383 stroker build HELP opinions

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wickwine

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« on: January 28, 2014, 12:41:19 AM »
Alright so I'm actually building this motor for my 76 c10 swb drag/street truck. I'm curious as to what kind of hp and torque I can expect and what routes I should take and what compression i should expect and what kimd of fuel i can be expecting to run. ill list what I have below

010 .030 over 4 bolt block
400 3.75 stroke crank already machined
6 inch rods with KB flat top pistons
Vic jr intake
64cc Vortec heads off a circle track crate engine
Gm racing cam .435Int/.460Exh lift and 212/220 Duration with 112 lob separation
Comp cams 1.6 roller tip rockers (so lift will actually be .464/.490 if I did the math right)
Double roller timing set.
800cfm q-jet. 

sorry this is non boat related. So cal is pretty much the only forum I get on.


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jyeager

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« Reply #1 on: January 28, 2014, 01:01:20 AM »
Alright so I'm actually building this motor for my 76 c10 swb drag/street truck. I'm curious as to what kind of hp and torque I can expect and what routes I should take and what compression i should expect and what kimd of fuel i can be expecting to run. ill list what I have below

010 .030 over 4 bolt block
400 3.75 stroke crank already machined
6 inch rods with KB flat top pistons
Vic jr intake
64cc Vortec heads off a circle track crate engine
Gm racing cam .435Int/.460Exh lift and 212/220 Duration with 112 lob separation
Comp cams 1.6 roller tip rockers (so lift will actually be .464/.490 if I did the math right)
Double roller timing set.
800cfm q-jet. 

sorry this is non boat related. So cal is pretty much the only forum I get on.


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My dad had a 383 he built for his ultra. 10.5 to 1, bout the same cam with a set of world 202 heads on it. it made a tad under 400 HP.
Hope this helps.
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« Reply #2 on: January 28, 2014, 07:49:30 AM »
Aww damn, I thought this was gonna be a Mopar thread.

Stroke a 383 Dodge and you get an awesome 472 cu in that will go 500hp/550tq with stock heads and a streetable cam.
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« Reply #3 on: January 28, 2014, 08:08:23 AM »
That 'racing' cam is a bit (LOT) lazy for a 383
the heads are gonna be the 'bottle neck' in that combo
I'd say at best 350 hp, ~ 400+ lb. ft. though
very similar to gm's ht 383
What trans and gears?

I'm doing a similar build-
.480/.480, 230* @ .050 (w/ 1.6's- .512/.512)
190cc runners, 62cc chambers,
~10:1 C/R

Dan'l
CJ/RR 212...under construction  "Pistol Annie"

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« Reply #4 on: January 28, 2014, 12:15:05 PM »
No disrespect intended, but your original post said, “drag/street truck.”  I just don’t think you will be very happy with this combination.

Again, what transmission?  What size tire are you running?  If you will be running an automatic and don’t already have one set in stone, consider a THM700-R4/4L60 which has a 3.06 first gear ratio and wont eat HP with a heavy rotating internals like a THM400 will.  The THM200-4R can also be built bad ass and has a 2.74:1 first gear along with light weight internals.  Consider 3.23 to 3.55:1 gears if you are running around a 26” to 28” tall tire.  3.73 to 4.11:1 or lower will kill your top speed unless you are running > 30” tall tires.  I would run as much stall in the converter as you can live with.

If your block is not decked and has the stock deck height of 9.025, your KB pistons will be .020 in the hole.  Depending on which pistons you have, 5cc or 7cc volume valve relief notches, and your head gasket choice, (without milling your block) you will end up with approximately 10:1 to 10.6:1 compression.  With the block at standard deck height, you will end up with a quench distance of .059 to .061 because your pistons will sit .020 in the hole.  Tightening up that quench will help promote a more even burn and, even though your compression will be higher, it will most likely make your engine more detonation resistant.

If you zero deck the block, your gaskets will determine the quench distance.  For example, if you choose a Fel-Pro composition style gasket, you will then have a quench distance of approximately .039 to .041 according to Fel-Pro’s advertised compressed gasket thicknesses.  Your compression will then end up in the 10.4:1 to 11.1:1 compression range.

With all that said, your cam selection and iron heads will probably be a detonating nightmare on pump gas.  I ran a similar combo on a 340 Mopar a while back and HAD to run a mix of race gas and premium to calm it down.  Going to a 242 degree duration @ .050 calmed it down further.

If I recall correctly, out of the box, those heads flowed about 238 CFM at 28” at .450 valve lift.  After that, they stall real bad and the flow number drop big time.  With those numbers, those heads are capable of ~450HP +/-, but everything has to be right to get there.  At some point, you are going to want to upgrade those heads.  A higher flowing head will like your 6” rod combination better.  If you plan on upgrading your heads, switching to aluminum will cause a loss of heat retention in the chambers.  All else being equal, the engine will act like it has lost a point of compression.

With your cam selection of 212/220 @ .050 tappet lift, that engine will turn about 5,000 RPM.  I would really recommend a larger cam, especially one with a tighter centerline of 108.  The cam that you have will sound “stock” and will also build lots of cylinder pressure contributing to your detonation problem.

With the small ports of your Vortec heads, your engine will produce a lot of torque, which will be good to help get your heavy truck moving, but will limit your RPM capability.  You can install a larger duration @ .050 cam, but you will get to a point where it just wont RPM up any higher.  Again, since you used the term “drag/street truck,” (I assume mostly street) try to keep your cam duration @ .050 under 235 degrees.

If you are doing mostly street driving with occasional track time, those Vortec heads will make a lot of low end torque on a 383, so you should build accordingly.  Your Vic Jr. intake might give you a few more HP over an RPM AirGap, but in the RPM range where your engine will mostly live, it will hurt all around drivability.  In my opinion, it just isn’t worth it to lose torque down low for 5 HP at peak RPM.  If you have it, run it, but if you still need to buy it, consider the RPM AirGap.

Cheers,

Joe
"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013

wickwine

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« Reply #5 on: February 05, 2014, 11:41:40 AM »
Sorry for the late response but I'm running a 4.56 gear with a mini spool. 32" tire(305/50or 55/20) can't remember atm. The cam is kinda a pos I'll admit I was just curious because its why I have and I guess the intake I have isn't a vic jr it's an RHS 23 degree ez efi/carb single plane intake, it's kinda like a mix of an air gap and vic jr. I'll be doing some work to these heads as in machining for more lift, screw in studs and guide plates. Possible light port work. I'm lookin at some retro solid roller lifters and a 288/298 duration 588/588 lift 106 lobe center. Probably with 1.6 roller top rockers may get a set of 1.5 full rollers.


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