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Thread: 350 sbc build need advise
          
   
   

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  1. #16
    Travlin55 is offline CHR Member Visit my Photo Gallery
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    Well, yes that does make sense especially when these Pistons don't seem to have any good identification on them. I may look into another set of pistons to bring it back to say 10.5.1 as well as having the block decked
    Last edited by Travlin55; 03-15-2019 at 06:19 AM.

  2. #17
    techinspector1's Avatar
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    Quote Originally Posted by Travlin55 View Post
    Well, yes that does make sense especially when these Pistons don't seem to have any good identification on them. I may look into another set of pistons to bring it back to say 10.5.1 as well as having the block decked
    Hold on there Hoss. The block will likely have to be bored and honed to the next oversize , +0.060", which could make the cylinder walls too thin, depending on core shift when the block was cast.

    There are thin wall blocks and there are thick wall blocks in the same engine family. All production blocks are cast. Casting is a mature, but not particularly exact process. There will be core shifting and such going on that will make one block come down the production line with pretty much equally thick cylinder walls all around, then the one right behind it could have thin walls on one side of the cylinder and thick walls on the other side.

    The thrust side of the cylinder on a small block Chevy is on the inboard side of the cylinder on the driver's side of the block and the outboard side of the cylinder on the passenger's side of the block. Most engine builders will prefer to have 0.200"+ on the thrust sides of the cylinder after boring and honing. Other areas around the bore can be slightly thinner. Famed engine guru Smokey Yunick said he likes to see a minimum of 0.135" anywhere in the cylinder after boring and honing. He said further that there must be enough mass in the walls to quell vibrations set up by the piston rings skidding up and down the walls (yep, he said they SKID, rather than moving smoothly up and down). Smokey used to cut windows into the cylinder blocks and install glass panels so he could witness what was actually happening with the motor running. If these vibrations are not kept under control by the mass of thicker cylinder walls, they can transfer to the water jacket side of the cylinder wall and separate out little air bubbles from the cooling water, which then cling to the wall and prevent cooling water from getting to the wall to cool the cylinder.

    Now you know why an over-bored block with thin walls will have a tendency to over-heat.

    Ultrasonic equipment is used in most shops to determine the cylinder wall thickness of a block. This equipment has come down in cost over the last 20 years, but is still in the $1000 range. Affordable for a shop or even an engine builder who builds a few high-buck engines a year, but still a little pricey for the home-builder. Check with automotive machine shops in your area to find out if any of them have the equipment to sonic-check your cylinder walls before you buy yourself into some trouble with money invested into a freshly bored and honed block that is useless except for a door stop.

    The other thing is, you must build your motor to the fuel that is available to you. If that fuel is pump gas that is available down on the corner, then you will need to pull back a little on your expectations. It is generally accepted in the hot rod community that current fuel quality will support as high as 9.5:1 static compression ratio if the motor is using iron heads, which are slow to shed heat. If you want to invest in a set of aluminum heads, then you can safely build the motor to 10.5:1 static compression ratio. Anything over 10.5:1 will require E85 at the pump or racing gasoline or racing ethanol or racing methanol.

    Using aluminum heads has aspects that must be paid attention to as well. In order to prevent fretting the soft aluminum material, thicker composition head gaskets must be used. For instance, several aluminum cylinder head manufacturers recommend the builder using Fel-Pro 1003 composition gaskets with their heads. These are 0.041" thick, so to end up with a squish/quench somewhere between 0.035" and 0.045", the builder must zero deck the block so that the pistons come up even with the block deck at top dead center. Since one of the goals in building the motor is to retain as much metal in the block as is possible, it becomes attractive to use a piston that has a very tall compression height so that a minimum of material must be removed from the block decks to arrive at ZERO DECK. Skip White Engines sells the Wiseco line of forged pistons that feature a +0.015" compression height over the stock 350 Chevy dimension of 1.560", so that with these 1.575" pistons, you need to cut the block only 0.010" to achieve zero deck. This is one of the best kept secrets in the hot rod community. I used Wiseco pistons in a racing go-kart in the early '60's, so I can bear witness to the quality of the brand.

    https://www.skipwhiteperformance.com...orged-pistons/

    https://www.skipwhiteperformance.com...-pistons_7452/

    Pretty good prices in my opinion, for a piston and ring package of this quality.
    .
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  3. #18
    jerry clayton's Avatar
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    My sugestion---------get an later year block set up for roller lifter camshaft-------and altho I have several in the shop , for myself I would chooze a Dart that I could build with bore and stroke to get it out to 427 cid and add a nice set of aluminum heads-------
    By popular opinions-just a grumpy old man key board bully--But really, if you are going to ask for help on an internet site, at least answer questions about what you are asking about-----

  4. #19
    Travlin55 is offline CHR Member Visit my Photo Gallery
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    Quote Originally Posted by techinspector1 View Post
    Hold on there Hoss. The block will likely have to be bored and honed to the next oversize , +0.060", which could make the cylinder walls too thin, depending on core shift when the block was cast.

    There are thin wall blocks and there are thick wall blocks in the same engine family. All production blocks are cast. Casting is a mature, but not particularly exact process. There will be core shifting and such going on that will make one block come down the production line with pretty much equally thick cylinder walls all around, then the one right behind it could have thin walls on one side of the cylinder and thick walls on the other side.

    The thrust side of the cylinder on a small block Chevy is on the inboard side of the cylinder on the driver's side of the block and the outboard side of the cylinder on the passenger's side of the block. Most engine builders will prefer to have 0.200"+ on the thrust sides of the cylinder after boring and honing. Other areas around the bore can be slightly thinner. Famed engine guru Smokey Yunick said he likes to see a minimum of 0.135" anywhere in the cylinder after boring and honing. He said further that there must be enough mass in the walls to quell vibrations set up by the piston rings skidding up and down the walls (yep, he said they SKID, rather than moving smoothly up and down). Smokey used to cut windows into the cylinder blocks and install glass panels so he could witness what was actually happening with the motor running. If these vibrations are not kept under control by the mass of thicker cylinder walls, they can transfer to the water jacket side of the cylinder wall and separate out little air bubbles from the cooling water, which then cling to the wall and prevent cooling water from getting to the wall to cool the cylinder.

    Now you know why an over-bored block with thin walls will have a tendency to over-heat.

    Ultrasonic equipment is used in most shops to determine the cylinder wall thickness of a block. This equipment has come down in cost over the last 20 years, but is still in the $1000 range. Affordable for a shop or even an engine builder who builds a few high-buck engines a year, but still a little pricey for the home-builder. Check with automotive machine shops in your area to find out if any of them have the equipment to sonic-check your cylinder walls before you buy yourself into some trouble with money invested into a freshly bored and honed block that is useless except for a door stop.

    The other thing is, you must build your motor to the fuel that is available to you. If that fuel is pump gas that is available down on the corner, then you will need to pull back a little on your expectations. It is generally accepted in the hot rod community that current fuel quality will support as high as 9.5:1 static compression ratio if the motor is using iron heads, which are slow to shed heat. If you want to invest in a set of aluminum heads, then you can safely build the motor to 10.5:1 static compression ratio. Anything over 10.5:1 will require E85 at the pump or racing gasoline or racing ethanol or racing methanol.

    Using aluminum heads has aspects that must be paid attention to as well. In order to prevent fretting the soft aluminum material, thicker composition head gaskets must be used. For instance, several aluminum cylinder head manufacturers recommend the builder using Fel-Pro 1003 composition gaskets with their heads. These are 0.041" thick, so to end up with a squish/quench somewhere between 0.035" and 0.045", the builder must zero deck the block so that the pistons come up even with the block deck at top dead center. Since one of the goals in building the motor is to retain as much metal in the block as is possible, it becomes attractive to use a piston that has a very tall compression height so that a minimum of material must be removed from the block decks to arrive at ZERO DECK. Skip White Engines sells the Wiseco line of forged pistons that feature a +0.015" compression height over the stock 350 Chevy dimension of 1.560", so that with these 1.575" pistons, you need to cut the block only 0.010" to achieve zero deck. This is one of the best kept secrets in the hot rod community. I used Wiseco pistons in a racing go-kart in the early '60's, so I can bear witness to the quality of the brand.

    https://www.skipwhiteperformance.com...orged-pistons/

    https://www.skipwhiteperformance.com...-pistons_7452/

    Pretty good prices in my opinion, for a piston and ring package of this quality.
    .
    Ok so, after much pondering and considering the great information you have provided I think I'm going to have simons machine here in charelston hopefully give me a thumbs up on the bore as is at .040 as it was built only 3000 miles ago.I'm now considering a 383 kit with wiseco Pistons as suggested and having the block decked as suggested.
    I will then possibly go with skip whites aluminum heads, maybe still use the air gap intake? and possibly a 750 Holley? Still not sure about the cam but feel a roller would be a nice touch? By the way what's the difference between a regular 383 crank and a scat crank?
    So, what do you think? Please keep in mind this has been a learning curve for me.
    Last edited by Travlin55; 03-16-2019 at 07:35 PM.

  5. #20
    techinspector1's Avatar
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    Quote Originally Posted by Travlin55 View Post
    Ok so, after much pondering and considering the great information you have provided I think I'm going to have simons machine here in charelston hopefully give me a thumbs up on the bore as is at .040 as it was built only 3000 miles ago.I'm now considering a 383 kit with wiseco Pistons as suggested and having the block decked as suggested.
    I will then possibly go with skip whites aluminum heads, maybe still use the air gap intake? and possibly a 750 Holley? Still not sure about the cam but feel a roller would be a nice touch? By the way what's the difference between a regular 383 crank and a scat crank?
    So, what do you think? Please keep in mind this has been a learning curve for me.
    Forged pistons generally require a little more piston to bore clearance than a cast piston, so you could be in good shape if the walls are relatively straight and the bores are round. The shop might be able to put the extra clearance in the block for you with just a precision hone job using the proper grit stones to match up with the piston ring material being used. I don't know if you knew that different piston ring materials require different roughness on the walls, but yeah, they do. Then, there is plateau honing. Read through the process here, the more you learn, the better you will be prepared to go head to head with the guy at the machine shop.
    https://www.enginebuildermag.com/200...e-refinishing/

    Although some fellows will tell you that you don't need the pistons in hand for the machine shop to finish hone the block, I will caution you that we are dealing with human beings here, and human beings make mistakes. MY VERY BEST ADVICE TO YOU IS TO TAKE THE PISTONS AND RINGS TO THE MACHINE SHOP BEFORE THEY BEGIN HONING ON THE BLOCK.

    The rings will have to be gapped according to the piston manufacturer's instructions. Wiseco calls for the top ring on a 2618 (this is the piston alloy designation) "piston to be used in a hot street application" to be gapped at 0.005" per inch for each inch of bore. So, a bore of 4.040" times 0.005" equals 0.0202". I would be OK with dropping the two ten-thousandths off the end and gapping the top rings at 0.020" (twenty thousandths). Wiseco calls for the second rings to be gapped at 0.0055" per inch for each inch of bore. So, a bore of 4.040" times 0.0055" equals 0.02222". Again, I would be fine with using only 3 places past the decimal point and calling the second ring gaps at 0.022" (twenty two thousandths). The idea behind this is that any blowby that gets past the top ring will be vented past the second ring because of the wider gap in the second ring. The top compression ring and the second oil control ring do their jobs by closely fitting the bottom of the rings to the bottom of the piston grooves, so any high pressure area between the first and second rings could upset this arrangement. The third set of oil rings, the expander and rails, will be in a low heat area, so whatever gap is on them from the factory will probably be OK. Pow-Wow with the machine shop about this. You can pay them to gap the rings or you can purchase a ring gapping machine and do them yourself. HINT: I would rather do them myself. It adds another skill to your engine-building knowledge.
    https://www.youtube.com/watch?v=uAguO3EPzcI
    Here's a hand-turned model where a buddy would turn the crank while you manipulate the ring on the tool.....
    https://www.summitracing.com/parts/pro-66785

    You'll find that there is more to aluminum heads than just being aluminum heads. While I would have no problem recommending the Wiseco taller compression height pistons and piston rings from Skip White Engines, I would have to pull my recommendation on aluminum heads from them. Unless I am mistaken, all of their offerings are cast in China or other offshore location where everyone copies everyone else and nobody seems concerned in the actual flow capability of the heads. You buy cylinder heads for the flow that they are capable of, not for the money you're going to save because the Chinesium heads are cheaper than the heads that flow correctly. Currently, there are only two manufacturers that I would call on for heads, Airflow Research and Pro-Filer. AFR casts up the Rolls Royce of heads and charges for them commensurate with their quality. There is another head, the All-American by Pro-Filer that flows nearly as well as the AFR head, but is about $400 cheaper for the pair.

    Here's the Pro-Filer, you'll end up with a total investment of about $1200 into the pair of heads. That will be complete with screw-in studs (I'd opt for the 7/16" studs instead of the 3/8" which come standard on 350 heads), guide plates, valves, seals, locks, springs and retainers, ready to bolt on and go. Use ONLY valve springs that are recommended by the cam manufacturer for the cam you will use. These heads, bolted onto a 383 with 10.0:1 to 10.5:1 static compression ratio, 230 degree intake duration @0.050" roller tappet cam, 850 CFM carb on a dual-plane, high-rise intake manifold and a set of 3/4" diameter primary, equal-length headers, H-pipe immediately after the collectors, will generate 500+ horsepower and 500+ lbs/ft of torque. Your current differential would last about 5 minutes.
    https://www.profilerperformance.com/...ree-heads.html

    There is no regular 383 crank. Chevrolet never made a 383. It's a hybrid that was concocted by hot rodders by turning down the main journals on a 400 crank so that it would bolt into a 350 block. The 400 crank has the same rod journal size as the 350, but has a 3.750" stroke instead of the standard 3.480" stroke of the 350.

    Scat is an aftermarket manufacturer that has been making hot rod parts for Volkswagens for decades now....and has morphed into a new business model by casting up 3.750" cranks to fit into 350 blocks. Journalist and hot rod guru expert David Vizard has written that he has used Scat cranks for the past few years, taking as much as 550 horsepower out of a 383, without a single failure. When you put a 383 together with stock 5.7" rods, there is interference at some points with the cam lobes. To fix this, you grind on the rod at the big end to make clearance. I will not recommend using stock type rods in such a build though, and would strongly recommend using Scat 6.000" rods instead. They are manufactured to clear the cam lobes and will also allow a larger diameter crank so that balancing doesn't cost you an arm and a leg for Mallory Metal. Internal balancing is far superior to using a damper with offset weight and flexplate with offset weight.

    Pro-Filer casts up the All American heads with 64, 70 or 72cc chambers, it is pretty easy to get to the static compression ratio that you want by juggling the chamber volume with various piston crown configurations.

    I can appreciate that this has been a learning experience for you........and I expect for a few other fellows as well. There are others in the hobby who could make me look stupid though, and I really wish they would show up and share themselves.

    .
    Last edited by techinspector1; 03-17-2019 at 07:32 AM.
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  6. #21
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    Busy this afternoon, but will sit down and list all the part numbers and procedures for you this evening.
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  7. #22
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    Wiseco #KP456A4 4.040" pistons w/12cc dish to be used with 6.000" connecting rod, including rings. Piston compression height (centerline of wrist pin to crown), 1.275".
    Scat 6.000" connecting rods.
    Using Fel-Pro 1003 gaskets with 64cc combustion chamber and zero decks, static compression ratio will be 10.25:1. Use Pro-Filer heads with 210cc intake runners for killer power to 6000.
    Use 850 CFM carb on tall dual-plane intake. If your air gap does not make the motor buck and snort in cool or cold weather, use it. Otherwise, use a Weiand 8150.
    Order the whole mess balanced.
    Use a 2-piece front cover to make fitting the thrust button or changing or phasing cams easy.
    https://www.summitracing.com/parts/c...make/chevrolet
    I like a nylon thrust button because it's not necessary to tear the motor down and clean out all the shrapnel when a roller bearing thrust button frags.
    .
    https://www.summitracing.com/parts/cca-202/overview/
    Last edited by techinspector1; Yesterday at 03:37 AM.
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  8. #23
    Travlin55 is offline CHR Member Visit my Photo Gallery
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    My friend, your knowledge has been eye opening for sure and you have been incredibly helpful! I really cannot thank you enough. I will start putting parts together and talk to the machinist in a week or so. Will let you know how it works out. JT
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  9. #24
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    After more research, I'm gonna pull back a little on the heads, from 210cc intake runners back to 195cc's. You will need a little more velocity to fill the cylinders at the top end and 195's will work great on a 383 at 6000 rev limit.

    After much hand wringing and gnashing of teeth, I have landed on a cam and lifter kit that I think will maximize the package.....

    Howards CL110265-12 kit includes retrofit Howards hydraulic roller lifter cam and 16 Howards roller lifters. Always buy the lifters with the cam from the same grinder or supplier. There are lots of "white box specials" that are offshore junk that is reboxed to look like USA-made parts. The younguns reading this should learn that there are many, many shady characters in the world who are less than honest and will take your hard-earned money to sell you junk.
    Advertised duration 286/294 degrees
    0.050" duration 233/241 degrees
    Valve lift 0.530"/0.545"
    112 degree lobe separation angle. This should still allow pretty good manifold vacuum for power brakes.
    108 degree intake centerline
    116 degree exhaust centerline
    Lopey idle, recommended for hot street and bracket racing.
    10.0:1 and up static compression ratio advised. (Your 10.25:1 SCR will be right on the money).
    Effective operating range 2400-6000 rpm's, 3,000 rpm stall converter advised. Call Freak Show Converters.
    https://www.yellowbullet.com/forum/s...d.php?t=407030

    Order the 195cc All American Pro-Filer heads with #93 spring package, 0.650" valve lift potential, 1.437" dual hydraulic roller valve springs with steel retainers and seals, all assembled and ready to bolt on. And just a heads-up here, do not screw any bolt or nut down against the aluminum head material without using a quality hardened flat washer under the bolt head or nut.
    Get yourself an ARP bolt/nut/washer catalog. They make good stuff.
    https://arp-bolts.com/

    There are some pretty good quality STAINLESS STEEL headers on ebay for reasonable prices if you look around for them. Yeah, they're offshore, but headers are not a moving part, so look around for a set of long-tube (about 30" primary pipe length and 1 5/8" or 1 3/4" primary tube diameter) headers. DO NOT, under any circumstances, install shorty headers on your motor. They are a complete waste of time and money....... Look for the thickest flange material that you can find. Thin flanges will warp up like a potato chip from the heat of operation and spit out the gaskets.

    Give some thought to what you will do for a differential because if you use enough rubber to hook up, that's the next victim. Differentials are just like all other parts of an automobile, you can buy junk or you can pay the price and get a quality piece of machinery. I'd be thinkin' Mopar 8 3/4", Ford 8.8", Ford 9", GM 12 bolt.

    Mount the battery or batteries in the trunk, in the EXTREME REAR on the EXTREME PASSENGER SIDE of the car. Use a steel frame to sit them in, with minimum 3/8" allthread and nuts securing them to the frame structure of the car. Go to a welding supply shop and purchase 2-0 welding cable and copper lugs to run the lines to the starter and ground on the frame close to the starter. Solder the lugs to the cable. At the same time, grind down to bare metal and ground the starter to the body. Remove the padding and carpet at the foot of the passenger compartment and drill a hole up above where the passenger's feet would go. (Make sure you are not drilling through something in the engine bay). After grinding down to bare metal around the hole in the engine bay, install a bolt and nut through the hole to secure the ground cable to the starter. Use another cable to ground the starter to the frame. Same deal, grind to bare metal, then use bolt and nut. Now, you will have the body grounded to the frame, the frame grounded to the starter and the starter grounded to the body. After all the grounds are secured, you can go back with some silicone and slather the connections, making them air tight and waterproof. I'm teaching you how to bulletproof the car.

    Before you lay out the green for a new differential, you can install an air shock on the right rear only of the car. Alter the air pressure in the shock (mount an air valve on a bracket off the rear bumper. You can even mount a gauge in the trunk to tell you the pressure if you want.) until you get two equal black stripes from the rear tires on acceleration. Use some old skinny tires to get this set up properly. Once you find the sweet spot, you'll see how the front end comes up nice and square on acceleration. Then you can change to wider and wider tires until you bust the differential. HAHAHAHAHAHAHA. Watch the street-driven doorslammers at the drag races and you'll see that the driver's side front of the car comes up first. That's because a front-motor, rear-drive car twists in such a way that the left front gets light and the right rear gets light, while the right front and left rear get heavy. That's also why you will always see a worn-out right rear tire on a tire screeching Ricky Racer car, while the left rear tire still looks new.This air shock trick is the cheapo way to equalize traction before you lay out the dough for a posi rear. The upside is that the differential is still a one-legger and the car drives easy. The only down-side is that when the car is parked, the right rear will be a little higher than the left rear, but if you can live with that, you're dialed in for traction. If someone mentions it, just smile at them and tell them "Yeah, that's the way it turned out".

    If you are planning a new fuel tank, mount it to the extreme passenger side of the car and as far to the rear as you can. You want all the weight on the EXTREME right rear of the car.

    OK, that's about the best I can do for you for now. I know there will be other questions, so I'm here to help you.
    .
    Last edited by techinspector1; Yesterday at 04:38 PM.
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