2. Are the ports in the stock '41 manifold big enough for the carb or do they need to opened up?
3. Will the manifold flow enough to support the carb?


Seems like a great way to get maximum supportable carburetion on a stock engine for someone who isn't interested in fooling around with dual carbs.


Stromberg BIG 97
stromberg big 97
New Stromberg BIG 97

[tubman]

I can't really offer any direct help, but I will tell you that your ideas are correct. I have a 255ci Merc in my '51 Ford club coupe with a bored out late Mercury manifold and a Rochester 2G from a 283 Chevrolet and it runs great. The 2G is about equal to two 94's without the complications.

Multiple carburetors are for cars without hoods, not daily drivers.

[SoCalCoupe]

Originally Posted by tubman

I can't really offer any direct help, but I will tell you that your ideas are correct. I have a 255ci Merc in my '51 Ford club coupe with a bored out late Mercury manifold and a Rochester 2G from a 283 Chevrolet and it runs great. The 2G is about equal to two 94's without the complications.

Multiple carburetors are for cars without hoods, not daily drivers.

Thanks for the feedback. Did you bore out the manifold yourself? Thoughts on where to get advice on steps in the process?

[J Franklin]

Fun thoughts, I once had a 1957 Chevy with a Corvette 283 305 Hp dual quad setup. It was fast but got seriously faster after adding one Rochester carb and manifold from a 365 HP 327. The car then was dynoed at 335 HP after just that change.

[tubman]

Originally Posted by SoCalCoupe

Thanks for the feedback. Did you bore out the manifold yourself? Thoughts on where to get advice on steps in the process?

I used a tool called a "Rota-Broach" to bore out the Merc manifold to match the throttle bores on the carburetor. I used an extra 2G base as a guide and did it with my cheap bench-top drill press. I have done several manifolds (both aluminum and cast iron) with no problems. The Mercury manifolds have plenty of "meat" to allow a 1 7/16" bore. I believe "Ol' Ron" on this forum has said that the Ford 3 bolt carb manifolds sometimes will not accommodate this size without breaking through to the exhaust heat chamber. This is why I grab any late Mercury manifold I come across. A "small base" 2G bolts directly onto the Mercury manifold.

[aussie merc]

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yes they work fine without any mods to manifold but to get the best out of them you will need to massage the intake passages Stromberg actually post the directions for this on their web site

[SoCalCoupe]

Originally Posted by aussie merc

yes they work fine without any mods to manifold but to get the best out of them you will need to massage the intake passages Stromberg actually post the directions for this on their web site

Found the article. https://www.stromberg-97.com/cms/upl...ify-intake.pdf


In a nutshell, enlarge the throttle bores to 1.4" (not totally necessary) and remove the webbing between the bores at least an inch down. That's only slightly less than the 1 7/16" that Tubman has heard was a bit too much for a Ford manifold.



The way it's written sounds like the emphasis is on removing the webbing rather than drilling out for bore size. Have to take a close look at the manifold to see about removing some of the webbing; don't really know how they're designed/constructed.

[tubman]

Please be aware that the 1 7/16" throttle bore measurement I quoted is for a small base 2G Rochester. I am not sure that the "Big 97" is quite that large, so you may be able to get away with it. Back when he was racing at Danbury, I believe "Ol' Ron" and the rest of the guys had problems with the 2G's on Ford manifolds; the new "Big 97's" may work ok.

2 BBL manifolds are cheap and available - try it.

[V8COOPMAN]

Originally Posted by J Franklin

Fun thoughts, I once had a 1957 Chevy with a Corvette 283 305 Hp dual quad setup. It was fast but got seriously faster after adding one Rochester carb and manifold from a 365 HP 327. The car then was dynoed at 335 HP after just that change.

Hmmm....The only two dual quad 283s in '57 were rated at either 245 or 270 brake horsepower. In fact, 283 bhp was the highest offered that year with the solid lifters & Rochester F. I.

And I know just a little bit about the L-76 365 bhp Corvette engines offered in '64 & '65 Vettes. I just sold my '65 365 horse coupe that I've owned for 35 years, not to mention the 365-327 in my '40 Ford coupe. 365 HP engines have a Winters aluminum intake #3844461 with a "2818" HOLLEY carb. DD
.

[tubman]

I thought the 365 HP 327's had AFB's or Holleys.

[tubman]

Originally Posted by SoCalCoupe

Found the article. https://www.stromberg-97.com/cms/upl...ify-intake.pdf


In a nutshell, enlarge the throttle bores to 1.4" (not totally necessary) and remove the webbing between the bores at least an inch down. That's only slightly less than the 1 7/16" that Tubman has heard was a bit too much for a Ford manifold.



The way it's written sounds like the emphasis is on removing the webbing rather than drilling out for bore size. Have to take a close look at the manifold to see about removing some of the webbing; don't really know how they're designed/constructed.

I just looked at this thread again. You have to realize that the later (post '33) Ford intake manifolds were dual plane designs, designed to take advantage of the newly developed 2 barrel (Stromberg 48 and 97) carburetors. Although I have never experimented with it, I would have to believe that removing the separation ("webbing") in the intake manifold would be counter productive because of this

[Lawrie]

I cut up an old 35 manifold and there is not enough metal to enlarge the bores with out breaking into the heat risers.
Lawrie

[V8COOPMAN]

Originally Posted by tubman

I thought the 365 HP 327's had AFB's or Holleys.

It did....a 2818 HOLLEY! *See the post just above.

I'm thinking that the last AFB was on '63 340 HP Vette, and on the '65 409 hi-horse engines in sedans. DD
.

[J Franklin]

My 283 was a'59 Vette engine, I was told the carb was a Rochester but It was a long time ago so maybe things are foggy. What I remember most about the setup was the tune center having a hard time believing the hp output on the dynometer. When I raced and won over larger engined cars they made me pull over and show them that they were beat by a 283 three speed Chevy. Forgot to mention it also was blueprinted and clearenced. I ran it at Lyons Drag strip in California.

[Tinker]

I think running a large 2 barrel single carb on a flathead is a great idea vs duals. It's an interesting idea outside a 4 barrel intake and that. To take it back on topic outside of what carb is on a sbc350.



Can you run a 4 barrel intake with a two adapter? If so can you run a roundy-round 2 barrel holley 350 cfm well?


Probably have to find a flathead truck manifold that runs a big 97. Bolt patterns are probably the same but I don't know on the big lincoln flathead blocks.


you could probably make an 2" adapter.

[Ol' Ron]

I've always run the 2GC on a 4bolt merc intake bores out . Never had a problem, also ran the modified Chevy dist. Great combination.
On thestock car I used an early 33/34 "camel back" intake bored out tho fit the 2gc, however I had to sleeve the bore I used some alum tubing and epoxy You can use the 2gc or big 97 with an adapter, but you don't get the benefit of the larger carb. Either bore and sleve your 40 intake or use a late merc intake.

[51 MERC-CT]

Originally Posted by Tinker

I think running a large 2 barrel single carb on a flathead is a great idea vs duals. It's an interesting idea outside a 4 barrel intake and that. To take it back on topic outside of what carb is on a sbc350.



Can you run a 4 barrel intake with a two adapter? If so can you run a roundy-round 2 barrel holley 350 cfm well?


Probably have to find a flathead truck manifold that runs a big 97. Bolt patterns are probably the same but I don't know on the big lincoln flathead blocks.


you could probably make an 2" adapter.

Did make an adapter once for a 350 Holley and determined it to be a waste of time.
Now I just run a 4 barrel carb on a 4 barrel manifold.
The carb functions (in my case) as a 2 barrel carb at least 99.999% of the time.

[tubman]

I feel I should clarify a couple of things.

First, regarding "Chevrolet carburetors"; These are actually called "2G"'s and are made by Rochester. They come in two distinct versions : "small base" and "large base". which are actually quite different from each other. The mounting bolt pattern is the main difference, which is important, as the "small base" uses the same mounting bolt pattern as the Holley's used on '49-'53 Mercury's. The "large base" versions have a slightly larger mounting bolt pattern which really complicates things, as it is not close enough to use by elongating the bolt holes, but close enough that it makes fabricating an adapter difficult. The "small base" versions came on 265 and 283 Chevrolets and perhaps other GM products. They were used mainly in the late '50's and early '60's, and as such, are getting hard to find. A 2 barrel for an "sbc350" would definitely be a "large base" and as such, would be pretty useless for our purposes.

As to Ford truck vs. car manifolds, I don't think there is any differences other that the part numbers on the later manifolds (8BA vs 8RT). The carburetor mounting pattern and throttle bore sizes are certainly identical. As to Lincoln (and large ford truck) manifolds from the 337 ci flathead, they are completely different with no possibility of interchange.

[Grassman]

51 MERC-CT, what 4bbl carb do you use, I'm wanting to do he same on my 47 pu, thanks for your reply. Grassman.

[1952henry]

The manifolds Tubman referenced actually have 8BA8RT cast into them. So, yes, they are the same. And no 97s came on these from the factory.

[scicala]

"I'm thinking that the last AFB was on '63 340 HP Vette, and on the '65 409 hi-horse engines in sedans. DD"

I know this isn't Ford stuff. but the 327 Chevy also used the Carter AFB on the 300 HP version through 1965. The 327/250 HP used the Rochester 4GC.

Sal

[51 MERC-CT]

Originally Posted by Grassman

51 MERC-CT, what 4bbl carb do you use, I'm wanting to do he same on my 47 pu, thanks for your reply. Grassman.

Running an Edelbrock 1403 (500 cfm) with crossover linkage to orient the carb the way I want it.

[SoCalCoupe]

Great discussion, learning a lot here. Looks like matching the intake is not as simple as hoped for. Trying to learn the differences between all the 32-53 intakes. 49-53 intakes not worth the trouble on a stock 41 engine. There are five 32-48 single-carb intakes on eBay right now between $40 - $100. Pretty cheap to experiment on one of them.


Never heard of a "camel back" intake but if was trying to think up a name, that would be it for 4 of the 5.



Distributor is a stock 1941 diver's helmet so need unported vacuum for the advance brake like on my stock '41 manifold. Don't understand why none of the ebay manifolds have a vaccum port for the distrubutor and windshield wiper. Maybe they're all 42-48?


Seems like it wouldn't be too hard to just drill a vacuum port into a runner and install a bung, would it? Just wouldn't want to drill into a heat passage.


Just for the record, my performance goal is to comfortably keep up with 70 mph traffic on the interstate.

[V8COOPMAN]

Originally Posted by scicala

"I'm thinking that the last AFB was on '63 340 HP Vette, and on the '65 409 hi-horse engines in sedans. DD"

I know this isn't Ford stuff. but the 327 Chevy also used the Carter AFB on the 300 HP version through 1965. The 327/250 HP used the Rochester 4GC.

Sal

You know what, Sal? You Sir, ARE absolutely correct. I had completely forgotten about the 300 horse cars. In fact, never owned a Vette with any of the lower horse engines except for my very first....a '59 with 230 horse. Good catch! DD
.

[V8COOPMAN]

Originally Posted by 51 MERC-CT

Running an Edelbrock 1403 (500 cfm) with crossover linkage to orient the carb the way I want it.

MERC ....That is one NICE, well-thought-out adapter. Of course, I would have expected no less from you. Slick piece! DD

[SoCalCoupe]

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Obviously I’m trying to make this an easy job and avoid boring and sleeving an intake.


Maybe the first thing to do is simply chamfering an 1/8” around the bores to match the carb and intake surfaces and avoid the step. Maybe boring down an inch or two isn’t necessary. Stromberg really wants us to remove part of the web between the two ports but says “[o]pening up the web to around an inch deep would still do the job.”



Stromberg says, “BIG97s also feature a new oval shape, carved out just under the throttle plates, which brings the two separate barrels of air together before they hit the intake plenum. This ‘early plenum effect’ allows any cylinder to draw from … [both]… barrels combining the strong torque/easy drivability characteristics of a dual plane intake with the kind of power curve improvements more usually associated with a single plane.” Here’s a picture.


They go on to say that, “[t]he intake manifold modifications recommended here enhance that effect…”


Here’s Stromberg’s dimensioned drawing of the Big 97.





Their recommendation says, “Your first task is to open out the carb intake ports to avoid a step under the carburetor.” They also note that “Research shows that most of the flow is down the center of the port, with very little activity near the walls, so there is very little to be gained by perfect matching or polishing.”



Maybe I’m reading into it only what I want it to read but it would be nice avoid extra work.

[51 MERC-CT]

"Their recommendation says, “Your first task is to open out the carb intake ports to avoid a step under the carburetor.”

To me. this says it all for normal use.

[SoCalCoupe]

OK. I'll be the guy to try out a single Big97 on a stock 1941 flathead.



Spent countless hours looking at flathead intakes on the internet trying to understand the playing field, new to all of this. This one looks a lot like mine (stock 1941.) It has a "shelf" with a vacuum port on top of a dual plane manifold. Looks like it would be REALLY easy to port match (not bore) this to the BIG97 to remove the step and take out some of the webbing to mostly meet the Stromberg recommendation and not risk cutting through to the heat riser.




Very cheap to buy one of these manifolds on eBay.



What's bothering me though is how to clean the shavings out of the manifold before installing it so none of them end up in the engine. Really hung up on the cleaning step. Never done anything like this before and don't have tools like a pressure washer, media blaster or even compressed air.


Recommendations please.

[J Franklin]

Soap and water should be able to flush it clean. Use a hose & nozzle.

[34fivewindow]

Originally Posted by tubman

I thought the 365 HP 327's had AFB's or Holleys.

Only 327 with the AFB was the 300 and 340 hp engine.

[Ol' Ron]

I don't see the advantage in running a "Bell mouth" on the intake port to run a larger carburetor.
Gramps

[Bored&Stroked]

Originally Posted by 34fivewindow

Only 327 with the AFB was the 300 and 340 hp engine.

That is correct - had a 62 and a 65.