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SBC: 383 cid cam selection

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Alright I have a question cause I get mixed results from reading other people builds on forums I was needing a ball park idea on what cam I should run. This is the first motor I'm building so wanna do it the right way. I'm building a 383 stroker with the Eagle Street/Strip rotating assembly with the 18cc Dish pistons , I beam rods Forged 5140, 8"harmonic balancer, mid-rise performer intake (idle, 5,500 rpm) Vortec Heads with screw in studs , 1.6 rockers and beehive springs which reading is (supposedly good for up to .550 lift) also running some 1.5"inlet and 2.5" outlet long tube headers. Seen where some said this would be 10:5:1 Comprsession than some said it be 9:4:1 so that's the part I'm confused at cause I don't want too much cam but also want to get the most I can out of it. Should also mention don't plan to ever take the motor past 5500 RPM. This motor is going in a street/strip bracket car will have a th350 behind it with B&M street/strip rebuild with the shift cable also a transbrake if that matters and looking at a 2000 rpm holeshot converter but that also depends on the cam and what it needs. Thanks in advance
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· Registered
364 Posts
Good luck on your build. Hope it gives you lots of enjoyment on the street and the strip. A critical factor for compression ratio is your cylinder heads. Do they have 72cc combustion chambers, or 64 cc? And this will also have an effect on your cam selection. Since your car will be dual purpose, you want to stay away from too radical a cam which will make it unpleasant to drive on the street. And if it's a bracket racer, you want to target the e.t. range that will keep you from breaking out. Also, is your vehicle a "lightweight" or a heavier car? Sorry to ask so many questions but it's the only way we can make an intelligent recommendation. :)

· Registered
1,425 Posts
Forget the Performer manifold and get a Performer RPM which is MUCH better suited to a 383.

Vortec heads (GM 64cc I assume) and 18cc dish pistons, but how far down the hole are the pistons?

In case you don't have it, here is a list of parts for adding GM beehive springs to GM Vortec heads. Prices are from 2015.

LS6/LS2 springs
GM 12499224 (blue) $61
OD: 1.20”
Spring rate: 375#
Installed Height (GM spec): 90# @ 1.800", 126# @ 1.700"
Open Pressure: 295# @ 1.250, 314# @ 1.20”
Max Lift: 0.570" (installed at 1.800")
Top ID: .650”
Top OD: 1.055”

Retainers and locks for LS spring ID and Vortec 11/32” valves
Installed @ 1.75” with approx 110# pressure
Comp 787-16 retainers: $52 (Allows for .050" more installed height than stock Vortec retainers)
Comp 648-16 locks: $24

I don't have notes on max safe lift, but as I recall it was around .510" with springs installed @ 1.750".

· 1949 Ford Coupe RESURRECTION
1,201 Posts
As I recall, vortec heads have a limiting issue with valve lift and spring landings requiring machine work for springs and limited to 0.48" lift at the valve stem.??? Correct me if my memory is slipping..

· Registered
41 Posts
I wouldn't mess with a flat tappet cam these days with the low quality lifters out there.

What gears are you running? That will make a difference in cam selection. You also need to calculate compression, 9.5 or 10.5 will also make a difference.
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