how to choose a cam? is there a straight answer?

[euroz06]

Hey all,

so ive been thinking about a cam for 5 years, and maybe ill pull the trigger on one. But what always stops me is the fact that there is never a clear answer on this.

So is there a way to make this simple? I have a 383 (68) that is stock, with 650 carb. I don't want a race car, just a street driver, but with a nice lope sound and low end torque. I spoke to one local shop, he started putting these insane packages for me, which involves adding intake, port polish heads, bigger carb, big cam (but then ur dealing with issue of vacume, i have 68 charger with vacume headlights).... and I'm like, is there a simpler option, but then he says yes, but its not going to be much of an upgrade for amount of work that needs to be done.

So, is there a simple cam package, where you still have daily drivability, not compromising on comfort, sounds good, and not requiring to change half the engine? I watched a ton of vids, and read some magazines about tuning 383, and I came out more confused than going in.

To add to this, this package that the local shop put together, was about $4-5k (depending on all upgrades, to include a different torque converter). And now and then I see built engines selling for about that much, so its another big item to contemplate.

And what about putting a modern hemi... at that price point, this idea comes across as well... (my engine is not original to the car, but is in good condition).

 

[4speed68rt]

Look at an Edelbrock performer package. Camshaft, lifters, valve springs, timing chain. Something like that, whatever brand it is. Summit probably has their brand in a similar, mild street, low lift, medium duration, set-up. I'm not sure about how much labor they will charge you to install it. Do it yourself...

 

[cr8crshr]

Personally, I wouldn't look at Edlebrocks offering. You need a MOPAR-specific cam provider and the best out there is Hughs Cams. At least in my opinion that is and I have only run theirs in my previous builds...cr8crshr/Bill

 

[YY1]

Short answer-

Yes*


* but it involves a fair amount of math, and has "soft" areas where "I'd like____" and I'd accept____" are used instead of hard figures.

 

[69a100]

Here we go again!
As Steve Dulcich has said many a time.
For a street engine, Keep your duration no more than 10% over stock, and your lift no more than .050" over stock, and you'll have a street machine that can run on regular gas and can use a stock converter. Good Luck

 

[68BabyBlue]

I have a close friend who had dumped considerable money into Ford projects, and has been around the block on the cam issue. He has also driven four of my GTXs with various set ups and has formed opinions based on that experience. We have both reached the same conclusions after years of driving these things on the street.

I've had two GTXs with the Hemi grind cam - a stock numbers matching Hemi car with an automatic and 3:73 rear, and a factory A33 car with a 3:54, factory four speed, and a Purple Shaft .284/.284. The Hemi car had nice street manners, in addition to all the top end they are known for. The A33 car, with an otherwise stock original 440 was a pain to drive, with no upside IMO on the top end. My Ford buddy proclaimed it was a totally sucky street car. The key was the relatively high first gear ratio with the factory four speed. Not enough low end torque.

I had the cam changed to a Comp Thumper, gained low end torque, kept the idle, all other components stayed the same. Buddy said it still wasn't great, let me drive his Ford Galaxie rat rod with motor home cam, 4 speed top loader, and 3:23 rear, I had to agree his was the better street car.

The install on the Comp Cam was about $900 out the door. I kept the original cams in all my other stock 440 GTXs, and never regretted the decision. I'll never forget meeting Herb McCandless at the Chrysler Nationals, and getting his opinion that for the street, it was pretty hard to beat what Ma Mopar installed at the factory. It's more than just the cam - it has to work in combination with numerous other components.

So there isn't a simple answer, how much you want to spend has a lot to do with it. I'm an old guy who drove the cars new, so I'm less enthusiastic about modifications than many others on this site.

 

[4speed68rt]

When you ask a shop for something that you aren't knowlegble about, they probably try to think of all of the things that you will complain about, and try to cover all the bases, then charge you enough to have to re-do the job if necessary, to make you happy. It doesn't have to be that complicated, just bring them the cam and components you want, and get it installed. Don't make them decide what you want...

 

[Black_Sheep]

The most well mannered “fun” vehicle I have is my 454 powered ‘58 Apache with an RV cam. It idles smoothly and makes a ton of torque from off idle to around 4500 rpm, right where you need it. Engine vacuum is strong so the power brakes work well and I was able to keep the stock converter. Drivability is excellent…

 

[HawkRod]

So I'm going to go out on a limb and and NOT talk about a cam. I suspect you want a little more pizazz out of the car.

One of the greatest single things you can do to any combination is have the distributor recurved to give better advance and make the engine more rippy. Do this, in combination with a truly well tuned carburetor, and you can make the exact same car behave totally different.

Start with the basics. Everyone wants to go immediately to cams, intakes, heads, whatever, but often times overlook the simple aspects of proper "speed tuning" for the street. Make sure you car is tuned right before you go to the next step.

 

[beanhead]

If you want the best match, and aren't sure what all the numbers mean and how they affect each other and your combo as a whole the best bet is to talk to a pro...tell them all the details they want to know and let them guide the choice.
These guys are as good as you'll find IMO when it comes to Mopar engines---
Dwayne Porter/Porter Racing Heads
Mike Jones/Jones Cams
Tim @ Bullet Cams
The Racer Brown guy (Jim?)
Bob Karakashian/aka Mr. Six-Pack

 

[Don Frelier]

I think we need more background information.

Questions:

1. Is it the original 1968 engine, never been apart or modified?

2. How many miles on it?

3. Have you done a compression test? If so numbers?

If it is the original untouched engine they can run smooth and drive fine, BUT they get tired.
The timing chain stretches the valves sink a bit and the ring seal is not what it used to be.

Depending on ring seal (if it's good) you could pull the heads and have them redone (springs checked) put a new timing chain on what you have.
Degree in the cam (advance it some) tune it and it might surprise you for a couple hundred in parts and a bill from the machinist to rework the heads with the cam that's in it.

 

[Triplegreen500]

Cams are a tradeoff. You have to decide what characteristics you want out of the engine, which you can tolerate, and which you canNOT tolerate no matter what. They also determine where the power is - low? Midrange? Top end? That comes down to your car, your gearing, and your driving style. Ask yourself what you want to accomplish - sounds like you want a lope (you can do that by turning down your idle speed, for free - just keep an eye on oil pressure!), and low end torque. Look at how you drive - do you typically limit your revs to 3k? 4k? 5? Where do you spend most of your time - 2-3k? 3-4? Used to be (not sure if this is still the case), cams would advertise their powerband in the specs. That, or you can ask the manufacturer. Most - if you can get someone on the line - will be able to give you an idea of what results you'll see with your specific package.

I used to run a MP 360/380 crate motor in my Satellite wagon. I forget the compression, but it was a single plane intake and the cam was 288/292 with .513" lift - it LOPED, but in that big heavy street car it did fine on the street. I had power brakes...once, at a stop. Release and try to use them again, and I'd have to find neutral, rev it, and build some more vacuum to stop again. 2,400 stall converter 727 with a reverse/manual valve body, and a 3.23 suregrip and it was great on the street, and surprising on the track (mid-high 13s at over 100 in a stock steel body wagon with full interior and all glass, on street tires). It was more a mid-high rpm setup between the cam specs and the single plane intake, but it wasn't "flat" down low by any stretch. Pulled like a locomotive all the way to where I set the 6AL's rev limit at 6k. Ran it that way for close to a decade.

You just have to decide what you want. And, as mentioned above - you may be able to attain your goals without having to do major surgery like installing a cam. And most times, you won't get the full benefits of a cam without other breathing modifications - intake, exhaust, carb, and possibly (depending on the magnitude of the change) fuel.

 

[euroz06]

So more details:
i have Auto 727, 3:55 posi (489 case), 3 inch headers, electrical cut outs, MSD electrical. Currently, the engine runs out of breath at 4k rpm. It starts smoothly, runs very smooth. I have about 7-8k miles on the car, after restoration. I believe the engine was refreshed at that time (it looks great/clean). I think its tuned for street, it always starts with half a turn (if it didn't sit for a week lol). I like in Miami, and it runs very cool and very nice, I've never had it overheat in traffic.

When i open my cutouts, at idle it sounds dope, even better when I have the AC on... however, once i start driving, it sounds like a boat/motorcycle. I would like to have better sound with cutouts closed AND with cutouts open. Also, I used to have 255/50/17 tires in the rear (that were older), and i was able to spin them on take-off (nothing crazy, but was able to get it to spin them). Now I've upgraded to 285/40/17 Nitto nt555's, and I can't spin them I'm sure if i hold my brake to the floor and floor it, i could brake them loose, but id like to be able to light them up off the line if needed.

 

[Budnicks]

In a word IMHFO NO,
it's not just a straightforward answer
it's far more complicated than that...
If you want it done correctly, not run into problems later...

Here's a lil' stuff to chew on
I know some here will say;
"it's going overboard or too much info"
or to dumb it down
Well I disagree, I don't do that...
I didn't like it when it was tried on me "way back when",
when I didn't know **** either... almost 50 years ago
IMO you will never have too much good info,
to decide what's right, for your specific build/engine choices etc.
Mostly no question is a bad question when 1st learning...
Now,
I may not answer them, I may ignore you or the thread
& leave it to someone else...
But don't be afraid to ask...
Usually, someone here will answer it...

you need a camshaft that matches
many other parts to/of the car
& what your intended end use ?, "actually is",
what you can tolerate, not some pie-in-the-sky "what if's"

since you don't have that knowledge
you will be dependent
on a trustworthy & honest &/or probably a skilled tech to lead you thru such a deal

adequate cooling system, is needed
you will be creating more heat now,
added HP is a function of 'the creation of heat'/more BTUs
(sort of, long explanation)
make sure it clear of all rust & old antifreeze, a good flush would be in order

what is the actual compression,
cylinder bore size "stock bore" is 4.250"
on a stock 383 that hasn't been bored
other common bore/piston sizes
0.010" over 4.260"
0.030" over 4.280"
0.040" over 4.290"
0.060" over 4.310"
383cid "stock stroke" is 3.38"
bore in inches x bore x stroke x 8 x .7854 = cids
(stroke to can/will effect compression, longer stroke more compression)
*** also some other determining factors are as followed;
how much down in the bore the, pistons are at TDC & the bore size
combined with combustion chamber size
(stock 906 heads are like 88-96ccs)
& head gasket thickness stock is a steel shim at 0.020"
most aftermarket head-gaskets like FelPro permatorque
are 0.039" torqued down
is all needed to make an accurate compression estimate
or a dome etc. sticking up
*** you can also use a compression tester,
it'll get you in the ballpark
(or leak-down tester, to see if the engine ring or valve seal is good)

if you haven't already fallen asleep after all that
we are just getting started

The actual amount of true piston-to-valve clearances
intake valve to piston coming up on TDC
that clearance is usually the biggest issues
(caution; Generally, on a stock 383/440 most OE iron heads (like the 906s)
some will need to have the top of the valve guides machined down
& many will change too a different style or valve seal while you're at it
or it will/could have interference with the base of the valve spring retainers
or keepers/locks, it's about a max gross valve lift of 0.510"-0.520"-ish
depending on manufacturing differences/tolerances,
the gross valve lift = camshaft lift x rocker ratios,
before running into serious problems in the 68-70 906 heads)

Gears
depending on duration, much lower gears could be required

Converter
again depending on duration, much more gear & converter, may be required
the converter is a very important part of the combo
especially with a "more aggressive" camshaft change

or a better clutch for a manual

Intake/induction, stock or alum. aftermarket
hood clearance (?),
a K&N or Moroso drop base air cleaner may cure that issue
an Edelbrock Performer RPM is a great alum. dual plane street manifold
make great power too, from just off idle, 1,500 to about 6,200rpm/wide RPM range

Exhaust,
something in the 2-1/4" - 2-1/2" duals out the back range
don't skimp on mufflers
use with an H or X pipe about after where the trans-cross member is located
Headers ?
1-3/4" to 1-7/8" tube size for a 383 is more than plenty,
with 3" or 3-1/2" collectors
(could be a necessity depending on build/style selections & choice)
they will certainly help it breathe
"much better, maybe 10% flow across the board"
also about the same amount of, 10% more HP/TQ #s too...

the engine is just a huge air pump
what goes in
must be able to come out freely

Cylinder heads, stock or aftermarket/alum or cast iron
& what mods/machining need to be performed to have "said camshaft"
valve springs, valves, rockers, push-rods (needed for that specific camshaft)

Carburation (size & style/brand) a 750cfm (or 770cfm-780cfm vacuum) is plenty
(I prefer Holley style carbs, or the new Street Demon 3 bbl, looks damn good
I'm personally not a huge fan of the Edelbrock/Webber 'Carter AFB or AVS 'knockoff carbs'
some people here/MoPar land, really love them... I'm not one of them people)
a 650cfm is probably plenty, but nothing wrong with a lil' bigger
as long as it's jetted & set up correctly,
air restriction (too small of a carb) can be a huge HP killer
& IMO for mainly street driving, a vacuum secondary with an electric choke
is all you'd probably need...

Fuel pump could be another consideration,
a good quality Mechanical fuel pump is usually adequate
the fuel pump rod material too, dependending on what style of camshaft
is chosen *** a billet or roller will need a special bronze tipped rod...

or EFI (a bit more expensive & a bit more technical too)
I won't go into that here, that'd take 2 pages alone

Good hot Ignition "system",
to help burn all that extra fuel you'll be adding
(like mentioned above)
an advanced curve, with lighter springs inside the distributor,
to have the mechanical advance come in quicker
for street use a vacuum advance pot is good
(you may want to look into an advance' limiter disc, from FBO @ 4secondsflat.com)
*** or even a different material on the cam gear, on the oil pump drive,
that gear material depends on what type of camshaft/materials chosen
a billet like hydraulic roller or solid roller, with require a special bronzed gear

A nice hot spark
a good hot coil & low ohm resistance plug & coil wires

Timing chain & gear set
a nice double roller, timing chain & gear set,
with multiple settings adv. or retard on the crank gear,
so it can be advanced or retarded as the build style requires
(I advised to degree the camshaft in too, but many people at your level
don't or won't)

finally the camshaft
for a reg. driver 'stop light to stop light' street warrior
I'd suggest something within these ranges
*** 274*-ish to about 284*s of advertised duration
(much more than that level of duration, the vacuum will suffer,
power brakes would need a pump, AC would be out)
will wake it up a tone, still give it a tumping idle,
that bucket tee, bucket tee, bucket tee, bucket tee
sound at like 950rpm idle
stock OE HP 1968-70 383-440 cam
is in the 264* - 268* advertised duration range
at about 0.464"-0.468" range/gross valve lift hydraulic flat tappet...
Something in the *** 0.484" gross valve lift
(with a 1.5:1, a true stock stamped steel (is more like 1.48:1) rocker ratio)
to maybe on the more aggressive side of
*** 0.510"- 0.520"-ish (with a real 1.5:1 rockers) gross valve lift range
still be very street-able, much more than that will require specialty,
rockers, pushrod, shafts etc.
*** it will really wake it up, sound really good too
you could go with a split duration intake & exhaust, will have different lift & duration
usually more lift & duration on the exhaust...


*** Cylinder heads continued;
This may piss of some people, or purists, but it's reality/truth...
"deal with it"
The org. production heads on a BBM 'are a serious choke point'
(aside from the org. Max Wedge heads or 426 Hemi,
but we aren't talking about either of them)
In reality, it's been said;
To be like like having a 'small-block Chevy head' (very simular design & size ports)
on a big block Chrysler, with a much bigger bore...
they need more port volume, then they can make "more serious" power...

(It's; why the 'max wedge' head had was org. designed, & why the new alum. heads
that flow so much better like 40cfm - 50+cfm better than best 'stock cast iron heads',
right out of the box, they flow better than many mildly ported 'cast iron heads' too...
And with many of the new heads, with bigger valves too, in many cases they are
"so much better too", much better port design, even in the 'std size port' opening...
Also most alum. heads run cooler generally too, it will dissipate heat quicker,
*** be carefull on a 4.25" bore too big of an intake valve, over a 2.14"
will generally require some grinding at the very top of the cylinders
(use a head gasket for a template) to unshroud the intake valves,
*** that area that flow around them, at wide open intake lift,
will be blocked some otherwise...
*** 400s with the bigger 4.350" bore or the 440s with a 4.32" bore or bigger
aren't a problem generally)

Also
*** make sure to soak the lifters in 'break in oil', for at least a few hrs,
overnight pref.
*** make sure you use a break in oil with zinc added
when it starts up the 1st time
*** do not let it idle very long at all after the 1st start up,
it needs to be ran
at like 2,500 rpm at like 15 min.'s, to break it in properly,
or it can/will go flat
keep it outside & a hose handy to refill the radiator after it's purged the bubbles
or thermostat has opened, or it could get really hot...


after all the rest of the considerations
it may dictate what is needed above
that may help or just confuse you even more,
you asked
not every aspect was even covered,
but it gives some good detailed info to help decide
maybe, even sound a tad bit more knowledgeable
when on the phone, when they ask you for specs of your build
it will also help educate you, on what's involved in a camshaft change

I hope some of that helps,
you make a good informed decission
on what cam & the mods required

Good luck