How do you find TDC?

[TT/Ameasap]

I thought I could pull a plug and put a rope with a knot on the end, but thought there was a better way?

I would like to hear how you do it without the timing cover.

Thanks

 

[GN HEAD]

I used a degree wheel and a piston stop. I fabricated the piston stop out of an old spark pulg and a bolt that would fit inside the metal part of the plug, after I broke out the center part, and extend into the cylinder, an inch and a quarter or so, then welded it into the plug. Be sure the piston is no where near TDC and put the piston stop in #1 plug hole and with all other plugs out, GENTYLY rotate the crankshaft unitl the piston touches the stop....again...GENTLY. Record the reading on the degree wheel, now rotate the crank in the opposite direction until it touches the stop again. Record the reading.....now, exactly half way, between the recorded measurements is going to be the exact TDC. Don't forget to grind the end of the bolt, round, just as a precaution, so it doesn't scuff the piston.

 

[TT/Ameasap]

since I have the pan off, I was thinking of putting a dial indicator on # one piston and rotating to 0.

 

[MSDGN]

If the timing chain is there...with the timing cover off just line up the marks on the cam gear and crank gear...cam gear mark in the 6:00 O' clock position and crank gear mark in 12:00 O' clock...that's TDC (compression stroke)...

 

[TT/Ameasap]

cam is already out.

 

[pacecarta]

the keyway is cut dead center of the #1 journal
point the keyway on crank to center of #1 cylinder thats puts #1 piston at the top


curious as to why you need to find TDC with no cam in engine ???
deck height i could see but TDC no

 

[TT/Ameasap]

Im replacing a worn cam to a roller cam. I took everything apart and read in a book that I should find TDC before anything. So your saying I can just put the roller cam in and line the timing gear mark at 9 and the crank at 12 to put it tdc?

 

[pacecarta]

until the rocker arms go in there no chance of hitting valves when alianing the gears

i'm sure the 9oclock was a typo, its 6:00 on cam gear 12:00 on crank (dot to dot ),
with crank gear at 12 the #1 piston is at tdc

TDC compression will only come into play after the rocker arms are on

after cam is fully installed and rockers are on with balancer in place you will have to rotate engine and feel for pressure in #1 cylinder to find TDC compression stroke , as you feel pressure continue to rotate until timing mark on balancer is 1.45" past zero on balancer , then you can prime the engine and then drop the cam sensor in and set it either with the casper tool or voltmeter method

 

[TURBOTWIN2]

Uh, with no cam and the oil pan off, don't you simply just need to bring the #1 piston up to the top? You could then find the exact center by a variety of methods. HTH.

 

[TT/Ameasap]

Uh, with no cam and the oil pan off, don't you simply just need to bring the #1 piston up to the top? You could then find the exact center by a variety of methods. HTH.

Thats what im thinking now. Why couldnt I put a indicator on it to be exact and install the cam with the dots at 6 and 12?

 

[noahzark]

im degreeing my cam on my engine as we speak...using the degree wheel and a dial indicator on the lifter body of number one cylinder...not really getting the right readings as per my cam card at the moment...so not really sure what im doing wrong...

basically zero the dial indicator and zero the degree wheel...at the point the intake lifter is on the bottom/flat of the cam lobe....timing chain is lined up at 6 and 12

turn engine clockwise until the intake lifter starts to ramp upwards and dial indicator starts to move...when dial ind hits .50 lift write down degree wheel reading....continue to turn engine and when lobe is at the top of revolution and dial ind stops moving you can record your total lift example...@110 lobe...
then continue to turn until dial ind starts to move back and when it hits .50 lift on the downstroke downside of the cam lobe record the reading on the degree wheel...

apparently those two readings should match the ones on the cam card that comes with the cam purchased...my numbers arent really matching up and not so sure what numbers on the card i need to match...btw im doing all of this obviously with the timing cover off and just using piston number one and just one lifter set....

going to try again tomorrow anyone who can be more specific for this method would help...i dont have a piston stop nor do i have the heads installed to make my own spark plug piston stop so thats why im doing the lifter method...not to mention it is supposed to be the most accurate way to degree a cam anyway....

thanks for help or input...noah.