Chevy Nova Forum banner

Finding TDC

3200 Views 29 Replies 9 Participants Last post by  JRouche
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
21 - 30 of 30 Posts
So would the assumption of the two factory marks be that one was zero and the other the 36-38 total mark ?
How do I tell if my balancer has slipped...got me worried.
I will borrow a dial indicator to check the TDC again..... to be more accurate
You don't stick your finger in the spark plug hole, you place your thumb over the hole to create a small seal. When the engine comes up on the compression stroke, the air int eh cylinder will blow past your thumb. That's how you know your on compression and not exhaust.

The only way to tell if a balancer has slipped (accurately) is to use the piston stop method and find where the true TDC mark should be. If it actually lines up with one mark on you balancer, then your balancer is fine.
Another way would be to remove the left valve cover and rotate engine until both ent.&ext. valves are closed (rockers on #1 are all the way up) This to would be TDC or 0 on balancer across from pointer. RIGHT ?
Another way would be to remove the left valve cover and rotate engine until both int.& exh. valves are closed (rockers on #1 are all the way up) This to would be TDC or 0 on balancer across from pointer. RIGHT ?
Remember this question was about indexing the balancer not setting in the distributor. Checking the valve position can help determine if you are on TDC compression or TDC exhaust when installing the distributor.

The valves will stay closed longer than just at exactly TDC compression. The timing mark is relative to the piston not the cam, so it won't tell you when the piston is at the top of the stroke.
Remember this question was about indexing the balancer not setting in the distributor. Checking the valve position can help determine if you are on TDC compression or TDC exhaust when installing the distributor.

The valves will stay closed longer than just at exactly TDC compression. The timing mark is relative to the piston not the cam, so it won't tell you when the piston is at the top of the stroke.
oh i forgot its way off subject but i want to thank you paul and your brothers and sisters for doing a fine job over there be safe and come home soon . be safe keep your gear tight and most of all keep your butt down :yes: and if you are state side then welcome home :thumbsup: :salute: :usa: these colors dont run !!!!!!
Another way would be to remove the left valve cover and rotate engine until both ent.&ext. valves are closed (rockers on #1 are all the way up) This to would be TDC or 0 on balancer across from pointer. RIGHT ?
Again, yer just eyeballin it. A simple indicator, a cheap one on top of the piston is what you need. I find it funny when many folks want cam specs., usually at .050" of valve lift, and feel thats important but dont think the crank angular position is just as important, IT IS.. JR
We all have different way's to achieve the same goal.It doesn't take much "eyeballin" to see both rockers on #1cylinder at there highest point before ext. valve starts to open.I'm not saying it's the only way,Just one of the ways to find TDC on the compression stroke.
We all have different way's to achieve the same goal.It doesn't take much "eyeballin" to see both rockers on #1cylinder at there highest point before ext. valve starts to open.I'm not saying it's the only way,Just one of the ways to find TDC on the compression stroke.
Again...doing it that way won't tell you when the piston is exactly at TDC. All the rocker position will tell you is which stroke your engine is on.
We all have different way's to achieve the same goal.It doesn't take much "eyeballin" to see both rockers on #1cylinder at there highest point before ext. valve starts to open.I'm not saying it's the only way,Just one of the ways to find TDC on the compression stroke.
You eyes can't see a 1 degree movement in the crankshaft, let alone by watching the rockers. The rockers will not tell you when the piston is at TDC. Yes, you do it your way to find the compression stroke, but then you must measure to find true TDC.
We all have different way's to achieve the same goal.
Well I guess so. There is a good way, a "gooder" way and a firm way. To each his own really. Just trying to help out a guy :) Im pretty sure I know where my TDC is :) Right between BDC and somewhere in between :) JR
21 - 30 of 30 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top