So let me get this straight... You're saying that when you line up the marks, coming up on compression stroke, it is not on TDC? It is still before TDC at that point when the marks line up?

I just now found true TDC on my motor using the degree-in-a-cam technique, and then I set my distributor like we're supposed to, and now my P1345 code went away, and it runs really smooth, but it feels really soggy and has less power now. Should I just go by the marks and reset it?

Can somebody verify exactly where the #1 piston is when these marks are lined up as per the diagrams in the DIY tech article? I'm puzzled. I've set up quite a few V-8s and they are straight forward, but I don't know why these 4.3 Vortecs seem so much more complicated to me. I just need to know where the piston is supposed to be when the 2 marks are lined up, so that I can determine if my harmonic balancer ring has slipped or not, or if I sheared my crank key. It shows absolutely no signs of slipping at all on the ring though. Looks tight as can be, and is dry, with no oil or anything saturating it. I had this set up once before at the time I rebuilt the motor and had it all right (back then I also had to make some mark so I remember), but I just replaced the dist. gear this time around and shimmed up the endplay and put the thing back in on the same tooth, but the rotor was pointed slightly different. If I put it a tooth forward or backward, it is way off. I shimmed the endplay down to .015 inch from about .060 inch, and I figured this had something to do with why I had to elongate my holdown bolt-hole to get more movement so I could get my rotor to line up to the proper point with the '6' on it. And also, when I found the true TDC (verified it 3 different times), none of the marks on the balancer line up to anything. This is why I'm so puzzled. I don't have the scan tool to check the cam retard offset, so I have to figure this out the logical way.

I don't know, maybe the soggy feel it has now is because I need to do the CASE relearn procedure. ?

 

did you ever find a solution?

 

Well, I left it on TRUE TDC which is where none of the factory marks line up at all, and it ran fine, but felt soggy on acceleration, but no codes. After driving it around for awhile (didn't have time to mess with it after that), after more miles put on it, it seems the soggy feel just kind of faded away. It doesn't feel soggy any more, but I still would like to find somebody who has the proper scan tool so I can check the cam retard offset for real, because I would rather set it with that so I would know for sure how close it is. But it seems to run fine now. You know, with human perception, it is hard to tell if the soggy-ness fully went away or if I just got used to it. This is why I want to check it. But I just haven't had time to get back to it. I may just take it to a local shop and have them check it for me. I have made the distributor adjustable now, so setting it would only take them about 10 mins. But it does run fine on both the CNG and the gasoline, and there are no codes and it passes inspection anyways. I guess stay tuned for part B when I final DO get it checked.

 

I dont know if this helps or not, but i just worked on a 95 blazer, and judding off the back of the crank pulley was a little mound that indicated TDC, and slightly offset was another mark, to adjust the valves.

Wait this doesnt apply yours is a 96 sorry.

 

??? ojosch did not get an answer an i want to know also , what do you mean ? "You need to be on the compression stroke for #1 (not TDC #1) and line up the two marks as shown. " are you saying just be somewhaere on the compression stroke on the #1 and line up the marks ?

lined it up and it went right in this time but it wont land exactly on the 6 mark on the dist cup edge . very close but no fire . should i just ply with it ? maybe set it a hair before the mark ?

 

I think that is exactly what I said... What part wasn't clear? I have used that procedure a number of times and never had the trouble any of you are experiencing... Are you sure you are on the compression stroke? Have you tried rotating the crank a full turn and dropping the distributor in?

 

yes i am sure its number 1 on the compression stroke set to the mark . went ahead and turn it back around one time on th eexhaust set to the mark and the dist wil not fall in all the way , it will ONLY go all the way in when im on compression and on the mark.

i notice the number 6 on the edge is past the #1 post in the cap . why set the rotar to a position past the post ? is this so it fires before tdc?


i also got it one gear back so it lands on the #1 post but that no good either , im %100 sure im doing everything as stated . im going to put a straw or something in #1 sparkplug hiole to see if the marks on the balancer are correct .


i have read a million discriptions and am confused about what mark some say is true

i see 2 grooves in the pully and i see a inverted V at about 1 oclock and a long narrow V at about 5 oclock on the case, when the second grooves lands on the 1 oclock the first lands on 5 oclock , correct ?

 

Well, I'm still not convinced that my harmonic balancer didn't shear the key, or that perhaps the new distributor gear I installed is indexed slightly different from the original (thus throwing off the distributor alignment). Or perhaps even that the machinist might have exchanged my crank without me knowing it, for a different one when I had mine in getting ground, and maybe had a different keyway position?

At any rate, what I wound up doing way back then was to ignore the marks on balancer, and I made a special bolt that would screw into the #1 spark plug (PLEASE DISABLE THE STARTER MOTOR BEFORE DOING THIS), and I manually with a wrench on the balancer, ran the piston up til it touched the bolt screwed into #1, then made mark on the balancer. Then you reverse, and turn the motor manually with a wrench backwards all the way around, until it again touches the bolt you have in #1 spark plug hole, and make another mark. Then make a 3rd mark exactly in between the other 2 marks, and that is calculated TDC. This spot should be fairly exact. Now, remove the bolt from #1 spark plug hole and put the spark plug back in.

Then line up the new TDC position you just calculated and then modify the distributor so it has more adjustment. I just drilled out the hole on the hold down bracket to a larger size and used a large flat-washer on the dist bolt so I could turn the distributor a bit. Then drop the distributor in and line up the arrows and lock down the bolt. If the distributor doesn't drop down all the way, it is because the oil pump drive shaft is not positioned in the correct spot to line up to the slotted fitting on the bottom of the distributor. You can either pull out the distributor and turn the oil pump shaft with a long flat-head screwdriver (trial and error, til it lines up and dist drops down), or you can bump the starter with a remote start switch until it drops in all the way, and then bump it back to TDC compression stroke and line the marks up again to verify that that your arrows indeed still line up in the distributor, and then lock it down.

It should start, run and be ok, but if it throws a code P1345 then simply adjust the distributor bits at a time, until it doesn't throw the code anymore and that should be within the tolerated spec. As far as I can tell, they designed it so that as long as it runs and does not throw the code 1345, then it is close enough for the computer to be able to adapt it in to run optimally.

I still never got around to manually checking the exact Cam Retard Offset spec, but since mine doesn't ever set the code 1345, and has adapted and seems to run fine, then I just kind of call it 'good' in my mind.

Edit: You probably don't even need to find TDC nearly this exact as I outlined above, as you could probably just have a friend poke the straw into the #1 spark plug hole and you can be underneath, turning the crank little bits, back and forth with a breaker bar on the crank nut until you find a rough TDC location (on compression stroke of course), and drop the dist in, enough to get it running, and then just adjust it so you don't get any codes.

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ok well apon looking into #1 cylinder with my bore light i see the piston is at tdc and the markings on the pully are correct . when i drop in the dist. it lines up with the oil pump slot and fits in all the way , the rotor contact is on the forward edge of the 6 mark , there is a small box around the contact point of the rotor and it is within the box (if this means anything) but the following edge .as to my previous question the 6 mark is in front of the actual post to the #1 wire , and i assume this is so it fires a split sec before TDC ,

the instructions say within a degree or 2 and i am right on the forward edge of the 6 mark so i feel it is safe to say if the 6 mark is in front of the actual #1 cap post and if im landing on the front of the 6 then i am that mutch more early with the spark . givin issues like gear wear, timing chain wear and so on i am going to do the same and make the distributor clamp slightly adjustable so i can move the mark (and contact)forward and have the 6 be dead on with the rotor contact

ll bring photos if this works , this is probably what happens when you try and take the human factor out completely

 

nope #1 tdc on the mark put the dist with the modified lock down on so the contact ws dead on instead of on the forward edge . and all i heard was one flame poof out the exhuast ? coil fires , timing is on, fuel pressure is there , IFL it should at least run crappy if im this close . but not one good fire ?