hows this 383 combo

grumpyvette

grumpyvette

Administrator
Staff member
"HEY grumpyvette, hows this combo look, for my 1967 nova with a 4 speed muncie , its a weekend toy, Ive lightened up the car as much as I physically can on a budget, the car will get used mostly for about 50% hot street and 50% track time running grudge races, so limited street use.
here the combo,


scat 9000 crank
scat pro comp I beam rods 5.7"
probe flat top forged pistons -4cc (10:1) block will be 9.015 decked
Dart platinum 200cc 72cc CNC heads 2.02 / 1.60 valves
lunati voodoo 60112 hyd roller
Duration @ 0.050" :231/239
Gross Valve Lift:.535"/.550"
Lobe Separation Angle / Intake Centerline:110/106
edelbrock rpm air gap
750cfm vac secondary Holley carb
dui distributor
Erson 1.6:1 ratio roller rockers
Holley 750 or pro systems carb?
3.73 gears"
 
that looks like a well thought thru street & strip combo, the only changes Id suggest is swapping to just a bit larger cam.
and a solid roller lifter, i don,t like spinning a cast steel crank to high in the rpm range but SCATS 9000 series is usually a decent crank thats stronger that the typical factory cast iron crankshafts
as I think you'll get noticeably more hp in the upper rpm range,with a larger cam

http://www.summitracing.com/parts/LUN-60133/


383combo1bn.jpg

the milder cam

383combo2bn.jpg

the more radical cam

youll simply trade a bit less off idle torque, wich may help your launch traction, for a bit more upper rpm range power,which should help your cars MILE PER HOUR POTENTIAL, the software dyno only shows about a 20hp gain, with the swap, but my experience shows, closer to 30 extra hp, in cases like this and much better valve train control and extra 400-500rpm of useful power and over all better manors, you might also consider a 100hp- 150hp nitrous plate system, but because of the cast steel crank I would not exceed 100-150hp shot of nitrous or run over 6300-6400rpm
 
Here are some engine specs

Engine specs

383 SBC (4.030 bore x 3.75 stroke)
One piece rear main GM block
Scat crank & rods
KB hypertec pistons (flat top) 11.5 to 1 compression
Custom HYD roller 240/248 @ .050 .595 lift 112 LSA
Comp 1.6 rockers

Top End
Dr J’s Ported RPM Air Gap
Dr J’s Competition ported AFR 195 heads (resized to 220 cc)
Increased CSA to 2.54 @ pinch , Resized bowl and reshaped short turn.
Heads flow 304 cfm @ .600 lift 2.08 intake 1.60 exhaust
Dr J’s modified Holley 1050 4150.

NOTICE THE 11.5:1 COMPRESSION and 600HP

7234782_n.jpg


457847_n.jpg
 
Just trying to get the ball rolling here if anyone has thoughts or advice, below is a list of my parts that i now have, and links to view them.

Intake
http://www.summitracing.com/parts/EDL-7501/
Heads
http://www.summitracing.com/parts/BRO-1021007/
Carb
http://www.summitracing.com/parts/HLY-0-76750RD/
Cam
http://www.summitracing.com/parts/CRN-119661/
Rocker Arms
http://www.summitracing.com/parts/CCA-19001-16/
Lifters
http://www.summitracing.com/parts/HRS-91160/
Pistons
http://www.summitracing.com/parts/SRP-138089/
Rings
http://www.summitracing.com/parts/TSR-T3690-30/
Crank
http://www.summitracing.com/parts/ESP-10352375057I/
Rods
http://www.summitracing.com/parts/ESP-5700BBLW/
Timing Cover
http://www.summitracing.com/parts/CLO-9-221/

70cc Chambers + Flat top pistons result in 10.3:1 CR
I’m running a holly mechanical fuel pump, and a high volume oil pump, larger volume oil pan, and windage tray. The rotating assembly has been all individually neutrally balanced, so I will swap out the flex plate for a flywheel to run a manual. ARP main, rod, and head bolt, and clevite 77 bearings in mains and rods. Here’s a questing; eagle recommends MAX rpm on the rods @6000RPM, if the crank, rods, pistons, harmonic balancer, and fly wheel have all been individually neutral balanced. Am I SAFE to run any higher rpm? I was hoping to redline at 6500RPM because I think it will still be pulling well after 6k, and I don’t want to lose out on HP! AM I dreaming with my current setup? What do you think of the parts? I matched everything up as best I could. Any limiting factors?



http://www.summitracing.com/parts/ESP-5700B3DL19/


Id strongly suggest upgrading the connecting rod choice I know Id sure sleep better with the better rods, the additional cost won,t really raise the total cost that greatly but the connecting rods are easily 30%-50% stronger, the swap to a manual transmission will help this combo, but keep in mind youll want to have a rear gear ratio in the 3.73:1-3.90:1 in most applications because that cam is not going to pull well until its spinning at about 3000rpm or higher, and the stronger rods with the much stronger 7/16" rod bolts will make the rotating assembly noticeably stronger, the $200 or so saved with the cheaper rods seems like a bad idea, considering whats at stake if a rod bolt snaps or you spin a bearing, the basic combo looks really well thought thru other than that, but Id suggest long tube headers and a low restriction exhaust be added if not there currently.
theres nothing obviously wrong or in obvious need of changing in your listed combo, theres ALWAYS ways to improve any combo,it will take you a few hours but read thru these links and sub links it will save you months and hundreds of dollars, I would advise a good SFI rated flywheel and blow proof belhousing

viewtopic.php?f=69&t=3814

viewtopic.php?f=71&t=447&p=9152&hilit=+clutches+brief#p9152

viewtopic.php?f=52&t=5078

viewtopic.php?f=32&t=430

viewtopic.php?f=44&t=38

viewtopic.php?f=50&t=428

http://www.airflowresearch.com/articles ... 5/A-P1.htm

http://www.airflowresearch.com/articles ... 1/A-P1.htm

http://garage.grumpysperformance.co...-for-truck-build-sbc-engine.12050/#post-57645

viewtopic.php?f=32&t=430

viewtopic.php?f=69&t=519

viewtopic.php?f=71&t=447&p=9152&hilit=+clutches+brief#p9152

viewtopic.php?f=71&t=741



http://www.hotrod.com/articles/1206phr-383ci-small-block-chevy/

http://www.superchevy.com/how-to/76178-chevrolet-ht-383-engine/

http://www.enginelabs.com/news/dyno-video-qmp-builds-500-horse-383-stroker/

http://www.chevyhardcore.com/tech-stories/engine/building-the-little-383-small-block-that-could/

http://royalpurpleconsumer.com/wp-c...-block-in-six-easy-steps-hot-rod-magazine.pdf

reading thru these should provide some insite
 
Last edited by a moderator:

I have one question and one suggestion, first my question.

Aluminum rods have to be replaced every so often, how about the CompCams aluminum
rockers. Will they need replacement before a steel rocker.

I would suggest upgrading from the 3/8" rocker studs to 7/16" rocker studs or a girdle. Don't
forget to buy the rockers with the right size stud for what ever is decided.

 
Id say that rocker stud diam. is a valid concern, but once you install a rocker girdle its far less important, for the obvious reason if all 8 rocker studs are physically locked together at both ends, and the valve train rigidity's significantly increased, thru the use of the rocker girdle which I generally suggest if your going to build a serious combo

http://www.summitracing.com/parts/SUM-141010/?rtype=10

SUM-141010.jpg
 
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