View Full Version : Checking mechanical timing idea.

01-07-2011, 05:42 AM
Ok I was thinking of a way for 5s guys to check mechanical timing using a ruler. What I was thinking was measuring from the rotor to a fixed point on the engine at 0* TDC on the crank. I know this is not by the bgb but with it being easier to do guys might be more inclined to checking it that way first. Without having a engine to try this out on I don't know if it is possible. And the other problem to this idea is the amount the rotor will move compared to one tooth on the cam gear. I am thinking this might be to small to measure with a ruler or other simple measuring devices. Just throwing this out there to see what people think or could try if they have a engine out of a car to try it on.

01-07-2011, 07:27 AM
Well the rotor would turn at about half the speed of the cam, so it would probably be extremely difficult to see how far it moves if the cam gear was moved by one tooth. I mean you might be able to tell if you have someone ELSE move the cam gear while you watch the rotor... But the other thing I would see is it would only be a judge of your camshaft timing. You know. If you broke a timing belt or something, that test would be basically worthless.

01-09-2011, 02:39 AM
I guess I didn't explain it well enough. If you put the crank a 0* TDC then if the timing belt was off one tooth on the cam gear it would show a little difference in position on the rotor. So all I have to have for reference is one of my 3s cam gears so being one tooth off is 7.824 degrees per tooth if I am calculating it right. 360 degrees/46 teeth=7.824. So with out having a rotor her I cannot find the diameter of what the outer most part or corner of the rotor will spin. Lets say 2in. diameter. So the circumference would be 6.28 in. so lets break it into 1/16 of a in. so lets just make it easy and say 6.25= 100. so now 360/100=3.6*.

So now if my thinking is right if you are one tooth off on the cam gear you will move the cam 7.824 degrees. If so then the rotor will move 7.824 degrees. So now the rotor moving 7.824 degrees at a diameter of 2in. Then a 1/16 of a in. of rotation will be 3.6 degrees. The Rotor in turn will move a little over a 1/8 in. since it would = 7.2 degrees at a 1/8 in.

So with a engine that has the correct mechanical timing taking a measurement of the rotor to a point that is 90* of the rotors position that is fixed. Then what the measurement would be to the same fixed point with the cam gear timing one tooth gear off.

Edit: One thing that might change is the width of the rotors head so this could change measurements depending on manufacture also. So that could be a down fall of this idea also.

Hopefully this explains my idea a little better.

01-09-2011, 03:17 AM

Whats wrong with using the timing mark on the cam?
It sounds like your unnecessarily complicating things.

01-09-2011, 03:55 AM
Sorry yes the explanation is complicated. It was just to get my idea across. The process is simple. Take what ever a stock or slightly modified celi needs to get the dist. cap off then take a measurement to a point on the engine that has been measured out before and see if the rotor is off like my examples 1/8 in. If it is then verify with taking off the valve cover upper timing belt cover and checking it with a mirror. I am talking something that could be verified very easily on the side of the road with a ruler and a few tools. like a few screw drivers and a ruler.

Thanks for the reply McCelica and alltracman78 for the replys. Like I said this might be a stupid idea so I am trying to back it up with good responses that make it a good idea. Since everything on a engine is a reference point this could be another one.

01-09-2011, 07:31 AM
OR..... you could just pull out a timing light, and check your timing. If your cam has jumped a tooth, then you won't be able to set your timing. Keeps you from having to dig under the car to set the car at TDC..

01-09-2011, 07:47 AM
I see the timing light deal. One thing the rotor in the distributor will have the same degree of timing to the cam. They are mechanically connected kind of like the cam gear and cam.

01-10-2011, 03:53 AM
If the 3S is off 1 tooth, it usually still runs. Runs like poo, but runs.
I don't think the 5S will run if it's off a tooth.

But usually if you lose timing it's more than just one tooth, and just comparing the rotor to the #1 plug wire on the cap will tell you.
You will still have to turn the crank by hand though.

The timing light trick will work with older cars and is a pretty good idea, but I don't think it will work on 96^, or anything else with an actual crank sensor, though if your timing is off like that it should throw codes.

01-10-2011, 05:23 PM
Well the rotor would turn at about half the speed of the cam

Um no, the rotor will turn exactly the same as the cam. the rotor is is connected to the cam. im sure you ment the crank right? yeah thats what i though you said

01-11-2011, 08:00 AM
Um no, the rotor will turn exactly the same as the cam. the rotor is is connected to the cam. im sure you ment the crank right? yeah thats what i though you said

That is what I meant. Thanks.

01-11-2011, 02:49 PM
5S will run if its off a tooth.

However, the 5S is so stupid easy to pull the valve cover off you might as well just do it the correct way. Not saying your idea doesnt have merit, it does, and its feasible, if YOU know it was set properly from the get go, but Id still rather just use the mark under the cover as it doesnt lie and it knows best every time.