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CALMINI Cam
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The CalMini cam: The CalMini cam is what I consider a relatively inexpensive mod, but it takes either some time to install or more money to have someone else do it for you. The step was taken rather blindly and on faith of CalMinis claims. I had not met or talked to anyone that had done the install so I was unsure what the results would be. For those that can't wait, jump to the Impressions section. Be sure to see the Update section as well.
The Cam: The cam came packaged with a sheet of photocopied instructions and a small container of grease. The instructions are rather simplistic and high-level, generally meant for someone who knows their way around the engine bay. After reading them, the first thing you'll probably want to do if you've never done this before is get an Isuzu factory manual to fill in all the details of R&I -ing the cam. Incidentally, I highly recommend getting an Isuzu manual. Places like Haynes makes manuals as well, but my experience with them in the past with other vehicles leads me to believe that they are not as nice as the factory manuals. They're probably adequate though if you happen to like them. The factory manuals are available from Helm Inc. The cam itself seems well-machined. The bearing surfaces were very highly polished to a mirror-like finish. The lobes themselves were machined and pretty much smooth but nothing near what the bearing surfaces were. According to Cal-Mini, the bearing surfaces are polished such because there are no cam bearings. The bearing surface rides directly on a film of oil between it and the pedestals in the head so the surface needs to be very smooth for a friction-less assembly. For the lobes, it isn't as critical because the rocker arms are very hard and highly polished. Makes sense to me I guess. This is the first cam I've installed and it's not like the lobes were rough. They were smooth but not polished like the bearing surfaces. CALMINI reports that this camshaft gives the following performance gains: Increases Performance 8-12% The stock Isuzu 4ZE1 cam profile uses 111 degree centers, .231" lift, and 170 degrees duration at .050" lift. CALMINI's cam uses 108 degree centers, .241" lift, and 175 degrees duration at .050" lift. These numbers are from the re-print of this article on the Off-road.com Isuzu pages.
Was it worth it? Would I do it again? I'd have to give a resounding "yes"! The first time I drove it after the install though, I was worried. It had a severe flat spot from idle up to 3.5K rpm. I stalled it backing out of my driveway (and it's slightly down hill). There was next to no low-end torque anymore, but once I hit 3.5K rpm, it took off like a two-stroke getting on the pipe. While the oomph was nice, I drove it to work the next day and decided that I couldn't live with it like this for daily driving much less offroad. There was still a couple things I wanted to check, mostly the ignition system (I had at the time a Jacobs Omnipak piece-o-crap) and ignition timing. My first thought was maybe the cam timing was off, but I KNEW it was on as I quadruple-checked it putting it back together and made absolutely sure it was on correctly as I didn't want to pull everything off again. I called CalMini that day to get their advice. Was this something you had to live with for the higher-rpm performance? Their catalog said the low-end torque would remain relatively un-touched. I talked to Steve at CalMini (who I later learned was the owner) and the answer was that there was definitely something wrong as the cam should not effect low-end so much. After some deliberation and questions about my install, his suggestion was to check the cam timing and ignition timing and then check back with him. I stopped on my way home that night and bought a timing light and some new plugs (figured it was time for them anyway). First thing I did was check the timing. According to the manual, timing should be checked at 900 rpm and should be 12º BTDC. Mine was at around 8º. I reset it to 13º BTDC, taking advantage of an extra degree of advance that the OmniPak is supposed to let you do. The result was phenomenal. The low-end came completely back and it ran like a charm. What's better, at the 3.5K mark, the engine still pulled hard and really climbed right up to (and past, oops!) red line. I'm not entirely sure what happened to cause the ignition timing to get screwed up. The only thing I can think of is that I may have jumped a tooth between the cam and distributor drive gear putting the new cam in. The distributor contains the Crank Angle Sensor and is used to indicate to the ECM where TDC of the pistons are so a change in the relationship between the cam and distributor (such as jumping a tooth) will put it out of whack (I think). I'm assuming that I jumped a tooth and that made a difference of about 4º in where it fired. Adjusting the distributor then put it back to where it was supposed to be. This is a guess, but I'd just make sure to set the new cam in in the exact position as the old one came out to avoid the possibility.
I've been driving with the cam for about a month now. My mileage before the swap was around 15 - 16 MPG city and 20 highway. My first tank of gas with the cam saw the mileage around town drop to a very depressing 12 MPG. After seeing that, I decided to try driving somewhat sanely again. i.e. Not flooring it from one stop light to the next. Mileage went back up to 16 and has been staying at 15 - 16 ever since. One thing to note: I live in Arizona so if my truck is running, the AC is on high. All in all, the performance increase was definitely noticeable. For about $150 bucks it was worth it too. No special tools are needed other than a timing light. A basic metric socket and wrench set should suffice. A manual, good lighting and a day or two should be all you need.
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