Will this be a good Cam?

[tyoneal]

I am replacing a solid roller with a hydraulic cam in an effort to gain enough vacuum to run an a/c. Would like to keep as much power as possible.

The Engine

400 ci Bowtie Block
JE pistons
Callies crank
Howards rods
Brodix Track 1 Aluminum Heads (Ported)
Stainless Shaft Mounted Rockers rockers (Crower)
Crower Cam, Solid Roller, It is a symmetrical grind.
Duration at 0.050" is 252 degrees,
advertised duration is 285 degrees.
Lift at the lobe is .388,
intake side, lift at the valve is 0.621",
exhaust lift at the valve is 0.582".
Compression 10.5:1
Rockers, 1:6 intake, 1:5 Exhaust
lifters, are pressure oil-fed units

About 550 hp

Great Power from 3000 to 6500

Revs limited to 6500

Rear Gear 3.90:1

Tremec 500 5 speed

Cam Recommended By Crower
Crower Camshaft Specification Card
Part Number/Work Order Number 00403
Engine Application 262-400 CHEVY
Grind Number 224HR232

ADVERTISED CAMSHAFT SPECIFICATIONS:
INTAKE:
Duration: 286º
Lift: 0.552
Clearence Hot: 0

EXHAUST:
Duration: 294º
Lift: 0.540
Clearence Hot: 0

The specifications listed above are based on a rockerarm ratio of
1.6 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.
The information below is for degreeing cam only. Correct only at .050" tappet lift.

INTAKE

Opens: 3.0 BTDC
Closes: 43.0 ABDC

EXHAUST

Opens: 56.0 BBDC
Closes: 0.0 ATDC

LOBE SEPERATION

114º

Duration at .050"

Intake: 226
Exhaust: 236

LOBE LIFT

Intake: 0.346
Exhaust: 0.360

If using "Lobe Center" method of degreeing, cam should be installed on an intake centerline of: 110º
NOTES:

Should make Great Power from 2700-6200 RPM



Cams damaged by excessive spring pressure, over shimming, valve train bind or retainers contacting the guides are void from warranty. Refer to the "Important Camshaft and Lift Information" booklet included with each new Crower camshaft to avoid any break-in problems.
==============================================

If Possible, could I get some insight on how well this cam will satisfy my expectations?

Has anyone used this specific Cam?

How would you expect this Cam to behave on the street?

How well would you expect this Cam to Make Power?

Any guess on actual Power Output?

Multiple thoughts would be greatly appreciated.

Thanks,

Ty

[PTAddict]

That's a very big change in cam. The solid roller is near race spec, the hydraulic roller I would consider to be fairly mild on a 400.

With 114 LSA, you've got 3 degrees overlap at .050 lift, which should give a mild lope at idle with about 15-18 inches vacuum, depending on idle speed. The motor will have strong low and midrange torque, with decent upper RPM power. Depending on intake and carb, horsepower would likely fall in the 450 - 475 range around 5600 - 5800 RPM peak, with about 500 ft-lb around 4000.

I would consider this cam to be biased for frequent street driving with occasional "for fun" track use. It certainly does not take advantage of the aggressive nature of the rest of the motor (large port heads, shaft rockers, etc), but that may not be what you want.

[tyoneal]

PTAddict

I have always heard to start out a bit conservatively, then if you wanted to try a larger cam you could always put in a new one. Cams are cheap compared to the lifters.

Based in what you said, it still should be pretty lively........I hope.

More thoughts??

Ty

[tyoneal]

If the above specs for the Hydraulic Roller Cam are mild, what would be typical specs for a big Hydraulic Roller Cam, that would still make enough vacuum to run a/c, and make its power between 3000 and 6400?

Any and all responses are welcome.

Thanks,

Ty

[PTAddict]

Originally Posted by tyoneal

PTAddict

I have always heard to start out a bit conservatively, then if you wanted to try a larger cam you could always put in a new one. Cams are cheap compared to the lifters.

Based in what you said, it still should be pretty lively........I hope.

More thoughts??

Ty

That's not a bad strategy. I consistently tended to overcam my motors early on, and it's almost never worth it.

A bigger HR cam for that motor would have 8 - 10 degrees more duration on a 110 or 112 LSA. Idle would become quite lumpy, and idle vacuum would drop to 10-12 inches - whether that's enough for A/C I can't say, but it's usually considered not enough for power brakes without a cannister or vacuum pump. Which, come to think of it, suggests that you should be able to plumb in a cannister and/or pump into the A/C vacuum supply as well to compensate for poor idle.

The HP estimates I gave you above might be a bit conservative, depending on how extensive the port job is on those Track 1s.

[tyoneal]

Originally Posted by PTAddict

That's not a bad strategy. I consistently tended to overcam my motors early on, and it's almost never worth it.

A bigger HR cam for that motor would have 8 - 10 degrees more duration on a 110 or 112 LSA. Idle would become quite lumpy, and idle vacuum would drop to 10-12 inches - whether that's enough for A/C I can't say, but it's usually considered not enough for power brakes without a cannister or vacuum pump. Which, come to think of it, suggests that you should be able to plumb in a cannister and/or pump into the A/C vacuum supply as well to compensate for poor idle.

The HP estimates I gave you above might be a bit conservative, depending on how extensive the port job is on those Track 1s.

--------------------------------------------------------------------------------------
PTADDICT:

Thanks again for your time.
The brakes will be supplemented with a Hydra-Boost unit. I am looking at a bit more cam, but I wanted to contact the people here for some thoughts before a final decision is made.

I'm hoping several others will chime in so further ideas or experience can be considered.

Thanks,

Ty

[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.

==============================================

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
==============================================
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".