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Best way to get engine to TCD for cyl #1?

Just curious if any experienced mechanics want to share a little trick(s) here. What is the best way(s) to know when a cylinder (let's say #1) is at TDC?

Next, is there a way to know whether it's TDC after the compression stroke or after the exhaust stroke?

I ask because I'm getting ready to do a couple timing belts on a couple different vehicles. One is very strait forward, but the other one seems a little more involved. I've had to get a cylinder at TDC before, but I had the valve cover off and could watch the valves opening and closing... I'd prefer not to take the valve cover off every time I need to get a cylinder to TDC though.



Appreciate the replies, minus the remarks... :-P

BTW, both the cars are mine, and they are both non-interference engines. I wouldn't be doing a timing belt on somebody else's car if I knew it were an interference engine.

6 Answers

  • 1 decade ago
    Favorite Answer

    Remove the #1 spark plug,hold your thumb over the plug hole and rotate the engine by hand.When you feel pressure you are coming up on

    compression.Continue to rotate the engine untill the timing mark is at 0 and you are there!

    Take out all the plugs and it will turn easier.

    If you can't see the plug hole you could screw in a compression gauge.

    Hope this helps.

    Source(s): Old guys rule!
  • ?
    Lv 6
    1 decade ago

    Apart from the obvious timing marks you can insert a thin rod in No1 plug hole and raise the piston to its highest point.

    If you have a distributor, with number 1 @ TDC the rotor will be pointing to number 1 lead when number 1 is on compression.

    If you don't have a distributor then you have to take off the valve cover and see where the cam lobes are.

    With number 1 @ TDC the cam lobes on number 1 should be facing away from the valves for the compression stroke and towards the valves for the exhaust stroke

    Source(s): Jules MIAME; M SAE Aust. Automotive technician, lecturer and examiner
  • 1 decade ago

    If you do not know, than you should let a real mechanic change the belt. Why? because some engines have zero tolerance for the gears or belt to be off even one tooth. If anything is not as it should be, you could slam a piston into a valve when you crank the engine. At that point you will be looking at head removal and valve replacement. In some cases you will have to buy a complete set of valves because single valves are not available.

    Only other advise, is check with your local library. Most have technical areas with Mitchell or Motors manuals. Some even have computer programs you can access and print instructions and diagrams.

    Good Luck.

    (retired mechanic)

  • 1 decade ago

    First you will need to identify the timing marks. That info is available in any repair manual. You will need a repair manual for this. Then, if such vehicle is equiped with an ignition distrbutor, you will need to align such timing marks as directed and also follow the ignition distributor rotor position, which will point to the spark plug wire for the cylinder at TDC of the compression stroke. If you follow the repair manual, it should be a slam dunk. All this will help and save the time and effort in removing the valve/cylinder head covers/s.

    Shoot any more questions you might have.

    Best wishes to you.

  • ?
    Lv 6
    1 decade ago

    Wow dude, I feel for the poor people that are getting their cars worked on by you. Cam -crank marks vary by the engine design. Some require the cam and crank marks to align in a straight line. Some motors have marks cast into the head/block/timing cover that have to align ,: ie dohc engines with 'silent shafts' . The cams have to be in a certain area as well as the balance shafts in relation to the crank being at tdc. Can`t wait to see what happens if you get to do a 4 cam v6 GM product. Don`t have the correct tools? Don`t do it. BTW , if you stick your finger down the plug hole when you crank it over, you can tell when it`s on the comp stroke, then just line up the crank marks. You Do know hoew to do that right?

  • 1 decade ago

    You are kidding right Richard hit the nail on the head don't touch it unless you know what you are doing. I have been working on cars for 40 years so I know what I am talking about.

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