3.0 roller cam LSA

[87turbodance]

I was looking at my stock 2000 3.0 cams and my Diamente cams and I noticed that the front cams appears to have a much wider lobe separation angle then the rear cams on both sets. Here's a couple pictures. Perhaps this is why the front bank typically is much more varnished than the rear bank.




---------- Post added at 10:55 AM ---------- Previous post was at 10:53 AM ----------

My slider cams appear to have the same LSA for the front and rear cams

[Force Fed Mopar]

IIRC the front and rear cams are different, to balance out the engine somehow. I think due to exhaust restriction?

[87turbodance]

There is definitely a lot more overlap on the rear cam with the roller cams! Slider cams have the same profile for front and rear bank. I always thought that it was only the 24V motors that had different LSA on the front and rear cams to give a broader power band. It looks like the 3.0 12V also has this as well.

Or am I looking at this wrong? I would have thought that someone else would have pointed this out by now.

[RoadWarrior222]

Oddness, maybe the crossover pipe sucks harder and evacuates the front bank better... (Due to exhaust gas momentum)

Though the varnish I would attribute to the fresh air coming in the back valve cover and all the PCV fumes going out the front valve cover.

[Ondonti]

Well I don't like this finding. Its certainly not based on the front having a better exhaust manifold :P

I don't really know how much effect this has because the pistons seem to pop fairly evenly side to side. I would say the rear pistons are more prone to breaking a ringland with OEM gaps. I only broke rear bank pistons the 2nd time I messed with a bone stock gap motor with too much boost. First time all blew up except one front piston (but they blew on separate occasions). Might mean nothing. More overlap should mean more reversion, meaning more inert gas in the cylinders, meaning lower combustion temperatures and pressures....

I believe the slider cams have a lot less meat on them...I can't remember what I had measured before on them.
I would like a balanced set of cams with the next set I have made.

[87turbodance]

I'm assuming this is why RPW made billet cam blanks. If we had matching cams I think we'd be able to produce significantly more horsepower albeit with a peakier power curve. I'm going to measure my slider cams and my roller cams and post the numbers next week.

Anyone know if it is possible to re-grind the sliders to a roller profile and then get the lobe tips heat treated after?

[RoadWarrior222]

BBQ them? To heat treat. Like for input shafts.

[87turbodance]

I don't think a bbq will get hot enough. I was reading about heating the lobe tips with a oxy / acetylene and then covering the cams in crush BBQ charcoal to case harden them. Anyone with experience with this?

[RoadWarrior222]

Well in that case, pick a kettle BBQ off the curb, put a ductwork elbow in the bottom, with a grille over it, over load the thing with charcoal, fire it up, pack the cam in the coals then blow a leafblower in the bottom.

[Ondonti]

(I have noticed this before but I never thought about the consequences) This sorta makes all the cam #'s lies.....

I don't know if the slider cam has enough meat to get anything out of it. The short side of the slider cam is much longer then the roller and I believe the measurements are much smaller.

My wonder is about how close you can get the roller LSA when you do a deep regrind...
Posting up ALL the pictures I took of my cams back in March 2006. Looks like he fixed up the LSA as much as he could. Since its a turbo cam I think he wanted to get that overlap as consistent as possible.

These were Diamante cams. I went with Diamantes because I assumed they had a little more meat to work with. Sorry, I really don't have time to set up my degree kit to measure. Maybe later this year. This is a great topic to converse about and keep going.
I have some more cams in storage somewhere but I have been failing to find a lot of things after moving back to Seattle. I might have throw away one of my slider cams, the other is still in its head. They are junk anyways.

[87turbodance]

Looks like the LSA is pretty close on both of those cams. I would really like to put together as much info as we can on all the different flavours of stock cams so we can find out which is the best for different applications and which one is the best to use for a regrind. I'm going to take some measurements of my slider cams and my 2000 van roller cams when I get a chance and post them up.

I remember reading that the roller rockers are 1.6:1, are the slider rockers the same ratio as well? They look to be very similar.

[RoadWarrior222]

There was some small change in official power or torque numbers in the last couple of years, so the 2000 van cams would be interesting. Though it may just have been the programming, or other component change.

I have 88 sliders (in running motor) and 92 rollers (in spare motor) to decide between for the all out N/A build...

I've heard it said though, for "well run in slider cams" 60,000 miles or so, they get surface hardened and you can use them with rollers. Not with a fresh grind though.

[Ondonti]

Looks like the LSA is pretty close on both of those cams. I would really like to put together as much info as we can on all the different flavours of stock cams so we can find out which is the best for different applications and which one is the best to use for a regrind. I'm going to take some measurements of my slider cams and my 2000 van roller cams when I get a chance and post them up.

I remember reading that the roller rockers are 1.6:1, are the slider rockers the same ratio as well? They look to be very similar.

All the info is on boosted mopar. I believe the sliders are only 1.38 (I am the one who did the math, its documented there, not my head) and the cam also has less lift by itself. Sliders are TINY.

I would love a lot of information on this subject. I need a new regrind for the Duster and I want that primo starting point. My cam grinder treats the surface of the lobe. You can see the discoloration in the shaft from treating each lobe.

The year of the cam is going to need to be carefully documented so no bad information is created as we move forward. I know its hard to go back in time for the info. I have a 1997 set of heads in the shed, a set of 1994 rollers, and then 2 sets of 1992 diamantes (should be 1992). Then a slider set (with one possibly disposed of). I hope I can tell the 1994 and 1 set of diamante apart.
Never seen anyone break down the coding on them.

[87turbodance]

Well, I'm going to do some measurements on my '89 slider cams and my 2000 roller cams this week or next. I have "?Diamante?" roller cams in my car now that I started for the first time since the heads and cam swap this afternoon. The Diamante cams I have I got from KnightMoves91 who got them from Jory so I don't have any first hand knowledge about where they actually came from. I compared my Diamante cams to my 2000 van rollers and they appears identical with simple measurements with a vernier and carefully "eye balling" them beside my 2000 rollers. I'll throw a slider cam in my scrap slider heads and measure the rocker ratio again to double check your measurements. Looking at the sliders, they appear to have less lift then the rollers but without the split LSA between the front and rear cams.

When I do get re-ground cams I'm thinking about getting a deep re-grind on the sliders and then getting the lobes heat treated. I'm really not sure what the best route is.

Have you ever had a chance to measure a 3Si 12v cam set?

[Ondonti]

3/S are the same. Only different real cam is the montero, and its "weaker" based on supposed shop manual type numbers. More torque, less power. Diamantes are just supposed to have a tiny bit more duration, nothing that would be measurable with caliper.

I was looking at my regrinds in the Mechanical heads when inspecting the squeaking valve stem issue (which I have decided is actually just one of the rockers polishing the retainer because I didn't grind it down enough) and it seems I still have plenty of meat left to grind away, and grinding deeper would help lift the rockers a bit higher off the stem so I could use some of the adjustment.
Thinking about maybe even grinding all the way down to the shaft level on the lobes. Not sure what the downside of that is, or why cam lobes are a certain size.....to spread the wear?
You can still see the machine marks on my regrind lobe peaks and they have about 5k miles on them so I would not worry about longevity if your cam guy treats the lobes. The mechanical roller is narrower so it will also wear a smaller contact patch (not a good thing but I don't think it matters!). I think I remember that the base circle on the slider cam looked really small, I think its actually smaller because I found that the longer short side slider rocker would need more clearance, and it also seemed apparent that the rocker shaft is located higher in the slider head for the same reason. Those heads required basically no grinding on mechanical rockers to get them to fit even with non reground slider cam.

Not sure how hard slider cams are to find these days.........might be something we all need to start collecting. I don't have much time for the junkyard these days.
BTW, in the pictures posted in the first post, the base circles are either very different, or the shaft thickness is much less in one of the cam sets.....