One For Herecord Books

KENNHON · December 14, 2009

WELL, here is one for the record books---- i've been working on B/B since1969.... NEVER have i had a sheared distributor drive... Well, on my '96 Vortec... just that happened. when i posted before i thought my cap and rotor are bad... so i took off the upper intake; replaced cap and rotor, new MSD wires,coil.... and checked shaft for any 'sloppiness'... NONE when i turned over engine,,, the rotor did NOT move!!! got a friend over fidddled with shaft, turned over again, and rotor moved a half turn... that was it~~~

Of Course, now, i haveta remove distributor.... HERE IS QUESTION... is there any external reference mark for TDC for #1 cyl. anywhere thatis visually accessible?

ken1mod · December 15, 2009

Remove #1 plug. Front, drivers side plug. Place finger over plug hole. Have friend bump starter. You will feel large pressure pulse. This is top of compression stroke, number 1 cylinder.. What I do not know is if there are conventional timing marks on these engines. If ther are , you will now be close to tdc, number 1 cylinder and that is wher the rotor must point to fire the engine correctly.

If you have a distributor, there probably are normal timing marks. This is not as hard as it may sound. I have done this several times and it does work quite easily.

Ken

KENNHON · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Nytemare · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Buy a TDC whistle.

Oh and BTW..initial timing with advance bypass disconnected is 4* BTDC. So to set things up properly you will need a degree wheel too.

KENNHON · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Buy a TDC whistle.

Oh and BTW..initial timing with advance bypass disconnected is 4* BTDC. So to set things up properly you will need a degree wheel too.

I am NOT making myself clear... all the blow whistles,timing wheels,etc. will NOT work!!!! there is NO marks of ANY KIND on outside of engine!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a blow whistle won't work[it' starts blowing before TDC for one thing]....IF there are no OUTSIDE marking how would ya know EXACT TDC???? i've been working on B/B's since 1969... ALL had marks[on balancer to coordinate with marker just above balancer---THERE IS NONE on '96 to 2000 454's!

Nytemare · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Buy a TDC whistle.

Oh and BTW..initial timing with advance bypass disconnected is 4* BTDC. So to set things up properly you will need a degree wheel too.

I am NOT making myself clear... all the blow whistles,timing wheels,etc. will NOT work!!!! there is NO marks of ANY KIND on outside of engine!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a blow whistle won't work[it' starts blowing before TDC for one thing]....IF there are no OUTSIDE marking how would ya know EXACT TDC???? i've been working on B/B's since 1969... ALL had marks[on balancer to coordinate with marker just above balancer---THERE IS NONE on '96 to 2000 454's!

WOW...and you've been working on engines since 1969????

You dont know how a TDC whistle works....WOW.

Let me make this fool proof....A TDC whistle makes a sound as it approcahe TDC/BDC...when it hits TDC/BDC it makes a Schrill sound...louder than any other sound. As your coming up to TDC/BDC you look to see which valve just shut and if it was Intake than you have TDC. You may have to remove the Valve cover....

dlstewart01 · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Buy a TDC whistle.

Oh and BTW..initial timing with advance bypass disconnected is 4* BTDC. So to set things up properly you will need a degree wheel too.

I am NOT making myself clear... all the blow whistles,timing wheels,etc. will NOT work!!!! there is NO marks of ANY KIND on outside of engine!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a blow whistle won't work[it' starts blowing before TDC for one thing]....IF there are no OUTSIDE marking how would ya know EXACT TDC???? i've been working on B/B's since 1969... ALL had marks[on balancer to coordinate with marker just above balancer---THERE IS NONE on '96 to 2000 454's!

WOW...and you've been working on engines since 1969????

You dont know how a TDC whistle works....WOW.

Let me make this fool proof....A TDC whistle makes a sound as it approcahe TDC/BDC...when it hits TDC/BDC it makes a Schrill sound...louder than any other sound. As your coming up to TDC/BDC you look to see which valve just shut and if it was Intake than you have TDC. You may have to remove the Valve cover....

Or just stick a dial indicator in the spark plug hole... you can't miss when you reach TDC.

Nytemare · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Buy a TDC whistle.

Oh and BTW..initial timing with advance bypass disconnected is 4* BTDC. So to set things up properly you will need a degree wheel too.

I am NOT making myself clear... all the blow whistles,timing wheels,etc. will NOT work!!!! there is NO marks of ANY KIND on outside of engine!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a blow whistle won't work[it' starts blowing before TDC for one thing]....IF there are no OUTSIDE marking how would ya know EXACT TDC???? i've been working on B/B's since 1969... ALL had marks[on balancer to coordinate with marker just above balancer---THERE IS NONE on '96 to 2000 454's!

WOW...and you've been working on engines since 1969????

You dont know how a TDC whistle works....WOW.

Let me make this fool proof....A TDC whistle makes a sound as it approcahe TDC/BDC...when it hits TDC/BDC it makes a Schrill sound...louder than any other sound. As your coming up to TDC/BDC you look to see which valve just shut and if it was Intake than you have TDC. You may have to remove the Valve cover....

Or just stick a dial indicator in the spark plug hole... you can't miss when you reach TDC.

Unless you hit BDC...which is the same height...than your 360* out on the crank and 180 out on the cam...again you need the valve cover off.

Hell...I have done it with a welding rod down the plug hole. You again remove the cover...than you roll the engine over till #1 intake is open...than you roll the engine until you get the the rod up to max height and it just starts to drop, than you go back about 1* or so...when the rod is at max height #1 valves will be shut and you are at TDC.

dlstewart01 · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Buy a TDC whistle.

Oh and BTW..initial timing with advance bypass disconnected is 4* BTDC. So to set things up properly you will need a degree wheel too.

I am NOT making myself clear... all the blow whistles,timing wheels,etc. will NOT work!!!! there is NO marks of ANY KIND on outside of engine!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a blow whistle won't work[it' starts blowing before TDC for one thing]....IF there are no OUTSIDE marking how would ya know EXACT TDC???? i've been working on B/B's since 1969... ALL had marks[on balancer to coordinate with marker just above balancer---THERE IS NONE on '96 to 2000 454's!

WOW...and you've been working on engines since 1969????

You dont know how a TDC whistle works....WOW.

Let me make this fool proof....A TDC whistle makes a sound as it approcahe TDC/BDC...when it hits TDC/BDC it makes a Schrill sound...louder than any other sound. As your coming up to TDC/BDC you look to see which valve just shut and if it was Intake than you have TDC. You may have to remove the Valve cover....

Or just stick a dial indicator in the spark plug hole... you can't miss when you reach TDC.

Unless you hit BDC...which is the same height...than your 360* out on the crank and 180 out on the cam...again you need the valve cover off.

Hell...I have done it with a welding rod down the plug hole. You again remove the cover...than you roll the engine over till #1 intake is open...than you roll the engine until you get the the rod up to max height and it just starts to drop, than you go back about 1* or so...when the rod is at max height #1 valves will be shut and you are at TDC.

We got a winner here...

Spurshot · December 15, 2009

A dial indicator will tell you approximately where TDC is if you just rely on it to show you the highest point of the piston travel. The problem is that there is dwell of the piston at TDC on any engine. If you use a dial indicator to measure a given point of the piston traveling up, you can mark that point on the pulley and reverse the rotation back to the same piston height and mark the pulley again and then split the difference on the pulley by measuring. That will be TDC within the requisite tolerance. The same can be done with a sparkplug piston stop.

Nytemare · December 15, 2009

This is very true...I am not a fan of piston stops though...just in case you rotate to fast and score the top of the piston.

Also...you can tell with the whistle by the sound...the compression stroke is much louder different sound than the exhaust stroke...but if you have hearing damage like I do...there is no real difference in sound until it reaches the top of the stroke...thats why I have to remove the valve cover.

Also...you should remove the cover if your unsure....this is the easiest way...I am a big fan of the TDC whistle......if you couldn't tell

minibike132 · December 15, 2009

The problem with the 'age-old' method for TDC is just that!!! you can APPROXIMATE TDC/compression... BUT you can't FINITELY determine TDC.. there are NO marks [on balancer-or otherwise to tell you PRECISELY where TDC is---at least, i can't find ANY marks!]... And with computer controlled spark control... you haveta get EVERYTHING spot on... Also,you see, in '96-up... there is also,a CAM POSITON sensor/control that controls WHEN fuel is inj. to each cylinder!!!!---if too soon---WASTED fuel... too late---low power... so correct TDC is mandatory

Forgive my ignorance but what is B/B?

I can assure you exact TDC isn't as critical as you are thinking. As a matter of fact your thinking is a little backward. The reason there is no mark is that if you are close you are good enough for the pcm to make the corrections. The timing is alot more critical on one without computer controls. With this one either you are a tooth off or you are not, it's that simple. I can't post the manual but I'll give you a couple of highlights.

Straight from the manual, there is nothing real critical about exact TDC...

Bring cylinder number one piston to TDC (Top Dead Center) of the compression stroke.

Align the pre-drilled indent hole in the distributor driven gear with the white painted alignment line on the lower portion of the shaft housing.

Using a long screw driver, align the oil pump drive shaft in the engine with the mating drive tab at the end of the distributor shaft.

Once the distributor is fully seated, the rotor segment should be aligned with the pointer cast into the distributor base.

• The pointer has a (8) cast into it, indicating the distributor is for an eight cylinder engine.

• If the rotor segment does not come out within a few degrees of the pointer (8), the gear mesh between the distributor and the camshaft may be OFF by a tooth or more.

• If this is the case repeat this procedure to achieve the proper alignment.

KENNHON · December 16, 2009

WELL, finally, Mr. Sure-Shot, u understand what my problem is...[i do know what a tdc whistle is!!!WHEW!-50 years---- tell me NOT to rely on them!!!--- they are NOT exact! BUT, i must get back to original problem--- NO spark AFTER coil wire---- as i took off cap, and saw rotor not turning when eng. cranking... it HAD to be one of 2 things!!! sheared distributor shaft, or stripped gear... Well, today i got the bloody thing out and the teeth were GONE on about half of the teeth---ALL were worn big time. I've always had since day one Mobil One 5W-30... Always changed filter[K&N] same time [5,000 miles].... This distributor is COMPLETE JUNK[it's PLASTIC!!!!!!!!!!!!!!!] there was no slop in the bearings, but when i got distributor out the top bearing was 'squeaking'! .. Guess that was too much drag on gear... The gear on camshaft LOOKS fine.

Thanks to the guy the told me how to put a new distributor in!!!! i ordered a 'lifetime' warranteed Napa one for replacement....

KENNHON · December 16, 2009