Will this be a good Cam?

[tyoneal]

PTaddict:

This should be in line with the rest of the engine modifications. Please take a look and see if you agree. If I wanted less cam, I could just go down to 1:5 Rockers all the way around.

I called Crower again and ended up with this set up. It is as close to the current solid roller in the car.

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Part Number/Work Order Number 00404
Engine Application 262-400 CHEVY
Grind Number 232HR240
ADVERTISED CAMSHAFT SPECIFICATIONS:

INTAKE: Duration: 294º Lift: 0.54 Clearence Hot: 0
EXHAUST: Duration: 310º Lift: 0.564 Clearence Hot: 0

The specifications listed above are based on a rockerarm ratio of 1.5 IN
1.5 EX

RECOMMENDED VALVE SPRING INFORMATION:
Part # 68390-3 Single Dual X Triple
Approximate spring pressure: valve closed: 110/120 LBS.
valve open: 340/350 LBS.


8.0
BTDC 4.0
ATDC

ABDC
48.0 60.0
BBDC

The information below is for degreeing cam only. Correct only at .050" tappet lift.
INTAKE Opens: 8.0 BTDC
Closes: 48.0 ABDC
EXHAUST Opens: 60.0 BBDC
Closes: 4.0 ATDC

LOBE SEPERATION 114º

Duration at .050" Intake: 236
Exhaust: 244
LOBE LIFT Intake: 0.36
Exhaust: 0.376

If using "Lobe Center" method of degreeing, cam should be installed on an intake centerline of: 110º
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Since I have two ratios of rockers on the current set up (1:5 ex. and 1:6 In.) It throws the actual numbers off on any cam I get, short of a custom grind. If I put 1:6 on the exhaust as well, the lift on the above cam becomes, .579 intake and .602 Exhaust, with the Duration staying at 236/244 @ .050. The LSA will also be the same at 114 degrees.

The tech at Crower said this set up will up my vacuum and really let the heads breathe. It should make great power from 2900 to 6300 rpm's, and since it is a 400 ci. low end grunt shouldn't be to bad.

If you have any thoughts or comments, please let me know.

Thanks,

Ty

[PTAddict]

This is definitely a more aggressive cam, and will easily put you into low/mid 500s in HP with fully ported Track 1s. It's going to idle fairly lumpy, but will still be streetable. Since you're using a manual trans, you can bump the idle speed up if you want less idle shake and crisper off-idle throttle response.

IMO, there's no need to go to a 1.6 rocker on the exhaust. Extra high exhaust lift on a normally aspirated motor usually doesn't produce more power to speak of - it's the intake side which benefits more from extra lift, due to the larger diameter of the intake valve requiring more lift to max out the port flow.

Sounds like a fun motor. Enjoy.

[tyoneal]

PTaddict

Thanks for the information.

I was concerned that not keeping the ratios of lift the same, that it might not run as well as it should.

Is there a lot of slack in the specifications numbers of a Cam where performance doesn't degrade if it is not run or cut according to a specific set of numbers?

Thanks,

Ty

[PTAddict]

Originally Posted by tyoneal

PTaddict

Is there a lot of slack in the specifications numbers of a Cam where performance doesn't degrade if it is not run or cut according to a specific set of numbers?

Basically, yes. The most important specs of a cam are actually the "valve events" - the opening and closing points of intake and exhaust valves. The optimum valve events for a given application depend on a bunch of parameters - port efficiency, valve size, intake runner length, cross section, and taper, compression ratio, header specs, and then desired operating parameters like peak power RPM, idle quality, etc, to name just some of them. Any off-the-shelf cam will only be a rough approximation of the "ideal" valve events, and variances from the specs of that cam may improve or degrade performance.

Cams for OEM engines these days start out as quite precise optimizations from very advanced engine simulation software, with final refinement in real world dyno testing. As performance enthusiasts, we don't have access to these kinds of simulation resources, so we have to rely more on advice from cam manufacturers and fellow enthusiasts. But nobody - not Crower, and for sure not me, can tell you for sure the "perfect" specs for your cam. Fortunately, you can still get very good results by being "close enough".

[tyoneal]

Originally Posted by PTAddict

Basically, yes. The most important specs of a cam are actually the "valve events" - the opening and closing points of intake and exhaust valves. The optimum valve events for a given application depend on a bunch of parameters - port efficiency, valve size, intake runner length, cross section, and taper, compression ratio, header specs, and then desired operating parameters like peak power RPM, idle quality, etc, to name just some of them. Any off-the-shelf cam will only be a rough approximation of the "ideal" valve events, and variances from the specs of that cam may improve or degrade performance.

Cams for OEM engines these days start out as quite precise optimizations from very advanced engine simulation software, with final refinement in real world dyno testing. As performance enthusiasts, we don't have access to these kinds of simulation resources, so we have to rely more on advice from cam manufacturers and fellow enthusiasts. But nobody - not Crower, and for sure not me, can tell you for sure the "perfect" specs for your cam. Fortunately, you can still get very good results by being "close enough".

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PTaddict:

Thanks for your explanation. It is clear now. I appreciate you taking the time to educate me.

Ty