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  #1  
Old Oct 6th, 12, 06:41 PM
lukenordman lukenordman is offline
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Default 500+ hp 427 bbc

I need help with building a 427 BBC. It cant be over 10.5:1 because I want a pump gas car that will some times go to a track it can be forged can be 500+ hp....how would you go among building one of these? So far all i know is it should be bored .030 over and have nice heads like brodix
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  #2  
Old Oct 6th, 12, 08:24 PM
Big Dave Big Dave is offline
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Default Re: 500+ hp 427 bbc

You are going to need to spend most of your money on heads and valve train because to hit that power level you are going to need to spin it above 7,800 RPM on every shift.

That means titanium intakes and Inconel exhaust valves triple wound PAC alloy springs Isky Red Zone solid roller lifters, a plastic 4500 single plain intake a single dominator 1150 cfm carb good ignition box (MSD7 Digital) and ARP bolts and studs with a chromemoly crank and hollow dome Diamond, JE, or Mahle pistons with long rods to keep the weight down.

Your going to need a minimum of 7/16th inch diameter push rods (most use half inch because of open pressure and harmonics) chromemoly shaft mount rocker with a higher than stock ratio (2.0:1 is fairly common in pro stock that twists 11,200 RPM on a shift with the same stroke you are using only they have a bigger bore to fit up against the 500 cube limit on displacement). You are going to be using titanium in your valve spring retainers to keep the weight down.

To keep the air flow up you are going to need good flowing race heads, which won't be a good head for the street. Same for the induction and cam. A radical solid roller cam that will make the power you want will be ill suited for the street. This is the issue with trying to make the most power you can out of a small displacement big block. it has to be too radical for the street. When these cars were on the street in 1969 (I owned an L-88 and ran it on the street) you had Sunoco 260 (108 octane) in every town and city at 47 cents a gallon. Because of this simple access to "pump gas" in 1969 I could run 12.5 pistons on the street. I was also running twin 660 cfm center squirt Holley carbs on top of an Edelbrock tunnel ram and had a Vertex mag for ignition. I was running a custom ground solid roller Crane cam since Harvey was only a three hour drive away and ground one to meet my car's needs (defined as getting me as close to a nine second Camaro as I could afford to build throwing $27,000 1969 dollars at my goal which was a lot of money back then). That is how I know how much power the 427 makes and where in the RPM range it makes it compared to a bigger, big block that runs on lower octane because it is below the 9.4:1 compression ratio that is the upper limit of premium gas today with a big block's poor combustion chamber design). I make a dyno proven 753 horse power with 640 foot pounds of torque but not with 427 cubes but with a 582. It looks just like a 396-427 (short deck standard ports single four barrel) and it even says 402 cubes on the intake air cleaner decal, but it isn't.

It doesn't rev as high as the 427 used to but that allows me to run 4.56 rear gears instead of the 5.38 gears I used to run with the L-88 for much better gas mileage (I get 6mpg now). Of course the difference between the old 47 cent Sunoco and my current $3.79 a gallon means I pay more but my current engine is much more fun on the street as it can smoke a set of street tires for a full quarter mile.

Big Dave
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  #3  
Old Oct 6th, 12, 08:46 PM
lukenordman lukenordman is offline
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Default Re: 500+ hp 427 bbc

So what would a set of brodix bb1 heads forged internals a good intake and carb get me then? At a 10.5:1 cr
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  #4  
Old Oct 7th, 12, 09:36 AM
Big Dave Big Dave is offline
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Default Re: 500+ hp 427 bbc

The exact same expense as a 496 only with less power.

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  #5  
Old Oct 8th, 12, 07:42 AM
StraubTech StraubTech is offline
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Default Re: 500+ hp 427 bbc

Hyd or solid roller you can achieve your goals. I have a customer north of you that has 10.5 to 427 + .030" with the Brodix race rites and she made 637HP at 6600 rpm. Nice thing about this build was torque. She we 567# ft. Bill Waters is the customer and she is in a 66 chevelle.

The brodix heads need exhaust split over somewhere of 12 to 14 degrees at .050" Other heads like the AFR need a narrower split. The right cam is crutial here. Either can make the same power but will need the correct cam.
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  #6  
Old Oct 8th, 12, 04:22 PM
jp71ss jp71ss is offline
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Default Re: 500+ hp 427 bbc

I didn't think it would be as hard as Big Dave said. Hook him up Chris!
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  #7  
Old Oct 8th, 12, 05:05 PM
62novaSBC 62novaSBC is offline
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Default Re: 500+ hp 427 bbc

just over 500hp can be done around 5500rpm
so nothing fancy is needed especially if youre using aftermrket (oval) heads. 950 carb, RPM intake, 1 3/4" headers and a mild cam will make 500+.
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  #8  
Old Oct 8th, 12, 09:36 PM
lukenordman lukenordman is offline
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Default Re: 500+ hp 427 bbc

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Originally Posted by StraubTech View Post
Hyd or solid roller you can achieve your goals. I have a customer north of you that has 10.5 to 427 + .030" with the Brodix race rites and she made 637HP at 6600 rpm. Nice thing about this build was torque. She we 567# ft. Bill Waters is the customer and she is in a 66 chevelle.

The brodix heads need exhaust split over somewhere of 12 to 14 degrees at .050" Other heads like the AFR need a narrower split. The right cam is crutial here. Either can make the same power but will need the correct cam.
yes tell me how you acheived this!?!? i have started to consider a "427" aka 496 with 427 badges and all since its a 427 block. i want something 550+ hp but...can power heat&ac and run around town
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  #9  
Old Oct 9th, 12, 10:14 AM
62novaSBC 62novaSBC is offline
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Default Re: 500+ hp 427 bbc

Chris thats really similar power to my 420sb
can you tell a bit more about the induction and cam
would like to see how the 2 engines match up
even tho 1 is a SB and 1 a BB... kinda interesting
thanks
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62 Nova cruiser
383/200-4R/12-bolt w 373s
224/224 HR cam
1.57 10.97 @ 121.2
67 camaro
pumpgas 420sbc HR cam 641hp
1.39, 9.79 @ 137.5

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  #10  
Old Oct 9th, 12, 12:09 PM
StraubTech StraubTech is offline
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Default Re: 500+ hp 427 bbc

It has as set of race rites. Crane Shaft system. I can't remember the cam but it is around 254/268 @ .050 on a 107 LSA. Pump gas 10.5 to 1. Peak power was around 6700
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  #11  
Old Oct 9th, 12, 05:53 PM
Big Dave Big Dave is offline
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Default Re: 500+ hp 427 bbc

Quote:
Originally Posted by 62novaSBC View Post
Chris thats really similar power to my 420sb
can you tell a bit more about the induction and cam
would like to see how the 2 engines match up
even tho 1 is a SB and 1 a BB... kinda interesting
thanks
You can get 1.7 horsepower per cubic inch with the same level of development on a big block that will only make you 1.25 horse per cube. Most builds on a big block net little more than 1.00 horse per cube (hence the 450 horse 454 LS-6 in a Chevelle or Corvette back in the sixties when they were running much higher compression ratios).

Modern cams and CNC machined heads that match a professional porter's best effort (or at least a best effort that he was willing to not only put his name on it but allow the world to see it) allow a tremendous improvement in small block heads ability to breath. They do not even resemble the heads that Chevy bolted on top of the 265 back in 1955. The big block on the other hand has not had an improvement in head design since the late 1968 change over to open port heads. Because of their cavernous 121 cc chamber designed for a high compression dome, not a set of dished pistons deny a big block the benefit of turbulence created by squish found in the small block.

Cavernous ports keep peak port air flow to a minimum at low RPMs which allows the fuel to fall out of suspension when it hits the cylinder wall because of the dog leg bend in the head to avoid the push rods. Unless you are willing to twist a big block to RPM levels that would scare a small block 283 you will not be able to reap the advantage of those large head ports.

In general at 7.0 liters (427 cid) the small block is going to make more power, for less money, and still be 180 pounds lighter than the 427 big block. If you are racing which engine would you build if you were desiring to win a race as opposed to clinging to a motor that was replaced by the 454 in 1970 and no one including Chevrolet ever looked back from that point. All of Chevy's race motors that displaced 7.0 liters for road racing or drag racing actually displaced 430 cubes and used a 4.400 Bore and a 3.470 inch stroke in an all aluminum block with cast iron dry sleeves. They didn't use a 427 in anything but stock class and super stock because the rules required it.

Big Dave
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  #12  
Old Oct 10th, 12, 09:09 AM
62novaSBC 62novaSBC is offline
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Default Re: 500+ hp 427 bbc

the 427 Chris did made 1.5hp / cube, and Chris did a cam for a 509 which also made around 1.5hp / per cube... this is all pumpgas stuff, so I dont see where this limitation of 1hp /per cube you speak of comes from?
this is all with very streeetable cams.

there are also some killer BBC heads out there now, you just need to get a decent casting in the right hands, and 350-450+cfm is yours, a far cry from 60s castings. For smaller/low rpm BBs theres oval ports that have the right cross section for low rpm, while still flowing mid 300s, you can make 600-700hp with oval ports nowadays, pretty easy, including with 049 castings. Theres pumpgas BBCs makin 800-900 nowadays

you can make decent power (650-700) with a SBC, buts its gonna cost more, aftermarket parts need to be used, while a BBC can use stock parts, block, crank, rods, heads, to make the same power.
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62 Nova cruiser
383/200-4R/12-bolt w 373s
224/224 HR cam
1.57 10.97 @ 121.2
67 camaro
pumpgas 420sbc HR cam 641hp
1.39, 9.79 @ 137.5

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  #13  
Old Oct 10th, 12, 09:19 AM
62 NovaWagon 62 NovaWagon is online now
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Default Re: 500+ hp 427 bbc

Quote:
Originally Posted by 62novaSBC View Post
the 427 Chris did made 1.5hp / cube, and Chris did a cam for a 509 which also made around 1.5hp / per cube... this is all pumpgas stuff, so I dont see where this limitation of 1hp /per cube you speak of comes from?
this is all with very streeetable cams.

there are also some killer BBC heads out there now, you just need to get a decent casting in the right hands, and 350-450+cfm is yours, a far cry from 60s castings. For smaller/low rpm BBs theres oval ports that have the right cross section for low rpm, while still flowing mid 300s, you can make 600-700hp with oval ports nowadays, pretty easy, including with 049 castings. Theres pumpgas BBCs makin 800-900 nowadays

you can make decent power (650-700) with a SBC, buts its gonna cost more, aftermarket parts need to be used, while a BBC can use stock parts, block, crank, rods, heads, to make the same power.
Exactly...
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  #14  
Old Oct 10th, 12, 12:36 PM
StraubTech StraubTech is offline
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Default Re: 500+ hp 427 bbc

http://www.chevelles.com/forums/showthread.php?t=393748

This is an OEM 215 Headed 427 that is 9 to 1 with one of my solid rollers. He has owned the car for 26 years.
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  #15  
Old Oct 10th, 12, 03:51 PM
Big Dave Big Dave is offline
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Default Re: 500+ hp 427 bbc

Quote:
Originally Posted by 62novaSBC View Post
the 427 Chris did made 1.5hp / cube, and Chris did a cam for a 509 which also made around 1.5hp / per cube... this is all pumpgas stuff, so I dont see where this limitation of 1hp /per cube you speak of comes from?
this is all with very streeetable cams.

there are also some killer BBC heads out there now, you just need to get a decent casting in the right hands, and 350-450+cfm is yours, a far cry from 60s castings. For smaller/low rpm BBs theres oval ports that have the right cross section for low rpm, while still flowing mid 300s, you can make 600-700hp with oval ports nowadays, pretty easy, including with 049 castings. Theres pumpgas BBCs makin 800-900 nowadays

you can make decent power (650-700) with a SBC, buts its gonna cost more, aftermarket parts need to be used, while a BBC can use stock parts, block, crank, rods, heads, to make the same power.
I was making around 760 Horsepower out of my L-88 in my 1968 Camaro RS-SS with deluxe interior based upon an et of 10.13 which I accomplished by way of a solid roller cam, and ruining 1200 cfm on a tunnel ram through 5.38 gears with 14 inch wide Compound W Firestone slicks shifting at 7400 RPM. It can be done but the engine wouldn't run on the street today; at least not on pump gas.

I make more than that now with a 9.4:1 compression ratio with enough torque to put an Impala on it's back bumper shifting at only 5400 RPM and it has a nice smooth quiet (well muffled) exhaust. I can pass it off as a 305 with an exhaust leak if no one looks under my flat stock hood. If anyone actually looks the decal says 402 and it looks stone stock except for the wrapped header pipes. With my Nitrous bottles full (I have the port injectors hidden under the manifold with only a set of hoses running through a set of holes bored in the back of the Dart Big M block) the crankshaft horsepower exceeds a thousand, but I can still get 6.8 mpg if I were to actually try. Rather than miles to the gallon a more important metric is tires per month. I go through quiet a few of them if I am showing my disdain of rice burners.

Big Dave
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