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Old 06-15-2005, 05:04 AM
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SBC Destroked

Hey guys and gals,

I have a 1962 327c.i./250hp engine that originally came out of a 1962 Corvette. I have plans for this little machine. . I need to find me a good 283c.i. steel crank (to destroke it of course) and a good set of chevy 5.7 rods and walaa, i'll have me a Chevy 302.

Could anyone be of some assistance and help me macch some heads up to it? A guy that built a 1971 454c.i. (complete roller motor) that came out of a SS El Camino which he dropped in a 1990 Chevy Silverado, short bed regular cab truck told me i need about a 60cc or 62cc chamber set of heads with the big valves.

Any help matching some stuff up would help alot.

Thanks

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Old 06-15-2005, 05:58 AM
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i would build the 327
nothing beat cubic inches.
also keep in mind those chambers with those numbers youll have to run race gas.
at lest 105 octane.
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Old 06-15-2005, 07:53 AM
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With 62cc heads and flat top pistons your compression ratio is going to be around 10-1. The 302 Z/28 compression ratio was around 11-1. They did not require race gas, just premium pump gas.

Casting #3927186 is for 69-70 302/350 64cc with accessory holes. This head can be found with 2.02" intake valves (high perf) , or 1.94" intake valves (300hp 350).

I would try and find a set of those. The 1.94" heads are fairly easy to find and are very affordable. If however you plan on installing larger valves (2.02") and machining for screw in studs and guide plates, then I would try and find a set of the hi perf models that already have these additions.

Vince
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Old 06-15-2005, 08:15 AM
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What is this engine for?

If you are looking for rpms then any 350 with a big cam and good valve springs will rev to 7000+rpm without anything special. Why give up 50 cid?
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Old 06-15-2005, 08:28 AM
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I think it a cool idea to be a little different. 350's are like shoes everyone has a pair.

I would not waste money on old stock heads, the newer heads are so much better and will allow you to make a lot more power. Since this is not a numbers matching deal no need to worry about it. You might want to look into pistons before you buy any other parts, just to make sure you can get a good set that is in your price range.

Royce
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Old 06-15-2005, 09:47 AM
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Quote:
Originally Posted by camaroman7d
I think it a cool idea to be a little different. 350's are like shoes everyone has a pair.
Royce
I agree, a 302 would be cool. The most expensive part of this build is going to be the pistons. I believe they are still availiable from TRW. A set of old sytle cast iron heads can be had for a song, as well as the 283 crank. If I remember correctly most 283 cranks were forged, making it even better.

Vince
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Old 06-15-2005, 09:57 AM
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Quote:
Originally Posted by camaroman7d
I think it a cool idea to be a little different. 350's are like shoes everyone has a pair.

Royce

the 350 is a great all-around engine, power, torque, and some sort of fuel economy too. Parts are cheep, but it's great to see something different.
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Old 06-15-2005, 11:04 AM
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Spending money to reduce the displacement of your engine without an increase in cylinder wall thickness?

Why?
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Old 06-15-2005, 12:45 PM
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If you want to be different you could stick diaper pins though your nipples. hahahaha. No, wait.. that is pretty standard now-a-days. hahaha

I guess one man's nightmare is another mans dream. I still don't understand why to give up free hp and torque just to be different. Plus the aftermarket performance market is geared towards 350 and 383's. So, it will be hard to get a head with small enough chambers to make any compression. Maybe a later model 305 head (58cc) but those don't flow well. And it is always better (for flame travel) to make compression with small head chambers instead of big domes.

A 302 can make the same hp as a 350 but takes another 1000 rpms to do it. But the torque will never be there. With some lower gears, a 302 would run nice but seems kind of silly to me to go through all that.

I can see the value of a very mild 283 cid, if the reason for building it was for fuel economy.

????

Oh well, Good luck with your 302 project.
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Old 06-15-2005, 01:05 PM
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If you are on a budget I would recommend the late model 305 Vortec heads with 58cc combustion chambers. i hear they outflow the double-hump 2.02's
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Old 06-15-2005, 01:32 PM
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With the reduced displacement I would go with unported vortecs- well maybe touch up the exhaust side. There are better heads, but you won't need the flow numbers so why even worry about it. I like that you're doing somehting different. Also, consider 6 inch rods it'll give you a better rod ratio and less side loading which will help the bore's wear and tear (especially at higher rpms).

Remember to go with a smaller cam than you would with a 350. And since you're being different, I would think you're obligated to do a slightly lumpy solid.

I really like anything that is a decent build up of a less than common engine (Ford 302s, Chevy 350's, or chrysler 360's).
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Old 06-15-2005, 02:04 PM
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If it`s planned to rev and I`d think that`s the point of a 302, then you`ll need a good set of rods, the factory stockers of that age were not very good, I`m not sure who still makes 5.7 rods in the small journal sizes in the aftermarket, But I imagine if you hunt around you`ll find some. If it were mine I`d stick with the 327, it can rev just as well and still perform very admirably without so much of a torque loss, you have to remember, torque is what moves you around and it`s what you feel, I never cared much for engines I had to wait for them to tach before I felt anything, I like out of the hole power, but that`s just me.
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Old 06-15-2005, 02:45 PM
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The guys are right, that a 302 is NOT s torque engine. I made the assumption you knew what you were getting into and would plan accordingly (steep gears, high stall, or stick, light car). The 327 is a great engine and so is the 350. Maybe if you stated your goals and what the car will be used for as well as a few details about the car we cam give much better/accurate advice.

I like to see people do different things. If all out power and torque is what you want then I agree 100% with the guys above.

Royce
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Old 06-15-2005, 10:29 PM
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Hey

Hey guys thanks for the flaming and help. . .

LOL

Anywho. . . Okay, torque. . . well if i was pulling a tanker truck out of a ditch, I would need torque, like mad even. . .

But, someone said something about waiting all day for it to "rev up", WRONG in my opinion. . A destroked 327c.i. engine to a 302c.i. engine (actually 301 by the calculation) would hit 2:1 ratio to the 383 "stroker's" firing. . therefor probably not having as much torque (unless you wanted Gene Fulton to build it) as the 383,400,406,410, etc., BUT wind quicker.

So, you're looking at 10gRPM's easy.. Sorta like an Indy car. .

And these 302 engines that came out in the '68 and '69 Z-28 camaros had like 290hp @ about 2500RPM, BUT at 5000-6000RPM, these motors probably had 600hp or darn near close to it, because they "wind" so tight. .

So, what would be the first step for this engine? Firstly I need to take it and have it dipped in acid and have the block cleaned at a machine shop, then I need pistons or what??

Pistons would probably run me the most. . .

One more thing, lol, If i also bored the engine .030 over, what kinda cubic inches would that be? 327 with a 283 steel crank with a 30 thousandths overbore?

Thanks
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Old 06-15-2005, 11:10 PM
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Well lets debunk some of these "truths".

1) Weight of the rotating assembly is what control how fast the engine revs, the bore to stroke ratio actually has very little to do with it.

2) You likely will never be able to rev your 302 to 10000 rpm unless you own a money tree somewhere, and if you did you would soon find out that a 302 SBC has the same weaknesses as any garden variety 350. Forget the legends, its all BS. The engine never made 600HP stock at any rpm, the engines were derated to 290 HP to compete more favorably with the dominant 302 SBF's at the time in a specific races series, didn't work however as Ford did the exact same thing. The reason for the derating was the allowed racing weight of the car was calculated from the factory rated HP, you can imagine the lying the mfg's did to be on top. Apparently the hp was correct but was measured at the torque peak not the HP peak, just over 400hp was typical for both the SBF and the SBF with the Boss Ford having an advantage up top because of the head design breathing better on the long tracks, the Chevy's had the advantage on the short tracks.

3) Destroking any engine because of a historic racing displacement is just silly and a waste of money especially when it offers no advantage whatsoever.

Without a numbers matching block it will be worth less than your typical 350 SBC built in the same manner and all you will have is bragging rights to those that know little about engines. If I had a dime for every one of the engines I went to look at that their owners "claimed" to be 302's and after a cursory glance were immediately recognizable as a garden variety 283, I would be a rich man.

Forgetaboutit.
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