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2.6 cam specs table!

101K views 79 replies 29 participants last post by  NCEvets 
#1 ·
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 ... ?id=194422
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
Per Jlemond>
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
Lift .345
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
Calmini 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.
 
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#2 ·
I bought my cam from Independent 4X and they must only sell the 260 because nothing was mentioned of a choice. Thats probaly a good thing I would have just been confused any way.The cam does just what it is said to do, it does increase the power at the lowerend up thru the mid range. But much past 3500-3800 and it flattens out.My 2.6 has a Calmini header and a reconfigured ECM(Jet Performance). The one thing that I wasn't happy about was fuel milage offroad (14-16 down to 12-14). Just a side note I keep reading posts about cam timing with people saying not to use the balance pulley to set the cam because it may have slipped. Isn't that impossible to do becuase you have to have everything back together befor there is a mark for TDC? It may effect Ign. timing but not cam timing unless I missing something. Dave
 
#3 ·
outofrshell said:
I bought my cam from Independent 4X and they must only sell the 260 because nothing was mentioned of a choice. Thats probaly a good thing I would have just been confused any way.The cam does just what it is said to do, it does increase the power at the lowerend up thru the mid range. But much past 3500-3800 and it flattens out.My 2.6 has a Calmini header and a reconfigured ECM(Jet Performance). The one thing that I wasn't happy about was fuel milage offroad (14-16 down to 12-14). Just a side note I keep reading posts about cam timing with people saying not to use the balance pulley to set the cam because it may have slipped. Isn't that impossible to do becuase you have to have everything back together befor there is a mark for TDC? It may effect Ign. timing but not cam timing unless I missing something. Dave
A slipped balancer (& therefore a slipped timing mark) does affect ign timing not cam timing, however it can make a diff. Its all related so if the spark happens @ the wrong point in compression you are just losing power. This can happen on either side of TDC:

Too far Before TDC - The piston has to fight not only the increasing pressure from the compression stroke, but also the ignited fuel/air charge that is now expanding as it burns.
_This will make the engine more prone to stalling @ low RPM/High load (trying to idle over an obstacle or up a steep hill, or letting out the clutch too fast without enough gas pedal to back it up), but it will improve top end performance as the 'accidentally advanced timing' is just doing what the ECU would do @ high RPM, which is begin the burn Before TDC of the compression stroke to ensure that all the fuel/air charge is done burning by the end of the power stroke.

Too far After TDC - Some of the ignited fuel/air charge is still burning when the exhaust valve begins to open.
_This will likely make the bottom end a bit more snappy as the compression stroke is complete before the burn begins, however the top end of the RPM range will suffer because even though the ECU is trying to advance timing for the higher RPM it can't fully compensate for the 'accidentally retarded timing' so burning fuel pours into the exhaust header.

Either way will still run, just weaker then it should be, maybe hard to get a solid idle AND decent road performance.

~psguardian
 
#4 ·
Very good explanation kinda refreshes it for those of us who are forgetting more than what we thought we knew back then. A simple way to check balancer is just make sure everything lines up with keyway on crank might not be 100% but does indicate a problem if its off a little. Another thing is use a mirror to line mark on crank gear to mark on block it makes it much eisier to get it dead on. Dave
 
#6 ·
what are the mileage & power characteristic differences between;
stock / 260 / 270 / 3tech - that would work out to what? 275? 280?
What tires & gears are you running? (its time to buy head parts can you tell? :lol: )

~psguardian
 
#7 ·
I can't tell you how the 3tech cam is yet, as I'm in the process of putting the motor back together. I am also throwing a garrett turbo on it and installing a megasquirt ecm in it. Other than that the trooper is completely stock. I hope to finish it by the end of this summer, and will take some pics and report on how the finished results are.
 
#8 ·
yenkoz28 said:
I can't tell you how the 3tech cam is yet, as I'm in the process of putting the motor back together. I am also throwing a garrett turbo on it and installing a megasquirt ecm in it. Other than that the trooper is completely stock. I hope to finish it by the end of this summer, and will take some pics and report on how the finished results are.
That should be fun, punching it up to 10:1 or higher? I don't think you will count in my normal comparison lol. but will be a nice build to see.

~psguardian
 
#10 ·
yenkoz28 said:
No I will be keeping the stock 8.3:1 compression ratio as this is ideal for a boosted application.
No I mean boost included. :) Under full boost what will the compression be?

~psguardian
 
#12 ·
Delta 270 cam

I recently rebuilt my 2.6 and put a delta 270 cam in it. now, all evaluations must assume that the motor is running stronger as it has been rebuilt. so take that into consideration.

Low end torque doesn't seem to suffer. it drives just like it did before with gentle driving. but when you need to wind out a gear, it really comes alive. The stock plateau-ed power band is gone and now it drives more like a car, with power increasing steadily as RPMs increase. I don't have a tach, so i cannot be specific as to where it really comes alive. if i had to guess, I would say around 2,500 RPMs. it is a LOT faster now. It revs faster than before. not like my suzuki sportbike, but you get the idea. I would HIGHLY recommend this cam to people who do mainly on road driving. Before, it seemed like there was no point in winding out a gear, but now, there is all kinds of power to be had up high.

This is not the cam for people who really value their truck's off road, low speed capabilities. While the low end torque generated does not seem to be affected, it must be noted that there are NO gains in the low to low-mid department.

I do have to let my truck warm up a little longer, but this is the only driveability drawback i have encountered.

Steve
 
#13 ·
Calmini cam and exhaust system
I have been using the calmini cam for a couple of years now. The lash adjustment specs are .006 in .010 exhaust.

One of the things that I have noticed about using this cam is that it pairs very well with the calmini headers and 2.25" exhaust. Not only did the mid range power improve tremendously. The power seems to come on really strong like a 2 strokes power band around 1800 to 2200 rpm which makes the truck instantly feel very light and nimble and the power band doesn't give up until my foot or wallet does. It reves way higher then the stock cam ever did and the engine doesn't have that "I'm shaking apart" feeling/sound above 3,500 rpm's with this cam. The performance isn't quite as noticable when paired with the auto tranny but shines like a pretty penny with the perfect gearing of the mua5 trans.

The biggest things I like about this cam is that there is no negative effects using this cam at all that I can tell. the low rpm torque is good and cold weather start up and driving before the engine warms up doesn't make a difference in the way it runs.

I'm suffering an injector problem right now that is effecting my short trip gas mileage but on the open highway I'm happy to report 20 mpg even with kc lites on the roof and 31x10.50's. I would recomond it to anyone that can still find one. It would be worth getting 100 buyers together to get calmini to make another run of them. :D
 
#14 ·
Rollins that's a pretty good description of the way I remember my old one. Calmini in my 1st trooper. I've always run 32s and with stock gearing had to be over 65mph indicated to get in the sweet spot of the cam in top gear. I hope to get the one I've got now installed this spring. It should work great with the 4:77s and 32s. I was up in some steep mountains today in PA and really miss being able to wrap up 3rd gear at highway speeds. The 260 will rev but doesn't want to and isn't providing any oomph up in the rev range. It won't accelerate up the real steeps in 4th.

You are correct about the exhaust. I installed my 1st calmini with the stock exhaust. It helped. 6 months later I added the header and exhaust and that really woke the engine up. Providing the above specs are correct that would make sense. I did some reading about Lobe Center Angle when compiling the above. The article said that decreasing the LCA could actually help the cylinder filling but tended to make an engine more affected by back pressure. As in the exhaust needs to be just right for the particular camshaft to make it really perform. This pretty much proved itself on my 1st truck. Took 3 tries to get the exhaust right.
1st try was 2.5 from collector back with high flow cat and straight throw muffler+revved like a sport bike and huge loss of low end torque and loud!
2nd try was to add a second muffler(SS glasspack) after the muffler to quiet it down=A step in the right direction but still loud and low torque.
3rd try changed to a custom reverse flow muffler 2.5in 2.25 out= Bingo much quieter, still revved like crazy but got all my low end torque back as well. With a header and big pipe the exhaust cools pretty quick which makes it contract so you don't need the big pipe behind the muffler. Too big of a pipe actually slows down the exhaust so much you lose the scavenging effect of the headers. This was all done in SS. Expensive experiment.
 
#15 ·
:) UP!

Hello,

FYI I have degreeing a 88' 2.6 cam into my 2.3 head and it was:

IO 22º ATDC
IC 76º BBDC
EO 58º BBDC
EC 16º ATDC

with

INTAKE LASH .006
EXHAUST LASH .010

i got

INTAKE DURATION 278º
EXHAUST DUR. 254º (decreasing lash it would increase )
LSA 114º (decreasing lash it probably be modifyed a little)
OVERLAP 38º (decreasing lash it would increase)
INTAKE LIFT .381

It could there be some minor error, but I get a surprisingly long intake duration and closing, more than claimed for performance cams.
I´ve just finalized a massive shaving, porting and valve job in my 4ZD1 head. I had good results, but I still need fine tuning and working in the exhaust system and probably a better cam (more lift and less duration), if it doesn´t need pull the head out again... :?

cheers

pat
 
#16 ·
where are you measuring your duration. most cams measure duration at 50% of lift. As in from 1/2 way up the ramp till 1/2 way down the other side. That shortens it up considerably if you are measureing from the beginning of the ramp til the end.
 
#17 ·
squatch said:
where are you measuring your duration. most cams measure duration at 50% of lift. As in from 1/2 way up the ramp till 1/2 way down the other side. That shortens it up considerably if you are measureing from the beginning of the ramp til the end.
I thought duration was measured from 0.050" lift ->max lift -> back to 0.050" ?

~psguardian
 
#18 ·
Yes, I´ve measured over timing pulley, and seat-to-seat timing, multiplying by 2 to convert in crank degrees.
See ie. the mark where I´ve found intake closing, in the wheel shows ~128 after TDC or 38 BDC, that is 76 crank degrees.


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I have a repair manual of trooper 2.3 (believing it is the same cam) and it says 21-65- 55- 20 for the real timing events.
But I am realizing now that the advertised timing in reality should be measured at HOT clearance... :?. So I should do a new experiment...
 
#19 ·
Advertized timing is just that. There are so many variables and ways to measure a cam it's hard to get apples to apples comparisons. Manufacturers advertize what they are trying to sell in a way they think will sell. I like your degree wheel. If I can get my hands on one and a dial indicator I may try to do an apples to apples. I have in hand a stock '88 2.6 cam. delta 260, Calmini cam.
 
#20 ·
Any trick to ordering the 270 from Delta?
 
#22 ·
260* Delta cam

Before and after on my 89 RS Trooper 4.77 gears and 33" tires: Calmini header > 2.25 exhaust pipe > turbo muffler.

With the 260* Delta nearly the same below 2000 rpms. Noticeable improvement 2500 thru 5000 rpms. Stock cam was dead above 5000, the 260* Delta is better but falls off by 5500 rpms. Which is fine with me, I rarely rev over 5k rpms.
 
#23 ·
To me the Delta 260 feels like a strong stock cam. A little more torque at the bottom but it's got no more to give at 3k rpm. Still doesn't like to rev any more than the stocker. You'll get more power but don't expect it to feel like you made huge changes to the engine. I'll let you know my NEW impression of the Calmini in a few weeks with luck. I ran one for years and it is a noticable difference. Especially from 3k up. But that was a while back. I have been lucky enough to get my hands on one and it should be in the Trooper before Hallowwharrie if all goes well.

Does anyone in my area have a degreeing kit? If so I would like to do a comparison of the 260 that's in my truck and the Calmini. I could probably do the stocker as well. I have all 3. That way we could do an apples to apples measurement on them in my trucks while I'm changing cams. I just can't justify dropping the $100+ bucks for the kit right now just to do this.
 
#24 ·
Her I come back again...!

Squatch you can make your wheel printing this picture. I didn´t do still the new experiment... :roll:
http://www.escortfocus.com/Degree_Wheel.jpg

I believe my cylinder head mods still need some help at road speeds.

I was thinking in ordering a cam from US and Delta guys haven´t answered my e-mails. But no problem now, I already know that indy4x sell it as well.
Only I have the following questions... Which one would be better, 260 or 270 for 2.3 engine? (to be used 70% on road). Would I need to change valve springs to install it...?

Thanks
Patricio
 
#25 ·
Thanks, I hadn't thought of printing one off. I still need the dial indicator and such though.

No you won't need to change valve springs. Neither of those cams is too radical. I do like using the elephants foot valve adjusters to take up the slack of the cam regringing process.
This is just one example of what they are. http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0588617028

As far as which one is better I'll leave that up to you. Most buy the 260 for torque down low. Only one person here I know of has the 270. Only you can decide what you want or like. It's like going to a Corvette Rally and talking cams. Ask 100 people and you will get 100 different answers for which is the best for that engine.
 
#26 ·
BUMP

What's the word squatch? Ever degree those cams for side by side proof? I just managed to save a calmini cam from the scrap pile so I'll be joining you in the world of rare cams.

Also if you need a pointer for the degree wheel wrap a chunk of coat hanger or stiff copper wire around any random bolt and bend it into position. 0* the crank & just spin the degree wheel until 0* lines up with your home made pointer.

~psguardian
 
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