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-   -   Top/Bottom End Alignment (https://blazerforum.com/forum/engine-transmission-35/top-bottom-end-alignment-100401/)

Mods 10-28-2019 06:06 PM


Originally Posted by LesMyer (Post 714948)
OK sounds like removing the remainder of a broken off bolt somewhere.

Better remove the balance shaft and find out why.

The bolt itself was one of the three for the large cam timing gear (speaking of anyone know where to buy a set at?), and i've got the entire stub down to the beveled edge already removed and the threads chased to be absolutely sure all is square, Going to remove it anyways as i dont like how stiff it is, but its almost assuredly not that.

LesMyer 10-28-2019 08:04 PM


Originally Posted by Mods (Post 714979)
The bolt itself was one of the three for the large cam timing gear (speaking of anyone know where to buy a set at?), and i've got the entire stub down to the beveled edge already removed and the threads chased to be absolutely sure all is square, Going to remove it anyways as i dont like how stiff it is, but its almost assuredly not that.

The cam retaining plate screws are GM #10105912 - Summit Racing or local dealer
The balance shaft retaining plate screws are GM #14093637 - Summit Racing or local dealer
The three large bolts holding on the larger timing gear through the lower balance shaft gear - you can match that up at Ace Hardware out of grade 8 bolts.

LesMyer 10-29-2019 07:35 AM

Here's the specs and GM P/N for the three bolts holding the timing gear onto the camshaft.

Bolt, hex, 5/16-18 x 1 3/8 (cm/shf spkt) 09419033

Only reason not to get them from ACE is if the bolt length is wrong or the bolt heads are different. DO NOT use standard hardness bolts in this application. Minimum grade 5.

If you can't find them locally they don't seem to be available from GM online but you might try a GM dealer. Alternatively, this place claims to have aftermarket bolts that work.
https://trupar.com/p/general-motors-bolt-09419033

Mods 11-02-2019 10:00 PM


Originally Posted by LesMyer (Post 715002)
Here's the specs and GM P/N for the three bolts holding the timing gear onto the camshaft.

Bolt, hex, 5/16-18 x 1 3/8 (cm/shf spkt) 09419033

Only reason not to get them from ACE is if the bolt length is wrong or the bolt heads are different. DO NOT use standard hardness bolts in this application. Minimum grade 5.

If you can't find them locally they don't seem to be available from GM online but you might try a GM dealer. Alternatively, this place claims to have aftermarket bolts that work.
https://trupar.com/p/general-motors-bolt-09419033

Gotcha. Will keep all that in mind after the balance shaft is removed/inspected, i have a bad feeling that one of the bearings crumbled or unseated for some reason based on how it feels when turned.

error_401 11-03-2019 03:06 AM

Definitively investigate these bearings.
When you remove the timing gear from the balance shaft it should turn freely.

Mods 11-03-2019 10:36 AM


Originally Posted by error_401 (Post 715181)
Definitively investigate these bearings.
When you remove the timing gear from the balance shaft it should turn freely.

Before i get that far into rebuild territory is it possible that its just due to the lack of oil pressure?
The motor hasnt been ran in over 3 years with no timing cover and the water pump removed, And while i highly doubt its the cause i want to rule everything out before doing anything major.

error_401 11-04-2019 06:10 AM

No offense!
A bit of a problem here as we don't know how knowledgeable you are with engines. In all honesty from the questions, it sounds as you are in a bit over your head.
May want to consider asking somebody who knows his ways around engines for assistance.

For the previous posts and future explanations: Very carefully read the statements. We are all trying our best to be precise.
When I or other members refer, i.e. to the gear of the balance shaft - we mean the gear on the balance shaft.
Nothing to do with the camshaft, nothing to do with the crankshaft to camshaft drive.


I doubt that you have disconnected or removed the gearing from the balance shaft. (At least I hope you have not and it involves some Torx nuts which are usually not in a normal toolbox.)

Assumptions:
- engine is upright, which means correctly positioned. Crank down, heads left and right up. Form of a "Y".

The whole thingy is connected (interconnected) as follows:
  • the crankshaft has the small chain sprocket on it with the single dot mark which should point up.
  • the camshaft has the large chain sprocket on it with the single dot mark which should point down. (The two should actually be aligned with each other kind of a ":")
  • the chain connects the two and makes the camshaft turn only half the revolutions of the crankshaft.
  • behind the large chain sprocket there is the drive gear for the balance shaft. (fine toothed diagonal gear - also has a dot mark on it.)
  • above that, and in mesh with the gear on the cam, is the same gearing for the balance shaft. (The larger gear on the cam and smaller on the balance shaft makes turn the balance shaft again at crankshaft speed - it also has a mark which has to be aligned.)
Now to your questions:

If "ALL" is assembled it is hard to turn, because whatever shaft you turn (crankshaft, camshaft or balance shaft) it will turn the whole engine and valvetrain assembly.
Normally you can only turn an engine over, by using a wrench with at least 3/4 of a foot lever on the crank pulley or alternator pulley nut.

We have referred to "disassembled" state. If you remove the gear drive from the balance shaft, the balance shaft should turn freely.

Before running the engine I would consider priming the engine on the oil side. This will require an oil service including filter and will require a drill and an adapter for the oil pump to be turned with a drill to get the whole engine primed with oil. This will also mean bringing the engine into the proper position #1 TDC ignition and remove the distributor.
Search the internet for priming an SBC.

Good video on the front of the engine and cam drive.

Good video on all the alignment balanceshaft, camshaft, crankshaft (portuguese, but hey - a picture is worth more than words.)

Have a look at time 13:00 the balance shaft and the gearing

Series of videos on a whole 4.3 V6 rebuild. On marine engines the accessories and cooling are different but the 4.3 V6 has been fitted to hundred-thousands of boats.
Don't look at the workmanship. No wonder half the repairs never make more than a couple thousand miles. (i.e. hanging the camshaft into the first bearing and not supporting it, will warp the bearing).
Nevertheless gives a good insight into the innards of our Blazers V6.

Oh, and nearly forgot my build thread which shows some stuff as well.
https://blazerforum.com/forum/builds...ueprint-92047/

Mods 11-04-2019 03:11 PM


Originally Posted by error_401 (Post 715242)
Now to your questions:

If "ALL" is assembled it is hard to turn, because whatever shaft you turn (crankshaft, camshaft or balance shaft) it will turn the whole engine and valvetrain assembly.
Normally you can only turn an engine over, by using a wrench with at least 3/4 of a foot lever on the crank pulley or alternator pulley nut.

We have referred to "disassembled" state. If you remove the gear drive from the balance shaft, the balance shaft should turn freely.

None taken, I will freely admit that i've not worked on a motor this complex before, most i've worked on are small hobby motors and 2 strokes, and while i have a solid understanding of the mechanics behind how these larger motors work i've not done anything with one that would be considered "actual experience" in building or repairing outside of general vehicle maintenance .

I initially created this thread as the initial issue seemed to just be the cam/crank timing, Then in setting that it was found that the balance shaft is exceedingly stiff, with the Cam chain gear and balance shaft drive gear removed it requires alot of leverage between the Dowel pin and the center shaft to rotate.

In contrast the Cam can be freewheeled by simply rubbing your finger on the outer edge of the gear face. from what i can find elsewhere and from whats been said in the thread that level of stiffness is abnormal, So pretty much - Should i cut my losses and send the motor off to a mechanic to a shop to be rebuilt, Or is inspecting the Balance shaft and bearings something that can be done without too much in the way of specialized know-how, is what im trying to figure out now. The motor is in a "disassembled" state within the context of your post, Still inside the TrailBlazer with the only components missing being the Waterpump, and the Cam chain gear and the Balance shaft drive gear removed.

LesMyer 11-04-2019 09:13 PM


Originally Posted by Mods (Post 715261)
None taken, I will freely admit that i've not worked on a motor this complex before, most i've worked on are small hobby motors and 2 strokes, and while i have a solid understanding of the mechanics behind how these larger motors work i've not done anything with one that would be considered "actual experience" in building or repairing outside of general vehicle maintenance .

I initially created this thread as the initial issue seemed to just be the cam/crank timing, Then in setting that it was found that the balance shaft is exceedingly stiff, with the Cam chain gear and balance shaft drive gear removed it requires alot of leverage between the Dowel pin and the center shaft to rotate.

In contrast the Cam can be freewheeled by simply rubbing your finger on the outer edge of the gear face. from what i can find elsewhere and from whats been said in the thread that level of stiffness is abnormal, So pretty much - Should i cut my losses and send the motor off to a mechanic to a shop to be rebuilt, Or is inspecting the Balance shaft and bearings something that can be done without too much in the way of specialized know-how, is what im trying to figure out now. The motor is in a "disassembled" state within the context of your post, Still inside the TrailBlazer with the only components missing being the Waterpump, and the Cam chain gear and the Balance shaft drive gear removed.

Well, I wonder if the front bearing on the balance shaft became as rusty as the crank snout did...... You will have to remove it to find out. Just take the two screws out of the plate and tap the balance shaft forward with a dead blow hammer. If the bearing is bad, AFAIK it is not a serviceable part and you will need to replace the balance shaft assembly. Rock Auto has them for $90. Good luck.

odat 11-04-2019 11:38 PM


Originally Posted by Mods (Post 715261)

I initially created this thread as the initial issue seemed to just be the cam/crank timing, Then in setting that it was found that the balance shaft is exceedingly stiff, with the Cam chain gear and balance shaft drive gear removed it requires alot of leverage between the Dowel pin and the center shaft to rotate.

In contrast the Cam can be freewheeled by simply rubbing your finger on the outer edge of the gear face. from what i can find elsewhere and from whats been said in the thread that level of stiffness is abnormal, So pretty much -The motor is in a "disassembled" state within the context of your post, Still inside the TrailBlazer with the only components missing being the Waterpump, and the Cam chain gear and the Balance shaft drive gear removed.


In less I've been asleep at the wheel while following this the valve covers have never been removed so the rockers are still tight and set - If so just how is the cam free wheeling with the rubbing your fingers on the gear face - as it turns it will be opening and closing valves and hard to turn .... Are you sure you are not backwards in thinking which is cam and which is the balance shaft ..... Just thinking out loud here but maybe worth asking .....


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