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Hello Fellow Enthusiasts!!!; I know!!..I know!!...another dreaded "Cam" question.....might as well talk about religion or politics. Well let's open this "Can of Worms".....Purchased a Comp cam a few years back whilst collecting parts for a "Future Rebuild". The specs for the cam are as follows. It's a hydraulic roller cam.
Int Exh
Avg Duration: 276 290
Dur @ .050: 220 230
Valve Lift: .591 .588
Lobe Sep: 106

I'm NOT as thin-skinned as a defective Chinese condom, so PLEASE be honest in your comments. I believe the narrow lobe separation will hinder my desire to build a high-revving Cleveland. I currently have accumulated the following parts...a Virgin bore 351C 4 bolt main block that has been magnafluxed & sonic tested for thickness. H beam Eagle stock length rods. Ross Racing pistons. Scorpion Race Series 1.73 ratio roller rocker arms on 7/16 shafts with guide plates. Jomar stud girdle. Professionally ported & polished iron 4V head with titanium intake valves, stainless exhaust, titanium retainers & keepers & dual springs. Knife edged & profiled 4MA Cleveland crank weighing 50lbs. ALL bolts are ARP. Aluminum flywheel & pullies. Kevko baffled oil pan & Milidon windage tray. Comp cam hydraulic roller lifters. Blue Thunder intake manifold with a Holley 4779 carb. 180 degree headers. MSD distributor & ignition system. Ford SVO High Performance full roller multi-index timing chain set. High flow aluminum water pump, Victor Reinz head gaskets, etc, etc, etc. Tried to collect....."The Best of the Best" ( without breaking TOO MANY Piggy Banks)....NOW I NEED THE CAM!!!....I want a "HIGH REVVING" 6,500+ Cleveland that will idle nicely & PULL throughout the powerband!!! I looking for a Unicorn in a field of 4 leaf clovers???!!!....HELP!!!......Mark
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The 106 is really a comp cam timing but is a streetable cam in a Cleveland. What Comp Cams has done is made a real street/strip cam.

I think that you will find that the C responds to the 106 and makes it come alive at rpm.

I think, it's always dangerous to try to anticipate what the designers were thinking, was that the 5.7 with iron heads is likely a little sluggish off of idle anyway? Why not put it into it's rpm range sooner?

The entire line of the "street/strip" CompCams Cleveland cams are built on the 106. They do push the limit though.

I have the solid lifter version with the .605 lift. It revs like an electric razor. You can definitely feel the difference with this timing over 3000 rpm vs a real street cam. The engine is not sluggish with this timing at all.

Over 3000? You feel it off of idle. THIS IS your 500hp Cleveland.

Smaller port heads also quicken the throttle response to it a lot. I'm using A3 heads that came off of a circle track car to go to smaller ports.

Can you make a scientific experiment with it and test every possible combination available to you on a engine dyno...sure? Some have and will continue to. Power to them. I haven't got time for the pain.

Strangely enough, mine wants to idle at 650rpm vs. the expected 1,000 to 1,100 rpm. Once the engine cover is on, it is quiet in the cabin but with my 180 headers it sounds like a marching band at idle. Boom, boom, bada, bada boom, boom.

Listen to the sound bite that CompCams put up on their web page. That's mine at 1,000 but mine idles down much more. You can hear the differences between the idles with the different duration series.

If you love Harley Davidsons you will love it. If not you will hate it for sure. With a free flowing exhaust, it sounds like a 5.7 liter Harley would.

It has actually turned this now into a project to quiet the headers and mufflers down, but anyone with a Pantera would understand that even with the stock set up. This isn't a car a cat burglar should have picked, but is that a political statement? I don't know? Roll Eyes

I personally think it turns the engine into a true street/track engine but that's just my opinion. A lot of people want their car quiet like a Prius so that they can sneak up on you? As far as being opinionated, if you vote you are political, if you say "oh God" when you think you are dying, you are religious and if you like the tall Barbie over there with the long legs that unfortunately for her hasn't seen her feet since she turned 14, then fill in the blanks.

All depends on your own personal expectations and desires? I'll paint her toe nails for her, and tell her the shoes look great. She doesn' need to see them? I can accept the trade offs. Wink
Last edited by panteradoug
Hello Doug; Very much appreciate your thoughts, inputs & experience with a 106 LSA cam. I am be the equivalent of...."Even a blind squirrel finds a nut" in regards to buying this cam. Your explanation of the 106 LSA helping the large port 4V head "get into it's rpm range sooner"...makes Perfect Sense!!!, plus you have experienced the 106 LSA not being a hindering factor in the 351C's ability to REVVVVVVVVV!...send me your mailing address, your my "Newest Pal", have to get you on my Christmas card mailing list!!!....My Best Regards!!!!!, Mark
if you like the tall Barbie over there with the long legs that unfortunately for her hasn't seen her feet since she turned 14, then fill in the blanks.

All depends on your own personal expectations and desires? I'll paint her toe nails for her, and tell her the shoes look great. She doesn' need to see them? I can accept the trade offs.

roll on floor Too funny! Pure wisdom!

Rocketship - With a 106 LSA you need a free flowing exhaust. Sounds like you're planning that with 180's. Just be sure to select a free flowing muffler. Dan Jones originally recommended a similar cam for my engine with a 106 LSA, but revised the LSA when he realized I was planning to run Ansa GTS mufflers.

My cam:
Duration @ .050: 224/232
Lift: .578/.588
LSA: 110 (Dan's revised LSA recommendation was 108, but my cam grinder pushed for 110)
No a 106 won't hinder the rpm. Quite the contrary.

Well you may consider yourself a blind squirrel but you definitely have found a nut in me. I'm certifiable. My friends are afraid to tell me though. I think they find me entertaining? Roll Eyes

I would get as many opinions on this subject as you can. Try to get to hear the engine running with the cam though. That will help right there.

I looked at a lot of cam profiles and think that the Comp Cams are the most recent profiles.

Many of the big name companies go back to the 60s and 70s and may be dated.

I think that after looking at as many dyno results as I could came to the conclusion that these heads need lift to work. .580 is on the low side.

The heads show flow gains to over 700 lift.

I thought 605 would be a good place to try considering the limited amount of time I put on the car, wear due to more lift is less of an issue, at the moment anyway.

My cam is 244 @ .050 and has 74 degrees of overlap.

I find it no worse then my 347 that is 236 @ 050 and has 62 overlap.

One of the great things about camshafts is that if you don't like what you have, get another one and try that.

They don't let me have mail at Xmas time. The paper is sharp.
HEY Doug!!!...With the straight jacket they keep you in, don't the nurses read you , your mail, no reason to worry about a paper cut. Don't feel alone!!!...I'm in the rubber room next to you.

How interesting would it be to have a test mule 351C motor, a Dyno, & about 50 different cams. Like a "Pot Luck" dinner, only "Cams are being served". Myths would be dispelled, Truths would come into light, the blind would see, the deaf would hear....Hallelujah!!!!....& Pass the plate! GENEROUS!!!...I need a set of AFD heads!!!.....Mark
Garth. Her legs are so long that she asked me to help her shave them... Eeker ...that takes forever when you use whipped cream instead of shaving cream and when you have to lick the whipped cream off. It makes your tongue feel fuzzy. Now is that a trade off or what? Razzer's Grace and Marty?

Dan Jones has been attempting to dyno as much of this information as he can. He has already done alot. Enough in fact to feel confident to offer to design custom cut cams for guys (or girls).

The feedback has been very positive, like from Garth, on the designs.

He's a busy guy but you might inquire with him for help with the cam. Apparently he really likes doing it?
HEY Doug; I was a child of the "60s" & "70"s...& spent many a day n night in a drug induced haze!!!!....The Jefferson Airplane use to play in Golden Gate park, they had a Victorian house in the Haight Ashbury. There is a reason I date Japanese women exclusively....the money I save on razor blades, I spend on MORE Whipped Cream "&"...."THe cherry on Top"!!!!!.....Mark
Originally posted by PanteraDoug:

Dan Jones has been attempting to dyno as much of this information as he can. He has already done alot. Enough in fact to feel confident to offer to design custom cut cams for guys (or girls).

The feedback has been very positive, like from Garth, on the designs.

He's a busy guy but you might inquire with him for help with the cam. Apparently he really likes doing it?

Dan is a very generous guy. He spends alot of time and money researching Cleveland combos and shares all of his research/knowledge. Many have made contributions through Paypal to help him out with parts/dyno time costs etc. (hint,hint..)
Originally posted by 1Rocketship:
Originally posted by PanteraDoug:
"...and the White Night is talking backwards..." Far out Man! Big Grin What ever happened to free love? Why do I get charged so much? Peace V
Inflation....HEY Doug; Maybe it costs you more, cause they charge by the inch......Mark

I was at a SAAC Convention 30 years ago and the guest speaker that night was Walter P. Johnson, President of Ford Motor Company.

He said " hold on to your 289's, 302's, 351's, 427's, 428's, 429's. They are something that likely the world will never see again, and in the measure of a car, just like in the measure of a man, it's inches that count."

I kid you not, he was the President of Ford Motor Company. I had to pick myself up off of the floor! Wink

I need to go "feed my head" now. Wink
Last edited by panteradoug
> It's a hydraulic roller cam.
> Int Exh
> Avg Duration: 276 290
> Dur @ .050: 220 230
> Valve Lift: .591 .588
> Lobe Sep: 106

Are you sure that 106 is the LSA and not ICL (Intake Centerline). Most of
Comps street grinds are on a 110 LSA but are installed 4 degrees advanced on
a 106 ICL. Do you have the cam card? If it really is a 106 LSA, that's too
narrow for a 351C with the sort of duration and specs you are talking about.

> I want a "HIGH REVVING" 6,500+ Cleveland that will idle nicely & PULL throughout the powerband!!!

A 106 LSA with 220/230 degrees @ 0.050" is not going to idle well or make
very good power. The 10 degree intake/exhaust split only makes things worse.
I went too narrow on the LSA for the 351C dyno mule. That cam was:

228/232 degrees @ 0.050" lift (280/284 @ 0.006"), 0.588"/0.588" lift,
107 LSA, 68 degrees overlap, installed in the engine on a 104 intake centerline.

We picked the cam specs before I had access to Dynomation (the tool I now use
to design cams). I used Vizard's cam spec rules-of-thumb and came up up with
a compromise cam since we were testing a bunch of different heads (iron 2V and 4V,
CHI 3V, Pro Comp, A3 and C302B high ports, etc.). However, I made a mistake and
subtracted 2 degrees from the LSA for canted valves when I should have added
2 degrees so the LSA was off. Later I re-designed the cam using the Dynomation
simulation program. I validated the simulation model using dyno data gathered
from several 351C, 393C and 408C engines on Dave McLain's dyno. The new cam came
in with specs:

228/234 degrees @ 0.050" lift (282/288 @ 0.006"), 0.620"/0.580" lift,
111 LSA, 63 degrees overlap, installed in the engine on a 106 intake

If I had added 2 degrees to 109 instead of subtracting, I would have also
gotten 111 degrees using Vizard's simplified rules-of-thumb. Compared to
the original cam, the simulation suggests it's worth about 20 HP at 5800 RPM,
being better everyhwhere in the RPM range. Vizard's testing suggest that
109 degrees would yield similar performance but have a rougher idle. Narrow
it further and you'll start to give up power and have worse manners.

Here's a right up I did a while back on Vizard's rules of thumb. These are
simplifications of what his cam design software does but yield a good starting
point and check on my Dynomation simulations.

In "Be the Camshaft Expert" (July 2006 issue of Popular Hot Rodding) David Vizard
presents some rules of thumb for selecting cam specs based upon what he's learned
in developing a cam selection program. The program was reportedly 18 years in the
making and uses data gathered from several thousand cam tests. The basic idea is
that. for a given engine, there is an ideal lobe separation angle that works best
over a relatively wide range. This ideal LSA is primarily a function of cubic inch
displacement (CID) per cylinder per inch of valve diameter, as well as compression
ratio and valve inclination (canted or inline). Once ideal LCA is known, you pick
the desired overlap via application:

1. Street towing 10 to 40 degrees
2. Regular street 30 to 60 degrees
3. Street Performance 50 to 75 degrees
4. Street/Strip 70 to 90 degrees
5. Amateur Race 85 to 100 degrees
6. Professional Race 95 to 115 degrees

Overlap is the period when both intake and exhaust valve are open and serves
to set the RPM range over which the cam will be best suited. More overlap
means a rougher idle and poorer low end response due to reversion of the
exhaust charge into the intake plenum as well as loss of "effective"
compression ratio (compression is literally blown out the exhaust port at
low RPM). Where you fall in the overlap range is a function of valve size
per cubic inch. Big valves on a 302 use the low end, a 350 with typical size
valves use the mid-point, big inch small block or big block, use the right
hand side. Cam overlap sets the RPM range in which an engine will best operate
and the total overlap is a function of the cam duration and lobe center angle
(LCA). If you know the ideal LCA and the RPM range you wish to operate in,
the duration falls out of the equation.

In the article, Vizard presents graphs of cubic inch displacement (CID) per
cylinder per inch of valve diameter versus ideal LCA. The graphs are for inline
valve heads with compression ratios between 9:1 and 11:1. If canted valve heads
are used, the ideal LCA is adjusted by adding 2 degrees to minimize the reversion
(canted valve heads are more susceptible to reversion than typical inline valve
heads). The optimal LCA is also adjusted for compression ratios outside the assumed
range. Once LCA and overlap are known, duration falls out of the equation. Maximum
lift is a function of the intake valve diameter. Large valve heads will continue
to gain flow for relatively large lifts so the maximum lift for a Cleveland is
usually set by other considerations (seat and valve guide lift, piston-to-valve
clearance, etc.).

In the article, Vizard presented the results of a test demonstrating the
importance of picking the right LCA:

Ideal LCA for that engine was 108 degrees. Narrowing to 105 degrees made
similar power but had noticeably worse idle and low speed characteristics.
Widening to 111 degrees lost power. Another LCA test was performed on a
302 Small-Block Ford and repeated on a stroked (347 CID) version of the same


"When used in the 302, the 276/280 roller hydraulic cam on a 110 LCA proved
optimal, as even a 1 degree change either way produced worse results. Using
a SCAT stroker kit, this engine was stretched to 347 inches and re-tested
with the original 110 LCA cam. The stroker kit really helped both power and
torque. When the 110 LCA was replaced with a more appropriate 108 LCA cam,
the output made a further jump to the tune of some 20 lb-ft and 20 hp. The
108 cam in the 347 gave as much in terms of idle and vacuum as did the 110
LCA in the 302. Dozens of tests such as this show conclusively that the
overlap and LCA--not the duration--are the first steps toward generating a
cam spec."

At low speed, lots of overlap is bad as it hurts low end but overlap helps
as the RPM increases. To a degree, you can offset overlap with static
compression. Another point raised in the article is that, for most V8's with
reasonable heads, the ability to raise low speed torque with compression
increase holds to around 285 to 290 degrees (at lash point) of cam duration.
After that, drop off is faster than an increase in compression can recover.
In another article ("Compression Comprehension") about running up to 12:1
compression on pump gas, Vizard presented the results of a compression test:

"When used in conjunction with a bigger cam, increased compression can
work wonders for the entire curve. When a 265-degree cam (gray curve)
was substituted for a 285-degree cam (blue curve), a substantial drop
in low-speed output was seen. Raising the CR from 9:1 to 12:1 recovered
almost all the lost low end and gave a further increase in top-end

I wrote a little computer program based upon the article. The required
inputs for the simplified program are:

bore diameter (in inches)
crankshaft stroke (in inches)
intake valve diameter (in inches)
static compression ratio
canted or inline valve heads
desired overlap (picked from the ranges listed above)

Vizard's cam selection program is not available to the general public but I
know for a fact it takes much more into consideration than the simplified
rules presented above. A friend has run his program and it uses actual head
flow data, port size (length and cross-sectional areas), valve diameters,
rocker ratios, desired idle vacuum, compression, bore, stroke, fuel octane,
thermostat temperature, rod length and more. Basically, it attempts to feed
the "air pump" in the most efficient manner, given the parameters entered.
What it doesn't do is tell you what ramp rates you need. The recommendation
is to use the most aggressive ramp you can tolerate for your application.
However, more aggressive lobe shapes are noisier, wear more quickly and are
harder on valvetrain parts so that neds to be taken into consideration as

The simplified program assumes you'll use the same lobe profile for intake
and exhaust. There's also an implicit assumption that the exhaust flow is
reasonable compared to the intake. Vizard also suggests the rocker ratio
on exhaust is best kept 0.1 to 0.2 of a ratio lower than the intake ratio.
The exhaust is under higher pressure and blows down early in the lift cycle
plus the exhaust is less sensitive to valve acceleration than the intake but
is sensitive to duration. I noticed in the Engine Masters Competition, most
of the entries were using shorter rocker ratios. I tested this on the dyno
mule 351C and we did indeed pick up average power (mostly in the mid-range).
If an existing cam's LCA is too wide, higher ratio rockers may increase output.
For rocker ratios between 1.5 to 1.9, each 0.1 ratio increase on the intake,
the LCA needs to be spread by 0.75 to 1. Be aware there are cases where the
ideal lobe center may be too narrow for acceptable street manners. For instance,
when stroking an engine (keeping all other variables constant), Vizard suggests
tightening the LCA up by a degree for something like every 16 cubic inches
increase in displacement. That will lead to very tight lobe centers which may
not be acceptable for certain applications. For instance, an engine equipped
with mass-air EFI (which will measure reversion flow as if it were induction
flow) might not be too happy with 104 degree lobe centers. Vizard's full-up
program allows you to specify idle vacuum to get around problems like that
but the simplified program doesn't have that sort of flexibility.

Another thing to be aware of is that narrow lobe separation angles require
an efficient exhaust with minimal back-pressure. If you have a bunch of
back-pressure (from things like restrictive mufflers or headers that turn
down sharply at the exhaust port exit) it will hurt a narrow lobe separation
angle engine more than a wide one. A quote from the article drives home this
point home:

"Let's make one thing clear here: Big (but not excessive) overlap is a prime
key to big power numbers, but only if your exhaust system sucks. Literally.
If you have ever heard that an engine needs a little backpressure, you might
want to ask yourself why an engine would want an exhaust system that literally
pushes exhaust back into the combustion chamber rather than sucking it out.
The simple answer is, it doesn't. If a big-overlap, big-cammed engine has an
exhaust system with any measurable backpressure, the price paid is a big drop
in output."

If your exhaust system is restrictive, it may be wise to err on the side of
a wider LCA (better yet fix the exhaust).

Since large valved heads tend to increase flow through high lift levels,
the lift recommended by Vizard's rules may be excessive for heads equipped
with large valves. The recommendation is to use a lift consistent with your
reliability goal (higher lift wears valves, guides and seats more quickly).

More info on Vizard's cam rules can be found at:


Dan Jones
So there you go. Essentially this means there is no perfect cam.
You are trying to balance factors in order to maximize output in the rpm ranges where you want it.
Right there, that factor, where you want it, is a major factor as to why people like or hate specific cams.
Turns out so many people when they get what they asked for, really didn't want that at all?
Cams that are really orgasmic for open track events are sometimes a lot more then you want to put up with on the street.

The question is now, what's the best compromise for Rocketship?

Not nearly as comprehensive as Dan's but try this one for fun.
Last edited by panteradoug

Originally posted by 73 l:

what is the differenc between lsa and lcl ...

LSA is an acronym for Lobe Separation Angle ... which is the only camshaft spec that is expressed in camshaft degrees. All other camshaft specs are expressed in crankshaft degrees. It is the number of camshaft degrees between the center-lines of the exhaust lobe and intake lobe.

LCL is not accurate, the first letter in that acronym is an I. ICL is an acronym for Intake Center-Line. It is the number of crankshaft degrees between top dead center and the intake lobe's center-line. Locating the centerline of the intake lobe is used as one method of checking or verifying the timing the camshaft.

Modern aftermarket cams are almost always timed by their designers in such a way that the ICL is 4° to 6° less than the LSA. In the case of your cam the 110° ICL is 4° less than the 114° LSA. This timing is also expressed as being 4° advanced.

Here's a picture

The numbers are expressed in the terms in which you would use them, there's really never a need to convert one term in order to relate to the other.

However, to satisfy your question, 1° of camshaft rotation = 2° of crankshaft rotation. The camshaft turns at half the speed of the crankshaft. The camshaft only rotates once for each time the crankshaft rotates twice. The piston makes four strokes, twice up and twice down, during the time in which the camshaft makes one rotation.

One interesting mathematic aspect of the LSA:

(exhaust centerline degrees + intake centerline degrees) ÷ 2 = Lobe Separation Angle

Originally posted by No Quarter:
when they get what they asked for, really didn't want that at all?

My experience is that most people go overboard on duration, and get a screamer engine that's only fun for the first three trips.

I agree. That is 99% of the problem. Most do not understand what they are asking for. Then when they get it the response is no, that's not it, it can't be.

Fuel injected, dual overhead cam engines have a lot of advantages. Very peppy, rev very easy, lots of low end torque.

Cars that are at home on the track are rarely on the street also. The advantages of one tend to be mutually exclusive of the other.

I think the answer with the Cleveland would be that most would be happy with a much larger displacement engine that was quiet mild.
Last edited by panteradoug
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