[Stan Weiss]

This is a Crane / Pontiac 041 RAIV cam valve lift curve with different rocker arm ratios.

The green line is with 1.75:1

The red line is with 1.65:1

The Blue line is with 1.5:1

Stan

[Jay S]

I don’t know how Crower rates seat timing on their flat tappet cams, but that Crower Flat tappet has about as slow of accelerations as you will find in a flat tappet solid cam. The info on the cam card that really reinforces that is the minimum seat pressure of 105 lbs and the max lift pressure is below 300 lbs, that spring rate figures out to be just over 300 lbs per inch. To be able to run those spring recommendations for the duration and lift of that cam it would have too have low accelerations. I have an older General Kinetics solid cam from 70s ground very similarly, it will outlast anything in a modern more aggressive grind. But it can leave a good amount of HP (60+) and/or tq (90+) untapped depending on what it is used in. There are reasons to run cams like that, it comes back to how willing you are to sacrifice for power versus longevity.

Since no other info was mentioned on the engine there is no way to determine what the possible out come would be switching to a roller.

[Jay S]

I have read Harold’s example on the chevelle’s forum before. I have had both the profiles he mentioned. If your “going for it” on a roller you can also run a 28* intensity cam of Harold’s, and versus the 33* to 35* intensity cams he was comparing, make more tq and power. Especially on the TQ. Bigger increases for the HP are possible too with more duration to use the extra accelerations more effectively, generally lift increases also. That is comparing Harold’s examples though, not to the Crower. Performance versus longevity is a factor, sometimes it isn’t worth the extra abuse.

[grandam1979]

Are your times listed at the bottom with this camshaft?

[Stan Weiss]

Originally Posted by Jay S

I don’t know how Crower rates seat timing on their flat tappet cams, but that Crower Flat tappet has about as slow of accelerations as you will find in a flat tappet solid cam. The info on the cam card that really reinforces that is the minimum seat pressure of 105 lbs and the max lift pressure is below 300 lbs, that spring rate figures out to be just over 300 lbs per inch. To be able to run those spring recommendations for the duration and lift of that cam it would have too have low accelerations. I have an older General Kinetics solid cam from 70s ground very similarly, it will outlast anything in a modern more aggressive grind. But it can leave a good amount of HP (60+) and/or tq (90+) untapped depending on what it is used in. There are reasons to run cams like that, it comes back to how willing you are to sacrifice for power versus longevity.

Since no other info was mentioned on the engine there is no way to determine what the possible out come would be switching to a roller.

Jay,
Would you happen to have a lobe file for that GK cam? Back in the '70s I ran a GK 320M in a SBC it was 280 @ 0.050". I have some numbers I took back then every 10 crank degrees using a 8" degree wheel and dial indicator. The lift curve looks good, but the velocity no. But the velocity looks pretty good with a little smoothing. On this cam the max velocity is just about the max you can run on a .842" diameter lifter.

Stan

[Jay S]

Stan,I believe I do some specs from the GK cam that you could piece together a pretty accurate file, similar to what you mentioned. But nothing like a cam DR file. The duration numbers I have for it are every .001” up to .010” on open and close, then every .005” thru .050”, and every .010” on the rest of the lobe. It was 277*/284* at .050” and .392”, 398” lobes, 107 LSA.

[Stan Weiss]

Forget I had data from a GK 321 Roller since I never got to run it. This shows the 321R against the 320M that I did run.

Stan

[PAUL K]

Originally Posted by Stan Weiss

This is a Crane / Pontiac 041 RAIV cam valve lift curve with different rocker arm ratios.

The green line is with 1.75:1

The red line is with 1.65:1

The Blue line is with 1.5:1

Stan

Hi Stan, would you have an easy way to quote the duration at .050 with the different rocker ratio's? I can see each ratio increased duration off the seat just curious what that number might be at .050 for the different ratios.

[Jay S]

Originally Posted by PAUL K

Hi Stan, would you have an easy way to quote the duration at .050 with the different rocker ratio's? I can see each ratio increased duration off the seat just curious what that number might be at .050 for the different ratios.

If Stan doesn’t, I have a program that will do that.

BTW Stan, the GK I had was a 316M, not a 320.

[Stan Weiss]

Originally Posted by PAUL K

Hi Stan, would you have an easy way to quote the duration at .050 with the different rocker ratio's? I can see each ratio increased duration off the seat just curious what that number might be at .050 for the different ratios.

Paul,
Is this what you want?

Stan

VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00000____54.80_|_125.20_|_360.00_|__39. 12
_________0.00600____31.84_|__98.92_|_310.76_|__39. 05
_________0.01000____26.66_|__87.45_|_294.11_|__38. 99
_________0.02000____19.48_|__71.92_|_271.39_|__38. 82
_________0.04000____11.12_|__60.95_|_252.07_|__38. 51
_________0.05000_____8.00_|__57.35_|_245.35_|__38. 37
_________0.07500_____1.45_|__50.18_|_231.64_|__37. 91_<<<_0.050_Cam_Duration
_________0.08250____-0.29_|__48.31_|_228.01_|__37.75
_________0.08750____-1.43_|__47.09_|_225.67_|__37.57
_________0.10000____-4.12_|__44.21_|_220.09_|__37.37
_________0.15000___-14.18_|__33.72_|_199.54_|__36.08
_________0.20000___-23.73_|__23.98_|_180.25_|__34.28
_________0.25000___-33.32_|__14.25_|_160.93_|__31.96
_________0.30000___-43.49_|___4.01_|_140.51_|__29.14
_________0.35000___-54.83_|__-7.42_|_117.74_|__25.50
_________0.40000___-68.65_|_-21.28_|__90.07_|__20.19
_________0.45000___-89.31_|_-41.84_|__48.86_|__11.16

=====

VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00000____54.80_|_125.20_|_360.00_|__43. 03
_________0.00600____32.76_|_100.58_|_313.34_|__42. 97
_________0.01000____27.66_|__89.88_|_297.54_|__42. 91
_________0.02000____20.50_|__73.52_|_274.02_|__42. 73
_________0.04000____12.38_|__62.46_|_254.83_|__42. 41
_________0.05000_____9.37_|__58.92_|_248.29_|__42. 26
_________0.07500_____3.11_|__51.98_|_235.09_|__41. 87
_________0.08250_____1.45_|__50.18_|_231.64_|__41. 70_<<<_0.050_Cam_Duration
_________0.08750_____0.38_|__49.03_|_229.41_|__41. 52
_________0.10000____-2.17_|__46.30_|_224.13_|__41.32
_________0.15000___-11.48_|__36.46_|_204.98_|__40.01
_________0.20000___-20.22_|__27.50_|_187.28_|__38.57
_________0.25000___-28.81_|__18.71_|_169.90_|__36.49
_________0.30000___-37.80_|___9.69_|_151.89_|__33.98
_________0.35000___-47.35_|___0.04_|_132.70_|__30.67
_________0.40000___-58.28_|_-10.87_|_110.84_|__26.46
_________0.45000___-71.63_|_-24.25_|__84.12_|__20.87
_________0.50000___-92.15_|_-44.61_|__43.23_|__11.27

=====

VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00000____54.80_|_125.20_|_360.00_|__45. 64
_________0.00600____33.41_|_101.53_|_314.94_|__45. 58
_________0.01000____28.25_|__91.35_|_299.60_|__45. 52
_________0.02000____21.13_|__74.61_|_275.75_|__45. 33
_________0.04000____13.13_|__63.35_|_256.48_|__45. 07
_________0.05000____10.19_|__59.87_|_250.06_|__44. 88
_________0.07500_____4.10_|__53.05_|_237.14_|__44. 40
_________0.08250_____2.48_|__51.29_|_233.77_|__44. 33
_________0.08750_____1.45_|__50.18_|_231.64_|__44. 23_<<<_0.050_Cam_Duration
_________0.10000____-1.03_|__47.52_|_226.49_|__44.04
_________0.15000____-9.95_|__38.06_|_208.10_|__42.76
_________0.20000___-18.31_|__29.50_|_191.19_|__41.32
_________0.25000___-26.44_|__21.23_|_174.78_|__39.50
_________0.30000___-34.72_|__12.83_|_158.11_|__36.97
_________0.35000___-43.49_|___4.01_|_140.51_|__34.00
_________0.40000___-53.08_|__-5.68_|_121.23_|__30.56
_________0.45000___-64.30_|_-16.95_|__98.75_|__25.40
_________0.50000___-78.87_|_-31.49_|__69.64_|__18.68

[Stan Weiss]

Originally Posted by Jay S

If Stan doesn’t, I have a program that will do that.

BTW Stan, the GK I had was a 316M, not a 320.

Jay,
The 320M was a cam I ran in my SBC.

Can you either post the numbers from your 316M cam here or email they to me?

Do you happen to have an old GK catalog?

Thanks,
Stan

[quick67bird]

Originally Posted by Stan Weiss

This is a Crane / Pontiac 041 RAIV cam valve lift curve with different rocker arm ratios.

The green line is with 1.75:1

The red line is with 1.65:1

The Blue line is with 1.5:1

Stan

Thank you Stan. The graph looks like duration is increased like lift is when the rocker ratios change. I kind of thought that, but the visual helps.

[quick67bird]

Originally Posted by Jay S

I don’t know how Crower rates seat timing on their flat tappet cams, but that Crower Flat tappet has about as slow of accelerations as you will find in a flat tappet solid cam. The info on the cam card that really reinforces that is the minimum seat pressure of 105 lbs and the max lift pressure is below 300 lbs, that spring rate figures out to be just over 300 lbs per inch. To be able to run those spring recommendations for the duration and lift of that cam it would have too have low accelerations. I have an older General Kinetics solid cam from 70s ground very similarly, it will outlast anything in a modern more aggressive grind. But it can leave a good amount of HP (60+) and/or tq (90+) untapped depending on what it is used in. There are reasons to run cams like that, it comes back to how willing you are to sacrifice for power versus longevity.

Since no other info was mentioned on the engine there is no way to determine what the possible out come would be switching to a roller.

I am looking for a bit more reliability for now. I had a couple of cam failures with the higher intensity flat tappet lobes quite a few years back. I still don’t know why as my break in procedure never changed. After the last cam failure I pretty much let my car sit for a number of years.

I bought this long block off of P-Dude a number of years back and decided to take everything out of mothballs and get my car going for some cruising a few years back. It seems to run pretty good. Hopefully this year I may go to a drag strip. So far playing on the streets with friends out in the country my car has not been beat. Now with the Mickey Thompson drag radials adding traction I am not having to come from behind too much anymore.

[quick67bird]

Originally Posted by Jay S

Since no other info was mentioned on the engine there is no way to determine what the possible out come would be switching to a roller.

The engine has kre Dport 74 cc heads.

lift......Intake......Exhaust.....%
100....77.1..........62.6.........81.1
200....150.6.........114.6........76
300....204.9.........152.9........74.6
400....250...........177.9........71.1
500....288.2.........200.3........69.5
600....319.1.........226.6........71
700....336.8.........239.7........70.5

P-Dude 455 long block filled to freeze plug holes
4.21 stroke factory crank
.035 SRP flattop forged pistons with standard valve reliefs
Steel H beam rods. I can’t remember the brand. P-Dude prepped

[quick67bird]

Originally Posted by grandam1979

Are your times listed at the bottom with this camshaft?

No sir. Those were with my old 6x headed comp cam 295s flat tappet cam. I have not had my car to the track in a very long time.

[Jay S]

Originally Posted by quick67bird

The engine has kre Dport 74 cc heads.

lift......Intake......Exhaust.....%
100....77.1..........62.6.........81.1
200....150.6.........114.6........76
300....204.9.........152.9........74.6
400....250...........177.9........71.1
500....288.2.........200.3........69.5
600....319.1.........226.6........71
700....336.8.........239.7........70.5

P-Dude 455 long block filled to freeze plug holes
4.21 stroke factory crank
.035 SRP flattop forged pistons with standard valve reliefs
Steel H beam rods. I can’t remember the brand. P-Dude prepped

I don’t think any of us were expecting you had that much head flow. Appears the compression is a bit over 11. I come up with (assuming you have 1.5 rocker on the Crower) just over 60 HP switching from that Crower cam and to a SR profile that isn’t all that aggressive with a lot more lift, or a very aggressive SFT with higher ratio rockers could come close to that also. If you were swinging for the fence with an very big aggressive solid roller, you could probably gain 115+ with the head flow on that engine. But from what you described for your goals, absolutely no reason to swing for the fence. Run that Crower and enjoy your car.

[Jay S]

Originally Posted by Stan Weiss

Jay,
The 320M was a cam I ran in my SBC.

Can you either post the numbers from your 316M cam here or email they to me?

Do you happen to have an old GK catalog?

Thanks,
Stan

I will email them to you Stan. I don’t have a GK catalog.

[Steve C.]

I suggest Crower has not changed but in my old Crower catalog from 20 years ago they stated the same 68405 valve spring for all their solid flat tappet cams listed, from 240 at .050 up to 274 at.050.

68405 spring listed here on page 176

https://www.crower.com/media/masterc...x.html?page=10

Rated 110 at 1.700"
382 rate
0.980 coil bind

The old Crower information rated it at 104 lbs seat pressure at 1.700

( Information provided in this post does not represent any endorsement. And unless specified it is not based on personal experience and is offered for general interest only )


.

[quick67bird]

Originally Posted by Jay S

I don’t think any of us were expecting you had that much head flow. Appears the compression is a bit over 11. I come up with (assuming you have 1.5 rocker on the Crower) just over 60 HP switching from that Crower cam and to a SR profile that isn’t all that aggressive with a lot more lift, or a very aggressive SFT with higher ratio rockers could come close to that also. If you were swinging for the fence with an very big aggressive solid roller, you could probably gain 115+ with the head flow on that engine. But from what you described for your goals, absolutely no reason to swing for the fence. Run that Crower and enjoy your car.

Sorry forgot rocker ratio. 1.65 rockers. Valves in these heads are 2.19 intake and 1.66 exhaust.

[quick67bird]

Originally Posted by Steve C.

I suggest Crower has not changed but in my old Crower catalog from 20 years ago they stated the same 68405 valve spring for all their solid flat tappet cams listed, from 240 at .050 up to 274 at.050.

68405 spring listed here on page 176

https://www.crower.com/media/masterc...x.html?page=10

Rated 110 at 1.700"
382 rate
0.980 coil bind

The old Crower information rated it at 104 lbs seat pressure at 1.700

( Information provided in this post does not represent any endorsement. And unless specified it is not based on personal experience and is offered for general interest only )


.

I am using the flat tappet springs Kauffman suggested for the solid comp cam they sold me. It was of similar lift and a little less duration at .050. I believe it was a faster and more aggressive ramp than this cam.