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post #1 of 11 (permalink) Old 08-24-2018, 11:30 PM Thread Starter
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Against popular opinion

I am going to build the 283 up... Are there a rocker arm, or manifold, or bolt on that is proven...

Like brand X 1.5 roller rockers
Brand x manifold
Brand x headers or ram horn
This exhaust......
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post #2 of 11 (permalink) Old 08-25-2018, 09:34 AM
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How far are you going with your build? (i.e. bare block, short block, long block)

You got to get it breathing first and the best way to do that is an aftermarket set of aluminum heads with dual springs and a set of solid roller lifters that will let you wind this thing up over 7,000+ RPM, this is where you will see your HP numbers increase. A simple early SBC air gap intake (edelbrock) with a 600 cfm carb (I would probably go with a demon carb as I hear they are easy to set up) will probably give you more on the fuel and air than your cylinders will ever need. You will also need MSD ignition as points won't handle the RPM's you will be reaching.

Until you get your heads and intake breathing you will not gain much by changing your stock ram horns.

You have to build a short stroke engine for high revs to get power out of them.

If your starting with a bare block I would stroke it out. I think if your block is a 62 or later you can put a 327 crank in it with minimal to no clearance work needed. The older blocks need a lot of clearancing and I've head it can easily get into the water jacket.

If your looking for a budget build: Boring it .030" and using good 305 heads and a 098 Duntov solid lifter cam would make a little more power.
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post #3 of 11 (permalink) Old 08-26-2018, 06:58 PM Thread Starter
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Currently has a cam, and a 600 or 650 carb... I want a new intake, carb, rockers...
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post #4 of 11 (permalink) Old 08-27-2018, 08:55 AM
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Quote:
Originally Posted by Darkoverlift View Post
Currently has a cam, and a 600 or 650 carb... I want a new intake, carb, rockers...
Is it a solid lifter or hydraulic lifter cam? Hydraulic lifter cams are limited in RPM generally around 6K to 6.5K. Solid lifter cams can go up to 8K and beyond. If you just want to put roller rockers on it you won't gain much if anything. If your running a hydraulic lifter set up a set of rockers from comp cams or such will work fine. The biggest thing I would look for is a rebuildable set of roller rockers.

As far as intake goes if your running stock heads the best you can do is an Air gap intake to attempt to cool the air fuel mixture a little. Tunnel ram intakes do good for High RPM, but they are dogs on the street.

You just can't gain a whole lot on a 283 without going into the heads and preferably the bottom end of the engine, or forcing more air in up front with a blow through carb and a turbo or belt driven super charger. Only issue is with a stock 283 bottom it probably will not hold up to much more than 3-4 PSI of boost for long as your stock pistons are probably cast aluminum and not forged, stock connecting rods just are not that strong and your crank is a small journal crank meaning it can take more RPM, but the added forces of forced injection may not be kind to it.

With the mods you are looking for you'll be lucky if you can squeeze out 10 - 15 more HP and those will come at a very high dollar to HP ratio. Engine builders that make high HP engines build a combo that starts with a rock solid bottom end design and then everything else is designed to work well with it.
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post #5 of 11 (permalink) Old 09-01-2018, 04:43 PM Thread Starter
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Who makes the head your speaking of?
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post #6 of 11 (permalink) Old 09-01-2018, 06:15 PM
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Vortec 5000 heads appeared only on light trucks from 1996-’97 L31 engines. They had raised Vortec ports with 1.94"/1.50 "inch valves. Earlier heads had the same ports but had smaller 1.84" inch intake and 1.50" inch exhaust valves. They both share the same 0.470" lift at the valve restrictions as the 350 Vortec heads. These heads will net you 26 horsepower over a fuelie head.

They do require their own self guided rockers that are different than the stock SBC parts (so if you have to waste money on a roller rocker that will save you 4-7 horsepower in parasitic drag, also known as friction, buy the self guided roller rockers). The horsepower discrepancy in parasitic drag varies as a result of open spring pressure. As the spring rate goes up, so does parasitic drag at the rocker.

When buying your new manifold buy the Vortec version to match the raised thinner ports and the ten bolt intake pattern with a different angle than the older SBC heads used before 1994. !997 was the last year for the 305, and 2004 was the last year for the 350 SBC so the SBC is disappearing rapidly from junk yards now. Better buy your 350 Chevy small block while you still can.

When I first started hot rodding the SBC the flat head Ford was as common as dirt in the bone yards and people wanted me to use one of them, or the more modern Thunderbird Y block Ford V8 as that is what everybody else was using. Funny how common as dirt changes, into greasy dirt in junk yards, that have product for sale only so long as they have customers buying the parts. Everyone today is buying an LS-3 or an LS-7 gen V small block Chevy, not 350's out of antiques. So I suspect that they will be gone soon enough, making a SBC as hard to find as a Flat Head Ford engine is today.

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post #7 of 11 (permalink) Old 09-05-2018, 09:52 AM
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If you just want to do the whole top end I would go with a kit like this.

https://www.summitracing.com/parts/e...make/chevrolet

You get a cam that matches intake, carb, and heads.
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post #8 of 11 (permalink) Old 09-05-2018, 12:16 PM
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Quote:
Originally Posted by Deadwolf View Post
If you just want to do the whole top end I would go with a kit like this.

https://www.summitracing.com/parts/e...make/chevrolet

You get a cam that matches intake, carb, and heads.

That specific 'kit' is NOT for a 283. It's for sbc engines with 4" bore. Check out the valves in the heads.


Pete
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post #9 of 11 (permalink) Old 09-05-2018, 12:36 PM
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Quote:
Originally Posted by japete92 View Post
That specific 'kit' is NOT for a 283. It's for sbc engines with 4" bore. Check out the valves in the heads.


Pete

If you look down at the QA section Edelbrock answered the small bore question. Due to the less than .450 lift on the cam it will work in a small bore 305 SBC. The 283 (3.875) has a slightly larger bore than a stock 305 (3.736). You would have to do a clearance check, but I would imagine you could go up to a .500 lift cam with the 283.
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post #10 of 11 (permalink) Old 09-05-2018, 03:00 PM
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Quote:
Originally Posted by Deadwolf View Post
If you look down at the QA section Edelbrock answered the small bore question. Due to the less than .450 lift on the cam it will work in a small bore 305 SBC. The 283 (3.875) has a slightly larger bore than a stock 305 (3.736). You would have to do a clearance check, but I would imagine you could go up to a .500 lift cam with the 283.
There is disagreement ( me among them) in the Q&A's (read 'see all answers'). Also, 305 is NOT listed in the "applications" section. There, only 4 " bore engines are listed.

I would not risk it.

Pete
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post #11 of 11 (permalink) Old 09-05-2018, 04:20 PM
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Bore is to small for a 2.02" intake valve, that is why the fuelie head that appeared for the first time on a 1957 283 horse 283 in a Corvette had a 1.94" intake valve. The biggest valve used in a 305 was the 1.84" intake valve. This is because the bore is too small to prevent the cylinder wall from shrouding the valve. A large shrouded flows less air than a smaller valve that is not shrouded.

Here is an illustrative picture of why no one builds 305 engines:


This is a picture of a 305 bore block photographed from the bottom looking up at a 2.02" head on top. The valves barely clear the edge of the bore, but are shrouded severely.

Bigger bore shorter stroke is what race cars are based upon (Pro Stock, Can-AM, and F1 racing). It is why everyone dropped the 283 the day the 327 hit the market. If I were to build a SBC motor for a full size it would be based upon the 4.125" bore 400 block (only it would be a Dart "Little M" Sportsman block).

Big Dave
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