Hyd roller to solid roller - cam specs opinions?

[KnightEngines]

Got a 383 holden I built a while back in for a freshen, upgrade from Hyd roller to solid roller, slight bump in comp & vac pump.

It's 4.03/3.75", 5.7" rod. short motor can turn 7500rpm no problem, over rev to 8000 would be safe.

It runs on E85.

Heads are ported VN iron, 2.055/1.6" valves, around 2.4" MCSA, flow as follows:

.1 - 66.5
.2 - 141.5
.3 - 188
.4 - 228
.5 - 256
.6 - 276
.7 - 294
.8 - 298

exhaust

.1 - 54
.2 - 103
.3 - 144
.4 - 174
.5 - 195
.6 - 203
.7 - 205
.8 - 209

Previously the motor was 12.3:1 compression with a 256/264 on 109 centres .660/.660" lift (1.65 rocker ratio) Crane hyd roller & Morel lifters, it made 580hp @ around 6400rpm - it was limited by lifter bleed at higher rpm.

Intake is a ported Harrop single plane, good for 650hp with the mods done, carb is a QF850 E85, headers are 4-1 with 1 3/4" primaries, 3" collectors with a 2.5" choke.

Aim this time around is to make peak around 7000-7200rpm & 630+hp.

Now this would all seem pretty straightforward, but there are some catches - it's going to be street driven, the owner lives out in the desert & doesn't mind doing a bit of warp speed on the highway, but also would like to drag race from time to time. So gearing is 3.5 & converter 4500rpm (9.5" converter).
He's open to *maybe* going to an 8" converter & 5000rpm stall & 3.7 gears, but beyond that will kill his fun.
Car weighs about 3300 lb.

I'm thinking of camming it around 264/268 on 108 centres, .438/.420" lobes, around .700/.670" valve lift. Lobes would be crane endurance racing.
Compression will be going up to 12.8:1 or thereabouts - I'd normally push it higher, but fuel is purchased in drums from 400 miles away & stored, so I'm wary of pushing the limits.
Addition of vac pump is mostly to keep moisture from E85 out of the oil & reduce windage in the tight holden crankcase, vac will be around 8-10", ring set is Mahle 1.5/1.5/3mm. Vac pump will likely be worth around 10hp on this one.

What say you?

[cjperformance]

I was thinking 268* & ~.700" on the intake till I got to the 3.5:1 gears.
So that said I will say you are right on with the 264* intake unless he definetly commits to 3.7 gears/5K stall.
But if he's a dessert runner then stay 3.5:1 with the endurance lobe you suggest mate.

[KnightEngines]

Yeah, with 3.9 gears & 5000 converter I'd be putting a 268/274 on 108 in it, but I kinda gotta be mindfull of the gearing!

[cjperformance]

How about less cam/comp, add a blower and 2.48:1 gears, that should make some top end on the highway

[Geoff2]

So you are going from hyd roller to sol roller, with 8* more intake duration with the new solid. It will probably make little difference.
The rule of thumb for comparing the power range of a hyd to sol cam is to add 8-15* of duration to the solid. If it is a tight lash solid with lash of about 0.012 - 0.014", add 8*; it is one of the older grinds with close to 0.030" lash, add 15*.

You have iron heads. I would run sol lifters on the existing cam lashed at 0.004 - 0.006".

[CamKing]

So you are going from hyd roller to sol roller, with 8* more intake duration with the new solid. It will probably make little difference.
The rule of thumb for comparing the power range of a hyd to sol cam is to add 8-15* of duration to the solid. If it is a tight lash solid with lash of about 0.012 - 0.014", add 8*; it is one of the older grinds with close to 0.030" lash, add 15*.

You have iron heads. I would run sol lifters on the existing cam lashed at 0.004 - 0.006".

That's not correct.
When going from a hydr to a mechanical cam, you add 4 degrees if the hot lash is in the .018"-.020" range. If it's a tight lash(.012"-.014"), you would only add 2 degrees.

[Geoff2]

I believe it is correct. If you take a hyd cam with 1.5 rockers, at the 0.050" tappet lift measuring point, valve travel will be 0.075".

Take a sol cam with 0.020" running lash. To achieve net 0.075" valve lift, the timing point moves from 050 to 0.063" tappet lift. With the same 1.5 rockers, gross valve lift is 0.095". Subtract the 0.020"lash, you get 0.075" net valve lift, same as the hyd cam.
If you look at a lift/degree curve, the duration difference between 050 & 063 is about 10 degrees. My own testing of different cam brands bears this out. So in this case, the sol cam needs to be about 10* longer in duration than the hyd, all else being equal.
Another pointer. The lift curve from 0.050" to 0.100" is fairly linear. So the difference is proportional. Looking at Isky roller lobes where they provide the 0.100" lift duration figures shows that on average, the difference in duration between 050 & 100 lifts is 30-32*. By proportion, 0.063" lift adds 8.3* to the 050 duration number.

[CamKing]

I believe it is correct. If you take a hyd cam with 1.5 rockers, at the 0.050" tappet lift measuring point, valve travel will be 0.075".

Take a sol cam with 0.020" running lash. To achieve net 0.075" valve lift, the timing point moves from 050 to 0.063" tappet lift. With the same 1.5 rockers, gross valve lift is 0.095". Subtract the 0.020"lash, you get 0.075" net valve lift, same as the hyd cam.
If you look at a lift/degree curve, the duration difference between 050 & 063 is about 10 degrees. My own testing of different cam brands bears this out. So in this case, the sol cam needs to be about 10* longer in duration than the hyd, all else being equal.
Another pointer. The lift curve from 0.050" to 0.100" is fairly linear. So the difference is proportional. Looking at Isky roller lobes where they provide the 0.100" lift duration figures shows that on average, the difference in duration between 050 & 100 lifts is 30-32*. By proportion, 0.063" lift adds 8.3* to the 050 duration number.

I hope you didn't spend too much time on your testing, because it was a waste of time. You're not even close.
Your first mistake was not calculating for the compression of the hydraulic lifter. You need to subtract about .006" to .009" at the valve.
2nd, the lift curve from .050" to .100" is nowhere close to linear. Il most cases, the velocity is increasing, and the acceleration is decreasing.

The easy way to measure the difference, is to know what the ramp heights are on the two different types of cams. On most of my mechanical follower cams, we use a .012" Lash ramp, this would give you an .018" hot Lash with a 1.5 rocker.
On hydr follower cams, everyone uses either a .004" or .006" hydr ramp.
This gives you a .006"-.008" difference in ramp height between the two types of cams.
That means, if you want to compare a mechanical cam to a hydraulic cam, the mechanical cam would have to be the same duration at .056"-.058", as the hydraulic cam at .050".
The lobe velocity at .050", on most cams is between .004"-.005" per degree, and increasing as it goes up in lift.
If you divide the .008" difference in ramp heights, by the .004" lobe velocity, you get 2 degrees. Now you double that, because you have to adjust for both sides of the lobe, and you get a 4 degree correction factor between the hydr cam with a .004" hydr ramp, and a mechanical cam, with a .012" lash ramp.

[Stan Weiss]

I believe it is correct. If you take a hyd cam with 1.5 rockers, at the 0.050" tappet lift measuring point, valve travel will be 0.075".

Take a sol cam with 0.020" running lash. To achieve net 0.075" valve lift, the timing point moves from 050 to 0.063" tappet lift. With the same 1.5 rockers, gross valve lift is 0.095". Subtract the 0.020"lash, you get 0.075" net valve lift, same as the hyd cam.
If you look at a lift/degree curve, the duration difference between 050 & 063 is about 10 degrees. My own testing of different cam brands bears this out. So in this case, the sol cam needs to be about 10* longer in duration than the hyd, all else being equal.
Another pointer. The lift curve from 0.050" to 0.100" is fairly linear. So the difference is proportional. Looking at Isky roller lobes where they provide the 0.100" lift duration figures shows that on average, the difference in duration between 050 & 100 lifts is 30-32*. By proportion, 0.063" lift adds 8.3* to the 050 duration number.

I hope you didn't spend too much time on your testing, because it was a waste of time. You're not even close.
Your first mistake was not calculating for the compression of the hydraulic lifter. You need to subtract about .006" to .009" at the valve.
2nd, the lift curve from .050" to .100" is nowhere close to linear. Il most cases, the velocity is increasing, and the acceleration is decreasing.

The easy way to measure the difference, is to know what the ramp heights are on the two different types of cams. On most of my mechanical follower cams, we use a .012" Lash ramp, this would give you an .018" hot Lash with a 1.5 rocker.
On hydr follower cams, everyone uses either a .004" or .006" hydr ramp.
This gives you a .006"-.008" difference in ramp height between the two types of cams.
That means, if you want to compare a mechanical cam to a hydraulic cam, the mechanical cam would have to be the same duration at .056"-.058", as the hydraulic cam at .050".
The lobe velocity at .050", on most cams is between .004"-.005" per degree, and increasing as it goes up in lift.
If you divide the .008" difference in ramp heights, by the .004" lobe velocity, you get 2 degrees. Now you double that, because you have to adjust for both sides of the lobe, and you get a 4 degree correction factor between the hydr cam with a .004" hydr ramp, and a mechanical cam, with a .012" lash ramp.

Mike,
Cam or crank degrees? Most of the files I have are of old profiles and lower lobe lifts but all are under 0.003" per crank degree @ 0.050" lifter raise.

Stan

[CamKing]

Stan, you're correct. My memory isn't all it used to be.
I looked up a few samples, and the velocity in crank degrees was .0025"-.0031", but you also have to remember it's increasing as it goes up.
A cam with a velocity of .0028" @ .050", can be .003" @ .055"

Here, I'll correct the math.

The lobe velocity at .050", on most cams is between .0025"-.0031" per degree, and increasing as it goes up in lift.
If you divide the .008" difference in ramp heights, by the .003" lobe velocity, you get 2.667 degrees. Now you double that, because you have to adjust for both sides of the lobe, and you get a 5.333 degree correction factor between the hydr cam with a .004" hydr ramp, and a mechanical cam, with a .012" lash ramp.
If the hydr cam has a .006" ramp, the correction will be 4 degrees.

[Geoff2]

Camking.

[1] The original figure of 8-15* increase in duration, for estimating the power range of a sol lifer cam compared to a hyd cam was not my figure. It was in the cam catalog of one of the big cam companies, I believe it was Crane.
[2] I did omit to figure the 'lash' of the hyd lobes.
[3] There is nothing wrong with my testing.
[4] You originally said I was 'not correct' with the 8-15 figure & to add 2* for a tight lash cam. Now you say to add 4*.

[Stan Weiss]

How long ago did you read that?

I can produce that result using a solid flat tappet cam. Of course it is over 50 year old tech.

0.030" lash with 1.5:1 rocker arm ratio = 0.020" lifter raise

CAM
_________0.00600___112.81_|_181.17_|_473.98_|__30.21
_________0.01000____90.58_|_160.43_|_431.01_|__30.03
_________0.02000____39.41_|_107.91_|_327.31_|__29.26
_________0.04000____16.09_|__71.28_|_267.37_|__28.44
_________0.05000____10.68_|__64.95_|_255.63_|__28.11 <-----
_________0.06400_____4.44_|__57.84_|_242.28_|__27.76 <----- If using .006 for hydr 13.34 degrees difference
_________0.06600_____3.63_|__56.92_|_240.55_|__27.68 <----- If using .004 for hydr 15.08 degrees difference
_________0.10000____-8.13_|__43.99_|_215.86_|__26.66

Stan

[bigjoe1]

I have always figured 8 to 10 degrees was very close ,and that has been my experience too.



JOE SHERMAN RACING

[KnightEngines]

Solid roller is just to extend the rpm range - hyd was having issues with lifter bleed above 6500rpm, heads/intake/exhaust etc are set up to make power to 7000-7200, but it wasn't getting there.
So I don't really need 'more' cam, just a 'similar' cam with non-squishy lifters.
We'll have about .050" more lift, quicker ramps & no squishy lifters, that should be enough to have it making power out 500rpm higher without negatively affecting the midrange.

[Geoff2]

Stan,
To answer your question, a long time ago. But it was in one of the major cam grinders catalog. Your figures bear this out.

Quote from another respected automotive source: "Most engine builders feel that 0.050"is closely related to the rpm range where the engine makes its best power. ........cams with 0.050 durations in the 215 to 230 degree range if using a hyd grind, or 230-240 degrees with a solid".