Iv'e have a question. To find tdc using a piston stop make sure piston is down in the cyl. Install stop in #1 spark plug hole, slowly rotate c/w until piston hits stop.mark spot on balencer across from pointer. Then rotate engine cc/w until piston stops again,also mark this spot across from pointer.Half way beteen these marks is TDC. remove stop ,rotate engine so the middle mark lines up with pointer.You should now be at TDC, Correct? Also i have a solid lifter cam(int.520exh.540. dur. @.050 int.244 exh252) To set timing,rotate engine from the 0 mark to mabey 18deg.btdc Remove dist. cap and verify rotor pointing to #1 dist. post, Sorry for being so long just wanted to be sure. Thanks to everyone
Finding TDC
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ARE you degreeing the cam or is it already to gether finding tdc is sometimes confusing i usually bump motor over until the dampners zero mark lines up with my timing tab zero mark remember its got to rotate twice this should put you at tdc. i will explain it again take out your piston stop out for now rotate motor over by hand til the dampner zero lines up with the timing tab zero mark. remember it has to rotate twice. if you only do it once you will have number 6 at tdc so go another 360 and blamo you should be at tdc. now install distributer the rotor should point to the corner of the #1 valve cover if it doesnt you may need to rotate the oil pump shaft to get it to line up. if your valve covers are off both intake and exhaust valves should be seated and #1 intake should just start opening if you where to rotate the motor again. i hope this helps there are other ways to do it also so im sure someelse will respond as well. my way is pretty easy
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oh ok are you having other issues as well or is it a fresh motor and getting ready to fire it up
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oh ok then try this if you have a starter bumper. unplug your distributer take off the cap pull # 1 spark plug out place your thumb over spark plug hole and bump motor over you should feel air blow your thumb off once you feel this stop bumping and look to see where you dampner mark is at. it might be at 8 degrees before tdc i try to get it to line up (dampner zeromark to timingt tab zeromark) now see where your rotor is at if its pointing to the coner of number 1 then you are all good if its pointed at the firewall your distributer is 180 out
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The procedure you described for finding true TDC is right on the money.
Were you able to find out why there was such a large discrepancy between your initial timing measurements and what is considered normal? I was looking for an update on that thread, but I think it may have been deleted for some reason.
Dan
It wasn't deleted: Timing Question ~Paul W
Were you able to find out why there was such a large discrepancy between your initial timing measurements and what is considered normal? I was looking for an update on that thread, but I think it may have been deleted for some reason.
Dan
It wasn't deleted: Timing Question ~Paul W
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hello dan where you refering to my answer or his original thread i dont want to post incorrect information on this site :yes:
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Yup, thats how you do it, pretty simple. I use an indicator down in the bore too, but all the same. Whats going on? Not sure your timing marks are right? Been there done that, like what do you trust if they dont match up. Well, the solid measurements dont lie. If you measured twice, three times if yer anal like me and the timing marks are still off then they are off. Just re-position your timing pointer. JR
I really don't know why the marks were so far off? I always check everything twice,But I made a mistake somewhere.I'll set TDC and that will give me alot of information.I wanted to make sure i was doing it right.Thanks so much everyone
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If youve smashed your thumb as many times as me than its readings would be inaccurate. I wad a paper towel in there.
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A couple of observations:
1. The marks are so wide there's a good chance you'll still be off a degree or two. I would use a small machinist square and a scribe.
2. If your observed mark is that far off from the factory mark, I would say the outer ring has slipped and is no long bonded to the inner hub. That balancer needs replacing.
You want to align your rotor to the #1 terminal on the cap, not some place near the #1 cylinder. The engine will start easier if you don't index the rotor to TDC. The reason is the spark plug doesn't fire at TDC. It fires at 8-12 degrees before TDC. Once you find compression TDC, rotate the balancer back to whatever your base timing, is then put the distributor in.
Another common timing mistake that people make is assuming that when the cam sprocket dots line up, the engine is at compression TDC. That's true on Ford's but not on Chevy's. Sprocket alignment coincides with #6 compression TDC and #1 exhaust TDC.
1. The marks are so wide there's a good chance you'll still be off a degree or two. I would use a small machinist square and a scribe.
2. If your observed mark is that far off from the factory mark, I would say the outer ring has slipped and is no long bonded to the inner hub. That balancer needs replacing.
You want to align your rotor to the #1 terminal on the cap, not some place near the #1 cylinder. The engine will start easier if you don't index the rotor to TDC. The reason is the spark plug doesn't fire at TDC. It fires at 8-12 degrees before TDC. Once you find compression TDC, rotate the balancer back to whatever your base timing, is then put the distributor in.
Another common timing mistake that people make is assuming that when the cam sprocket dots line up, the engine is at compression TDC. That's true on Ford's but not on Chevy's. Sprocket alignment coincides with #6 compression TDC and #1 exhaust TDC.
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:yes::yes::yes::yes::yes:
I also (on bonded rings) continue the final line into the center hub and on the crank pulley. They if anything ever "Slips" it's obvious at a glance.:yes:
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By George I think I got it.
I used the piston stop method then another method to determine TDC - I pulled out the threaded stop from the piston stop while in the #1 spark plug hole and put in a length of plastic tubing in . Placed the other end of the tubing into a clean clear plastic bottle of new engine oil. Cranked motor clockwise with breaker bar. As you keep turning the motor, bubbles will be blown into the oil until the piston reaches the top, when the piston starts back down, the oil will be sucked into the tube. I stopped when bubbles stopped and oil just barely drawn up 1 cm into tube. Pulled tube out of oil. Made a mark on the balancer. Put tube back in oil as you come around to # 1 pistion cranking counter clockwise, again bubbles will be blown into the oil from piston #1 until the piston reaches the top. Made a mark on the balancer.
Distance between 2 marks is 5/8 of an inch, so half of that is Zero.
The balancer had two marks/cuts I assume from the factory already in it. You can see them in picture as well as chalk marks I made of the 2 TDC marks.
So if all is well. I will make the Zero mark and line up my balancer tape with Zero and stick it on the balancer.
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I used the piston stop method then another method to determine TDC - I pulled out the threaded stop from the piston stop while in the #1 spark plug hole and put in a length of plastic tubing in . Placed the other end of the tubing into a clean clear plastic bottle of new engine oil. Cranked motor clockwise with breaker bar. As you keep turning the motor, bubbles will be blown into the oil until the piston reaches the top, when the piston starts back down, the oil will be sucked into the tube. I stopped when bubbles stopped and oil just barely drawn up 1 cm into tube. Pulled tube out of oil. Made a mark on the balancer. Put tube back in oil as you come around to # 1 pistion cranking counter clockwise, again bubbles will be blown into the oil from piston #1 until the piston reaches the top. Made a mark on the balancer.
Distance between 2 marks is 5/8 of an inch, so half of that is Zero.
The balancer had two marks/cuts I assume from the factory already in it. You can see them in picture as well as chalk marks I made of the 2 TDC marks.
So if all is well. I will make the Zero mark and line up my balancer tape with Zero and stick it on the balancer.
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WHAT??? No one uses a dial indicator?? Am I the olny one, its so simple and accurate.
Ok,,, I like your ingenuity and need to play with new methods, interesting. I just think about any air leaks from the valves or rings giving you some wrong readings. You stuff an indicator rod down in the hole and will see EXACTLY where yer TDC is. Rotate the crank around the other direction and take another reading, a lil simple math and there you go. It will be EXACT.. JR
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sorry guys for posting incorrect info. although i have tried the two other methods and they didnt work for me i have a degreed balancer on my motor with the tdc mark already in it. when i degree the cam i usually do the dot over dot method like comp cams showed and use the intake center line method, i also install my dampner at the same time to make sure everything lines up this way i dont forget i also write down everything. when im finished with degreeing the cam i usually install the distributer to make sure its in the right spot as well. i was only saying to use an area around number 1 as a referance point that way it goes in the same way it came out. and i dont stick my thumb in the spark plug hole ( dont fit ) but like i said im very sorry for posting the wrong info. i guess i still dont know what im doing yet :no:
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You do realize that when the cam dots line up that's not TDC compression on a small block Chevy? If you install the distributor at this TDC it will be 180 degrees off (360 crank degrees).
What the original thread was about was verifying the damper timing mark is true TDC. Never assume the mark on the balancer is correct. A 2 degree error is going to cost some power or risk expensive parts damage from detonation.
I agree that the most accurate way is with the heads off and use a dial indicator. Less accurate ways give less accurate results.
If you find your balancer is off significantly, then the elastomer ring has become unbonded and MUST be replaced. Don't just remark it, because it will continue to slip and never be right. the damper can no longer absorb vibrations if the elastomer is not bonded to the hub and outer ring.
Not to mention the outer ring might fly apart and hit you in the eye while you are looking at it with the timing light wondering why the timing doesn't stay adjusted.
What the original thread was about was verifying the damper timing mark is true TDC. Never assume the mark on the balancer is correct. A 2 degree error is going to cost some power or risk expensive parts damage from detonation.
I agree that the most accurate way is with the heads off and use a dial indicator. Less accurate ways give less accurate results.
If you find your balancer is off significantly, then the elastomer ring has become unbonded and MUST be replaced. Don't just remark it, because it will continue to slip and never be right. the damper can no longer absorb vibrations if the elastomer is not bonded to the hub and outer ring.
Not to mention the outer ring might fly apart and hit you in the eye while you are looking at it with the timing light wondering why the timing doesn't stay adjusted.
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