Solid Flat Tappet Street Cam

No comments eh? No interest in solid flat tappet cams?

Was the last one too hot for you guys? I once penned a Boss 351 replica cam … a milder camshaft than the last one.

For reference the factory Boss 351 solid tappet cam had the following specs:

Duration at 0.020 inch tappet lift (advertised) = 290°/290°
Duration at 0.050 inch tappet lift = 230°/230°
Gross valve lift at 1.73:1 rocker arm ratio = 0.502/0.502
Net valve lift at 0.025/0.025 lash = 0.477/0.477
----------------------------------------------
ICL = 111° ATDC --------(An earlier ICL synchronizes air flow capability more closely with air flow demand and makes more power.)
LSA = 116° --------------(A wider LSA reduces overlap, produces a wider and flatter torque curve; improves controllability.)
Seated Overlap = 58° ---(Limiting overlap to 60° or less improves vacuum, idle, low rpm torque and drivability.)
Seated EVO = 86° BBDC (An earlier EVO compensates for a muffled exhaust, improves idle, extends high rpm power, and reduces pumping losses.)
Seated IVO = 34° BTDC (Limiting the IVO to 30° or less improves vacuum, idle, low rpm torque and drivability.)
Seated IVC = 76° ABDC (A later IVC lowers the DCR, requires a higher SCR; can lead to reversion at idle.)

Horsepower was 370 peaking at 5800 rpm. The cam I penned provided 35 more horsepower (405 bhp peaking at 6100 rpm) AND improved drivability at the same time due to the modern lobes. Here’s the spec:

Duration at 0.020 inch tappet lift (advertised) = 278°/278°
Duration at 0.050 inch tappet lift = 230°/230°
Gross valve lift at 1.73:1 rocker arm ratio = 0.552/0.552
Net valve lift at 0.033/0.033 lash = 0.519/0.519
----------------------------------------------
ICL = 108° ATDC --------(An earlier ICL synchronizes air flow capability more closely with air flow demand and makes more power.)
LSA = 114° --------------(A wider LSA reduces overlap, produces a wider and flatter torque curve; improves controllability.)
Seated Overlap = 50° ---(Limiting overlap to 60° or less improves vacuum, idle, low rpm torque and drivability.)
Seated EVO = 79° BBDC (An earlier EVO compensates for a muffled exhaust, improves idle, extends high rpm power, and reduces pumping losses.)
Seated IVO = 31° BTDC (Limiting the IVO to 30° or less improves vacuum, idle, low rpm torque and drivability.)
Seated IVC = 67° ABDC (A later IVC lowers the DCR, requires a higher SCR; can lead to reversion at idle.)

The lobes have 48° major intensity, which is very sedate by today's standards, this should provide for good longevity. 230° duration at 0.050 with a solid tappet cam is comparable to 222° duration at 0.050 with a hydraulic tappet cam. This cam would provide an engine with a very street-able power band, one that an old fart like me would enjoy; 405 bhp is enough for me.

-G

Hello George,

I am interested since I need a solid flat tapped cam in the near future. But I'm too big a noob in the Ford V8 world that I do not know what is needed. Have to learn a lot first.

Not ready to pull my motor apart yet my friend. Thanks for the info, trust me you will get a call when I am ready. Smile

Hi George,

Here is the card for the solid lifter cam that came with my 1972 Pantera project. The engine was built about 20 years ago and had never been started. I worked with Clay Smith Engineering to get the motor ready to run and it ran quite well on a test stand.

Details about the motor can be seen on this thread:
http://pantera.infopop.cc/eve/...0045562/m/3661054166


Thanks, Steve

Hi Steve

I've kept an eye on your car's progress, I'm thankful for your posts. No specific questions?

I am hoping to get both good performance and good drivability from this cam. To say it another way, it would be nice if power came on at lower RPM's. It could happen because it has a 9:1 compression ratio by design (actually the second design). I am also hoping that there is adequate manifold vacuum to run the brake booster. On the test stand the engine was pulling about 12.8 inches HG. I think it is right on the fence for making the brake booster functional. But all of this is speculation until the car is painted, assembled, and driving. I am currently side tracked from this because I brought home another Pantera from Lancaster, CA in February. The car had been stored for decades and I am trying to get it on its feet. I am looking forward to getting back to this project shortly.

Here's your cam specs as I would detail them:

Advertised duration at unspecified tappet lift = 292°/292°
Duration at 0.050 inch tappet lift = 240°/240°
Gross valve lift at 1.73:1 rocker arm ratio = 0.552/0.552
Net valve lift at 0.021/0.021 lash = 0.535/0.535
----------------------------------------------
ICL = 106° ATDC --------(An earlier ICL synchronizes air flow capability more closely with air flow demand and makes more power.)
LSA = 108° --------------(A wider LSA reduces overlap, produces a wider and flatter torque curve; improves controllability.)
Seated Overlap = 76° ---(Limiting overlap to 60° or less improves vacuum, idle, low rpm torque and drivability.)
Seated EVO = 76° BBDC (An earlier EVO compensates for a muffled exhaust, improves idle, extends high rpm power, and reduces pumping losses.)
Seated IVO = 40° BTDC (Limiting the IVO to 30° or less improves vacuum, idle, low rpm torque and drivability.)
Seated IVC = 72° ABDC (A later IVC lowers the DCR, requires a higher SCR; can lead to reversion at idle.)

Based on valve lift this is a 415 bhp cam, peaking at about 6200 rpm (4V cylinder heads). In order for the engine to have good over-rev, the exhaust will need to be low back-pressure. The low back-pressure exhaust would help the low rpm performance too.

In terms of drivability the things that work against you are the 76° of overlap and the intake valve opening too early (IVO = 40° BTDC). I'm surprised you had 12.8 inches at idle. Some guys would like the rough idle. Its a cam designed to appeal to drag racers (and parking lot cruisers), with a rough idle, steep torque curve, and narrow power band. There's no way to adjust the timing and "fix" this cam. It is what it is.

The 4V Cleveland heads are tuned to make peak horsepower at 6500 rpm. The way you "retain" low rpm power with 4V heads is to keep the overlap and intake duration conservative, keep the DCR around 7.6:1 to 8.0:1, use a carburetor with annular boosters and a dual plane intake manifold with a full height plenum divider. You don't need a big cam to make power with the 351C-4V. In fact Ford intentionally designed the 4V heads so that the induction system defined the power band and made the horsepower ... thus allowing good performance even though a "street friendly" cam is installed. The 351C 4V makes more horsepower and has more high rpm performance with 50° of overlap than most engines have with 76° of overlap. This is the drum I beat continuously.

Yes, it is a drag race cam, and the motor was built that way originally. But Clay Smith Engineering explained to me that the cam is a relatively mild one and that some people use it for road racing. It did not have a crazy idle on the test stand. Since I already own it and it survived the initial startup and break in, I plan to give it a try. Perhaps it will be exactly what I want. Or it might be unusable and I will try a different solid lifter cam. A good friend of mine is an expert at swapping cams in a Pantera without pulling the motor.

You are going to need a vacuum pump with that cam. You don't have enough vacuum for the Pantera booster. You need above 14 and it works best at 17.

You are probably correct. One person at the shop said it will work with the booster and another said it will not (I think his words were "not even close").

Then the first guy said I might want to get a vacuum reserve canister.

Since it is thier cam, they said they can grind down the cam down if there is an issue.

quote:

Originally posted by SteveBuchanan:

... But Clay Smith Engineering explained ... that some people use it for road racing ...

Those would be the guys you see walking through the pits after the race with the brown spot in the seat of their pants.

.

I wouldn't worry too much about changing it out. It's nothing spectacular. Definitely old technology.

You can do a lot better now.

What you pick though depends on what you want the nature of the car to be.

To reach their full potential Clevelands need more cam than this.

If you just want a cruiser with an idle like a 53 Merc with a 429 in it, go another route.

Because of the short exhaust system even a mild cam in a Pantera tends to sound radical.

There is lots of debate on what to pick and if you ask 20 people you will get 20 different opinions. None of them are wrong. Just different perspectives.

quote:

Originally posted by PanteraDoug:

... What you pick though depends on what you want the nature of the car to be ...

I'm focused on the word "pick". The word leads a person into the mindset that the only choices are those available off the shelf. I pen my own camshafts, and have since the 1980s, because what's on the shelf doesn't provide what I want. Custom cams allow me to tailor the engine to have the characteristics I want it to have.

quote:

Originally posted by PanteraDoug:

... To reach their full potential Clevelands need more cam than this ...

That term ... "more cam" ... may draw the wrong picture in people's minds. A picture of high overlap, long duration, rough idling, and poor drivability. If that's what "more cam" means then I disagree with that perception.

If we can agree that the production block is more or less good for 450 bhp and 7200 rpm, within that limitation the Cleveland can be quite drivable with the opposite of "more cam" thanks to the performance attainable with modern cam lobes which provide more valve lift with less duration.

I know of a Cleveland producing 440 bhp at 6500 rpm using a 750 cfm Summit carburetor, Blue Thunder intake manifold, GTS exhaust system, 10:1 compression, and the "little" Crane HR-216 hydraulic roller cam. 440 bhp was attained in this case with "less cam".

The specs of the Crane Cam:
Advertised Duration (at 0.004 inch tappet lift) = 278°/286°
Estimated Duration (at 0.006 inch tappet lift) = 270°/278°
Duration at 0.050 inch tappet lift = 216°/224°
Gross valve lift (at 1.73:1 rocker arm ratio) = 0.562/0.586
LSA = 112°; estimated overlap = 50°

I also know of a Cleveland producing 500 bhp at 6500 rpm using IR fuel injection, a bundle of snakes exhaust, 10:1 compression, and the same "little" Crane HR-216 hydraulic roller cam. 500 bhp with only 50° overlap! The additional 60 horsepower of this second engine, using the same camshaft, was the result of higher volumetric efficiency and a better exhaust system. You gotta admit, the HR-216 cam is an unexpectedly small cam for a 500 bhp engine, and 6500 rpm is the lowest peak rpm you'll ever see 500 bhp made with iron heads, stock stroke, naturally aspirated, etc.

For perspective the Pantera teams raced in Europe during the 1970s with 440 bhp utilizing the production block, the iron crank, and a 7200 rpm rev-limit. Ford teams competed in NASCAR during the 1970s with 570 bhp engines utilizing the heavy duty Bud Moore & Tope blocks, fully counter-weighted steel cranks, and an 8500 rpm rev-limit.

Pick = select = make a choice. The builder needs to make a choice.

Custom grinds have always been available.

In an ideal world we would be able to hear, and drive the car with various cam profiles to help the decision.

That doesn't really exist.

Many don't really know what they want or what 300, 400, 500, 600 hp means.

It would be interesting to me to experience all of the variable choices.

I doubt that there is just one magical one that fits all, but maybe there is?

Probably a hydraulic roller design is the most efficient and the most practical currently.

It really depends on the use of the vehicle, type of vehicle and what the owner wants out of it.

I'm not a cam designer. I leave that up to others. I can only share my 45 years of experiences with others. Cams aren't just that black and white.

quote:

Originally posted by PanteraDoug:

... Cams aren't just that black and white ...

That is not my experience, I have found they can be reasonably predictable.

.

I’m looking at getting a solid flat tappet camshaft for a 393 stroker , 1970 Mustang Mach1 , if your interested I’ll talk with you about the build , thanks

this is the recipe i had Bullet cobble, looking forward to enjoying it soon i hope

351C Flat Tappet Mechanical, with additional Nitride and Lightweight EDM orifice lifters

In lobe: F285/355 @ 112* mathematic center .614" gross lift w/1.73 rar

Ex lobe: F295/358 @117* mathematic center .619" gross lift w/1.73 rar

LSA 114.5*

IVO = 30° BTDC

IVC = 75° ABDC

EVO = 85° BBDC

EVC = 30° ATDC

"Its a hot street cam alright. Idle like a boss 351 & rev to the moon. The powerband is a little like a 12 cylinder Ferrari back in the days when they used Weber carburetors. A little soft on the bottom end, but when it hits it stride it will crack your neck. Race car acceleration." ~ George Pence

Hey George, love your posts and insight. my 408 stroker had a 297,304 dur. 262,268 @.050. 661,637 lift solid roller on 112 LSA. intake closed at 59abdc running on e85. alum. heads 330 CFM @ 500 lift. ran too! good with poor street manners. changed intake from 8 stack EFI to a dual plenum opposed throttle bodies 65mm x2 and created a stumble off idle. so I have sent cam out to regrind and remove 10deg from int. and ex dur. and up the LSA to 114. all else to remain the same. it is a bumpy idle but not a daily driver so I don't care. I also dropped compression to 11:1 prior to cam swap. reason is I cant get E85 everywhere I go and that limits me. Never pinged or detonated confirmed when disassembled. Had 11Hg on a good day. hope to see a bit more with regrind. Manual Wilwood brakes so no worries there. Still it runs with the best of them. just a little louder. cams are not that difficult to swap in the Pantera just have a seat n relax, sort-of in the fetal position.

Grinder: Bullet Cams
Intake: Lobe #F285/355
Exhaust: Lobe #F295/358
-----------------------------
285°/295° advertised duration
290° average duration
Exhaust valve opening = 85° BBDC
Intake valve opening = 30° BTDC
60° overlap
Exhaust valve closing = 30° ATDC
Intake valve closing = 75° ABDC
------------------------------
250°/260° duration @ 0.050
0.585"/0.590" net valve lift (0.029" lash)
115° lobe separation angle (camshaft degrees)
Intake lobe mathematic centerline = 112.5° ATDC
Exhaust lobe mathematic centerline = 117.5° BTDC



Ford 351 Cleveland solid flat tappet street & road race cam
Grinder: Bullet Cams
Lobes:
Intake #FF280/371 (Asymmetric)
Exhaust #F292/373 (Asymmetric)
110° ATDC intake lobe mathematic centerline
115° BTDC exhaust lobe mathematic centerline

280°/292° advertised duration (286° average)
251°/263° duration at 0.050"

Indicators
29°/29° major intensity (advertised duration – duration at 0.050)
Overlap at 0.050” = 32°
Lobe separation angle = 112.5°

0.371"/0.373" lobe lift
0.022”/0.019” lash
0.642”/0.645” theoretical valve lift (1.73:1 ratio)
0.620”/0.630” net valve lift [(lobe lift x 1.730) – lash]
0.609”/0.615” factual valve lift [(lobe lift x 1.70) – lash]

EVO = 81° BBDC
IVO = 30° BTDC
Overlap = 61°
EVC = 31° ATDC
IVC = 70° ABDC