Dumb question 0n 427 BB
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 8,513
Likes: 501
From: Bussey, IA
Dumb question 0n 427 BB
Ok I have heard of bbc with intakes with oval ports, round ports, square ports and rectangle ports. I am guess there are really only 2 types, but my questions are :why the difference? How do you know what you have with out tearing off the intake?
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
If it's got the factory intake, you might be able to track down the casting numbers off that too. It IS possible to have the heads and intake mismatched- the bolts can't tell the difference. As stated above, the casting #'s on the heads will tell for sure, but the intake might give you a clue also.
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Safety Car
Joined: Aug 2000
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From: San Antonio TX
Beyond the value question posed by JNB, there is another practical consideration and that is the availability of rectangular port intakes that will fit under your stock hood.
As to the question of why the factory used oval or rectangular ports: The factory rectangular port heads were for the high performance applications where the engine would see higher RPM. They flowed more air than the factory oval port heads. If your engine isn't built for the higher RPM potential a factory rectangular port head offers, you will gain nothing from the effort. I used the word "factory" throughout to remove all doubt that the current aftermarket heads are not what is in consideration here. That is an entirely different consideration.
As to the question of why the factory used oval or rectangular ports: The factory rectangular port heads were for the high performance applications where the engine would see higher RPM. They flowed more air than the factory oval port heads. If your engine isn't built for the higher RPM potential a factory rectangular port head offers, you will gain nothing from the effort. I used the word "factory" throughout to remove all doubt that the current aftermarket heads are not what is in consideration here. That is an entirely different consideration.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
The air velocity thru the intake and heads is higher in the oval ports. The rectangle ports will flow more, but the bottom end is not too great because of the slower velocity. Once you get around 3500 RPM (depending on your cam), a BB with rectangle ports starts to breathe.
Le Mans Master
Joined: Apr 2007
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From: Graceland in a Not Correctly Restored Stingray
The following opinion is from a die hard rectangle port guy, so you can't say I'm just a hater...
Unless your planning on a comprehensive high-perf redux with a significanlty higher RPM power band (or perhaps building a huge displacement mill), swapping to rectangle ports isn't likely going to prove a step forward. Best to stick with the ovals unless/until that's what you're after. No flames, JMHO.
Unless your planning on a comprehensive high-perf redux with a significanlty higher RPM power band (or perhaps building a huge displacement mill), swapping to rectangle ports isn't likely going to prove a step forward. Best to stick with the ovals unless/until that's what you're after. No flames, JMHO.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
The following opinion is from a die hard rectangle port guy, so you can't say I'm just a hater...
Unless your planning on a comprehensive high-perf redux with a significanlty higher RPM power band (or perhaps building a huge displacement mill), swapping to rectangle ports isn't likely going to prove a step forward. Best to stick with the ovals unless/until that's what you're after. No flames, JMHO.
Unless your planning on a comprehensive high-perf redux with a significanlty higher RPM power band (or perhaps building a huge displacement mill), swapping to rectangle ports isn't likely going to prove a step forward. Best to stick with the ovals unless/until that's what you're after. No flames, JMHO.
Sorry skunk- I've been lookin' for the proper time to use that one- this is it..
Thread Starter
Le Mans Master
Joined: Aug 2010
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From: Bussey, IA
OK, what would you do to set up a BB for good solid street performance? Never had one before, so I am like a kid in a candy store. Dream of any and everything. Recommendations? Tips?
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
First thing is you need to figure out what you want the car to do. Cruise the highway? Be easy to drive? Kick the snot out of the guy next door's mustang? Embarrass the kid with the Camaro? Race on the weekend?
Are you looking at a complete rebuild or just heads/cam/intake?
Are you looking at a complete rebuild or just heads/cam/intake?
Race Director
Joined: Dec 1999
Posts: 11,094
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From: Sierra Foothills CA
First thing is you need to figure out what you want the car to do. Cruise the highway? Be easy to drive? Kick the snot out of the guy next door's mustang? Embarrass the kid with the Camaro? Race on the weekend?
Are you looking at a complete rebuild or just heads/cam/intake?
Are you looking at a complete rebuild or just heads/cam/intake?
To get useful advice you'll need to identify usage and power goals. BBs can range from 396 to 572 cubes or more, depending on how much you have to spend and what your starting point is. Do you have a block already or are you looking to start from scratch? Is it strictly for the street or would you plan on racing with it too? Do you have the car already and, if so, what rear gears, transmission, and tires do you have? As you can see, there's a bunch of missing info if you really want some help.
Thread Starter
Le Mans Master
Joined: Aug 2010
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From: Bussey, IA
I have a 68 coupe that is off frame right now. My Dad started on this project 20 years ago, rebuilt A arms and trailing arms. After he died, it sat untouched in my brother-in-laws basement. Dad was planning a numbers correct 327, but bill's son in law got desperate for money and scraped block. Anyway, Car has a 3.08 BB rear end and have a Rockcrusher 4 speed tranny. Yes, must beat the snot out of the Stangs and Camaros on the street and go down the hiway cruising too. I have the engine (427). Full race is more than I need so looking at cam, intake, carb and heads if needed. Already figuring a 750 dp carb so do the job, but haven't bought anything yet. Just got engine a few weeks ago.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 8,513
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From: Bussey, IA
At the point where I can do a complete rebuild- planning to check it all out anyway. Not sure what tires I will go with. May be kinda old school with Cragars and fat meat in the back and skinnies up front, but not decided yet.