Camshaft opinion

T

Thunderbolt

Well-Known Member
I have a SBC 350 with a Crane 274H06 cam, im about to put a Weiand 177 supercharger on it.
Is the cam way off?
LSA 106 is, well not optimal i think, but can work?



8.7:1 comp (static)
1 5/8 full lenght headers
E85 fuel (650 DP Quick Fuel or Holley 850 DP both E85 to choose from)

Cam specs:

Cam Style:Hydraulic flat tappet

Basic Operating RPM Range:1,800-5,400

Intake Duration at 050 inch Lift:218

Exhaust Duration at 050 inch Lift:218

Duration at 050 inch Lift:218 int./218 exh.

Advertised Intake Duration:274

Advertised Exhaust Duration:274

Advertised Duration:274 int./274 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.450 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.450 in.

Valve Lift with Factory Rocker Arm Ratio:0.450 int./0.450 exh.

Lobe Separation (degrees):106

Computer-Controlled Compatible:No

Grind Number:274 H06

Valve Springs Required:Yes

Quantity:Sold individually.

Notes:8.75 to 10.0 compression ratio advised.
 
You might be able to pull it off since your running E85.
The Cam LSA of 106 is real tight for super charged & turbo boost in general.
Have to look up the Crane Cam myself & get specs.
Figure out the dynamic compression N/A.
Then figure in Boost pressure your going to use or plan to.

E85 has a Motor octane of 105 typical.
Research octane is 115 average.
 
thats a cam designed for lower rpm torque and good exhaust scavenging ,
in an N/A engine.
you could improve the engine efficiency with a super charger equipped engine combo,with a bit longer intake and extended exhaust duration increase lift and a wider LSA.
obviously youll want to verify clearances
https://www.crower.com/camshafts/ch...orced-induction-noscam-small-base-circle.html

LiftCurveAread.gif


pistonposition2a.jpg


a cam for a super charged engine would be considerably different from one idealized for a tunnel ram intake,
now I'm certainly not suggesting adding a supercharger to most engines, won,t make more power,
at least over some rpm range with a tunnel ram or N/A (non-assited ) engine cam,
but you'll certainly benefit more from maximizing the components used to work with max efficiency under boost.
and ideally, a tunnel ram equipped engine would have both a tighter LSA in the 105-108 range and significantly higher compression,
usually in the 10.5:1 or a bit higher, and maximizing the exhaust scavenging and it might require more duration on the intake in relation vs the exhaust duration,
that might only have marginally more or need more duration if any more,
you'll sure run into issues with detonation much faster if you try to supercharge a high compression engine, without race octane fuel.
but that will hold true only if the duration and lift on the two cams is kept almost the same,
obviously, if you add duration and lift on the supercharged combo power tends to increase.
while a supercharged combo, would usually benefit from about 8:1 compression and a 112-116 LSA and more duration on the exhaust lobe, youll generally need a bigger fuel pump, and a larger exhaust cross sectional area,
as you'll be dealing with significantly more exhaust gas volume on a supercharged engine ,
and a tight LSA, will allow some boost to escape during the valve overlap.


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

http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

http://garage.grumpysperformance.com/index.php?threads/calculating-overlap-and-lsa-or-lca-etc.480/

http://garage.grumpysperformance.co...chevy-cams-and-a-few-similar-aftermarket.133/

http://garage.grumpysperformance.com/index.php?threads/camshaft-opinion.15053/

http://garage.grumpysperformance.co...mpression-ratios-work-better-with-boost.1894/



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

http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

http://garage.grumpysperformance.com/index.php?threads/calculating-overlap-and-lsa-or-lca-etc.480/

http://garage.grumpysperformance.co...chevy-cams-and-a-few-similar-aftermarket.133/

http://garage.grumpysperformance.com/index.php?threads/camshaft-opinion.15053/

http://garage.grumpysperformance.co...mpression-ratios-work-better-with-boost.1894/



related useful info you should read

http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

https://itstillruns.com/choose-cams-supercharger-7959078.html

https://www.enginelabs.com/engine-tech/inside-forced-induction-camshaft-designs-howards-cams/

http://www.kcams.co.nz/Menu/Selecting-A-Camshaft.php

http://garage.grumpysperformance.com/index.php?threads/supercharger-and-turbo-cams.1226/

https://www.hotrod.com/articles/hrdp-1011-cams-for-turbocharged-engines/

https://www.hotrod.com/articles/ctrp-1106-turbo-camshaft-guide/

Supercharged / Turbo Charged
Click to expand...
Supercharged engines typically have a shorter intake, longer exhaust, and wider lobe center angle (LCA).
Supercharged engines can continue pushing charge into the cylinder longer than an NA (normally asperated) engine, and also the greater pressure differential between the manifold and the cylinder means the cylinder is filled quicker. This means they like a shorter intake duration on a later centerline, compared to thier NA counterparts.
Higher cylinder pressure after combustion means more gas to get rid of, so the exhaust valve is opened earlier than on an NA engine. This means longer exhaust duration, on an earlier centerline.
Early exhaust centerline and late intake centerline means a wider LCA. This means there is less overlap which also helps stop the pressurized intake charge being lost out the exhaust valve.

Turbo Charged engines are more complicated.
Before the turbo charger reaches an efficient speed the engine behaves much like an NA engine, albeit a low compression one. This means to get the cylinder filled efficiently and producing good amounts of exhaust gas to 'spool up' the turbo the ideal would be a relatively tight LCA. However once the turbo has 'spooled up' and is efficient the engine behaves more like a conventional supercharged engine and wants a wider LCA.
Turbo engine camshaft selection, and the overall performance of the engine, is greatly effected by the turbo selection.
It is easier to get a turbo to spool up at lower rpm by choosing a smaller exhaust turbine housing than by manipulating cams. This means the cams can then be optimised for 'on boost' performance.
Typically higher boost levels, and higher rpm, require more cam duration. The main difference between supercharged and turbo charged engines, is that turbo engines do not flow from the intake out the exhaust, at overlap, as easily as a supercharged engine, and therefore tend to open the intake valve earlier. So turbo engines tend to have a longer duration intake than a supercharged engine, but still shorter than an NA engine.
The turbo charger should be selected before the camshaft, remembering that a turbo, much like a supercharger, can restrict power if it is not big enough.
Click to expand...
 
Last edited:
Thunderbolt said:
LSA 106 is, well not optimal i think, but can work?
Click to expand...
It will work, but will it work well enough to satisfy you?

With the the smaller LSA of 106° of your present cam, compared to the 114° LSA that Grumpy suggested,
the fuel mileage will be less. Some of your fuel/air mixture will be going out the exhaust valve during overlap.
That's just one consideration you have to make.

What static and dynamic compression ratio will you have with the present camshaft?
 
Last edited:
I agree with all said above. I will add that your cam is small to begin with, so the 106 ICL might work out fine.
Are there better choices - SURE. It being single pattern should complement the supercharger.
My NA 334 SBC (stroked 305) uses an ISKY camshaft similar to yours but has a 108 ICL.

Grind No./Type: 264-MEGA HYDRAULIC FT**
Application: Tremendous torque & good mid-range power.
9-10.5:1 compr., good idle, stock converter.
3.23-3.70 axle ratio. Up to 625 CFM Carb.
RPM-Range: 2000-5800
Valve Lift Int/Ext: .450/.450 (1.5), .480/.480 (1.6)
Valve Lash Hot Int/Ext: .000/.000
ADV Duration Int/Ext: 264/264
.050 Duration Int/Ext: 214/214
Lobe Center: 108 108° LSA /108° ICL = straight up

Your cam is not way out of the ballpark to start with. I say try it.
 
I think i will try the cam i have after your inputs, and i have a 327 i will rebuild in the future that will replace the 350, and better put the money in the 327 build, could maybe end up to be a 383....

A little off topic, i was very surprised how much better the 350 run with open exhaust, that cam sure needs good scavenging as Grumpy said.
 
I have Dynomation6 simulation software if you are interested in supplying the required input data!

Then we can compare the cam you have now with the other options.

Before you say yes, this is the beginning of what I would need. The list will grow from here depending
what kind of accuracy you need.

Bore & Stroke:

Rod Length:

Heads with flow numbers:

Combustion Chamber Size in CC’s:

Dome Volume: For a domed piston use a (-) negative number.

Valve Reliefs Volume: For a piston with valve reliefs use a + positive number.

Deck Clearance:

Head Gasket Bore:

Head Gasket Thickness:

Valve Sizes I/E:

Intake Manifold Model Type [Single or Dual Plane]

Model #:

Carburetor Size (CFM):

SCR & DCR: Or the info to calculate SCR & DCR

Header Tube Diameter: Small, Medium, Large (1-5/8", or , or)

Cam Card:

Cam Installed per Cam Card, or Retarded or Advanced:

Rocker Ratio:
 
I really would like to try that out, but som of the data would have to be estimated, guesstimated?
Please ask if can provide more data, below is what i can remember right now.


The short block is 100% stock 1974 Camaro 2 barrel, low milage, never rebuilt, well new cam, lifters and timing set.
Heads "Double humps" without accessory bolt holes from i belive a -68 327 motor, i can pull a valve cover after christmas.
Cam Crane 274H06, cant find a cam card online?
Stock rockers 1,5
Single plane Weiand 177 blower intake
Boost maybe like 6-7 psi?
Carburetor i have a 650 Quick Fuel and a 850 Holley 0-80844HBX both E85
1 5/8 full length headers (summit brand ceramic coated)
Head gasket i belive was a Felpro, NOT a steel shim, cant remember pn, must be 10 yeras ago... not much help.
 
It's going to be 8.4:1 static compression ratio stock.
Have to look up a stock Melling Cam to get cam specs.
Online.
Have to search.
At work now on break. Not possible till this evening.
 
maybe i was unclear, i dont write english so good, the engine is put togther with the parts above like 10 years ago, except for the blower,
 
It will be tomorrow before I can get to the simulation. My son is flying in today and then I have work.
 
There is no rush at all.
Im very greatful for all answers and help.
If my memory is not wrong, i belive i came upp with 8.7 in static compression when i measured volumes, i have the stock low compression chamfered edge pistons, and advertised stock compression was higher than it was in reality. I could have messed it upp of course :(
 
https://www.jegs.com/i/Crane-Cams/271/100172/10002/-1

Crane Cams Energizer 3/4 Race Hydraulic Flat Tappet Cam & Lifter Kit Lift: .450" /.450" Duration: 274°/274° RPM Range: 1800-5800

Crane Cams 100172 Details

1955-98 Small Block Chevy 262-400ci

*Note: In order to use these camshafts in 1955-57 265ci blocks, it is necessary to machine a small groove in the rear main journal of the cam to allow oil flow to the top of the engine.
**Note: Beginning in 1987, most of the V-6 and V-8 engines were equipped with hydraulic roller camshafts. There are differences in the block to accommodate a cam retention thrust plate and the anti-rotation mechanism for the lifters. These blocks are identifiable by bolt holes for a cam retention plate under the upper timing sprocket, as well as bosses and tapped holes in the lifter valley for lifter retention hardware. The camshafts on these engines have a step nose and smaller bolt circle on the front of the cam. An earlier model camshaft may be used in these blocks by using the appropriate timing chain set and adding a thrust button when using a roller cam.
1988-99 Chevrolet 305 and 350 V-8 engines (and some 1987 350 V-8 engines) use a different configuration camshaft core than the 1955-87 engines and cannot be interchanged.

ROUGH IDLE, MODERATE PERFORMANCE USAGE, GOOD LOW AND MID-RANGE TORQUE AND HP, MILD BRACKET RACING, AUTO TRANS W/2500+ CONVERTER, 2600-3000 CRUISE RPM, 8.75 TO 10.0 COMPRESSION RATIO ADVISED.

Grind Number: 274 H06
Operating Range: 1800-5800 RPM
Duration Advertised: 274° Intake / 274° Exhaust
Duration @ .050'' Lift: 218° Intake / 218° Exhaust
Valve Lift w/1.5 Rockers: .450'' Intake / .450'' Exhaust
Lobe Separation Angle: 106°
Max Lift Angle: 102° ATDC Intake / 110° BTDC Exhaust
Open/Close @.050'' Cam Lift: Intake - 7° BTDC (opens) / 31° ABDC (closes)
Exhaust - 39° BBDC (opens) / (1°) BTDC (closes)
 
I really need some good flow numbers for the SBC Fuelie Heads (Double Hump) if someone has
them. I found this, but don't have much trust in the numbers.

POST 6
https://www.camaros.net/forums/13-performance/16055-flow-numbers-gm-461-camel-hump-heads.html

I did read one test on flow #'s for a 461 (stock, untouched), the #'s were as follows:
.050" 1-38.9, E-20.9
.100" 1-57.9, E-44.0
.150" 1-79.6, E-60.7
.200" 1-104.7, E-82,3
.250" 1-125.6, E-101.9
.300" 1-148.0, E-114.4
.400" 1-175.2, E-129.8
.500" 1-187.1, E-132.6
.600" 1-188.5, E-139.5
.650" 1-188.5, E-139.5

These flow #'s were just something I found off the 'net, I don!t know how valid the data is. They are supposed to be for an
untouched 461 head with 1.94/1.50 valves. I hope this helps.

Using a default flow numbers from Dynomation6 for a stock head without any porting, I get the following.

Sim01_StockHeadFlowNumbers.JPG

I had to build my own calculator to get the seat-to-seat timing numbers from the 050 timing numbers for the
Crane 274H06 / 100172 camshaft. Usually I can get this from the cam card.

Sim01_CamTimingCalculator_Crane274H06.JPG

I wanted to start with no blower, just the basic engine. I used the following inputs......

E85 Fuel
Dual Plane Intake (Std Flow)
650 CFM Carburetor
8.7 Static Compression Ratio
Small Tube Headers / Open Collector

I will revise the graph below if I get better flow numbers for the double hump heads, then we can go
forward with any changes. I don't plan on going back if we decide to go ahead with changes such as
the blower or camshaft. Speak now or forever hold your peace.

Sim01.JPG

BTW, I don't have Desktop Dyno 6 (DD6) ..... I have Dynomation6.
 
I say your compression is too low. You are only starting with 8.7 STATIC, which gives you only 7.26 DCR with a cranking pressure of 144 psi.
And I'll bet that the Felpro .040" gasket brought it down even lower. Anyone else agree?
DCR.png

I was going to retract this because I remembered about the blower. But I will leave it since I already ran the calculator.
 
I calculated the compression with the thicker headgasket in mind, long time ago, but thats the best i can come up with.
I do have a aluminium intake, Summit Racing Stage 3, SUM-226010 but i didnt mention that because the blower uses a different intake.
The blower is a Weiand 177, 6506-1 with 6" Lower Pulley and 3.48" Upper Pulley, any chance of predicting the boost, just curious.
1.72 over driven. I think i bought a smaller top pulley also, this have been a slow working process... years :)

The dyno curve above looks, eh, 450 tq and 320 hp NA?

I use a Hughes GM25 converter, stalls at 2700 rpm. 3.42 rear end 12 bolt LSD.
 
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