I have learned a hard lesson these last 4 months.......as many of you all know my car runs poorly......missing like 100hp.

The culprit: It wasn't the tuning, it wasn't fuel, it was the opti, but it was not entirely the opti fault!!!

After noticing that a few header primaries were burning the JETHOT coating right off, I immediately thought it was my opti that was causing my overly rich conditions.

I was shocked at what I found....
1.) The opti electrical harness had 3 stripped wires at the opti connector. Cost me $118 from dealer.

2.) Ordered new opti from Jason Cromer $189 + $40 1 day shipping.

As I took off the 3 bolts that hold the opti in place I was shocked at how much slack there was between the opti and timing cover. There is at least 2 centimeters between the timing cover and the opti and I immediately thought the dowel pin was too long and it sure was.

Now I have to grind it down with my air grinder. The old opti was not sitting flat against the timing cover and was actually forced flat on with the bolts. The extra pressure created by the cam dowel basically ruined the bearings on the opti. I was so pissed my engine builder overlooked that critical step. I called them and they offered to fix it, but I said forget it I will do things myself. ** At this point I just about had it!!! **

So the lesson is.
1.) Always check the dowel length on any cam not made by GM. Supposely Comp Cams leaves that job to you. I have a Comp Cam Extreme 230/236 by the way.

2.) Always check the physical things first. I burned/stripped harness wires.

Thanks for listening, I had to vent. At least now, I am 99.9% sure this was my problem.

 

Hehe, so you bought a '95-'97 long dowl pin cam for a '93-'94 car? FYI, LT1 engines use two different dowl pin lengths... the '95+ cam has a dowel pin that's about twice as long! Like you said, the longer pin can be trimmed down to make it work in the '93-'94 cars... too bad your machine shop didn't catch that..

 

You are correct about the cam dowel lengths specific to different model years but that was not the case in my situation. I was very aware of this before I ever even first tore down my car.

Everything I purchased was for a 95' F-body in mind. My car is a 93. I puchased everything that is involved with Cloyes Double Roller / Vented Opti/ Elec WP conversion.

So I ordered everything for a 95 F-body and not a 93. I ordered a cam for a 95, Opti for a 95, etc.....so in my mind I thought it was safe to asssume that Comp Cams (or Racenet) would send me a cam for a 95 already adjusted for 95 specific dowel length.

I did not the engine rebuild myself, and I dangerously assumed that they (machine shop) would know enough about the Lt1 to adjust for this. (they hald told me they had already done at least 5 Lt1 engines previous to mine with no problems).

I have great respect for these guys. They have built great engines for other people. But I knew coming in that these guys were old school and not know much about more modern engines.

My moral of the story is to always check can dowel length first. Because in my case, Comp Cams or Racenet did not send me one with the correct length already preset.

thanks

 

Ahh, Racenet. You never had a chance. But whoever assembled your engine should have known better, no excuses. You don't force an opti into position. Either it's on right or it isn't.

 

If everything was for a vented opti setup, I can tell you with complete certainty that it was NOT a problem with the pin length, but an improper installation of the opti. I have seen two people install a '95+ opti incorrectly - instead of the pin going into it's proper location in the opti, they bolt the opti in with the opti shaft/cam pin phasing wrong (i.e., the pin is in one of the cam bolt recesses on the opti shaft instead of its proper recess). A clear sign of this is the opti bolts must suck in the opti to the timing chain cover. Again, this is not due to the cam pin! As bud said, it will go on all the way if it's installed right - if you have to suck it in with the bolts, it's on wrong.

 

The shop did install the opti right, just did not factor in the length of the dowel. There is only one way an opti can go in. The opti clearly marks in which slot the opti goes in. That is not the problem, the dowel hits inside the surface of the opti hole before it can sit flat. Instead of correcting for this, they forced the opti flat by tightening the bolts, but the opti was in the correct position. If it wouldnt, trust me my car would not even start, because the timing would have been so far off.

 

Like I said, I've seen it done _TWICE_, it can go on improperly if you suck it in with the opti mounting bolts (symptoms exactly like you describe). If the opti popped out after loosening the bolts a few *centimeters* like you said, there is no way it was installed right. I positive that the dowel pin supplied with that cam is the correct length - PLEASE at least keep an open mind about this before you mess up your cam by grinding down the pin!

Look at the opti that came off your car when you get home... check the face of the shaft that accepts the cam dowel pin. You'll notice that there is a slot for the dowel pin, and three recesses for the cam bolts. I have seen people install the opti incorrectly- the opti will go on almost all the way, but what they don't know is that the cam pin went into one of the cam bolt recesses. They suck the opti in with the bolts and then wonder why their car runs like crap. Check that portion of the opti, and see if you can find where the pin was located - if it took that much effort to bolt it on, then the pin will have left a slight mark where it was making contact on the opti... by bet is that you won't find that mark in the correct location.

 

I will check that...thanks for the tip.


This is how I come out with the dowel being too long.....


I place a small dab of grease on the cam dowel and then tried to slip in the new opti. By doing this, I was able to locate where the cam dowel was making contact. And I could clearly see where the mark was inside the proper cam dowel slot in the opti spinshaft.

If I look at the face of the opti shaft.

I see 3 recesses for the cam bolts, and 3 small rectangular slots with one of them clearly marked with another indentation demonstrating where the cam dowel should go in. This is where the mark shows up when doing the grease test. I know I am inserting the opti correctly and I can see where the grease on the face of the dowel makes contact with the inside surface of this clearly marked slot. It does not go in all the way, and the grease gets all smashed up.

Am I not seeing something clearly. Has anyone ever runned into this problem before.

Thanks for your advice, I greatly appreciate it. No one know how much.

 

Yep, if the shop installed the cam w/o trimming the dowel pin, it is definitely too long. Comp sends them out about .82-.84" long (so you can trim it to your desired length), and they need to be ~.62 for a vented opti. Not everybody knows this, and the result is a lot of bad opti's. I trimmed mine to about .62, used the grease method that you did, and it looked good. Just trim that sucker down a lil, get a new opti, and enjoy your extra 100 hp

 

Man, I have never heard of this... what is there reasoning behind not sending them out @ the correct length like every other cam type they sell? Is it possible that some of the cam pins just aren't tapped into the cam far enough? I've had four different long dowel pin CC cams in the past 3 years, and never had a problem with the pin length.

 

All Motor TA,

Did you personally go though this experience? Man, it just goes to show just how much detail goes into building an engine. But I got to love these Lt1's. Hopefully this thread can make it clear to everyone outhere, in that they have to check their dowels before installation.

Thanks

 

Yep, I personally went through this. Read this: http://web.camaross.com/forums/showt...hreadid=108247

 

I just installed a CC.The pin was longer on the new cam.I put it in and was going to grind it if needed.When i installed the opti it popped on flush.So I left it.Everything seems fine....my experience.

 

Sorry to be late with this news, but my opti-crap wiring harness also was messed up and I ordered it from gmpartsdirect.com for $66.23 shipped to my house. It is suppose to be here 6-2. I ordered it 5-27. I messed it up doing my opti-crap change!!!