To prevent this from going crazy again, I will again state my request and see what people have to offer. Here's the situation:

I've just acquired a second engine that I am going to put in my lancer. Therefore, I would like to add a cam. The reason I would like information about the grinds to request, etc is that there isn't anyone in my area that knows much about /6 engines, so I can't just go to my local cam grinder and say "do a good one for a street driver".

So I'd like some specific info as to what to request. Many people have given snippets--more lift, not too much overlap, etc. I'd like to be even more specific--actual numbers I can give the grinder.

Here's what I had posted previously on for advice:
Thanks!

MJ

*&%$@# *&$##@!!!

Sorry, just kidding.

D/W

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If it ain't broke, fix it!

Hey!,,,thanks for trying again! For maximum low end torque and around town driveability with your fairly low gears I would suggest a mild cam. You may even be best off with a stock later model cam (not hydraulic). If you want something a little wilder(not much) try the Comp 252. Dart 270s idea of advancing the cam a couple to 4 degrees with an offset key set might be something to try.

A good idea for you is to replace the timing gear and chain with a double roller set from Cox Brothers. Correct cam timing is often more important than the cam itself.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Several different cams will do what you want. If you're trying to control costs, the stock '71-'80 cam is a fine choice. It has a little more duration and lift than the stock '60-'64 cam.

'60-'64 cam is 232° intake duration, 228° exhaust duration, 8° overlap and 0.375" lift.

'71-'80 cam is 244° duration (intake and exhaust), 26° overlap and around 0.414" lift.

The '71-'80 cam is overwhelmingly the most easily available...it comes right over the counter as a stock replacement item at any parts store (the '60-'64 and '65-'70 cams are all superceded to the '71-'80 unit).

If you aren't on quite such a tight budget, the MP P4120243 cam is another step up from the '71-'80 cam. It has the same duration (244° intake and exhaust), a tiny tetch more overlap (28°) and more lift (0.436"). I run this cam in my '62 Lancer w/225, 2bbl, automatic and 2.93 gears, and it runs and drives very well. Nice and torquey but doesn't run out of breath when I mash the gas on the highway. This cam is no longer available through Mopar Performance, though there are probably remaining units sprinkled throughout the country.

There is the Comp 252° cam. I've no experience with it, so I won't comment except to say that plenty of people like it.

Custom grinds: You betchya. I'm sure sooner or later someone who's played with custom grinds will speak up and tell us what he's had made and what the results were.

LOL Dennis, you kill me. Just help a new guy out here that's not sure he knows the difference between a camshaft and crankshaft!

[quote="SlantSixDan] Custom grinds: You betchya. I'm sure sooner or later someone who's played with custom grinds will speak up and tell us what he's had made and what the results were.[/quote]

I have done some of this and guess what?.... I still don't have the "perfect cam".

Sorry everyone, I have recently started a new job at a different company and have not been around much so I "came-in late".... it looks like this has become a 'hot topic'!

A couple of things to keep in mind, most custom cam grinders all work off a set of "master profiles" the have collected these over the years. The masters are basically 1/4 inch thick steel plates that look like an oversize cam lobe and it bolts to the grinding machine. The machine follows the plate and grinds that master's profile onto the camshaft.
These masters are mostly made from exsisting cams. The grinder simply mounts the "donor cam" into the machine and copies the best lobe on it, to make a new master, then regrinds all the lobes "the same" from it.

The key here is that most grinders just "have what they have" in terms of profiles they can offer, some have more then others and more importantly, a few grinders actually understand the details of the profiles they have. (more then just advertised lift and duration) In this situation, we are mostly working with "big three" designed profiles that all these grinders have basically "borrowed" in order to regrind those factory cams.

The "real" cam grinders design and make their own profiles. This is not cheap to do but that where the Ed Iskydarian (sp) "Howards" and Racer Browns of the world got their "claim to fame".

Today it is much easer to do "one-off" custom grinds because you can buy a CNC controlled cam grinding machine where you can design any cam profile you want with 3D computer modeling software and then the machine will grind that profile for you.

OK, so much for the "how it's done lesson....

We have "beat to death" the "set" profiles that are out there, these are the "off the shelf" ones listed above. These are good cams for mild street but as we know, many other engine variables will impact the final "driveability". The three main factors are: cranking cylinder pressure, (in psi) cylinder head port velocities at various lifts and overall engine volumemectric efficiency number. We want to maximize all three to the fuel quality you have.


I think we quickly see that this is not stuff that the average person is going to get their arms around so that is where the "better" cam grinders, with good computer software (and knowledge to use it correctly) come into play. The best number you can give a good cam grinder are your cylinder head flow numbers.


OK, I think most are seeing that I am not going to directly answer this question with a "magic" cam profile, because I can't, I don't know enough information about your engine combination, your car, your driving conditions, the fuel you use and your tolerance for all the "trade-offs" you have to make. ( rough idle, power band placement, lash adjustment ease and noise quality, etc.) To be honest, I have a hard enough time getting cam selection right on the "purpus built" engines I assemble.

I do know that there is a 'gap' in the current off-the-shelf cam profiles that cover a "mild performance", 9 to 1 compression (150-160 psi) mild ported head SL6. The comp 252 is pretty good but a bit on the mild side, it is not "maximized".

I have a few of my own "split pattern" street profiles that I continue to refine, I think the recent one I am ready to test will be pretty good, I will let everyone in on this once I have that engine running.

One thing I'm struggling with is that the factory used "shorter" profiles on the exhaust valves with there dual pattern cams, everything I have researched points to using more (longer) profiles on the exhaust valve / port. I think the key difference is a factory iron exhaust manifold verse D. Duals or Headers. (NOS and Supercharged engines really need more exhaust valve "open time")

One other "tidbit" when it comes to mild cams, don't get 'hung-up' on the "big lifter" .904 Mopar 'high intensity' issue, it's not needed. Face it, this is a mild cam, you need to open and close the valves in some critical places, like around TDC and BDC. If you open / close the valve real fast, around those important points in the cycle, guess what, you get a lot of full open valve time, port velocity takes a 'dive' and you no longer have a mild cam.

The biggest issue I currently see with all the SL6 cams of today is not the profile but the quality. Finding a high quality SL6 cam is getting to be a challenge. Mis-drilled oil feed holes, bent shaft / run-out, soft material, poorly hobbed drive gears, etc. A failed cam is big time bad news on a new engine. Inspect cams carefully.
DD

Doug: THANK YOU for posting this!

It's pretty much exactly what I've been after from the start.

How about cam regrinding? Is this a good way to sidestep the difficulty in finding good quality cams? What are the limitations on what can be added/taken away when starting with a stock cam?

Anyone?

I have few regrind cams and have been happy with them. No gear problems to worry about, have 30k on a 0.540" one and no troubles.

FWIW, my Aussie Slant source says that shorter exh duration really works on the Slant - dyno tested... Guess those factory guys knew something, eh?

Lou

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Home of Slant6-powered fun machines since 1988

I'll put in my two cents, since I haven't bought a commercially produced cam grind in about twenty years...

All cam grinders, including the big brand names, have a master lobe catalog.

To order any cam you want, just look thru the list, specify the intake lobe, the exhaust lobe, the lobe separation angle, the intake centerline to be ground at, and the core to grind it on.

I don't agree with Docs assesment the large lifter diameter...

This is the Holy Grail for cam selection, and allows you to approach small roller profiles without the expense. In the GM world of, 842" lifters, we are acceleration limited, this means that you can only lift the valve so fast, before the stress on the lifter to cam lobe interface becomes to great and you risk wiping out the lobe on break in, or premature wear and short life span.

The open to close duration sets the charactaristics most of the average user will notice...the rpm range of the engine, its low speed torque, idle quality, tunability.

But that is only a small part of the problem. Any cam grind can have other parameters changed, and it will alter its behaviour greatly.

Such as...assume a cam of 252 degrees duration open to close(advertised duration, .006-.020 checking height, it all depends on the cam company for this figure) but assume we have two of these same cams.

If one cam is ground at 112 degrees lobe separation, it will idle smooth, have decent but minimal low end torque to mid range(relative to the next cam in my discussion) and then have a good top end charge. (if the cam is big enough, it will tend to feel like at some rpm, the cam "come on" like hitting a nitrous button or something.

Now take this same cam, and grind it on 106 lobe sep. The same cam will now have more overlap, because the lobes are closer together. This will produce a choppy idle, poor low speed response at low load(rough engine operation at say neighborhood speeds. The tight lobe sep produces very efficient cylinder filling and scavenging at mid rpm. This will make the engine seem very powerful in the mid range, but have a short rpm band or sweet area, power will fall off rapidly above some rpm.

Now take the first cam and advance it from straight up to say four or eight degrees advanced.

This will make the idle slightly choppier in exhuast note, but typically, can be tuned to run just as smooth. It will build power at a lower rpm. Typically the same power, but a few hundred rpm lower in the range. This is because by advancing the cam, we close the intake valve early, trapping the intake charge before the piston has time to start climbing the bore rapidly...this increases "effective compression" which is effectively trapping more mixture to compress.

The next thing to consider is area under the curve. Given a certain amount of open to close duration, the lobe could be designed with more, or less, aggressve lobes, increasing the amount of lift at any point in the lift curve.

The large mopar lifter allows the use of very aggressive profiles without durability issues.

I believe that as long as you choose your open to close wisely for your application, you cannot overdue the area under the curve to the point of loosing velocity at a level which hurts performance rather than enhancing it.

All the cams discussed for your app, are small enough that any increase in lobe aggressiveness will just give more benefit and not hurt performance.

My own first cam choice for my slant which I have not used yet so can only infer from previous experience in other apps, was chosen for mild compression(8.5:1) or so...low rpm (under 5000) use. Good low end torque, broad power band(feels the same for low to high rpm, no "coming on point")

To choose this cam, I go to a spreadsheet I created that calculates the effective compression. It takes into account rod length and the resulting change to piston position at any given crankshaft degree relative to rod length.

I know from experience that the most effective compression you can typically get away with on the street in a cool running, well tuned Pontiac engine, with detonation resistance taken into account at all points in the build proccess, and pump premium assumed 91-92 octane...is...7.5-8:1.

Now for those unfamiliar with effective compression, remember that we are talking the compression from when the intake valve actually closes...which at 65 degrees or so after bottom dead center can lose you an inch or more of piston travel at the bottom of the bore. Also, even high compression engines with big cams will only show 9:1 or so effective for the same reasons...in fact, high compression with a small cam will kill your engine in know time if you don't run killer gasoline.

So I go to the spread sheet and decide that since I want to run 87 octane in my slant, I will want to shoot for 7.25:1 effective compression...

A couple things need to be mentioned...I know I don't want more than about 270 duration because i want a low rpm engine, not a high revver. And, I know I don't want more than .500 lift, because I'm on a budget for this engine and I want to use as inexpensive parts as possible.

With these "knowns", I plugged in the numbers for my actual static compression, stroke, bore size...and the spread sheet calculates the effective compression on the compression stroke in crankshaft degrees.

So I scroll the list to find 7.25 effective, and it tells me I need the cam to close at 53 ABDC. So what to do now...

Well, we go backwards thru the proccess...I want the smallest cam that will get aggressive lobe(.050 cam spec)and lift in the .450-.500 range, and an rpm range under 5000.

So this tells me about 270 is the max duration open to close and still provide the idle close to what I want and an rpm range I want...but this would be the large side of what I am after for this application.

If I take 270 and divide in two...I get 135. I know that the intake closes at 53. So the midpoint of the cam is 135 and I need to find the installed centerline for a 270 cam with 53 closing point. 180(BDC)-(135-53)=?

The cam closes at 53, so 53 degrees of the 135 is used up after BDC. So 82 degrees from BDC is where the centerline is...98 degree intake centerline...

Well this brings an interesting conundrum...I would have to install a 270 cam at 98 IC to achieve the efective compression I want...this immediatly tells me that alot of people have chose 270 or more degree hop up cams for /6, installed them at advertised straight up of probably 110 or so degrees, which would kill your effective compression and make this engine a high rpm power producer, and low rpm disappointment.

So 270 is probably too large for my app...although I could install it at 98(or have it ground there) and it would probably work fine...but I think outside of what I want and risky to try and hope it has enough low end.

So...what to do...well what about a little smaller cam...say 260.
This choice gets me just about exactly what I want. 260/2=130. 130-53=78. 180-78=102 intake centerline.

Now I know from experience that installing cams in low compression engines(one of my claims to fame is 7.8:1 455 running low 12's with a cam EVERYONE said was two big, yet it ran awesome in all conditions, and got 14 mpg at 3500rpm.) is best done with an advanced cam profile, else any cam big enough to do the job will not have low end torque. I typically install cams in engines with low comp at about 104-100 IC. I have experimented with changing the cam timing over an entire season to gain knowledge on this subject.

So, if I choose a cam within a few degrees of 260, and install it at 102 IC then I will get the effective compression I want with an rpm range that should be right about 4500-4700 for shifts, and it is small enough for good idle quality and decent low speed torque...

Now what...well now I go to the cam lobe list...typically I use Reed Cams or Crower...but in this case I went to a local shop for cheap regrind of the lame comp 252 that I already had. Lame not because it doesn't run well, just because it is not optimized at all for the large lifter of a Mopar, and could have 20hp more just by choosing different!

So looking thru his lobe list I run accross not as many grinds I like as hoped for...mostly cause his list is small compared to a large company...and...how many grinds are optimized for a nice large lifter?

So I come accross some VW grinds and find what I want. I have chosen a symetricalacrosscause I know my exhaust is great with 2.25" duals all the way and headers. So I don't feel I need the extra duration usually built into many cams(my engine picked up 1000 rpm from the change to headers), and I don't think I need less exhaust although I have been thinking that perhaps the small bore would enhance blowdown and a smaller duration exhaust might be benificial because it would lesson overlap on larger cams...but I digress. My goal is basically to find a 260 or so lobe with as much .050" duration and lift as possible...

The best lobes are 260 @.010" / 234 @ .050" / .476" lift.

So I chose this lobe, I can't specify IC because it is a regrind, and where the grind is set is based on whats there, so I will have to degree the cam and used offset keys and such to get 102 IC.

Last thing is Lobe Separation. For an Automatic I usually run around 112 in milder engines to help idle against the converter. In my higher powered cars I have settled on 110 because it seems to give the best of both worlds, with my off idle to shift point(6500 in GTO) constant power. But because the Valiant is a four speed, with short tires, cruises the freeway at 3000+ rpm, I chose 108 because of the shorter rpm band, and the four spd keeping the engine in a narrower band thru-out a pass.

So the cam that goes into my mild buildup, will be a 260 degrees open to close, with 234 degrees at .050" lift, with .476" gross(before lash) lift, ground on a 108 lobe separation, and I will install it at 102 IC. Probably 100 to add 2 degrees for initial timing chain stretch.

I have chosen cams this way since MS Excel was first released and I wrote my first macros to do the Trig for piston position. All the engines my friends and I have built using these techniques have proven to be a step above similar combos, performed exactly as calculated and expected, and always with better low speed charactaristics than were thought possible for the cam and compression choice. I even chose the roller in my GTO this way when I had 9.022:1 compression and ran 11.50's @ 118 in daily(true daily) driver trim.

There is of course...a whole book I could write on all the stuff I left out, or the 20 yrs experience that has allowed me to make use of this information...and of course... by the time I make these decisions, the cam won't go in a 200k iold used engine. The engine will be built and "scienced" out all the way thru, with every possible blue printing check done. Even with cheap parts, there is no sustitue for the time it takes to do things right the first time!

I hope this helps get you thinking, and not just scare you into leaving the car alone...the gains that can be had by little details should never be discounted...its what separates the men from the boys!!!

Gearhead aka Karl

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64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

I want more! Knowledge, that is...

Now it's getting good! Somebody point this guy to a reputable cam grinder and get some REAL slant six cams back into production for those of us who don't know our lobes from our IC.

Why even buy an aftermarket cam if it isn't optomized?

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1980 Aspen 225 super six

I should have pointed out that most all large cam companies have optimized lobes available...I shouldn't even say optimized...but designed for more aggressive lobes for situations where a small lifter guy runs a mushroom lifter(larger dia face area under lifter bore) or racing classes with lift limits(so they optimize other criteria like lobe aggresiveness etc.

I know that the Reed catalog has an entire selection of lobes just for larger diameter lifters.

Also, there are "tight lash" profiles that although pushing safety limits(acceleration of valvtrain) on a GM, would be excellent on a Mopar big lifter.

So we don't so much need grinds, as just the knowledge that you can look up the cam lobes yourself and then call and order your cam, if you ask, the guy from the cam company can tell you any issues a particular profile might cause...such as risky breakin...although none of our spring rates are enough for that from what I've read on this board.

Gearhead

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64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

hehe i'm listening, esp since I am just about likely to get a comp cams 252

I,m so confused.