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Old 08-24-2016, 01:07 PM
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There are many factors but when comparing the same compression using two different chambers and pistons it is likely the any difference will be negligible.
The factors to be considered are flame front travel (domed pistons can interfere with this) and the geometry of the total combustion area. With a "D" cup piston in a smaller chamber versus a flat top piston in a larger chamber it will be close to the same unless the smaller chamber restricts intake or exhaust flow to and from the head. I would say that although there may be some small measurable difference it would be meaningless under most conditions.

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  #32 (permalink)  
Old 08-24-2016, 01:33 PM
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Skip White sells a 383 rotating assembly that is probably 1 of the best deals you can find for the money & would work well for the use you state.It has decent parts & comes externally balanced with either 5.7",or,6" rods.It includes a Scat crankshaft,Scat rods,Wiseco forged pistons,King bearings.It runs just under $1000.The pistons in this kit come with a taller pin hgt that doesn't require decking to the block to get to correct stack hgt.Just a cleanup pass if needed.The forged pistons are a little overkill,but,they don't hurt anything.
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Old 08-24-2016, 02:08 PM
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I suspect that SOME budget larger chambers are created by taking a 'standard' 64cc chamber and sinking the valves deeper
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Old 08-24-2016, 03:22 PM
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Quote:
Originally Posted by jokerZ71 View Post
Skip White sells a 383 rotating assembly that is probably 1 of the best deals you can find for the money & would work well for the use you state.It has decent parts & comes externally balanced with either 5.7",or,6" rods.It includes a Scat crankshaft,Scat rods,Wiseco forged pistons,King bearings.It runs just under $1000.The pistons in this kit come with a taller pin hgt that doesn't require decking to the block to get to correct stack hgt.Just a cleanup pass if needed.The forged pistons are a little overkill,but,they don't hurt anything.
It looks like the compression ratios for that setup is a little too high for my application though, no?
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Old 08-24-2016, 04:37 PM
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Quote:
Originally Posted by Evilash1996 View Post
It looks like the compression ratios for that setup is a little too high for my application though, no?
You can choose different volume pistons to tailor the build to your needs.You can also vary the head chamber volume to get where you need to be, at least on name brand heads.Most of the budget heads only come in 1 chamber size & some only come in 1 port size.
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Old 08-24-2016, 09:33 PM
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You mention your intended use is for street driving. Does this mean to car shows and cruise in's, daily seasonal driver, or year round daily driver. How many miles a year do you think?

HP all boils down to your budget. Joker can give you a recipe for a budget 355 with a set of Vortecs that will be high 3's to low 4's hundred HP. Eric and Vinnie will rattle off 383 build specs that will be another $1000 or so that will be 450-525HP.

You've already been advised to get the best heads you can afford, but some reasonably priced options are AFR, Brodix, or a set of Chad Speier worked Profilers - all can be had in the $15-1800 range. And I'm confident that there are others that can build and port a great head for similar money. If your budget is larger than that, then start looking into 18 degree heads and the power will add. And there are a ton options that are less that don't give up very much from the higher priced options. One item to definitely not compromise on is putting in a roller cam. The most economical way about this a using a roller block. But it isn't an outrageous amount of money to use a retro roller setup either.
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Old 08-24-2016, 11:01 PM
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BLOCK DECK HEIGHT; The measured distance from the centerline of the main bearing bore to the top of the block at the deck where the heads bolt on. The blueprint BDH for a small block Chevy block is 9.025", but due to factory manufacturing tolerances, it can be more or less than that.

STACK; The measured sum of dimensions of parts that you will use to fill the block. For instance, if half the stroke of a 350 is 1.74", the rod length is 5.7" and the piston you will use has a compression distance (the measured dimension from the centerline of the wrist pin to the flat part at the top of the crown of the piston just above the top compression ring and not including any crown) of 1.560", then adding these figures together will give you a stack dimension of 9.000". Some manufacturers produce their pistons with a shorter compression height to allow cutting of the block decks and still keep the same squish/quench. By the same token, some manufacturers produce their pistons with a taller compression height to allow the builder to tighten up the squish without cutting the block decks. If, for instance, your block deck height measures 9.020" and you use a piston that has a 1.575" compression height, then the piston deck height would be 0.005" and you could use a Fel-Pro 1014 gasket (compresses to 0.039") to produce a 0.044" squish/quench without cutting the block decks. On a 383 motor with a 5.7" rod, the piston compression height would be 1.425" or somewhere close to that, depending on whether the manufacturer built the piston with a taller compression height or a lower one. If a fellow were going to use a 6" rod in a 383, then the piston compression height would be 1.125" or somewhere close.

SQUISH/QUENCH; The measured dimension between the top of the piston and the underneath of the cylinder head with the head gasket in place. Most builders will shoot for a 0.035" to 0.045" dimension.

PISTON DECK HEIGHT; The measured dimension from the top of the piston crown to the block deck where the head bolts on with the piston at top dead center. Piston deck height plus head gasket thickness equals squish/quench.

It's going to make a difference whether you will run iron heads or aluminum heads. You can use any gasket with iron heads, but aluminum heads will want a thicker gasket that will give a little because of the dissimilar shrink and growth characteristics of the aluminum heads and iron block. A thin steel shim head gasket with aluminum heads could cause fretting of the aluminum, but a thin steel shim head gasket on an iron headed motor works great to reduce the piston deck height and to tighten up the squish/quench.

Squish/Quench should always be the most important dimension to you as an engine builder and you'll want to shoot for a clearance of 0.035" to 0.045". As the piston comes to the top of the bore for firing of the spark plug, the flat crown of the piston mates up with the flat squish pad of the cylinder head and the air/fuel mixture that is there gets jetted out and blown across to the chamber, where it homogenizes the air/fuel mixture, breaking up clumps of fuel and resulting in a better bang to make more power. A tight squish/quench has been called "mechanical octane" for its ability to allow the motor to make more power on a lesser grade of fuel and to prevent detonation on pump gas.

So, iron block and aluminum heads likes a little thicker head gasket to prevent fretting. That means that the piston will have to be closer to the block deck (less piston deck height) in order to allow the use of a thicker head gasket, while still keeping a thin 0.035" to 0.045" squish. The top manufacturers of aluminum heads will recommend gaskets with a 0.039" to 0.041" compressed thickness, so the builder would want close to a "zero" deck where the piston crown comes up even with the deck of the block. With a zero deck and a 0.039" thick gasket, the squish/quench would be 0.039". The other thing about aluminum heads is that they will like a gasket that has pre-flattened fire rings to prevent brinelling of the aluminum. The Fel-Pro 1003 would be a favorite for the 350 block, while a Fel-Pro 1014 would be a good choice for a 400 block.

On the other hand, an iron block and iron heads combination can use any gasket, as long as the heads and block deck are fairly flat and smooth. Some fellows will want to keep the stock 9.025" block deck height and use a thin shim steel head gasket of around 0.015" thickness. With a "stack of parts that measures 9.000", for instance, and with a 9.025" block deck height and a 0.015" gasket thickness (added together), the squish/quench would be 0.040".

So the bottom line is, measure the block deck height first, then decide if you can build the motor that you want with the stock block deck height or if you will need cut the block decks to coordinate the gasket thickness that you need in order to arrive at a 0.035" to 0.045" squish/quench, while taking into consideration whether you are using iron or aluminum heads. If you will measure the block deck height on all four corners of the block, you will probably come away with four different measurements and neither of the two banks will be parallel with the cam bore. What happens in a mass-production plant is that, for instance, the milling machine operator who cuts the finished decks of the block might miss cleaning out a chip from the previous operation and registers the next block improperly. It it is registered improperly, then it is cut improperly and you end up with the aforementioned four different block deck heights.

.

Last edited by techinspector1; 08-24-2016 at 11:21 PM.
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  #38 (permalink)  
Old 08-25-2016, 02:31 AM
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Usually a machine shop will want pistons to be with the block before it is bored and honed, they will measure the pistons and hone the bores to match the pistons.
Your best bet to get correct deck height is to have the cylinders bored and honed, mains line honed, and then do a 4 corner mock up and measure how much will be cut from the decks.
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Old 08-25-2016, 06:39 AM
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Keep in mind,if you plan to use the 383 kit from Skip White,the pistons in that kit will sit at approx. 9.015" in an uncut block.If using the 6" rod,the compression hgt of the piston will 1.140".The 5.7" rod uses a pin hgt of 1.440".Most off the shelf pistons for a 383 will be 1.425",or,a few that will have a 1.433" pin hgt.
If you're machinest cuts more than .010" from the decks,this will have the piston slightly above deck.
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Old 08-25-2016, 08:22 AM
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Do you know exactly which block you have.Approx year model?Can you give us the casting # on the block.This will be located on top the block,just behind the drivers side head?
You will need to know for sure which block you have before buying parts.This will tell us if it is a roller cam block & wether it's a pre87 2 piece rear seal,or,a newer 1 pc rear seal.
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Old 08-25-2016, 08:26 AM
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Quote:
Originally Posted by Evilash1996 View Post
Is it difficult to match the static weight yourself? I've never done anything like that before but from what I can tell its not too difficult as long as you have a scale.
Piece o' cake. I have always used a simple kitchen scale like this 5-star rated one from Amazon that has a resolution of 1 gram.
https://www.amazon.com/Kitchen-GDEAL...weighing+scale
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Old 08-25-2016, 08:37 AM
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Quote:
Originally Posted by Evilash1996 View Post
Main usage is street, I don't plan on racing this engine. As far as power, the most HP and torque I can fit into it while being able to used regular gasoline. As for the vehicle, don't have one yet. It was going to go in my father's El Camino but plans have changed. I've been looking for a cheap project car to start off with (basically to make a sleeper). But the price for muscle cars around my area are ridiculous. People are selling chevelles/novas/pontiacs etc. with trees growing through them for $3000.
Money talks. These guys may be ASKING those ridiculous prices, but asking price and selling price are 2 different animals. My favorite thing to do when looking for a new project is to snoop around in alleys and side streets to find derelicts that are NOT being advertised as for sale. You can sometimes use the license tag number to go to your state motor vehicle department and find out who the owner is if you take photos of the car with the tag being shown. If there is a law that will not let you do that, try making friends with law enforcement. Perhaps you or someone in your family know an officer that you could ask to run the plates and find out who the owner is and get you some contact information.
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Old 08-25-2016, 08:52 AM
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Rebuilding a 350 into a 383 stroker. Need help on pistons and deck clearance.

The easiest way to start the rebuild is to figure the parts stack. 1/2 of the stroke, compression height of pistons, and rod length. 3.750/2=1.850 + 1.440 + 5.700= 9.010" This is what you want to cut your deck to using this kit. Skip White Performance Detail Description This is the best price you will find anywhere! I would top the block with these ProFiler 195 cc Heads. Here is a description: SBC 23 Degree Cylinder Head, 11/32 Guides & Steel Seats
Intake Port Size: 195cc Intake Ports
Chamber Size: 72cc As Cast Chamber
Spark Plug Orientation: Straight Plug
Valve Job: 2.02/1.600 Valve Job
Assembly Options: Opt #93 Standard .650 Lift 1.437 Dual Springs, Steel Retainers, Keepers Assembled ADD $125.00
Casting Style: Standard Cooling
176 Total price $1263.72 BTW you can go a step up to the 210cc intake ports but looking at the flow charts the 195cc heads on a 383 cid engine are good up to 6500 rpm. 64cc chamber heads will give you a 10.98 c.r. and 70cc chamber heads will give you a 10.27 c.r. For the best performance and reliability a hyd. roller camshaft would be the best to use. You saved enough money on the rotating assembly to get a roller cam.
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Old 08-25-2016, 08:55 AM
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Quote:
Originally Posted by Evilash1996 View Post
That was my original question for this post. Do you think it's okay if I have the machine shop deck the block and afterwards from there I can choose the kit?
No, that's bass ackwards. Measure the block deck height, then shop for a kit that will fit into that block deck height, then cut the block decks to the correct block deck height for the kit and whatever head gasket you have to use, based on whether you will use iron heads or aluminum heads.

And by the way, you should plan to limit static compression ratio to no more than 9.5:1 with iron heads and no more than 10.5:1 with aluminum heads. I noticed in one of your posts that you said you wanted to run regular gas. Does that mean regular pump gas as opposed to racing fuel or does that mean that you want to be able to run on 87 octane "regular" pump gas? If it's 87 octane pump gas, I would recommend tightening up the squish to 0.030" to 0.035" and limiting the static compression ratio to no more than 9.0:1. That will mean using a very mild cam with maybe 204-206 degrees intake duration @0.050" lift and an operating range of roughly 1200 to 5000 rpm's.

Every engine build should begin with the available fuel quality.

.

Last edited by techinspector1; 08-25-2016 at 09:05 AM.
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  #45 (permalink)  
Old 08-25-2016, 04:41 PM
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Okay I gotta a lot to respond to.

I brought the block to the machinist today and it turns out the block was no good. Already had a sleeve in it and was basically a really heavy paper weight. My family knows the machinest personally so were going to use a 350 small block that he had on hand for a small price. He is going to deck the block as minimally as possible and then from there I was going to choose my rotating assembly and heads.

As far as the use of this engine, when I say street I mean as a weekend/sunday car. Not a daily driver just something to screw around with on the weekends.

As for the pump gas. My original intentions was to use 87 octane gas but if my compression ratio needs to be that low then I have no problem with using premium fuel if I need to. If I use premium gas I can go up to 10.5 CR without any detonation issues?

I'm a little confused on roller cams. If my block is older than 87 I can't use a roller cam in it?

And I'm in no rush to find the project car this will be going into yet. I find the best way to find cars was how you said, drive around in neighborhoods and look for cars hidden under tarps and in driveways.
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