Big T-65.

Using the piston stop toll is quite simple,,,and you should not fear anything when doing this...beacsue I have done more than I can count and if you are aware of what you are doing...you will not damage anything...and you will get POSITIVE RESULT.... NO GUESSING by looking at bubbles or anything else. No need to make this harder than it actually is.

Manually turn your engine (using a flywheel turning tool) to the point where you see the notch on the balancer and it is about 1-2 inches away from the timing tab.

Rotation direction of the engine is irrelevant because you are going to turn it the opposite direction when the piston makes contact with the tool you put in NUMBER 1 CYLINDER.

Remove NUMBER 1 cylinder spark plug and thread in the tool. Look at your spark plug and you will know that the amount of the bolt has to be further out than what you see on your spark plug. So thread it out a bit more than the length of the spark plug that goes in the combustion chamber.

Then turning the flywheel manually...SLOWLY rotate the engine until you feel it stop. IF you go past...because you are still turning the engine and it did not stop it.

Climb out from under the car and LOOK at your balancer notch. IF you went past about 1-2 inches...thread in the bolt IN a bit further...then turn the engine in the opposite direction.

Keep doing this until you get the engine to stop turning. That way you are not turning the engine full turns to get it...just because you went past the "0" mark on timing tab.

Take a marker and make a mark on the balancer at the "0" mark on the balancer.

Then turn the engine in the other direction until it stops again. Make a mark at the "0" on the timing tab.

The distance between the two marks is TDC

Remove your tool and choose what needs to be done next. Such as buying a new balancer or using the new mark you made to set the timing...BUT...just be aware...that for that day you timed your engine with the new mark...it will work...but there will be no guarantee that the mark will stay if the outer ring of the balancer has already begun to spin.

By turning the engine SLOWLY...it will give the engine time to bleed off compression. And if you have any worries about putting a nick in the top of the piston...well that is all depending on how well rounded and smooth the end of the bolts is. Mine is rounded very well and polished slick. And how FAST you are trying to turn the engine when you get close to the point of contact. And ..manually..I seriously doubt that you could by hand produce enough torque to actually but a significant nick in the top of the piston....seriously....think about it.

Also...you can thread the bolt in a long way which will make it make contact...then turn the engine back a little bit...then thread the bolt out a bit and do it again... and again until you get to the point where the piston goes past the bolt. The you know you can thread the bolt it an make contact. I do it that way so when I have my marks on the balancer...they are closer together. Make sense???

DUB

 

Also...you can thread the bolt in a long way which will make it make contact...then turn the engine back a little bit...then thread the bolt out a bit and do it again... and again until you get to the point where the piston goes past the bolt. The you know you can thread the bolt it an make contact. I do it that way so when I have my marks on the balancer...they are closer together. Make sense???

That is how I do it.

In the original posters case, I think if you just ran the stop bolt in on the compression stroke, and walked the bolt out as you brought the piston up to kiss the bolt, you could watch the timing tab and balancer mark. In this case, we just need to verify there is not a gross parts mismatch causing a reading error. You could fine tune the TDC check once you confirm you are near zero with the installed parts just to check for slippage on the balancer.

I have a feeling that the problem here is that there is centrifugal advance being added in at the set idle speed.

- Mark

 

Your post sounds like you have experience using this method to locate exact TDC of any cylinder BUT the poster may not and it's important to express caution rotating any engine over when there is something sticking inside a cylinder that could possibly cause damage to his engine.

Tim

 

That may be the case, who knows. The car runs great with the timing set at 8 deg. BTDC. (eight marks on the tab) I have the TDC Locator ordered. It should be in next week. I will report what I find out from it.

 

Physics 101.
F=MA ( Force = Mass times Acceleration)
So there is no possible way that turning the engine SLOWLY by hand will generate enough acceleration to generate enough force to damage a piston. It is less force than what is occurring in the combustion process. And even though the force is being concentrated on a specific point...the end of the ROUNDED/POLISHED bolt...the aluminum will not even get slightly dimpled. If in doubt...get an old piston and hit it with a ball peen hammer and see what happens when you hit the crap out of it. And how hard you have to hit the piston to get even a slight mark to show up...which will be greater force than a person turning the engine SLOWLY by hand.

You can pull your arm back and punch at a brick wall and break your hand when you hit it...BUT...if you slowly move your hand to the wall and make contact with the wall..you will NOT break your hand.

And I expressed that. CLEARLY...I do not write information that can cause someone to damage anything. Common sense would dictate that COFFEE is HOT and I do not need to be told that it is HOT. And I am NOT implying that you or anyone needs to be told it is HOT. I know some people have to told that COFFEE is HOT. And writing "SLOWLY"...should command a specific response to that....thus turning the engine SLOWLY. Number 1 cylinder is the only cylinder important in the owners diagnostics...and hope fully they know that cylinder number 1 is the cylinder on the driver side of the engine closest to the front of the engine.

By the owner is turning it BY HAND SLOWLY and if they read my post...there are steps to STOP any damage.

BigT-65

I have encountered many engines that have the wrong timing tab. One quick test or visual check I do is to make sure that the timing tab is close to the outer ring....due to the diameters of some balancers used by GM are different. It should have a basic gap between the two of about 1/8" if not a little bit more.

I can not help it if people read information... and can not process or comprehend it and USE it. I am NOT implying that anyone reading this has a hard time comprehending information...but if the a person doing their own service/diagnostic work have concerns....then they should STOP and take it to someone who can do it.

DUB

 

I suppose my timing cover could be incorrect. I never thought about it. After experimenting with lower idle speeds and 4 and 6 timing marks I put it back on 8 and went for a test drive. As it is that's the best setting for this car. I have the TDC locator on order. It should be in soon. I'll post the test results when I get it sorted out.

 

Can you post a pic of the tab and balancer?
Brgds;
Rene

 

This is what it looks like.

 

I could be wrong, but that does not look like the right balancer. Looks like the one on a 78 Chevy Impala I had when I ws 15? It also looks too thin. The pulley on the balance is set too far back (note the belt angle) or the water pump/pulley is incorrect.

Again, not familiar with non SHP balancers. The 8" one on my 365/327 is about twice as wide.

Mark.

 

The thin harmonic damper is correct for the 250-300 hp 63-65. [do not know about 66-67]. The keyway on the damper inner ring also lines up with the stamped line on the outer ring that is used for timing.... Regardless of the shape of the tab, 0 on the tab must line up with the stamped line on the balancer at TDC. I have in my hand a thin damper that also has a line stamped on the INNER ring that lines up with the line on the outer ring. This will allow to see if the outer ring has slipped on the rubber bond between the two. The line on the inner ring would be visible on yours if you remove the lower pulley. I also have in my hand a correct timing cover the distance between the tab and balancer is 1/4 inch. Keep us informed when you locate TDC and the timing mark.
Brgds,
Rene

 

I am going to change my water pump within the next week. I should be able to see all these things after all that is out. The pulley on the balancer does look like it is back a little from the water pump one. I'll have to look into that too.

 

The damper does not have any "orange" on it so it may have been replaced. If you remove the lower pulley check and see if there is a bolt in the snout of the crank. Original 250/300 HP 327's did not have a bolt. There are some good threads on removal/installation of these pressed on dampers. You mentioned replacing the water pump, you might want to test fit the pump and pulleys for proper aiignment. The damper locates the bottom pulley fore and aft, you may have to press the hub on the water pump further aft to locate the belt. Make sure you add the water pump pulley reinforcement if it does not have one all ready. Next up is the proper alternator alignment; proper pulley on the alt is key.
Keep us informed.
Brgds,
Rene

 

I took another look at the pulleys and they look more in line than they appear in the picture. I think they are OK.

 

I'm still working on this one. I am having a problem with my fuel pump now, I think. Anyway now the order of importance is fuel pump, then water pump, then TDC. When I get it sorted out I'll be back.

 

OK, so I went ahead and did the TDC test with the TDC locator tool. It turns out that the TDC mark on the balancer is exactly in between the two marks I made with the locator tool. So where do I stand now? Looks like the balancer is not spun. Does it mean that the timing tab is not correct? And what difference does it make if each mark on the tab is 1 deg and not 2? Someone let me know if this is true.

 

Am I right?

 

At TDC, The mark on the balancer SHOULD be on the O on the timing TAB. If this is so, then the balancer matches the tab and you can use the timing light and set base time with each mark on the tab equaling 2 deg. If it does not get back to us. We will tell you how to proceed.
Brgds,
Rene

 

Not only is the index on the balancer exactly in between the two marks I made with the TDC tool it lines up exactly with the zero on the tab. If I assume that each mark on the tab is 2 deg and set the advance at 4 marks BTDC the car barely runs. If I assume that each mark is 1 deg and set the timing all the way up to 8 marks the engine runs great. Look at the picture a few posts back. The tab has 8 marks before and after the 0. This setup must be 1mark equals 1 deg. The engine is not original to this car. The numbers on the engine pad are barely readable. The casting date looks like it's a 1964. I think this engine has a 1deg per mark timing tab.

 

No way. The marks would have to be half as close together, which would be very hard to read. While idle timing makes a difference, you should be more concerned with your total. There is no load at idle and a bunch of extra initial usually won't cause a problem. Keep in mind that whatever is added to initial is being added to total, which the engine sees while under load. In many cases too much total isn't noticed because the car isn't driven under conditions where the timing is all in AND is under a heavy load at the same time.

 

You are doing good! You have estabilished that your balancer and tab are accurate. This IS crucial because now you have a valid reference when using your Dail Back to 0 timing light. Next step is to read "How to Set Your Timing for Peak Performance", by Lars Grimsrud. It is available at V8FastCars@msn.com. or on this forum. Vetterodder is correct, do not worry about initial timing YET. Lar's Technical Information Bulletin is your next step...
Again,You are making good progress, keep us informed.
Brgds,
Rene