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Old 05-03-2011, 11:27 PM
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Bare Block 383 (Blower?)

I just bought a 383 bare block from Summit Racing and hope some of you experts can help me blueprint a build. Here is a link to what I bought: (http://www.summitracing.com/parts/SUM-150100/).

Helpful info:
1) Going in a '71 Nova
2) I'll spend what it takes, but the car needs a lot more work so my budget isn't totally endless
3) Would like to run 91 octane
4) Primarily a streetcar, but plan to run it down the local strip on occasion

I was thinking of starting with an Eagle rotating kit, probably H-beams with forged pistons, but not sure if I should get flat, domed, or dished pistons. Aluminum heads up top, but not sure what lifters, cam size, etc.

Oh yeah, I love the look of a blower, but live in the Arizona heat so worry about detonation problems. After reading some of the posts, it sounds like ideal static compression for a blower is around 8:1...without blower around 10:1.

I used to wrench years ago, but consider myself a novice these days and want to have fun building it with my 9 year old son. I guess the question of the day is---if you were starting from scratch, what would you build?

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Old 05-04-2011, 12:22 AM
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Quote:
Originally Posted by elixirmixer
--if you were starting from scratch, what would you build?
I'd do it the same way I did it 30 years ago. We bought a racing go-kart frame and built a kart for our son to race. Had more fun and spent more time with my son than if we had not had something to bring us together. We didn't have Junior Dragsters back then, maybe if I were doing it over today, I would opt for a JD instead of a Kart. I don't know, karting was an absolute blast. We were both up at 5 AM on Sunday mornings to load, having done all the adjustments and tuning Saturday.

Back in those days, there was a Grand Prix in Coolidge, Arizona every October. They blocked off the city streets with hay bales and made a road-race course right through the middle of town. It lasted Thursday through Sunday and we always took a motor home down for the event. My mom was still living then and we took her as well. The more, the merrier. I was in hog heaven as the crew chief and Rich was a very good driver. Sharon, bless her heart, was the chief cook and bottle washer. She made sure everybody stayed watered down and fed and also did part time duty as the official family nurse.

Don't misunderstand, racing is expensive, no matter what venue you choose. Sharon and I had to make some hard choices about whether we needed fresh tires for the kart or new clothes.

All I'm saying is, take a look at how you want to remember these fleeting days. In ten years, he will be gone, either to college or to a job or in the Armed Forces and you will have no further opportunity to enjoy him as a child.

Last edited by techinspector1; 05-04-2011 at 12:34 AM.
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Old 05-05-2011, 07:56 PM
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That sounds like a fantastic idea! There is no doubt it will be a load of fun, and one of the best ways to create great memories. I think one of my neighbors does some junior racing, I will have to look into it. Thanks for the idea.

I must admit, the Nova is my toy, but he get's into the fun. Any info on the build is still appreciated. Thanks for the post.
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Old 05-06-2011, 12:05 AM
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OK, with aluminum heads, I would be comfortable with 10.0:1(+/-) on pump gas. You need to leave yourself a little wiggle room for a bad load of fuel. You'll need to juggle piston crown configuration and combustion chamber size to arrive at the 10.0. Head gasket thickness and piston deck height (crown of piston to block deck with piston at TDC) are used to adjust squish, not static compression ratio.
You probably want to look for heads first. Here's a rough idea of SCR's with different heads and pistons....
7cc flat-top with 75cc chambers...9.68:1
18cc D-cup with 64cc chambers...9.68:1
12cc D-cup with 68cc chambers...9.87:1
18cc D-cup with 62cc chambers...9.87:1
7cc flat-top with 72cc chambers...9.98:1
12cc D-cup with 66cc chambers...10.08

Good practice in building a SBC dictates that you use the flattest piston you can. Dish pistons will work well also, but flats work better. You are in the enviable position of being able to custom design your build from scratch. Most fellows don't have that liberty.

Most fellows have found that an intake runner volume of around 195-210cc's works well on a 383 street/strip motor.

So, after you have found the heads you want, then choose your pistons....cast, cast hypereutectic or forged, with the crown configuration to arrive at your SCR target.

I know that Eagle crank looks attractive from a cost standpoint, but maybe you should do some investigation into what others have to say about it. Their quality control has been less than ideal. The Scat 9000 crank and rod kit, on the other hand, has good revues.

To adjust the squish, you'll want to add the piston deck height and gasket thickness together (you'll want to use a 0.039"/0.040" composition head gasket to prevent brinelling of the aluminum head) to arrive at the number. 0.035" to 0.045" is considered by many to be ideal on a SBC, so for instance, if you used a 0.040" gasket, you would want the piston at zero deck for a 0.040" squish or maybe 0.005" down in the hole at TDC, which would put your squish at 0.045".

As you look at parts for the build, you want to be adding up your "stack" height (radius of the crank, rod length and piston compression height). For instance, a 3.750" crank has a radius of 1.875", a standard 350 rod has a length of 5.703" and a standard 383 piston has a compression distance of 1.425". This stack would be 9.003", leaving a piston deck height of 0.022" on a virgin block deck. If you use a 6.000" rod instead, that will require a shorter piston compression height, so keep doing the math to see where you are on the stack.

Because of the cam you'll have to mate up with the static compression ratio, your operating range will be somewhere between these two extremes....
1400-5000
3200-6600
If this is not acceptable, then use a different SCR.

Last edited by techinspector1; 05-06-2011 at 12:29 AM.
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Old 05-06-2011, 12:12 PM
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I've never used Eagle parts but I got into a conversation with my machinist regarding some of the new equipment that is available. HE said that he WILL NOT use Eagle cranks, if a customer insist on one then he will mag the crank and grind it 10-10. He said that he has found them so far out of tolerance that he won't guarantee them even after he machines them. He likes the Scat parts better but some of those parts need a little help also. He said nowadays he always checks run out on any crank....buyer beware.
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Old 05-08-2011, 05:18 PM
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REALLY --- I was choosing Eagle because I thought they were good. Forums like this will help me a lot. Thanks for the advise on choosing heads first...I'll start there.
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Old 12-10-2011, 07:25 PM
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Hello again,

Well, I still have not bought anything except the below books and some suspension parts.

•High-Performance Chevy Small-Block Cylinder Heads (Cartech)
•How to Build High-Performance Chevy Small-Block Cams/Valvetrains
•How to Rebuild Your Small-Block Chevy
•How to Build Max Performance Chevy Small Blocks on a Budget

I was thinking about buying a SCAT rotating assembly to make life easy, but it appears the piston selection is limited and I am having trouble getting 10:1 compression. I bought the block from Summit, but they didn’t have any specs on the deck, just that it was machined and would be above zero deck height. Using 0.020 (guess) as the deck height, 75cc heads with 0.041 gasket, and flat 5cc pistons, compression is 9.39. Dropping to 65cc heads pushes it to 10.4.

After reading the books, I was leaning toward the selection below, but maybe I should go back to the drawing board to get 10:1.

•Airflow Research (AFR) 1038 - AFR 195cc SBC Eliminator Street Heads 75cc
•Fel-Pro Q1003 - Fel-Pro Performance Head Gaskets (.041)
•SCAT Rotating Assembly (SCA-1-41825) (Forged crank, H-beam 6” rod, Flat 5cc piston)
•Manifold (Edelbrock Super Victor)
•Crane camshaft (mechanical roller)
•Lifters
•Rockers

Crane recommended the cam based on my input of spinning a high rpm. The recommended CR for this cam 10-5-11.5. I am thinking it is too big, but might be ok with a manual trans. I should go with an auto, but the manual is just so much fun. Probably a 373 rear end.

I am sure there are many things wrong with the above plan, but to start small, my squish is too high, isn’t it? Am I wrong thinking deck height is a total guess until I put the bottom end together? The .041 head gasket is recommended by the manufacturer, maybe I can go thinner?
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