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Old 04-25-2010, 12:48 PM
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383 chevy stroker

my buddy has a 383 he pulled out of a k5 blazer, its a mild motor with flat tops and a rv and towing cam, he pulled bc it had a tick in it, come to find out it has 2 bad pistons, but it ran good, and kept good oil press,did smoke or anything, now this is where i come in, id like to get my hands on it and fix the prb's and put a comp mag 525'' lift cam in it and use some experimental heads with the casting num's (450) as the twin towers, force feeding it with a 600 cfm eledebrock @ first, with a victor jr. to derect the flow then to see where the 500hp mark is! anybody got any opinions?

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Old 04-25-2010, 01:00 PM
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more fuel

im no engine guru but i believe a 500 hp engine is gunne need more fuel. i would think that a 600cfm would choke it some, and that u should look into a 750
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Old 04-25-2010, 03:31 PM
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first what are the heads, i looked up any GM small block head's who's casting numbers ended in 450 and all i come up with is 176450 used on 262 and 305 in 75'-76' and 367450 used on 262,267, and 305 in 75'-81' and to let you know that during this time neither of these motors even made 150hp, the 262 was actually rated at 110hp in 75-76' so that should tell you something about the heads that you are trying to work with.

you're gonna be no where near 500hp, maybe 350-360hp if you can get those heads to flow about 220cfm at your max lift

now before trying to pick a cam you need to know what pistons you are using and what the negative cc is in the piston crown so you can pin point compression with a .040" quench and what ever compression ratio you're gonna get. basically you need to know your compression ratio first then you can look for a cam, you also need to take into account what the motor is going into (weight), what gears will be used, what stall you plan on using, and what is the intended use of the vehicle. next i would question why you would use a hydraulic flat tappet cam with so much duration and lift, personally i wouldn't use a hyd f/t cam with anything over .480" lift and no more than 230 duration @ .050, past that i would look into a solid f/t cam, now if you have the money then you should look into running a hydraulic roller cam, with the 305H's cam specs on a roller cam that would be possible, but i think that the cam you have picked will have this 383 turing 6500+rpm (well past what the heads could handle) and the hyd f/t lifters will end up failing, not to mention the cam lobes. and then you mention a 600cfm carb for a 383 turing 6500rpm (which this is what the cam you picked will want to have it running) you will need at least a 750 but i would certainly recomend a 825-850 carb. you seriously need to research what you want to do, and find some real combinations, cause what you have listed here is awfull
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Old 04-25-2010, 04:23 PM
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Quote:
Originally Posted by my87Z
first what are the heads, i looked up any GM small block head's who's casting numbers ended in 450 and all i come up with is 176450 used on 262 and 305 in 75'-76' and 367450 used on 262,267, and 305 in 75'-81' and to let you know that during this time neither of these motors even made 150hp, the 262 was actually rated at 110hp in 75-76' so that should tell you something about the heads that you are trying to work with.

you're gonna be no where near 500hp, maybe 350-360hp if you can get those heads to flow about 220cfm at your max lift

now before trying to pick a cam you need to know what pistons you are using and what the negative cc is in the piston crown so you can pin point compression with a .040" quench and what ever compression ratio you're gonna get. basically you need to know your compression ratio first then you can look for a cam, you also need to take into account what the motor is going into (weight), what gears will be used, what stall you plan on using, and what is the intended use of the vehicle. next i would question why you would use a hydraulic flat tappet cam with so much duration and lift, personally i wouldn't use a hyd f/t cam with anything over .480" lift and no more than 230 duration @ .050, past that i would look into a solid f/t cam, now if you have the money then you should look into running a hydraulic roller cam, with the 305H's cam specs on a roller cam that would be possible, but i think that the cam you have picked will have this 383 turing 6500+rpm (well past what the heads could handle) and the hyd f/t lifters will end up failing, not to mention the cam lobes. and then you mention a 600cfm carb for a 383 turing 6500rpm (which this is what the cam you picked will want to have it running) you will need at least a 750 but i would certainly recomend a 825-850 carb. you seriously need to research what you want to do, and find some real combinations, cause what you have listed here is awfull
this is all experimental, to see what i can get out of some 305 heads that flow more than the vortec's like 180 or 185cc intake, its had a good hoggin out done on both sides intake and exhaust and yeah it still has the 1.88 valves. im lookin at 10.0:1 or 10.5:1 comp ratio and the little 600 carb is just a test, i have a 750 layn around to see what it really has in the hp range, and the "roller" will have to wait for now (no funds for that) and the pistons will be flat tops 2 valve releifs.
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Old 04-25-2010, 04:26 PM
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Quote:
Originally Posted by beastlyschriefer
im no engine guru but i believe a 500 hp engine is gunne need more fuel. i would think that a 600cfm would choke it some, and that u should look into a 750
yeah i have a 750 layn here just wondering where id get with the 600.
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Old 04-25-2010, 05:39 PM
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i believe that stock vortecs are 170cc intake runners, now to what you mentioned. typicall 2 valve relief flat top pistons are about -4cc's now as long as you are setting your quench to about .040" then with those heads and those pistons you will be sitting at about 11.6:1 not 10ish:1. the experiment you are planning to do has been done many times before with all kinds of 305 heads, and to let you know they dont have 1.88" intake valves, from the factory those heads came with 1.71 intake valves. and those heads started off life as about 150cc intake runners with tiny exh runners, and if you do those heads it would be stupid not to use a dual pattern cam so that you have the exhaust valve open for longer to compensate for the crappy exh flow from the heads. back to what i was saying about a 383 with 305 heads, sure it will bump up the compression but you will be loosing so much top end it will be crazy, the 305 heads on a 383 wont be able to handle over about 4000-4500rpm and at that point the cam you chose would only be starting to make power.

i just reread you last post about the 305 heads flowing more than what a set of vortecs do, are you sure about that have you had them flow tested and if you have what numbers did you get, dont forget that head performance is not defined by maximum air flow, it is more defined as flow across the curve say .300-.500 lift as well as velocity during this time. when you go cutting a set of heads up you may be able to get the head to flow more air but you will loose velocity as you increase the cross sectional area of the port, this will drastically affect power from 2000-4500rpm where most vehicles do most of their driving

and your goal of 500hp is no where near realistic, like i mentioned before i think you will be hard pressed to even get 350hp from those heads, if people could just take a set of garbage heads and turn them into 500-600hp heads with just some machine work then that would be all people would do instead of looking for the proven performing GM head or a set of aftermarket heads. i have a something i like to day when i see someone trying to work a set of garbage heads here goes "you can polish a turd all you want but in the end you'll still just end up with a turd"

not trying to attack you but i still say that even though this is an "experiment" that these parts have been put together with absolutely no regard as to what actually works TOGETHER

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Old 04-25-2010, 06:22 PM
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Quote:
Originally Posted by my87Z
i believe that stock vortecs are 170cc intake runners, now to what you mentioned. typicall 2 valve relief flat top pistons are about -4cc's now as long as you are setting your quench to about .040" then with those heads and those pistons you will be sitting at about 11.6:1 not 10ish:1. the experiment you are planning to do has been done many times before with all kinds of 305 heads, and to let you know they dont have 1.88" intake valves, from the factory those heads came with 1.71 intake valves. and those heads started off life as about 150cc intake runners with tiny exh runners, and if you do those heads it would be stupid not to use a dual pattern cam so that you have the exhaust valve open for longer to compensate for the crappy exh flow from the heads. back to what i was saying about a 383 with 305 heads, sure it will bump up the compression but you will be loosing so much top end it will be crazy, the 305 heads on a 383 wont be able to handle over about 4000-4500rpm and at that point the cam you chose would only be starting to make power.

i just reread you last post about the 305 heads flowing more than what a set of vortecs do, are you sure about that have you had them flow tested and if you have what numbers did you get, dont forget that head performance is not defined by maximum air flow, it is more defined as flow across the curve say .300-.500 lift as well as velocity during this time. when you go cutting a set of heads up you may be able to get the head to flow more air but you will loose velocity as you increase the cross sectional area of the port, this will drastically affect power from 2000-4500rpm where most vehicles do most of their driving

and your goal of 500hp is no where near realistic, like i mentioned before i think you will be hard pressed to even get 350hp from those heads, if people could just take a set of garbage heads and turn them into 500-600hp heads with just some machine work then that would be all people would do instead of looking for the proven performing GM head or a set of aftermarket heads. i have a something i like to day when i see someone trying to work a set of garbage heads here goes "you can polish a turd all you want but in the end you'll still just end up with a turd"

not trying to attack you but i still say that even though this is an "experiment" that these parts have been put together with absolutely no regard as to what actually works TOGETHER
ok, the heads i cant tell you exactly what they flow, but you can sit them side by side and see the diff, sayn that they could fall on there face with the small valves, but i can say my buddy used them for a while on a 355 with 13.0:1 pistons with a 480" cam and a 750 to feed it, and it propelled a 65' chevelle down the 8th at low low 7's, but your prb rite its best to leave them off!
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Old 04-25-2010, 08:37 PM
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Quote:
Originally Posted by gofastz
my buddy used them for a while on a 355 with 13.0:1 pistons with a 480" cam
........
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Old 04-25-2010, 09:29 PM
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i second that Tech 1, for one most people would tell you that there is no such thing as 13:1 pistons, only combinations of rods, pistons, quench, and combustion chambers that make 13:1, another thing is that a motor with 13:1 pistons has no buisiness running a tiny .480" lift cam. antoher would be that a .480" lift cam would have a duration of around 220-230 @ .050 and in a 355ci engine this would put the power band at round 2500 (ish) to typically 5500 (ish) give or take a couple hundred RPM's on either side of the band, and you mention that this motor was used in a 65' chevelle, with the 64-65 chevelle's being the heaviest of all the chevelle's untill the mid 70's it would take a motor with over 525hp (and that is with some serious rear gears like 5.13+) to move this 3500lbs car (not including the driver) to say a 7.10-7.20 in the 1/8th. and to make that kind of power out of a 355ci engine you would certainly have to turn it over 6500rpm (that is NA). next we love "my buddy" stories, as 4/5 of them are BS and a knowlegable person can pick them out a mile away

this is not a site that you can come on to and BS your way through and expect people to believe you, cause there are way too many knowlegeable people that will call you out because we understand the math, and what it takes to make power

there is nothing wrong with not being the most knowlegeable, we all started off somewhere, and everyone no matter how much they think they know still has room to learn more. If you have some legitimate questions others and I would be more than happy to answer them, but dont get mad when you dont get the answer you want. we know what we are talking about and are honestly only trying to pass the knowlege on to others and help them out.
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Old 04-26-2010, 03:41 PM
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Originally Posted by my87Z
i second that Tech 1, for one most people would tell you that there is no such thing as 13:1 pistons, only combinations of rods, pistons, quench, and combustion chambers that make 13:1, another thing is that a motor with 13:1 pistons has no buisiness running a tiny .480" lift cam. antoher would be that a .480" lift cam would have a duration of around 220-230 @ .050 and in a 355ci engine this would put the power band at round 2500 (ish) to typically 5500 (ish) give or take a couple hundred RPM's on either side of the band, and you mention that this motor was used in a 65' chevelle, with the 64-65 chevelle's being the heaviest of all the chevelle's untill the mid 70's it would take a motor with over 525hp (and that is with some serious rear gears like 5.13+) to move this 3500lbs car (not including the driver) to say a 7.10-7.20 in the 1/8th. and to make that kind of power out of a 355ci engine you would certainly have to turn it over 6500rpm (that is NA). next we love "my buddy" stories, as 4/5 of them are BS and a knowlegable person can pick them out a mile away

this is not a site that you can come on to and BS your way through and expect people to believe you, cause there are way too many knowlegeable people that will call you out because we understand the math, and what it takes to make power

there is nothing wrong with not being the most knowlegeable, we all started off somewhere, and everyone no matter how much they think they know still has room to learn more. If you have some legitimate questions others and I would be more than happy to answer them, but dont get mad when you dont get the answer you want. we know what we are talking about and are honestly only trying to pass the knowlege on to others and help them out.
ah there ant nobody getting mad here, and i know i dont know everything, heck im just 25 and i enjoy putn chevy motors together, sometimes my mind goes wild, im still learning, but people think im crazy when i talk about them 305 heads, yal should see the port job done on them, they are BIG!
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Old 04-27-2010, 08:45 AM
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i can understand that they are big, anyone can cut the ports out huge, that is not the point of making the heads produce power, remember what i told you about the cross section area of the ports, this the measurement of the port side to side and then from top to bottom, the whole idea of creating power from heads is to keep the cross sectional area of the ports as small as possible and yet making the heads flow as much air as possible, you want as much veloctiy as you can get with as much air flow as you can get, when you go cutting the ports all up what you do is reduce the velocity of the air going through the ports at lower RPM (say 2500-5000rpm), you may increase the amount of air and possible velocity going through the ports at higher rpm (say 5000-6500rpm or so) but the goal is to increase the amount of air flow at all ranges in the rpm band without loosing velocity.

my prediction with these heads would be that from 2500-4500rpm this motor would be a dog, but from 4500-6000 it would wake up, but say you were racing someone with the exact same set up as you but with a set of heads with better velocity and air flow lower in the lift and rpm range then by the time you even hit 4500rpm you would be playing catch-up because they would be making more power off the line and all the way through the rpm band then you, basically they would whip your *****
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Old 04-27-2010, 09:24 AM
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If they really are that opened up (which I doubt but have seen done before before) then they will run like crap. You'll be severely limited at the valve which will lead to a VERY lazy port and a lot of problems. I'd forget about running those heads. as far as carb size- just double the hp level you want to get the cfm you need.
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Old 04-27-2010, 02:09 PM
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Originally Posted by ap72
If they really are that opened up (which I doubt but have seen done before before) then they will run like crap. You'll be severely limited at the valve which will lead to a VERY lazy port and a lot of problems. I'd forget about running those heads. as far as carb size- just double the hp level you want to get the cfm you need.
im going to have them cced and see if im crazy or not, but i called my buddy that i bought them from today and asked him agaiin, they were ported my a machinest but not sure on the flow!
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Old 04-27-2010, 02:20 PM
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Quote:
Originally Posted by gofastz
im going to have them cced and see if im crazy or not, but i called my buddy that i bought them from today and asked him agaiin, they were ported my a machinest but not sure on the flow!

i would seriously recomend you do have them flow tested, if you can find a shop in your area they should do it for about 80.00. i wouldn't just have them cc'd as that will only tell you how much volume is in the runners, that really wont tell you much of crap. the flow test would be money well spent cause it could save you the hasle of even going with those heads in the first place.

if you do get them flow tested then post the numbers from .200-.600" on here and we can tell you what you have
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Old 04-27-2010, 09:14 PM
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Oh look here i pull the 305 heads off the motor to look at them to see if i was crazy, like i said B4 they sport 1.88 valves!They will be going to the shop in the morning...
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