The Stovebolt Site Forums The Shop Area Engine Shop top dead center

Hiya folks...

looking for advice/tips on the best ways to determine top dead center on a 235.

we have a shop manual for the this needs to eb so and so forth...

I am asking about, how to actually know when the piston is at tdc ? putting our fingers over the hole doesnt' look to be a good measure of doing it...

so, advice is appreciated.

thanks.

If noone else gives you GREAT instructions, I will send them to you in the mornings mail. I'm just to tired tonight. been a loooong day.-LOL

Take off your valve cover . Keeping your eye on the # 1 intake valve ( second valve from the front ) turn the engine until you see the spring on that valve rise up. That indicates that the valve has closed. Continue to rotate the engine until you see the timing mark line up with the pointer on the bell housing . Now you are at TDC..

Be sure to rotate the engine in the proper direction. You can look in your distributor and make sure the rotor is going along in order with the firing order. 1 5 3 6 2 4 ..

Do not do what my buddy did. He put a pencil in the spark plug hole. The pencil wasn't long enough and he dropped it in the cylinder.

That finger thing is dangerous..I usually wad up a piece of paper and insert it over the hole tightly..disconnect the coil wire, jar the engine till it blows out. That's TDC. Works for me.

Seon, that will only be TDC if the timing mark on the flywheel lines up too. Otherwise you could be 180* off.

Heya everyone, thanks...

53 4 me: that seems like a straightfoward way of doing things... I think we are going to try that on our engine in a few minutes here.

Thanks.

I love you guys!

How close are you trying to get? The ball in the flywheel isn't true tdc, it takes into account the timing, which is what, 8 degrees before? Putting your thumb over the plug hole works, but you need to be turning the engine by hand, not with the starter. If you're trying to set the distributor, either method will get you close enough to start the engine. Otherwise, put a long pencil in the plug hole when the piston is near tdc.

Heya folks...

We got the timing lined up, and nearabouts top dead center... but we did not have cap off the distributor.. heh... so I am just curious, whihc way does it rotate? I mean we'll mess with it some more tomorrow or whatever... but thought I would ask.

Also, when we got the makr lined up and the spring closed down and all that...

we popped the cap off the distributor and the rotor seemed to be sitting between the points... heh...

anyhoo.. all advice appreciated!

Wooger, The rotor rotates clockwise. In my earlier post, I told you how to determine rotation. If I can take the time to write , you gotta take the time to read, lol..

Look at the firing order of the wires on your cap. Start at #1, look next at the # 5 wire, then # 3, 1 5 3 6 2 4,,, The rotor hits the spots on the inside of the cap according to firing order..

If you rotated the motor the wrong way you are not at TDC. If you did it correctly the rotor should be pointed at the lug inside the cap that is hooked to the # 1 cylinder wire..

Is this engine running ? It is possible that you have installed the distributor off one tooth on the camshaft...

Top dead center is top dead center no matter which way you turn the engine because you are only talking about the pistons in their bore. Nunber 1 and 6 will both be on TDC at the same time. Now if you are talking about no. 1 fire then turn the engine over till no. 1 blows your finger off the spark plug hole then line the ball up with the pointer and that will be no. 1 fire. To adjust the timing you will have to turn the engint a tiny bit backwards till the pointer is lining up with about 6 or 8 degrees before TDC and the distributer rotor is lined up with the hole where no.1 wire is pluged in. Set the points to the correct gap, use an ohm meter and turn the distributer the opposite direction of the rotor till the ohm meter breaks contact. The engine should be real close to the running timing.

well true TDC can be found by taking a old spark plug and making a piston stop.

by removing the porcelain insulator and running a tap thru the center of the spark plug body.

screw a bolt thru the plug body so there is about 1" sticking thru the engine end of the spark plug body.

round the end of the bolt nice and round and smooth on a grinder.

install the plug in to # 1 cylinder with the piston down in the cylinder.

install a pointer on a timing gear cover bolt that sticks over the front pully.
if there is no pointer there to start with.
you can make a pointer out of a piece of stiff wire or welding rod.

remove all the other plugs so the engine can be turned easy.

be very careful and slowly turn the crank by hand or with a wrench untill the top of #1 piston contacts the spark plug piston stop bolt end.

now mark the front pully right under the pointer

be very careful and rotate the crank the other direction until the piston makes contact with the piston stop again.

mark the pully again now split the difference between the 1st mark and the 2nd mark and mark the pully and you have true top dead center and a zero refrence if you are using a degree wheel

don't ram the piston aginst the piston stop or you will punch a hole in or damage the top of the piston.

remove your custom made piston stop plug and throw it in your tool box and it should work on any engine that has a 14 mm plug

cool huh learned that one in 1956 reading hotrod mag and still have the first one i made and have used it a gazillion times

Isn't there a mark on the flywheel indicating UDC (Upper dead center)? I could have sworn I saw such marks on my 51 235 and I know for sure they are on a 52 216 I spent several intimate hours with this weekend. :p

Eastwood has cute tool, the Whistle Stop. A whistle that screws into the sparkplug hole. You crank the engine by hand, when it stops whistling you are at TDC. I have never tried it myself, but their bizarre tools seem to work. I love the Colour tune, a spark plug window that you screw in, that allows you to adjust your mixture by the color of combusion in the cylinder.
David

Yo, 53 4 Me...

yeah... you did tell me, but my distrubotr cap isn't marked at all.. and I guess I forgot about reading that...

oops.

and we didn't have the cap off in our zealousness to try out your advice... so we'll try again.

Thanks everyone.

Oh...

the distributor wasn't in the engine... no coil, no wires...

and it turns over now... but no it doesn't not run yet...

any advice on best way to drop in the distributor?

maybe that is part of the problem... heheh

the madness continues!

and thanks to everyone... for all the advice.

Wooger, what I usually do is put the cap on the distributor while it is out of the engine. Make a mark with a pencil or a marking pen on the distributor to line up the # 1 wire hole on the cap. Take off the cap and transfer the mark to the inside of the distributor where you will be able to line the mark up with the rotor later on.

Spin the motor by hand to TDC # 1 as we told you about earlier. Then drop the distributor in so that the point of the rotor is lined up with your mark. The rotor will want to spin a bit as you drop it in because the cam gear that you are meshing into is circular.. Keep trying until you get the distributor all the way down with the rotor pointing at # 1....

Keep at it buddy, you will get it eventually....

Thanks 53 4 Me.

well the distibutor was not in the block to start with... it was in a box in the cab.



along with the carb... and some other doodads as well.

we will be for trying this...

thanks alot 53 4 Me.

-W