Technical How do you decide on an aftermarket cam?

Now days I always advise a hyd roller cam setup over a flat tappet cam.... slightly more power for same grind and no flat lobes to worry about. If you have a lobe go flat on a flat tappet cam it will cost you more than just going roller from the start. But its your motor so you decide what you want.

 

Unfortunately

 

The standard method for choosing a cam, is to ignore the recommendation of the cam manufacturer.
And choose the Fattest cam in the catalog
While you are at it......over carb it

and run 3:1 gears

 

You forgot a tight stock torque converter, and some really tall rear tires.

 

all of the above is good advice except a 460 and good gas milage don't equate. 454 and 460 just aren't going to get good milage and you probably want to stick with the 350 gears. tom

 

I have never used a roller cam, and never had any problems. That being said, todays oils aren't as flat tappet friendly as oils of just five years ago. However, good oil and an additive do work. For quite some time I have been using Racer Brown cams. Jim there is pretty clued in on what works where. Give him a call. 410-866-7660 after 2:00 weekdays. Most that can happen is you say no thanks.

 

In a carbed 460 with the 429 gears I'd go with a mild RV grind. Something that wakes up in the 1800-2000 RPM range and is done by about 5-5200. You'll tow well, have nice mid range response (like entering a freeway) and the cruise RPM with your gear should drop you just over where the cam's designed power band begins for the most efficiency (mileage). However, I did have an early injected 460 in a 250 HD back in 89. Empty at 80 MPH it would do 15 MPG with the A/C on. Not hateful, but fuel was like $1.59 or so. Loaded, towing, no matter what speed, 8 MPG. Even with 2 tanks I had to fill every 250-275 miles. Roller or not, you have a torque package there. Don't waste it with too much cam.

You may have done a search already but this might help narrow down your decisions:

http://www.mustangandfords.com/how-to/engine/big-block-engine-guide/

 

Comp cams has a relatively good dyno simulator that can help quite a bit.
It's fun to play with and see how different component changes manipulate the outcome.
But First you need to be honest about how you'll be using the drivetrain and what you want out of it. The components that you'll using will dictate what cam is best.
Best is also a relative term and has different meanings for different applications.

For a street use cam, best to me would be the highest average power levels throughout the entire rpm Range, not the highest peaks. Shooting for the highest peaks can drastically reduce the average and make your car a dog at anything below the peak rpm. Again this best would not be the best choice if the intended application was a race car.

The key is creating a combination of components that work well together and it's ALL a compromise. In the component equation You'll have constants that aren't up for change, you'll have open variables that are subject to change and you'll have closed variable that are forced to change for the greater good of the combination. Any of these components can occupy any category based on your situation. For example the rearend gears can be fixed because you simply aren't changing them, or they are going to get changed to accommodated the package. It's only confusing until you start nailing things down then it's simply connect the dots.

 

They use to be....but these days almost all motors use roller cams.

 

A roller cam is the way to go, reduced friction equals mechanical efficiency. If you are starting with a ground up engine build pick your cam based on what you intend to do with your car. If you are just doing a cam swap I would make sure it is compliant with the rest of your engine. I would not change a flat-tappet cam without at least replacing lifters, although I know it has been done.

I would not increase cam lift without changing springs or at minimum check spring tension. And don't forget about piston clearance.

 

Government said reduce emissions, government said reduce lead, auto manufactures responded with components that survive without the benefits that zddp provided, roller lifters. The OEM didn't change over to them because it was better, or cheaper, they were forced to.

Roller lifters, however are very traditional in max effort race engines.

 

Consider the amount of time the factory saves in NOT having to go thru a cam breaking in cycle during the****embly. TIME saved is worth more than what it cost for the new peices

 

Mechanical rollers are for race cars. Hydraulic rollers are the latest rage. They are expensive for older engines that didn't have them originally. I use Howard's retrofit hyd roller cams now, but they are pricey.

 

What are you guys doing about the dist gear when using rollers? The cam gear is a different metal and will destroy itself and the dist gear in short order. The brass/bronze gears are intended for really intended for racing, not street and attendant high mileage and low rpm, so their durability is questionable at best on anything but a trailer queen. Comp Cams has some new composite material they are using, and some are pressing on a cast iron sleeve gear onto a reduced OD spot on the camshaft where the gear normally is positioned.
Considered this awhile back when I chose a cam for my engine in BGII. Since I was unsure on these new solutions to an old problem, plus the valves and springs in the heads heads I have only can handle lift to about .550 without coil bind, I chose a solid lifter flat tappet cam.
Anybody experienced or hear reliable reports of how things are working out on these new methods on cam gears?

 

with l4e80 trans and 4:11 gears in O/d its equal to a 3:08 gear in my pick up and with the 454's lower end torque ( changed the cam to a towing cam from crane ( which is a little more lift ( .020 on th ex ) and longer duration on the exhaust ) added true roller rockers ,and added headers and opened up the exhaust ( still has emissions devices all working ) 2.5 duals ) it gets 14-18 mpg bobtailing ( if you keep it under 65 mph ) , with the trans in 3rd ( direct) at 65 the milage is 8-12 mpg

 

the crane cam I use uses the stock melonized Gm gear that comes with the factory roller motors , the gear is basically a special heat treated sintered gear ,several people I know use the comp cams with the same gear and never had issues with wear.
other than the few recall gears ( 1996-1999 improper heat treats ) , I have seen them last 250K without any problems and the recall gears were making it up to the 100k mark before failure .

my true billet roller cams ( bullet, and lunati) yes you have to use the bronze gear ,but withthte pontiacs you can do the oiling modification ( drill the plug on the pas side of the motor , and on chevys notch the distributor base for extra oil flow , and the gears will last 50K or longer and also not to use a heavy oil and HP pump as the extra strain kills the gear ) but as with older motors , I do spend a little more time in maintaince on them anyways and pulling the distributor only takes a hour or two to check in a full bodied car ( I got it down to 15 minutes by marking the base of the dist like they do on the later efi truck ones so you can line the rotor up and drop it in once set on tdc and it hits the same tooth . )

another thing about roller cams is the springs are stiffer due to the extra mass of the roller to help prevent valvetrain float and harmonics problems .

 

Enjoy reading the thread, if you all don't mind me getting involved with a question too ?? I have a'62 Ford w/stock 406 which has solids lifters. I'm planning to OH it so would you recommend hyd lifters, roller rockers, etc This car is not used for racing, - UNLESS ! of course, someone wants "see how they run". Otherwise it is not a daily driver, but a cruiser, driven a couple K miles a yr. Apprciate the advise.

 

Not sure on the 406 but some of the early Fords that came with solid lifter cams did not have oiling for hyd lifters.

 

The 406/427 motors (except for the one-year-only '68 and some late service blocks) are solid lifter only; no oil galleys for hydraulics. You could install a solid roller....

 

Saw a stock 350 vortec lose horse power with a change to a mild comp cams flat tappet. My thoughts were difference in friction loss. On the other side is cost a retro kit for a 460 roller is around $1000. That gets you cam, lifters, push rods all required plus springs retainers and timing.

 

I called the Summit Racing tech line they helped narrow down my selections to a Lunati and and 2 Comp cams. I narrowed it down to the 2 Comp cams and then called THEIR tech line.
I know the Summit Tech line is like a box of chocolates,but they gave me sound advice on that occasion.
The right "RV" cam will give you tons of torque and a nice idle.

 

I appreciate everyones response
mammyjammer has a good way to go about it

 

Spoke to my engine builder about what I wanted, HP, driveability, economy and the obligatory subtle sound. He factored in the transmission, did the heads and built the engine with all the goodies dependent on my budget, and determined what cam was the best and most practicable; lift, duration, lobe separation. I settled on a Howards hydraulic roller. Around this time I then sourced a convertor with stall to suit the engine and transmission combination.

 

Even the wording is confusing. A roller cam does not have roller bearings on the cam. I think it means lifters that have rollers. Or maybe rocker arms that have rollers.

My 1946 Harley has ball bearings on each end of the cam shafts.I'm still learning and now I find real roller bearings that fit the camshaft! Are these good?
http://www.ebay.com/itm/Ford-Racing...Parts_Accessories&hash=item4d279e3aaa&vxp=mtr

 

When you here or see "roller cam" that designates for use with roller lifters. The lobes are different shape and specific to the dynamics of a roller riding on the lobe vs flat tappet.

Those cam bearings need to have the blocks cam bearing boss enlarged.
Idk if they work, are worth it, or anything else.

 

Way back in 93 I bought a Crane roller cam that had an iron gear. It was a .672/.672, 252/262 @.050 for a BBC MK IV and used a standard dist. drive get up. Talk about easy on parts (!), I had hundreds of runs on the springs and they only lost 5 lbs of seat pressure and 20 lbs open. I removed the orings on the oil restriction plugs at the back, oringed the stock dist housing, had lots of oil up top and around the gear. I went to the billet steel/bronze gear gig when I went to a .714 as well as the new springs required. That .672 roller was an easy sell with the iron gear. It seemed every street racer was going big and serious back then. I can't imagine how far we've come in over 20 yrs with cam technology. I haven't had any reason to look into it, yet.

As an aside, Packard 8s used a roller cam follower in the 20s and 30s. The bigger senior 8s with the separate crank case and cylinders. Col. Jesse Vincent wrote about his changes to induce "...hurricane velocities..." in the intake and exhaust. They do run good for a big ol boat. Everything old is new again. I also recall reading something about Mercedes race engines having full roller bearings on the cranks. They were pressed together like hyper 2 stroke engines. Imagine that...