Has anyone tried a Rochester 2bbl carb. on their flathead V8. I have seen some adapters to put this carb on the stock intake and wondered if any of you flathead guys have done this swap or no anybody who has. Thank You in advance.

 

I haven't ran a Rochester on a Flatmotor, but I have on other engines.
Get them adjusted right they are as good as any.

 

i got an intake sitting here for i think i was told a lincoln or merc that has two carbs for it , one a stromberg that one of my granddaughter's dropped , oh well jus' kids , and the other a rochester. i've been trying to fab up an adapter to use a regular ford two barrel with no success yet when i've had time . i have also considered the intake and rochester, i've had lots of good luck with those on the street and modified for dirt racing . i'll have to have some bolt holes drilled and other various things done in order to use that intake , but it does have a automatic choke on it ! . so i'd say if ford used them im assuming , they 'd have to work fairly well . p.s. where'd ya see the adapters ?

 

Thank You for your response Dick. Do you see any advantage to running the Rochester? I have the stock Ford/Holley on my truck.

55f350, here is a link to one that I found.



http://www.speedwaymotors.com/p/808,...itemNo=5605159

 

I have heard rumors of there being factory four bolt on a flathead, I have seen pictures but as for seeing in person I have not.

 

I think what you are describing is the Mercury (car) "Teapot" Holleys. If I remember correctly they are 4-bolt 2-bbls. Weird looking things!

 

As far as a running Flathead is concerned, I see no difference.
Parts are easy to get, the carbs are easy to rebuild and tune.
If you're a restorer, forget the Rochester.
Myself, if I can afford it I'm going with sidedraft Webbers.
If I'm short on coin when it's ready to hit the road, it'll be dual stock twice barrels.

The Mercs did use a four bolt Carb, sidedraft airhorns to a downdraft carb. Not exactly K.I.S.S.

 

look in my gallery called flathead parts and there is a picture of the 4 bolt 2 bbl intake there . it's the one with the stromberg sitting on it . weird as it doesnt have all the bolt holes drilled like my 8ba's intake . thanx merten as you probably just solved a big issue with me as even with fuel pressure down to 2.5 pds and everything checking out on the holley its flooding out and dumping fuel in my pan . lots of oil changes eh . i cant beleive i hadn't seen that adapter before as speedway is one of the places im always looking at .

 

I have to wonder if there is any benefit (other than reliability, due to newer carb) to using a bigger carb with an adapter, unless you also port the block and put in a decent cam. The stock manifolds were optimized on cheapness, the stock ports are restrictive, and flatheads came with super-torque cams (peak torque is at 2,000 RPM).

The Canadian 8BA's/8RT's came with aluminum manifolds, that are avaliable cheaply and weigh about 15 lbs less -- that might be more of a boost!

 

Hi Ross,
By bigger carb do you mean dimensionally or CFM? Would anyone happen to Know what the CFM rating is for a stock Ford/Holley for the 239. I would imagine that the Rochesters would be all over the map depending on what application it was made for.

 

Holley 94 was 125 cfm.

 

125CFM?,I had no idea that it was that small of a carb.

 

Two-barrel carbs are rated at a different condition than 4-bbls; you can't directly compare one with the other. A 125 cfm 2-bbl is roughly equal to a 250 cfm 4-barrel. Not like a flatty is going to be at 7,000 RPM tho! They were built for low-end power, not like sewing machine motors they make nowadays.

 

Hi Ross,

We are not talking about 4bbl carbs here, the adapter is for a 2bbl Rochester.

Chris

 

Well as they say 390cfm is the most you should have on a 239 (with a 4 barrell). In saying that for a single 2 barrell I wouldn't go much over 200 cfm.
That is one reason why using multiple Holley 94s is so popular.

I think what Ross was getting to is that on a 2 barrell all the cfms are going through the motor at ALL times but on a 4 barrell at a idle only half the cfms are being used.