Need some advice from 2-bbl iron intake experts
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Need some advice from 2-bbl iron intake experts
We're building a full race 270" V8 which has to run with OEM iron intake and exhaust. The best available intake seems to be the older higher-rise 2-bbl. The later 4-bbl intakes are a lower profile.
Would something like the 600 CFM Quick Fuel 2-bbl on a theoretically better intake be a better choice than a 600 CFM Edelbrock on a lower profile intake? (I know OEM 2-bbls are rated at 3" and 4-bbls at 1.5", but are race carbs also rated that way?)
Yes, we hope to get both intakes on the flow bench in the near future.
Are there any other 2-bbls a better choice for road racing?
Would something like the 600 CFM Quick Fuel 2-bbl on a theoretically better intake be a better choice than a 600 CFM Edelbrock on a lower profile intake? (I know OEM 2-bbls are rated at 3" and 4-bbls at 1.5", but are race carbs also rated that way?)
Yes, we hope to get both intakes on the flow bench in the near future.
Are there any other 2-bbls a better choice for road racing?
Jack Vines
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Re: Need some advice from 2-bbl iron intake experts
OT I've always wondered about using 69 396 big block chevy iron 2bbl intake for classes requiring this. Seems to me a big block chevy would dominate?
Re: Need some advice from 2-bbl iron intake experts
Way OT, even for SpeedTalk, strokersix, but remember there are Olds and Pontiac 455" 2bbls and even the 430" MEL back in the day.strokersix wrote: ↑Sat Nov 17, 2018 7:07 pm OT I've always wondered about using 69 396 big block chevy iron 2bbl intake for classes requiring this. Seems to me a big block chevy would dominate?
Most of the 2-bbl classes usually are all 350" SBCs. What else runs in 2-bbl classes?
As a reminder, there are 4-bbl intakes for the Studebaker, but for fifty years now, I've wondered if with the right porting and the right carb, the 2-bbl intake might prevail.
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Re: Need some advice from 2-bbl iron intake experts
PackardV8 wrote: ↑Sat Nov 17, 2018 1:51 pm We're building a full race 270" V8 which has to run with OEM iron intake and exhaust. The best available intake seems to be the older higher-rise 2-bbl. The later 4-bbl intakes are a lower profile.
Would something like the 600 CFM Quick Fuel 2-bbl on a theoretically better intake be a better choice than a 600 CFM Edelbrock on a lower profile intake? (I know OEM 2-bbls are rated at 3" and 4-bbls at 1.5", but are race carbs also rated that way?)
Yes, we hope to get both intakes on the flow bench in the near future.
Are there any other 2-bbls a better choice for road racing?
Modify the 2bbl intake to accept a 4bbl.
Mill the carb mount surface flat.
Mill the plenum inlet to the larger throttle bore.
Mill the larger throttle bore profile down to the plenum floor.
Round off (radius) the intake plenum to manifold runners.
Possibly port match to the heads.
Drill and tap new carb stud holes.
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Re: Need some advice from 2-bbl iron intake experts
I've always been told multiply the cfm by .707 to find out what a 2bbl rated at 3" would theoretically pull at 1.5"
Personally, I don't ever remember hearing of anyone losing anything when going from a 2bbl to a 4bbl. But my profession isn't in engines specifically so I've not seen near what you all have.
Personally, I don't ever remember hearing of anyone losing anything when going from a 2bbl to a 4bbl. But my profession isn't in engines specifically so I've not seen near what you all have.
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bigjoe1 wrote:By the way, I had a long talk with Harold(Brookshire) last year at the PRI show. We met at the airport and he told me everything he knew about everything.It was a nice visit. JOE SHERMAN RACING
Re: Need some advice from 2-bbl iron intake experts
I have seen on multiple occasions where going from a factory 2bbl iron intake/carb to a factory iron 4bbl intake/q-jet made absolutely 0 difference in performance. Granted, these were not “full race” or even “1/2 race” sbc’s (307’s and 350’s with stock exhaust manifolds and stock or small cams), but I was pretty surprised that going going from a tiny Rochester 2G or slightly larger 2GC to a 750 Q-jet made no difference in 1/4 mile times or top speed.
I guess the biggest thing is going to be where the biggest restrictions are. How good are the exhaust manifolds on whatever it is your building? What kind of power will these things make? Is porting allowed?
I guess the biggest thing is going to be where the biggest restrictions are. How good are the exhaust manifolds on whatever it is your building? What kind of power will these things make? Is porting allowed?
Re: Need some advice from 2-bbl iron intake experts
Yes, for road racing a Weber 44 IDF would be great on a 270" engine.
Re: Need some advice from 2-bbl iron intake experts
Yes, Geoff, that thought had actually occurred to me. However, the reason the 4-bbl intake was made lower profile is hood and air filter clearance. The vintage saloon classes aren't allowed to run hood scoops and the Weber stands too tall on the high rise 2-bbl intake.
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Re: Need some advice from 2-bbl iron intake experts
if you are allowed an adapter between the carb and manifold why not use a curved adapter with the weber carb horizonal
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Re: Need some advice from 2-bbl iron intake experts
Some 30 years ago we stop watch, track tested a bunch of different factory cast iron intakes for both best lap time and driveability on a 1/2 mile flat oval track we rented for the day.PackardV8 wrote: ↑Sat Nov 17, 2018 1:51 pm We're building a full race 270" V8 which has to run with OEM iron intake and exhaust. The best available intake seems to be the older higher-rise 2-bbl. The later 4-bbl intakes are a lower profile.
Would something like the 600 CFM Quick Fuel 2-bbl on a theoretically better intake be a better choice than a 600 CFM Edelbrock on a lower profile intake? (I know OEM 2-bbls are rated at 3" and 4-bbls at 1.5", but are race carbs also rated that way?)
Yes, we hope to get both intakes on the flow bench in the near future.
Are there any other 2-bbls a better choice for road racing?
The best we had, (and we ran about 10 different ones), was an intake from a 340 HP Corvette engine which originally had a Carter AFB carb. I don't think it has been available new since the early 90's.
It is easy to spot as the front and rear runners are slanted not straight across.
Since then ... the Z-28 aluminum 4 brl. intake manifold was produced in cast iron mainly as a marine offering; it is still out there.
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Re: Need some advice from 2-bbl iron intake experts
Thanks for sharing. I truly appreciate it.travis wrote: ↑Sun Nov 18, 2018 2:17 am I have seen on multiple occasions where going from a factory 2bbl iron intake/carb to a factory iron 4bbl intake/q-jet made absolutely 0 difference in performance. Granted, these were not “full race” or even “1/2 race” sbc’s (307’s and 350’s with stock exhaust manifolds and stock or small cams), but I was pretty surprised that going going from a tiny Rochester 2G or slightly larger 2GC to a 750 Q-jet made no difference in 1/4 mile times or top speed.
I guess the biggest thing is going to be where the biggest restrictions are. How good are the exhaust manifolds on whatever it is your building? What kind of power will these things make? Is porting allowed?
JC -
bigjoe1 wrote:By the way, I had a long talk with Harold(Brookshire) last year at the PRI show. We met at the airport and he told me everything he knew about everything.It was a nice visit. JOE SHERMAN RACING
Re: Need some advice from 2-bbl iron intake experts
I'm trying to picture what intake this might be? The actual 62-63 Corvette 340 hp 327 had an aluminum intake. 300 hp 327 used a iron manifold.Walter R. Malik wrote: ↑Sun Nov 18, 2018 12:54 pm
The best we had, (and we ran about 10 different ones), was an intake from a 340 HP Corvette engine which originally had a Carter AFB carb.
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Re: Need some advice from 2-bbl iron intake experts
It is cast iron... it might have been a different horsepower but, that is what I was told.novadude wrote: ↑Mon Nov 19, 2018 2:49 pmI'm trying to picture what intake this might be? The actual 62-63 Corvette 340 hp 327 had an aluminum intake. 300 hp 327 used a iron manifold.Walter R. Malik wrote: ↑Sun Nov 18, 2018 12:54 pm
The best we had, (and we ran about 10 different ones), was an intake from a 340 HP Corvette engine which originally had a Carter AFB carb.
In the 90's, new ones were still available from the dealer and we bought several. It used a Carter AFB 4 barrel carb with the smaller AFB bolt pattern and exhaust ran around the underside, front of the carb at the manifold carb pad. we plugged those exhaust access holes.
EDIT: I looked-up some of my real old invoices and the part number was #03852569.
EDIT: This appears to be an iron exhaust manifold we bought, oh well.
Last edited by Walter R. Malik on Mon Nov 19, 2018 4:05 pm, edited 2 times in total.
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Re: Need some advice from 2-bbl iron intake experts
Aluminum 340-350 hp manny. L79 design usually had 585 cfm Carter, different years had t-stat in different location.Walter R. Malik wrote: ↑Mon Nov 19, 2018 3:43 pmIt is cast iron... it might have been a different horsepower but, that is what I was told.novadude wrote: ↑Mon Nov 19, 2018 2:49 pmI'm trying to picture what intake this might be? The actual 62-63 Corvette 340 hp 327 had an aluminum intake. 300 hp 327 used a iron manifold.Walter R. Malik wrote: ↑Sun Nov 18, 2018 12:54 pm
The best we had, (and we ran about 10 different ones), was an intake from a 340 HP Corvette engine which originally had a Carter AFB carb.
In the 90's, new ones were available from the dealer and we bought several. It used a Carter AFB 4 barrel carb with the smaller AFB bolt pattern and exhaust ran around the underside, front of the carb at the manifold carb pad. we plugged those exhaust access holes.
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Re: Need some advice from 2-bbl iron intake experts
This iron manifold was Genera Motors part number #03852569. I'll keep looking as this appears to be an exhaust manifold we bought.novadude wrote: ↑Mon Nov 19, 2018 2:49 pmI'm trying to picture what intake this might be? The actual 62-63 Corvette 340 hp 327 had an aluminum intake. 300 hp 327 used a iron manifold.Walter R. Malik wrote: ↑Sun Nov 18, 2018 12:54 pm
The best we had, (and we ran about 10 different ones), was an intake from a 340 HP Corvette engine which originally had a Carter AFB carb.
Last edited by Walter R. Malik on Mon Nov 19, 2018 3:59 pm, edited 1 time in total.
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