Well, Summit and Jegs techies are no help ....they don't know if their kits will work on an LT1 or not. Mine is actually a 94 but I said 97 because I have converted to the vented opti and ED timing set and my cam has the longer pin. The stack of components is causing my ICL to be 108 instead of 106 like it should be .....the exhaust is off in the same way so it's not the grind of the cam that's wrong. So we figured the best way to fix it would be with an "even" degree bushing kit ...preferably one with drill bit already included. Then I'll go in LT1 Edit and take out two degrees of timing across the board.

 

I've been looking into the same issue. I had my cam ground with 0 advance and I think I need +4 to get more cylinder pressure.

Anyway, I don't like the bushings because it's one more part to come loose. Plus, they have to be oriented exactly right to avoid making the cam gear eccetric.

The best solution I found was these:

http://www.lunaticams.com/Accessories/DegKeys.html

Haven't tried one yet, but it seems like an easier installation with less pitfalls.

Mike

 

Won't this throw the injector timing off due to moving the cam location in relation to the opti phasing?
Assuming your running a factory ecm still.

 

Yes, and more importantly the ignition timing will also be off. The injector timing being off by a few degrees will not cause any problems, but the ignition timing will definitely need to be adjusted to compensate.

I think that the best way to approach this is to install an electric water pump and traditional adjustable SBC timing set. This will require clearancing the timing cover. Degree in the cam and change reprogram the PCM to compensate for the timing change. For every degree you advance the cam, the timing should be retarded a degree.

Rich Krause

 

Why would you do that? See responses to quotes below.

If a person has the mechanical ability to install a bolt, along with using some common sense logic, there is no problem with reliability or install.

The best solution I found was these:

http://www.lunaticams.com/Accessories/DegKeys.html

Haven't tried one yet, but it seems like an easier installation with less pitfalls.

A very acceptable alternative. Easier? LOL.

Guys, what leads you to believe the injector/ignition timing is correct to begin with? How do you know that you wouldn't actually be correcting it with the degreeeing process?

The tolerances, and stackup of same (and possibility of error) of the linkage between the crank and cam hasn't changed since......well, who knows when. If the cam/crank timing/phasing is off, expect to fuel/ignition timing to be off also. The opti (and hence injectors) is driven off the cam dowel. It is extremely unlikely the dowel is not indexed to the cam lobes correctly. (Afterall, isn't the dowel used to index the shaft in the cam grinder, to grind the lobes?) That implies if the cam to crank timing is off, it is due to the camshaft itself, being improperly indexed. IOW, entire shaft is off in relation to crank, locating dowel.

Approaching the cam degreeing process, on an LTx engine, should be no diff than any sbc.

A search will locate several posts of mine, in archives, in regards to degreeing cam.

 

Hmmm, this is weird .....I have what looks like the same thing and it came with my keyed hub, I had no idea what it was as it did not fit with the hub in any way possible so I never bothered with it.

FWIW I do not want an electric waterpump or want to pay for one ...I like proportional cooling and the reliability of the stocker. Nor would I want to convert to a SBC timing set when I paid big bucks for this ED set. So using a cam bushing is a reliability issue? ....I thought this was pretty common practice, my mechanic has done it many times on non-LT1's.

Sounds like there is no way to correct the injector timing being thrown off ....I hope it really isn't critical. Anyone know what PN I need for an "even" degree bushing set or where I can get one? ....Arnie? ....the Summit and Jegs guys just have no idea ....

Just to clarify, I don't think the cam is ground improperly because my ECL was to be 118 and checked in at 116 .....ICL was to be 106 and checked in at 108 ....so the exhaust and intake are off in the same way. Maybe what Arnie is saying is that if the dowel drives the ignition in relation to TDC and the cam is correct, perhaps the ignition timing is actually two degrees behind in my case if this cam was installed straight up .....and will hence be corrected when the cam is redegreed ....causing no need for timing adjustment in LT1 Edit. Picture it at TDC and the centerline at 108 instead of 106, then picture the ignition timing still being based on 106 since the cam is ground correctly ....seems like the ignition timing would be off to me and redegreeing alone would correct it. Perhaps I have this backwards and what really happens is if my cam is just bolted in straight up the cam will just behave like a different cam but the ignition timing is still correct.

 

LOL Arnie is at it again.

For the rest Arnie and I have butted heads on this many times.

Everyone else in the real world agree's it throws off injector and ignition timing to the tune of 5-10 RWHP (As tested by many real tuners at +/-4 Degree's) as opposed to having the cam cut correctly the first time. No matter how much they changed the tune up they could not get that power back till they used a cam cut the way they wanted.

Now here is the exception. Early NON-Vented Optis were fine for drilling and indexing the Cam shaft as the gear position was not changed and the gear is what drove the opti NOT the dowel pin. There for it worked fine on thoses.

The best way to get by if you HAD to do this on a Vented system would be to index the opti after you drilled the Cam gear and indexed the camshaft. You MAY get away with slotting the opti contact points but there is not much room on the legs for that.

Arnie's 'Assumption' is every thing is all F***'d up to begin with and he is fixing it. Last time I checked Most of the people trying to do this are trying to change the cam possition from what they got there cam cut at and NOT fix some thing that was wrong to begin with. He 'Assumes' that every crank and timing chain set is wrong to begin with and that he is fixing the issue.

I have checked a couple of dozen timing setts since the last time this was brought up and have yet to see this problem Arnie Writes of. Running a degree wheel on both the crank and cam shaft to check referance after verifing TDC.

That is just what I have found guys and gals. My real world Testing has drove me in the direction I will continue to head. Arnie and I will just have to still agree to disagree

So to Move your cam two degree's to line it back up from the way it was cut(and yes it is cut on a center other then you ordered) you will be moving all others events that far off of the Crank from TDC.

Heck give it a try

 

Again, how do you know it is correct, to begin with?
If the cam is in need of degreeing, I'm confident opti/injector timing is off also. Correct one, you correct the other.

Anyone know what PN I need for an 'even' degree bushing set or where I can get one?

If you are, no need to look for something LTx specific. In this case, LTx is just another sbc. Related specs are the same.
There are others, of which I'm confident, but check with Isky. Comp Cams has them as well. Most cam mfrs. should be able to supply them. Otherwise it be as a lumber yard selling lumber, but not able to supply nails.

 

Hey Ellis.

Everyone else in the real world agrees it throws off injector and ignition timing to the tune of 5-10 RWHP (As tested by many real tuners at +/-4 Degrees) as opposed to having the cam cut correctly the first time.

Sounds like 'everyone else' is breaking some rules (when it comes to the LTx engine family).
The cam is usually NOT the problem. I explained what the problem is, (in great majority of cases) in above post.

No matter how much they changed the tune up they could not get that power back till they used a cam cut the way they wanted.

Are we on the same page? Who was referring to 'tuning' the cam characteristics or tailoring them to a specific track or torque curve? You're a mechanic Ellis, so you should know the difference between 'tuning' a cam... to reestablishing cam timing to intended engineering specs.

Now here is the exception. Early NON-Vented Optis were fine for drilling and indexing the Camshaft as the gear position was not changed and the gear is what drove the opti NOT the dowel pin.

Drilling and indexing cam? What you continue to stress, just reenforces my belief, that you do not understand what I am attempting to drive home here. You believe the cam/cam drive pin index, is at fault.

The best way.....after you drilled the Cam gear and indexed the camshaft.

Again! The cam is indexed off pin when grinding lobes. The odds, the index is not to engineering specs is rare, very rare.

Arnie's 'Assumption' is every thing is all F***'d up to begin with and he is fixing it.

Everything? That includes alot of components. I really don't know where you're getting this from. The person doing the assumin', is not me. Fixing (or correcting), yes, when necessary. Assume? No way! That is the purpose of checking. I don't assume. Ellis, you're the person doing the assuming, by insisting that I am assuming.

Last time I checked...are trying to change the cam position from what they got there cam cut at and NOT fix some thing that was wrong to begin with.

Again, sounds like the problem to me. I'm not attempting to reengineer the cam specs, or alter the torque curve. I'm fixing (correcting) an accumulation of tolerancing errors, WHEN NECESSARY. I don't ASSUME ANYTHING is wrong. I don't know anything is wrong til it is checked.

He 'Assumes' that every crank and timing chain set is wrong to begin with and that he is fixing the issue.

I don't have a clue where you're getting this from, Ellis.

I have checked a couple of dozen timing sets since the last time this was brought up and have yet to see this problem Arnie writes of. (I'm) running a degree wheel on both the crank and camshaft to check referance after verifing TDC.

Why the degree wheel on BOTH crank and cam? What are you checking? I could care less, whether each individual component is machined correctly. It is the package I am concerned with. That is the reason I made reference (earlier) regarding the stackup of tolerances. As an example only, if the (assembled) crank gear is retarded 20* and the cam gear is advanced 20*, (and any other issues not present), it is a wash, and you are home free.

Arnie and I will just have to still agree to disagree

I can agree with that.

So, to move your cam two degrees, to line it back up from the way it was cut (and yes it is cut on a center other then you ordered) you will be moving all others events that far off of the Crank from TDC.

Ellis, you have a one track mind. Again, where did you ever get the idea, this is what I am subscribing to? However, to take the paragragh at face value.... no sh*t shurlock, I AGREE!!

Ellis, I STILL have a 'thing' about you winking at me.

Note: For those that could care less whom is correct, I ask you, from what other forum could you get such entertainment.

 

LMFAO!!!!

"You're a mechanic Ellis, so you should know the difference between 'tuning' a cam... to reestablishing cam timing to intended engineering specs."

Yes I am and I under stand the operation and its intent. The problem is when you do this on a Vented Opti you change the relationship of the Opti events in relation to the CRANK shaft. To answer your other question

"Drilling and indexing cam? What you continue to stress, just reenforces my belief, that you do not understand what I am attempting to drive home here. You believe the cam/cam drive pin index, is at fault."

Yes if the cam was cut other then what was advertised(and that is what I usually find once the cam is checked in a fixture) using the bushings will put the CAM where you want it but once again change the Opti Timing events in relation ship to the Crank shaft events. UNLESS you are using a NON-vented opti in which case you can put the cam where ever you want it as the Opti is driven directly Off the gear it self and not the cam pin.

Next..

"Why the degree wheel on BOTH crank and cam? What are you checking?"

WHy Would I do this? By checking all events from the #1 TDC crank to the cam timed events will give you the ture inaccuracy you claim is happening. I have found Little inaccuracy with the new timing sets I have checked. By checking from true TDC to the cam alighnment pin you can find if there is a true inaccuracy at this point. This re-enforced My beliefe that that pin position was NOT at fault BUT the cut of the cam in relation to the pin it self was. I have found that it is much more likely that the cam is out of time the the timing set it self or the Indexing key on the crank shaft.

Your claim is you are re-establishing a correct alignment..... I have yet to find a truely in correct alignment with the parts I have used.

I guess what it comes down to is I have yet to find any thing to support your side of the argument as far as scewed build tolerances in the engines I have worked on.

I am Taking it You have and that is why to beat this so heavily.

I can tell you the Opti on my 427 SBC Gen I Is going to be indexed correctly and check for accuracy. Maybe then I will be siding with you but until then I will stand where I am

 

Hello Ellis. Unless you have a certified (for accuracy/inaccuracy) crank, crank gear, and cam gear, with which to check cams with, OR some way to verify the accuracy of previously noted items, (which means you a much more advanced/knowledgeable than I) you are, with due respect to you Ellis, blowing smoke up my rectal region. As I noted, if you possess this ability/knowledge, then I am waaay out of my league, compared to you, Ellis. If anything will shut me up, it is superiority (over me). And no, I am not being facetious here. Take care.

 

ROTFLMFAO!!!!

SO all along your problem was "How would I(Ellis) Know If it was the cam or parts leading up to it." I came up with a way to check it and now I am just flat not good or Knowledgable enough to check it. hehehe.

Please it is not that hard. Cam Dr makes checking cam's easy Screw the number one events. What about the other Seven LOL! Checking the rest is even easier. The number one Throw seems closer most times then the other three trows on the crank.

So as we stand You are FAR superior to anyone on earth and we shall leave you there.


BTW Smoke machines are $49.95 at the local store

 

Changing the injector timing by a couple of degrees will make no measurable difference in anything. Changing the ignition timing a couple of degrees will likely have an effect. I still like my way, because as I said it involves degreeing in the cam, and on that point I agree with Arnie - it's good to check. However, you also obviously need to degree in the cam when you intall the eccentric bushings, so I have no problem with that. As far as what set of eccentric busings to use, I am just guessing here but I don't see why they would differ for an LT1.

I won't get in the middle of Ellis and Arnie, but I will say that they aren't really talking about the same thing. If you read their posts carefully you will see that they are both right.

Rich Krause

 

OK, if you all don't mind let's just get back to this:

"Just to clarify, I don't think the cam is ground improperly because my ECL was to be 118 and checked in at 116 .....ICL was to be 106 and checked in at 108 ....so the exhaust and intake are off in the same way. Maybe what Arnie is saying is that if the dowel drives the ignition in relation to TDC and the cam is correct, perhaps the ignition timing is actually two degrees behind in my case if this cam was installed straight up .....and will hence be corrected when the cam is redegreed ....causing no need for timing adjustment in LT1 Edit. Picture it at TDC and the centerline at 108 instead of 106, then picture the ignition timing still being based on 106 since the cam is ground correctly ....seems like the ignition timing would be off to me and redegreeing alone would correct it. Perhaps I have this backwards and what really happens is if my cam is just bolted in straight up the cam will just behave like a different cam but the ignition timing is still correct."

Based on my ICL and ECL #'s what is wrong? The stack of components ...or is the cam ground wrong? To me it seems like it's the stack but you all are confusing me .....for me this is all just theory and I've never seen it in person, so all of this conjecture is a bit much to grasp. Rich (or someone else besides Arnie and Oneflyn') ..... 1. Is my cam ground improperly? 2. Will I need to retard timing by two degrees in LT1 Edit? .....I'm sorry but I just need for-sure answers.....

thanks for all of the attention to this matter....

so, I can buy the bushing kit that Summit and Jegs sell (the ones their own techies were so unsure of) for sbc's ?

 

I am too tired to think this through now and will post again in the AM. But my first thought is that if you get the bushings and install the cam as designed your timing will be 2 dergees retarded and need to be ADVANCED 2 degrees (in the PCM) to get it right. This might be backwards (I am mildly dyslexic and need to diagram it out in the AM) but your ignition timing will be off one way or the other.

However, since the timing is best set by seeing what works and not setting it to an arbitrary value, you could argue that it really doesn't matter if the timing commanded by the PCM and the "real" timing differ by 2 degrees. My cam is ground on a 109 degree ICL and installed at 105 degrees. I never "corrected" the timing but just tuned to give it the amount of timing it "wants". I did start tuning with very little advance to be on the safe side and crept up on what I finally settled at though.

Rich