All you need to do is put the cam in and put the timing set on, then you line up the dots. Cams for the lt1 are supposed to have 4 degrees ground into them from the cam supplier. correct? Changing anything will mostlikely make the car underperform. Atleast i would think so.

 

negative on lining the dots up.

thats what i thought until i talked to my builder. he said every cam needs to be degreed to make sure tolerances on the keyways, sprockets, etc are correct. boy am i glad we did that.

figured out the main reason my car had problems before the rebuild.

and i would have been enraged if installed the motor, broken it in, gone WOT, and it just falls on its face at 5000 rpm. 7 degrees advanced plus the 4 supposedly ground in, would make for a hella strong low end I would honestly rather have some retard in the cam than advance.

Im REALLY dissappointed in comp cams. 7 degrees is hella unacceptable. imagine if i was running juice on that cam.....boom bitch.

 

more info please guys... obiviously you have to corrset the cam timing before going to correct the ignition timing.

 

How severe of a problem is this?

Isn't it possible to install a cam in an LT1 and just line up the dots? I know lots of people have had success doing that...

 

JMB, seeing you have experience degreeing cams, I trust you will understand what I am about to post.

So are you guys telling me that I should go back and put it straight up?

Regardless of who stated to do so, or how you rationalized that you should, I'll state no! It is important the correct cam/crank relationship is achieved/maintained.

I tune the car myself so if tell me your opinions on what to do. Also if your saying that its just changing the igniton timing then why can't you just slot the opti bolt holes and adjust the timing that way or do it in the tune?

Actually it affects injector timing as well. Something that isn't part of pcm editing software AFAIK. PCM reprograming is suggested, not just to alter opti timing, but to address tuning (read driveability issues). Yes, physically rotating the opti housing will affect the injector timing as well. But, do you really want to? See below.

Cam/crank relationship corrections can be achieved with either an offset key or offset bushing around cam dowel. There are those that state not to degree the cam, noting this will alter the opti/injector timing. If the cam is not timed correctly with the crank, how can anyone guarantee opti timing is correct to begin with. In fact, if cam timing is off due to the crank keyway, crank gear, or cam gear, corrections WILL CORRECT the opti/injector timing. The one exception would be if the dowel location in the cam was at fault for the incorrect cam/crank timing relationship. How good are you at playing the odds?

 

Arnie,
I've noticed, that with your posts all you do is confuse, or maybe it's me. I think you try to project your inteligence too hardily. Keep it simple stupid.

Aron

 

Either that, or I am trying to hard to fake it.
If any of my posts (or parts thereof) are confusing, by whatever means, narrow down the confusing parts are well as possible, and then corner me. 'Course, that is figuring that I know enuf about what I am attempting to explain. Even if I do, sometimes when putting what one knows into words, something can get lost in the process. My posts are not meant to confuse. If that is what I am doing here, I am accomplishing zilch for my efforts. It has happened in the past, where I typed somethin', sat back and read it, (and B4 rewording it) said huh? So, if anyone is occasionally confused, they are not alone.

JMB, if I made things more confusing, certainly, repost.

 

Well, I will be the first one to profess absolute ignorance and step up to ask for a few clarifications:

1) How many ways can the crank sprocket be oriented on the snout of the crank? I thought it was keyed. (I know the HUB is not keyed)

2) How many ways can the cam sprocket be oriented on the cam? There are three bolts and a hole to stick the dowel through. That would lead me to believe there is again only one way it will go on.

3) Assuming 1 and 2 are failsafe, how, then, can lining up the dots ever lead to incorrect timing, excepting for instances of a misground cam or slack in the chain or other unforseen things. It would seem to me that if the chain is on, and the dots are lined up, there can only be one possible crank to cam position relationship?

4) For those who are simply replacing the stock cam and making no changes to the crankshaft or any other internal engine components, how neccesary, then, is it to degree the new cam? For instance, John Q Public installs HOTcam. Are you saying it is absolutely neccesary to degree it?

 

 

For those of us that have degreed cams, reality states something different. For those that are not aware, machined parts are done so within a tolerance range. No, (generally speaking) the parts are NOT machined exactly to blueprint specs. So what do you think happens when you stack up the tolerances? There IS a reason why people spend the effort/time to degree cam assemblies.

For those who are simply replacing the stock cam and making no changes to the crankshaft or any other internal engine components, how necessary, then, is it to degree the new cam? For instance, John Q Public installs HOTcam. Are you saying it is absolutely neccesary to degree it?

It runs doesn't it. Well, then it is not absolutely necessary. Will it make the most power/torque possible? I believe YOU can now answer that ?. As I noted above, if the cam is not correctly timed with the crank, don't expect the injector timing to be spot on either. But, it still runs, doesn't it? How particular do you want to be on your engine?

 

Whatever. Besides, I've got far too much class to even consider such.

 

I re-read it and this thread is making my head hurt It is a good idea to "degree" the cam in the sense of checking to be sure it installed with the proper relationship to the crank. No way it's not a good idea. However, if it is "off" there are multiple possibilities and things get kind of complicated in the sense of figuring out exactly where the problem lies. FWIW, an incorrectly ground cam is rare, at least in my experience. So usually, if the degreeing process finds the intake center line is not where it's supposed to be, you simply need to either advance or retard the cam until you correct the intake center line.

An Optispark equipped motor poses somewhat of a problem in this regard because the injector and ignition timing are keyed to the dowel pin in the crank snout. So if you advance or retard the cam you will also be changing the injector and ignition timing. Adjusting the intake center line may move the timing off, or correct it, depending upon why the intake center line was inocrrect in the first place. The timing sets and crank gears usually used on LT1's do not have the provision for adjustments. So far this has not happened, but if I were to degree an LT1 cam, and find it more than a couple of degrees off I would first carefully check and be sure I hadn't screwed something up. Then, if I still found an error, I would send the cam back and be sure it was ground correctly. If it was right, I am really not sure what I would do next. I guess I would look back everything again and make sure all the parts were in good condition and that I hadn't made some mistake in my measurements. Next step? Not really sure, since so far it hasn't happened. A couple of degrees (1 or 2) wouldn't bother me much, but more would. I will say that the injector timing isn't at all critical. But it would be a problem if the ignition timing were off more than a degree or two.

Rich Krause

 

"optical sensor" is all I have to say

 

Please elaborate...

 

Thats exactly where i am at rich. awaiting the word from comp on the cam. i double checked the ICL, took everything off, double checked again and it was the same. dots were perfect.

I would have been fine with a couple degrees, like 2, but not seven lol, hell no. i would actually rather have it retarded than advanced since you get lots of low end with the stroker.