Top Dead Center

[wishwick]

I replaced my timing belt and thought everything was ok because the car started and idled fine. Then I tried to drive it and it was obvious the timing was OFF.
I don't have any marks to line the crankshaft to TDC. How do I find top dead center? Someone told me that I could turn the crankshaft until cylindar one was all the way up and that would be top dead center. Is this true?

[2ndGenGuy]

Yeah, cylinder 1 being all the way up is top dead center. You might be able to pull a spark plug and shine a flashlight in the hole if you can get your head down there, or use a screwdriver as a feeler for the piston. Then you can feel for when the piston hits the top and starts to go back down. Just be careful, don't score anything up inside there!!

You should have a TDC mark on your flywheel. Try using a long skinny brush with some kind of degreaser down in the peep hole for the flywheel and clean it off. Likely it's covered in leaky oil from the rear main seal leaking. That's what was going on with mine. If you can get this clean, you can also get your ignition timing set properly too, which will save gas and give you more power.

If you can get it all clean, you should be able to find that mark...

[DDRaptor]

yeah my man i'm on the same book.
i'm gonna do mine tommorow so i'm gonna try what 2nd gen guy said.

err i have a question how whill i know the if im at the top at the comp stroke or the exhaust stroke.

[LX-incredible]

All 3 valves will be closed. An easy way to see if you are on the compression stroke is to take a hose that fits snug in the hole, and blow through it. If it is hard to blow through, the valves are closed.

[DDRaptor]

thank you that solves all my issues.

now i can start bright and early to redoing my timing.
wait err i think my engine is off by 2 strokes, so i would check the valves first to know what stroke the cam is at. then I should try to turn the crank 1 revolution then try to start again???

[DDRaptor]

hey these guys are right i fudged it up. genious (myself) set the timing wrong.

so belive me when i say that using a hose to test the shut valves works, and the screwdriver in piston one works too. i got my car to tart again i set the timing to exactly 15 using my light with advance, but it stills rns kinda sluggish only the gas mileage will tell.

[2oodoor]

some of these cars have the tdc mark on the flywheel, scribed, it is barely readable it is looks like this -T- the T letter and two hash marks
also you can try a little more advance timing on the dizzy to get it more crisp off idle, not too much though

[88Accord-DX]

TDC on #1 compression stroke is found by the 'T' mark on the flywheel or flexplate, with the camshaft sprocket lined up with both marks parallel with the head. No valves should be on the top of the camshaft lobes on #1 cylinder.
Base timing is set with vacuum lines plugged on the distributor & should hit the 'T' mark with a timing gun. Any variation + or - 5 degrees is probably worn shaft bushings.

[2ndGenGuy]

If the piston is at the top, it is the same for either stroke! The cam is what sets the stroke. Just make sure that piston is at the top, and line up the cam. Remember, the crank will be EXACTLY the same on either stroke, so it doesn't matter. I had to think about this myself, but the crank turns two times for each turn of the cam.

Just line up TDC, then line up the mark on the cam pulley. That will GUARANTEE that it's all good to go! :)

[DDRaptor]

yeah the crank does'nt really matter it's all in the head once i realized that i was able to set the timing 4 times until i got it right.

on my car i have on the flywheel i have 3 lines 2 black and one red between them. so i'm guessing that the red is TDC.

[2oodoor]

yeah the crank does'nt really matter it's all in the head once i realized that i was able to set the timing 4 times until i got it right.
on my car i have on the flywheel i have 3 lines 2 black and one red between them. so i'm guessing that the red is TDC.
no that is not it DDraptor, by all means it is a very honest mistake though, I dont know why they have so many marks. That is the mark for setting the ign timing with light. The red mark is 15 btdc if I am not mistaken.
To set up the cam timing you use either a white mark, which Ive never seen but that is what some books say, or the scribed T mark which is not painted at all.
Also, I dont think these cars can be set with #4 cyl.

I know none of this makes sense but trust me

[88Accord-DX]

nevermind

[DDRaptor]

Cylinder #4?? please don't tell me i did it all wrong in thinking that the cylinder closest to the drive belts is cylinder #1???

[LX-incredible]

No, cyl #1 is the closest to the belts.

[2ndGenGuy]

no that is not it DDraptor, by all means it is a very honest mistake though, I dont know why they have so many marks. That is the mark for setting the ign timing with light. The red mark is 15 btdc if I am not mistaken.
To set up the cam timing you use either a white mark, which Ive never seen but that is what some books say, or the scribed T mark which is not painted at all.
Also, I dont think these cars can be set with #4 cyl.
I know none of this makes sense but trust me

Those marks are there. They should be there. If they weren't, I wouldn't have been able to do my timing belt just recently. You can't feel or look for the piston on a CVCC motor. Also, when the distributor advances, the timing lines up with that, so it fires at top dead center when it advances. It's the best way to check to make sure your vacuum advance is working properly. Maybe your flywheel is just dirty... My stock one was, and you couldn't see the marks until we cleaned it off to transfer them onto the new flywheel. We marked it with a good notch on the new flywheel, then applied fluorescent orange paint. Easy to see now! :)

The TDC mark is WAY away from the 3 timing marks. Don't use those 3 to do anything except set your spark timing.

[DDRaptor]

ok phew. cool, does anyone else gets a weird sound after they had there belt replaced ever since my belt was changed if you hammer the gas down it shoulds like some piece of metal is vibrating and i have no idea what it is. also another question i wanted to ask is, how do you guys set the timing exactly

because when i first put it on an started it i had used a screwdriver to figure out the top and then i put the belt on right there and started it. Ran really bad. so i did it again i got it to the top then i put the belt on marked the tooth where it met UP and then moved the crank a bit so that the cylinder wasn't completely at the top of it's stroke but one tooth forward, and so far that seems to be good but it still does'nt have the power it used to have but i just filled up the tank yesterday and we will see how long it lasts.

[2ndGenGuy]

Sounds like your timing belt is still off. The crank moves really easily when you're trying to line the belt up on the cam. I hope you didn't just move the piston up until it touched the screwdriver and figured that was TDC. You need to feel the piston as it moves up until it quits moving up, but before it starts moving back down. Though this really is a last-resort kinda deal... you should really try to find the mark on your flywheel it's so much more precise...

I'm going to guess that you're one tooth off. It's sooo easy to do.

I wish Honda did the Accords like they did with the Civics, where the TDC mark is lined up on the crank pulley with a mark on the timing belt cover. That's SOOO much easier...

[DDRaptor]

I think instead of pushing it forward i should have put it one tooth back. and then use the dizzy to time the spark firing perfectly.

[2oodoor]

Also, when the distributor advances, the timing lines up with that, so it fires at top dead center when it advances. It's the best way to check to make sure your vacuum advance is working properly.
The TDC mark is WAY away from the 3 timing marks. Don't use those 3 to do anything except set your spark timing.

When the engine revved it is not firing at Top Dead Center, it advances BTC via vaccuum advance then the centrifical advance comes in. When you rev while looking with a timing light you will see it move from your setting at idle>> up to and then past the other marks if both advance systems are working right.
2nd GenGuy for a minute you totally lost me, then the last sentence tells me you are on the right track...:)

[2ndGenGuy]

So, I thought that the spark happened before top dead center, so that way the gas ignites as the piston is coming up, the ignition and compression happens at the same time at idle. Harder on the components, but you're idling so it doesn't wear...

But as the engine speeds up, you advance it, the timing gets closer to top dead center, for a more precise and powerful burn. And if you advance the spark so it fires slightly After TDC (as the piston is travelling down) you will get a more powerful, but slightly less complete burn. I thought this was because you're firing as the piston is already on it's way down, where the rod has the greatest mechanical advantage on the crank...

Do I understand correctly, or am I just way off? :)

[LX-incredible]

But as the engine speeds up, you advance it, the timing gets closer to top dead center, for a more precise and powerful burn. And if you advance the spark so it fires slightly After TDC (as the piston is travelling down) you will get a more powerful, but slightly less complete burn. I thought this was because you're firing as the piston is already on it's way down, where the rod has the greatest mechanical advantage on the crank...

Do I understand correctly, or am I just way off? :)
It's the other way around. Since it takes time to ignite the mixture, the timing is advanced at higher speeds. This ensures that the piston is being forced on by the fully ignited mixture and not being pulled down by the crank first.

[2ndGenGuy]

Wait, that's what I was saying... Timing is advanced at higher speeds.

Maybe I'm confused what timing advancing the means though. I thought advancing the timing causes it to ignite closer to or after TDC.

The stock timing at idle is set 15 degrees BEFORE top dead center, which is retarded timing compared to say 10 degreed BTDC, isn't it? Any ignition timing that is AFTER top dead center is advanced even further isn't it??

I thought that as the RPMs got higher, ignition firing before TDC got harder and harder on the block, pistons, rods, crank, etc. And this is why it advances closer to TDC; so it doesn't fire as the piston is compressing the mixture at such high speeds.

Does that make sense, or is that way off still?

[2ndGenGuy]

Okay, I just did some research. Googley Action. It makes sense now: Advancing the timing makes the spark happen sooner. So it would be further BEFORE top dead center. I was completely backwards before...

This article explains is well! And has some excellent math. Might look into playing with spark timing a bit to get a touch more juice out of the ol ES2.

http://www.miata.net/garage/KnowYourCar/S10_Timing.html

[Oldblueaccord]

I marked my crank pully once I got TDC since im over there cranking it with a rachet anyway. it helps get it close then I look thru the window to get it right on. I used chalk to highlight the T mark after I cleaned it. You can put a screwdriver in the flywheel teeth to jam it while your getting the belt on.

If you use a flash light you can see the top of the piston thru the spark plug hole. On compression stroke you can feel air come out of the spark plug hole as well with it all together.


wp

[DDRaptor]

So wait i still have to clean the flywheel with a toothbrush cause i never seen the T i need a good flashlight to see it. Good article find.

i wish i had a dyno lol, now i seriously have to find that damn T, so wait what do you guys do when you find the T do you place the belt right on there or do you move back or forward??? like i did.

Since the first time i did it i found top and put the belt on right there and i ran like crap.

[DDRaptor]

FOUND THE INFAMOUS T

Problem is it still ran like do doo, because the timing wasn't advanced enough with makes me believe that i need to move it ever so slightly forward by 1 tooth and then hopefully the dizzy can do the rest.

yes i used my timing light to check the advancement it was way under15 around 4-5deg. so i'm gonna try again and move the belt a tooth forward after finding T.

Laters.

laters.

[DDRaptor]

It took really long but i did it right now she runs and pulls like she used to, i lined up the T and took the time to make sure the cam gear was lined up with the block. It works perfectly i'm proud but embarassed that i took so long just to do a simple adjustment but now i'm extremely comfortable adjusting the timeing on my vehicle so I guess i have a learning curve but's it ok.

i would do a write with pictures but i don't have a camera anymore it died after 3 years think the lens died and poor right now, but i can do it in written but i don't think anyone needs that right now.