Ok here is the info I've been able to piece together. It doesn't all fit well. I invite anyone who has more info to please add to this sorta knowledge. I have every piece of info from Calmini from way back in the early '90s when I had most of their catalog on my Trooper but can't find the paper on the cam. The Calmini cam is no longer avail anyway. Here is an article I used for some of these specs.http://www.off-road.com/trucks4x4/artic
If anyone has any better specs for this cam please pipe up. That includes the lash specs which if I remember are the '87 2.3 factory specs not the '88 2.6.
These delta specs came straight from the boxes of new delta regrinds for the 2.3-2.6(thanks to ssm200 for the specs on his 270 cam).
Delta 260 653-260
Duration at .050 195 degrees
I assume nominal duration start of lobe lift to end of close at 260 degrees.
Lift at valve .411
Lash int= .006 ex= .008
Delta 270 653-270
Duration at .050 212
I assume nominal duration start of lobe lift to end of close at 270 degrees.
Lift at valve .415
Lash int= .006 ex= .008
Jerry Lemond recently stated that all stock Isuzu cams had 10MM lift which equates to 0.3937". I presume this to be at the valve.
He also stated that the rocker arm ratio in the 2.6 is 1:.65. Using this info I will try to adjust the following numbers. A lot of info with cams depends on who measured what and where they measured it. These specs came from the above article except where noted.
Stock Isuzu 2.6 cam
Duration at .050 170 degrees
I assume nominal duration start of lobe lift to end of close at 248-254 max degrees.
Lift (I assume at lobe) .231 x1.65 rocker=.38115 (.381) at valve.
Lift per JLemond 10MM=0.3937 (.394) (I assume at valve)
Lobe centers 111 degrees
Lash int= .008 ex= .008
Delta tells me they measured a stock cam at
Lobe centers 109 degrees
and rocker ratio at 1.5:1
I believe there are a couple of different stock 2.6 cams. Also with many things there is a difference between advertized specs and measured specs.
Calmini 2.3-2.6 cam
Duration at .050 175 degrees
Start of lobe lift to end of close ?
Lift (I assume at lobe) .241 x1.65 rocker=.39768 (.398) at valve.
Lobe centers 108 degrees
Lash int=.006 ex=.010
These should be '87 2.3 specs anybody have them out of factory manual?
In my experience The delta 260 cam pulls strong in the low end up to and slightly through 3K above that it will spin but nothing really to be gained besides RPM. I feels like stock cam in respect to revving. It will but doesn't really want to. Much more comfortable below 4k RPM.
My experience with the Calmini cam for 200k miles (but that's been some time ago) is much like the linked article states "Once I hit 3.5K rpm, it took off like a two-stroke getting on the pipe". That's pretty much what I remember I didn't lose anything noticeable In the low end but there was a real feel of being on the sweet spot at around 3.5K all the way to redline. The numbers above vs the Delta Cams don't really reflect this. I suspect something is not 100% with the specs I've shown. Of course the numbers don't tell all ramp profiles and many other factors com into account. I suspect that Delta 270 is a screamer as well!
At this point I have:
Stock 2.6 cam
Delta 260 cam
I also have a spare head. I would love to get the time to mount each one (along with a 270) up in the head and measure them with a cam degree wheel and a dial indicator at both the lobe and the valve at recommended lash. hopefully I will be able to do this before I install the Calmini cam in Red Beans. This would be a true apples to apple comparison.
Please feel free to chime in here with your impressions of these cams that you own. Also any info you can correct or update.
Just a note after doing some reading since I put this up. The spec for centers is also called LCA this is measured in cam degrees. All other specs on a cam are in Crank degrees. Remember the crank turns twice for every time the cam turns.