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Thread: 383 SBC rebuild questions
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08-03-2008 #1
383 SBC rebuild questions
I'm in the planning stages to rebuild my 383 street engine. My mains questions concern pistons, compression ratios (static and dynamic), and cams.
First off, here's what I have to work with:
350 block with cylinders that mic out ot about 4.034". I'm going to have it bored and honed to 4.040". I'm looking to have it decked to .000 after engine mock-up. I'd like to see .039" - .042" quench with the Fel-Pro 1010/1003 gasket. AFR recommends the 1003.
AFR 190 CNC heads...started out as 76 and milled by AFR to 68cc. They were then milled .008" to clean up slight engine damage (busted piston). Was told the final cc was about 66cc but I will measure the cc to be sure.
Cast steel (brand unknown...has "3004" printed on front counterweight) crank that needs the rod journals polished or turned .010". Mains will only need polishing and remain std size.
Accel SuperRam intake, runners, and plenum. Using the 89 Camaro ECM and will be tuned by PCMforless for a base chip.
1 5/8 Hedman shorties or 1 3/4 Headman longtubes.
Aftermarket T56 with 3.42 gears in an 86 Cutlass.
Since this is a street engine I'd like to keep compression at about 9.5-1 with 18cc dished piston or 10-1 with 12cc dish. I'd like to see this engine get at least 100,000 miles. Can a forged piston have this lifespan or should I stay with a hypereutectic? Enginge will not know nitrous or rpm beyond 6000. Pressed pin or floating pins? I'd also like to stay with 5/64 rings. I've been looking at KB hyper and forged pistons along with Probe FPS forged. Must keep pistons under $400 set due to budget. Ideas?
Hydraulic roller cam. I'm looking at 3 differant cams, all by Comp Cams. I will have them all ground on a 112 - 114 LSA.
XR270HR 218/224 .495/.502
XR276HR 224/230 .502/.510
XR282HR 230/236 .510/.520
All the XFI cams listed with the 113 LSA has lifts of .570 plus, more than I care to run. Cam ideas?
I'd like to see this setup run to at least 100k miles and get reasonable (20-25 mpg hopefully) mpg. It will be a mild to hot street cruiser, not a track car. I'd also like for it to sound as good as possible.
I know I ask alot of questions and I "may" be expecting alot of this engine. I'm open to all ideas and vendors are welcome. I will be building this engine myself.
DougDoug Gulley
66 C10 383, AFR 190, Accel SuperRam, Hyd Roller 230*/236* 280XFI, aftermarket T56, *under construction*
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08-03-2008 #2Registered User
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- Oct 2007
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- ridgefield ct
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well i have a xe274 in my 9.7:1 CR 383 and i wish i'd gone larger. there's no noticeable cam lope. and although it's fun there's some major torque on the botton end. enough that i'd like to change the cam timing to move the power band up some.
any special reason you're keeping the ECM? i have mine for the knock retard (and i had the parts) but i don't know if it's worth it or not.work in progress--for the next 10 years.
1987 monte carlo ss 383ci, 9.7:1, xe274 cam, vortec heads, 200r4, 3.73 posi.
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08-03-2008 #3Originally Posted by megaladon6
I noticed you are running a flat tappet cam. I previously ran a 218/224 110 flat tappet in a 350 and then went to a 218/224 112 hyd roller when I switched to the 383. Even though the durations are the same (at the measured .050" lift) the roller is really a bigger cam. More duration due to quicker opening.
DougDoug Gulley
66 C10 383, AFR 190, Accel SuperRam, Hyd Roller 230*/236* 280XFI, aftermarket T56, *under construction*
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08-04-2008 #4Registered User
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- Oct 2007
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- ridgefield ct
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- 876
i would have run a roller if i'd had the money or some more info on ZDDP/oilat the time. although the XE series of cams supposedly opens just as quickly as a roller. one of the car mags tested it and they did come out pretty even.
work in progress--for the next 10 years.
1987 monte carlo ss 383ci, 9.7:1, xe274 cam, vortec heads, 200r4, 3.73 posi.
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08-06-2008 #5
1st id say lose the 342 gears with the t56, my afr headed 355 in my nova nailed down 19 mpg with 410's and a gas eating holley 750 hp/dp on it, with 342's 6th gear will be unuseable. move up to some 373's atleast. as far as forded vs hyp pistons i have know idea? for free power and fuel mileage go with the lightest piston you can afford.
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08-06-2008 #6
I have been considering moving up to the 3.73 gears. My aftermarket T56 has the .63 6th gear so I think that would be about right. If I had the OEM T56 I'd run the 4.10's myself.
I'm leaning toward running the hypereutetic for the tighter cyl wall clearance. I'm still not sure about whether to run 9.5 or 10-1 compression and which cam to run. Decisions............
DougDoug Gulley
66 C10 383, AFR 190, Accel SuperRam, Hyd Roller 230*/236* 280XFI, aftermarket T56, *under construction*
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08-11-2008 #7Registered User
- Join Date
- Aug 2008
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- 67
I run a xr282hr in my 383-perfect match for 10-1 with afr195's
I also run KB hyper's with no problems
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08-12-2008 #8