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Old 10-28-2012, 09:10 PM
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1973 350 engine Block/build

Heys guys a I have a 350 block that i finally decided to take to the machine shop since I am taking some vortec heads there. I was told that the less I get it bored over the better. I was thinking going .030 over since thats very common but was told that i really shouldn go more that .015 over. the # on the block are K03 13 CKL and 731315647. I know its from 1973 which I thought the cylinder walls back then were alot thicker than today. Anyway if I go .030 over is it gonna hurt anything.

Thanks

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Old 10-28-2012, 09:55 PM
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There are thousands of small block Chevies running around out there with +0.060" overbore. You won't find pistons for a +0.015" overbore, but +0.030" is done every day. If you're in doubt, take the block to someone who has ultrasonic equipment and have them "beep" the cylinder walls. You'll want a minimum of 0.135" wall thickness after boring and honing. Some blocks will make it and some won't.
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Old 10-29-2012, 10:07 AM
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Ok thanks i knew that .030 over wouldnt hurt. Its very common to see 355 ci. They are everywhere.
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Old 10-29-2012, 08:01 PM
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Just one other thing, the machinist will check the bore as it is now and will tell you how much it needs to be bored. It may already be .030.....but whichever the case you will need to supply the pistons that you will be using to get it bored and honed properly.

The type of piston you choose will of course entail planning on the entire build as to what compression you will end up with....heads, cam, application entended for, yada....they all work together. If you don't plan on building it for 6 months or more then I wouldn't touch it, no reason to let it sit around with fresh macheeen work.
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Old 10-30-2012, 11:28 AM
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That makes sense. Let me ask you something else. Im trying to reach around 400 to 450 HP. I have almost everything I want in mind except for a good cam to match my vortec (L-31) heads which Im taking to the machine shop this week. Im getting the heads cleaned and inspected of course and milled down. also port and polished. Keeping stock 1.94 and 1.50 valves.getting new rocker arms and valve springs but dont know what to go with. So what do you think on valve spring, rockers and a cam that would push that power with these heads. Also how much should I get my heads milled for more Compression but still want to run pump gas. Below is other parts im going with.


SBC Scat 383 Crankshaft 1pc RMS 9103750 L Late | eBay

ill get a two piece rear main

Summit Racing® Hypereutectic Pistons SUM-17350-30 - SummitRacing.com
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Old 10-30-2012, 02:20 PM
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1973 350 engine Block/build

If you have a 1973 block you need a crank with a two piece rear seal. If you are going to build a 383 Stroker motor it would be better to purchase a complete rotating assembly such as one of these: Scat Engine Rotating Assemblies 1-90500 - SummitRacing.com or Eagle Street and Strip Rotating Assemblies 13004030 - SummitRacing.com The rotating assemblies come with a crankshaft, rods, pistons, rings, rod & main bearings. You need to know the bore size of the cylinders to order your kit. If you don't have the tools to measure them take it to the machine shop with your heads. I have heard some bad rumors on the Scat Series 9000 cast crankshaft so start a new thread on the Scat Series 9000 crankshaft here on hotrodders.com. The Eagle crankshafts are supposed to be better as long as you have your machinist balance the rotating assembly that's why I gave you the part numbers for the unbalanced kits. Another thing these are the kits for using the 64cc chambered L31 heads. On your heads get an estimate of the price for the work you want done. A stock vortec head cannot use over a 450 lift cam. Then compare it to this kit: https://sdparts.com/details/scoggin-...ter/sd8060arpm
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Old 10-30-2012, 02:36 PM
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Quote:
Originally Posted by allansmith859 View Post
Ok thanks i knew that .030 over wouldnt hurt. Its very common to see 355 ci. They are everywhere.

Its a good idea before doing any work to any OEM block is to have it sonic tested to make sure it a good piece before spending any money on cleaning ETC.

Don't go by core shift as thats not a very good indicator as I have alot of block where one cylinder failed a sonic test making the block junk for a performance build.
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Old 10-30-2012, 03:28 PM
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Let me play devils advocate. Been reading about shops saying core shift is a myth.That by vision inspection it isn't a good indicator for thickness because they have had some that passed and others that didn't.
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Old 10-30-2012, 03:46 PM
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Let me play devils advocate. Been reading about shops saying core shift is a myth.That by vision inspection it isn't a good indicator for thickness because they have had some that passed and others that didn't.
I have some blocks running with terrible core shift and were fine,
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Old 10-30-2012, 07:02 PM
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Thanks that link has the valve springs and rockers I can use to make the max lift .525. How would I determine the best camshaft for these heads.

Thanks for the help guys
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Old 10-30-2012, 09:22 PM
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Quote:
Originally Posted by cdminter59 View Post
If you have a 1973 block you need a crank with a two piece rear seal. If you are going to build a 383 Stroker motor it would be better to purchase a complete rotating assembly such as one of these: Scat Engine Rotating Assemblies 1-90500 - SummitRacing.com or Eagle Street and Strip Rotating Assemblies 13004030 - SummitRacing.com The rotating assemblies come with a crankshaft, rods, pistons, rings, rod & main bearings. You need to know the bore size of the cylinders to order your kit. If you don't have the tools to measure them take it to the machine shop with your heads. I have heard some bad rumors on the Scat Series 9000 cast crankshaft so start a new thread on the Scat Series 9000 crankshaft here on hotrodders.com. The Eagle crankshafts are supposed to be better as long as you have your machinist balance the rotating assembly that's why I gave you the part numbers for the unbalanced kits. Another thing these are the kits for using the 64cc chambered L31 heads. On your heads get an estimate of the price for the work you want done. A stock vortec head cannot use over a 450 lift cam. Then compare it to this kit: https://sdparts.com/details/scoggin-...ter/sd8060arpm
For these prepackaged kits to be priced as they are,there has to weak links in them.Trust in the fact nothing is for free and you do get in these "deals" exactly what you pay for.Now I am not suggesting he buy a $1,000 crank. But in the price range of $600 there is a significant difference.Bottom line is for him to put together his own rotating assembly.
A 383 wants in the range of 195 to 200 cc intake runner.Yeah I know guys that "have" done what.Those same guys done know what they are missing.
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Old 10-30-2012, 09:46 PM
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In answer to your valve spring question, use the springs the cam company suggests. It's easy to buy the "cam & kit", which is cam, springs & lifters.

Also don't be so caught up on horse power numbers, unless you dyno the engine you will have no way of knowing anyway. Build the best engine you can afford that is streetable, reliable and doesn't overheat. A max hp sbc is not very much fun to drive in city traffic.
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Old 10-30-2012, 10:09 PM
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1973 350 engine Block/build

Here is a link to comp cams website. Look at the bottom right at CamQuest and click on it. Just by browsing thru some cams it don't look like you are going to get 400-450hp with iron heads. Looks to me like you going to have to have a set of aluminum heads with large valves and have them ported as well. If the web page freezes on you just hit the refresh button at the top of your browser.
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Old 10-31-2012, 05:28 PM
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Quote:
Originally Posted by allansmith859 View Post
Heys guys a I have a 350 block that i finally decided to take to the machine shop since I am taking some vortec heads there. I was told that the less I get it bored over the better. I was thinking going .030 over since thats very common but was told that i really shouldn go more that .015 over. the # on the block are K03 13 CKL and 731315647. I know its from 1973 which I thought the cylinder walls back then were alot thicker than today. Anyway if I go .030 over is it gonna hurt anything.

Thanks
Here is a board brush at a 420 hp 383 using pretty common parts. I prefer to buy parts rather than kits so that I can control the balance and pay for it once. My preference is for an internally balanced engine and if you're careful with parts selection it can be done with an externally balanced crank often without having to add Mallory metal.

The camshaft really drives on the compression ratio, you need to nail down the cam then using its intake closing point to calcualate the DCR drive back on the parts and dimensions that make the corresponding SCR. See this calcualator <<< United Engine & Machine Co. Incorporated >>>



Descriptor Street Performance 383
Engine 418 horse 383
Bore 4.030”
Stroke 3.78”
Crankshaft SCAT 9000 Lightweight Forged
9-350-3750-5700 for 5.7 inch rod
9-350-3750-6000 for 6 inch rod
Con Rod SCAT Forged 4130 Prostock Capscrew
2-ICR5700 for 5.7 inch, 560 grams
2-ICR6000 for 6.0 inch, 595 grams
Piston Needs to be selected for DCR to SCR, rod length, ring pack width, weight
KB 100, F/T, rings 2x1/16 - 1x3/16, 11.1:1, 505/145 grams
KB 103, D dish 18cc, rings 2x1/16 - 1x 3/16, 9.7:1, 500/145 grams
KB 121, D dish, 28cc, rings 2x1/16 - 1x3/16, 8.8:1 528/145
Rings Prefer 1/16 Moly compression, 1x3/16 oil
Head L31 Vortec 12558060 lift mod, ported
SCR see pistons (.025 Deck, .019 gasket)
DCR Cam and piston dependent see United Engine & Machine Co. Incorporated
Intake valve 1.94” Back Cut 30/polished
Exhaust Valve 1.55” Back Cut 30
Rocker 1.6:1 Roller (more important that the fulcrum is roller than the tip)
Cam Comp XE268, 224/.447, 230/.480 110
Intake Performer RPM Vortec
Carb 750 Holley
Exhaust 1-5/8 Long Tube

Crankshaft power estimate
Torque 450 lb/ft @ 3400
Horsepower 420 @5500

When we build street and claimer motors this is (with a few twists for heads, cam, rockers, intake, and carb) a pretty common formula.
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Old 11-01-2012, 03:37 PM
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Thanks guys you all are a big help and have good advise. cdminter that cam guest link is a good thing to use thanks for the tip
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