Cam help for new 383 build

SenderoMan · Jan 7, 2017

My faithful 350 finally gave up the ghost this fall after many good years of service. The logical choice seems to be a 383, so I've started my research and am needing help selecting a camshaft.
My friend and engine builder Jerry Coon in St. Joe, Missouri would like me to go with a full roller assembly, but finances dictate that will not happen. So that leaves either a hydraulic or solid flat tappet to fit the budget.

This is going into a 1976 Camaro, which happens to be my first car that was many years ago!
It has fiberglass hood and bumpers and weighs about 3250 lbs with me and a quarter tank of gas. Turbo 350, 10" converter (stall 2800) and 4.10 gears with posi unit. Has Nitto Drag Radials 275/60/15 on rear, Competition Engineering traction bars and sub frame connectors.

The only parts from the 350 that are available for the 383:
are a set of Dart Iron Eagle heads (original ones, not the Platnium) 200 cc intake, 64 cc chambers, 2.02 intake and 1.60 valves. Crane Energizer roller rockers
Victor Jr. intake with Holley 3310-2 750 with adjustable vacuum secondary spring kit. Also have a 1" inch plastic four hole spacer.
Moroso Outlaw II 6 qt. pan with screen.

This is mainly a street, fair weather car that gets driven 500 miles or less a year. Will probably make it to the drag strip once or twice a year. The previous 350 had TRW forged flattops (four valve relief) pistons, with a Lunati 284/507 hydraulic flat tappet. 1.6 rockers were on the exhaust side, it ran 13.3's at 101-102 mph on some old, hard BF Goodrich TA radials.
Never got a chance to run it with the Nitto's.

Was looking at Skip White's rotating assembly with the 7.5 cc dish Wiseco pistons and 6" rods, which says will make 10.77 compression ratio. Will this be too high for my heads? Does anyone have personal use with this company and these rotating assemblies?

Thanks for your help!

Grumpy · Jan 7, 2017

well the math is not that difficult, a 1976 Camaro,
what your basically thinking of building is a rather common old school muscle car 383 ,
with a flat tappet solid lifter cam,
a 383 with its 3.75" stroke and 6" rods.and the resulting piston speeds,
and the intake manifold and 200 cc older dart,cylinder heads all point to about a 6300 rpm peak rpm
a 2800 rpm stall , converter and 4.11:1 rear gear in a car with a th350 transmission,with a dual plane intake,
with a 750 holley carb,
and mostly street use points, what your looking to build, in my opinion,would start out like this,
ID find a scat 9000 cast STEEL crank and forged pistons
and rods,rotating assembly,
that matched your block and heads to produce a compression ration nearer to 10:1
ID try to get the quench distance at about .040-.042
keep in mind theres no real replacement for added displacement
the increase from 350-383 in a sbc generally benefits you in two ways, it obviously adds the 33 extra cubic inches of displacement
and youll generally find your N/A engine makes about 1-1.3 hp and ft lb of torque per cubic inch, it also tends to effectively increase compression if the similar piston design is used simply because you compressing an increased volume per cylinder into the same size combustion chamber.
one other factor often over looked is the longer stroke of the 383 increase's mid and lower rpm port speeds this generally increases cylinder fill efficiency, in the lower and mid rpm ranges.
obviously if your going to supercharge or use turbos the piston and rods and crank assembly should be made to withstand the stress levels so a 4340 forged steel crank, forged pistons and after market forged connecting rods with the significantly stronger 7/16" ARP rod bolts are strongly suggested as is dropping the static compression to the 8:1 range to increase the potential volume of compressed fuel/air mix to be stuffed into and burnt above the piston.
Id point out that most transmissions are designed to shift at well under 6000 rpm and most hydraulic valve trains won,t retain best stability above about 6300 rpm, so going the 383 or the 406 SBC stroker route tends to maximize the SBC potential on a mild or mid range performance build
a CROWER 00350 flat tappet solid lifter cam ,would be something ID look for with that combo
EDM LIFTERS

Loves302Chevy · Jan 7, 2017

SenderoMan said:
Was looking at Skip White's rotating assembly

Stay away from Skip White"s JUNK!!!!!! I learned the hard way.

Actually, just avoid his no-name stuff. You can probably buy from him AS LONG AS YOU
ARE GETTING NAME BRANDS ONLY.

Your Crane Energizer rockers will not handle a solid FT camshaft due to the increased spring
pressure you will have to run. Most likely they will not clear larger diameter springs. You should upgrade.

BTW, Welcome and nice combo you have there.

busterrm · Jan 8, 2017

Crower 00355 solid flat would work with 10:1 if you retarded valve timing 5 degrees, would give some good tq low -mid range. Might need 1.6 rockers to lengthen the duration a tad and get peak lift to flow of heads. Just my opinion!

SenderoMan · Jan 8, 2017

I was told by a fellow member that they were shocked that Grumpy didn't require a photo! Found one with the old wheels and tires on it. It now has Weld Drag Stars with the Nitto Drag Radials.
Thanks for the heads up on Skip White's no name products.
Still trying to figure out how he's coming up with 10.77 comp. when on the Wiseco website has the -5cc at 10.5.
How much am I giving up by going with a hydraulic flat tappet?

Thanks for the help!

Loves302Chevy · Jan 8, 2017

SenderoMan said:
Still trying to figure out how he's coming up with 10.77 comp. when on the Wiseco website has the -5cc at 10.5.

It depends on the actual measured deck clearance and thickness of the head gasket. Also overbore.

SenderoMan said:
How much am I giving up by going with a hydraulic flat tappet?

As compared to solid FT??? Grumpy said,

Grumpy said:
a 383 with its 3.75" stroke and 6" rods and the resulting piston speeds, and the intake manifold and 200 cc older dart cylinder heads all point to about a 6300 rpm peak.

If you are really going that high, or higher, in the rpm band, then we are talking more about valvetrain reliability, rather than HP/TQ. 6500 rpm should be considered the limit for hydraulic flat tappets, unless you are planning on having lightweight (and expensive) valvetrain components.

Grumpy · Jan 8, 2017

yes a sbc engine with either hydraulic or solid flat tappet lifters,
that you expect to spin up over 6000 rpm,
would benefit from the addition of a rocker stud girdle.
the solid lifter flat tappet vs the hydraulic cam choice ,
generally benefits you in a bit better valve train stability ,
and of course the lobe designs differ between similar cams, and manufacturers,
BUT in my experience theres often, a 10-15 hp difference in the peak power,
if both similar cams and MATCHING valve springs,
are carefully matched to the application,
in favor of the solid lifter.
you will find these threads useful if you read thru and look thru sub links most people don,t take the time to research and plan their engine builds to match the application, and as a result they tend to think they all want 500-600 plus hp from reading the magazine articles , but the truth is that a responsive engine with massive torque in the useable rpm range make for a far better choice if the cars street driven, now thats not saying you can,t have both impressive horsepower and a great torque curve but just keep in mind every choice is a compromise and if you concentrate on building an engine that works in the rpm band you actually use rather than getting mesmerized by peak hp numbers alone youll have better results.
you'll
also need to keep in mind it does no good to build a killer engine that produces 500 plus hp at 6700 rpm and match it to a rear gear ratio and transmission gearing, and shift points or converter stall speed, that keeps the engine in the 1600 rpm-6000 rpm power range 90% of the time, if your smart your not competing for peak hp bragging rights your trying to build , impressive and instantly responsive torque in the usable rpm band.
Yes I've constantly tried to point out the fact that all the components in any engine, and correctly matching the drive train combos gearing, exhaust flow, intake and cam timing along with the fuel/air ratio and ignition advance curve must match the engines displacement and compression ratio, and the intended rpm and intended operational power range.
so many guy fail to understand that concept and as a result install mis-matched components that significantly restrict the power curve and the effective rpm range.
remember its that available torque at a instantly available rpm and how effectively you can access that torque that will allow you to move the car briskly,
the most common mistakes are not selecting the better available , and high flow rate heads that match the engines displacement and intended rpm range and the cam timing, and over camming the engine or not gearing or using the correct stall speed to match the application, is a sure route to reducing the potential performance, potential.
don,t forget, to read the thread on oil system mods,
and that a well designed 7-8 quart baffled oil pan and matching windage tray helps, engine durability,
quite a bit on any engine that's expected to produce decent horse power north of 5500 rpm

DEAL IN PROVEN FACTS NEVER GUESS , NEVER ASSUME
first step.
before you start panicking and potentially wasting money and time.
would be to assemble a single piston and rod assembly without rings,
but ideally with some old bearings on the crank and connecting rod and install the cam, in the block
( indexed with a simple,dot to dot timing on the timing gear sets should be ok at this point)
move that connecting rod and piston to all 8 locations and very carefully verify clearances (remember the rod clearance bevel faces the crank counter weight and the piston valve clearances face the outer block)through the full 720 degree rotational cycle, remember the cam spins at 1/2 the crank speed so the cam lobe comes close to the rod every other rotation,
and actually verify you DO, have or DON,T have a potential clearance problem
theres zero sense in runninbg around pulling your hair out and screaming until,
theres actually a PROVEN ISSUE too SOLVE (THERE MAY NOT BE!)
now if you find theres an issue to be solved you proceed using facts
and while your checking the cam lobe to connecting rod clearance check the connecting rod to block clearance ....yes the same minimum .060-.080 clearance is suggested

http://garage.grumpysperformance.co...earances-and-journal-surface.9955/#post-38385

generally its a minor easily done clearance job

http://www.scatcrankshafts.com/index.htm
don,t forget to verify the cam to connecting rod clearances
a cams VALVE LIFT is determined by the DISTANCE the lifter moves as the cam rotates under the lifter base as it moves from the cam lobe base circle
(the closest the lifter comes to the cams center line)
up to the cam lobes ramp to the lobes peak,
(the furthest the lifter up off or from the cams center line)
don,t forget to carefully check the piston skirt to crank counter weight clearance, it should be a MINIMUM of .080 thousands
heres some pictures taken of an engine assembly that use a crank designed for a MINIMUM of a 6.25" connecting rod that was used with a 6.135" connecting rod

you can clearly see where the piston pin boss was being hit bye the counter weights, even though the builder checked one piston and found it had .025 clearance during assembly

the result was a trashed engine with lots of damage

now if your like me and your an old geezer you tend to adjust hydraulic lifters with the engine at idle and you back off the rocker until it clicks, slowly tighten it just to the point the clicking stops and then add 1/4 turn, and lock the rocker nut set screw.

you can adjust solid flat tappet lifters in a vaguely similar way by inserting a proper thickness tappet feeler gauge between the rocker arm tip and valve tip,after loosening the rocker until there's more than enough lash clearance, too allow the tappet feeler gauge to slid in then slowly tighten the rocker nut to just the point where the clicking stops, remove the tappet feeler gauge and lock the nut on the stud at that point, you'll get a smooth rhythmic ticking which is exactly how a properly lashed solid lifter valve train sounds,

if your willing to use an old school flat tappet solid lifter cam,
Id suggest a crane 110921 flat tappet solid lifter design,
obviously you can't reasonably select the right cam for any application,
without matching its intended valve timing to the application,
and other components to be used.

http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

a cam like this will come very close to maximizing the port flow on a fuelie head,
on a properly designed combo in a 327-400 sbc,
but its not ideal for a daily driver style cars engine application,
as its designed to operate in the 3500 rpm-about-6800 rpm power band,
in a engine with properly matched drive train ,
and other engine components,
clearances and valve train.
http://www.cranecams.com/product/cart.php?m=product_detail&p=23968
https://www.summitracing.com/parts/crn-110921

that was a very well respected cam , used in the 1970s-90s
it made very respectable power,
its best with 10.5:1-11:1 compression and a dual plane intake like an edelbrock air gap,
and headers with a low restriction exhaust,
get the static compression down at 10:1 and degree the cam in strait up, you should get by with that 98 octane fuel.
and you'll want a manual trans or a 3200 stall converter and a 3.73:1 -4.11:1 gear,
most guys used a holley 750-780 cfm carb.
with 1.6:1 roller rockers and decent long tube open headers
,it' valve timing about maximized the power OEM, Chevy fuelie heads had available in most sbc engines

before you ask.
yes theres a similar version in a hydraulic flat tappet version, you get easy valve adjustment but it costs you a couple hundred rpm in peak power, and neither versions going to be ideal on anything but a serious performance car with the correct matched valve train, intake,headers,gearing etc., remember this class of cams is designed for road racing and drag, racing and serious performance with matched tires, suspension , gearing etc where youll rarely have the engine spinning under 3500 rpm

http://garage.grumpysperformance.co...er-rockers-and-stud-girdles.12208/#post-59297

http://garage.grumpysperformance.co...-in-vs-threaded-rocker-studs.2746/#post-43539

http://garage.grumpysperformance.co...ting-up-the-valve-train.181/page-2#post-19781

http://garage.grumpysperformance.com/index.php?threads/cam-lobe-aceleration-rates.2627/#post-8341

http://garage.grumpysperformance.co...-rocker-ratios-and-the-effects.126/#post-1193

http://garage.grumpysperformance.com/index.php?threads/bits-of-383-info.38/#post-17412

http://garage.grumpysperformance.co...ich-is-best-steel-or-aluminum.3124/#post-9141

SenderoMan · Jan 8, 2017

Yes compared to a solid flat tappet and 6300 would be peak in most of the 383 combinations that I have seen for street/strip use.
I know that hydraulic flat tappet are getting to be antiquated (like me!) but I also know that technology has helped them immensely. Just wondering if there is any power difference between the two or are solid just used to bet more rpm's?

Thanks Grumpy for the reply! I think we were typing at the same time.

Mark

Strictly Attitude · Jan 9, 2017

Grumpy cylinder 4 exhaust valve in that picture looks mighty misaligned there but yes I prefer a solid over a hydraulic. I personally want stability till about 7000 but my engine isn't exactly your typical street/strip engine either. I have looked into shaft mounts but seems a gurdle and set of good roller rockers will do the trick nicely. Again matching system parts to your setup and valve train needs is ideal here. Solid cam will not have any pumping loss in high rpm. The lifter tech has come a long way I like Isky SO202-H solid lifters but the break-in procedure with a flat tappet is critical. I might save for a roller setup in my new 383.

Grumpy · Jan 9, 2017

the picture of the rocker girdle is off the internet, and yes your correct that does look mis-alined

Cam help for new 383 build

SenderoMan

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Grumpy

The Grumpy Grease Monkey mechanical engineer.

Loves302Chevy

"One test is worth a thousand expert opinions."

busterrm

solid fixture here in the forum

SenderoMan

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Loves302Chevy

"One test is worth a thousand expert opinions."

Grumpy

The Grumpy Grease Monkey mechanical engineer.

SenderoMan

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Strictly Attitude

solid fixture here in the forum

Grumpy

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