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Author Topic:   TDC
intimidtr3
Dirt Full Roller

Total posts: 32
posted October 03, 2002 06:01 AM
I have a 77 350 that I bought and when i went to replace the timing chain the marks dont line up,been told that dots should point up and been told they should point towards each other,which is it?I need to put it together and I was wondering if they dont line up do you turn the cam until they do.Thanks for any help.

Geffy95x
Dirt Maniac

Total posts: 122
posted October 03, 2002 08:52 AM
Them there dot's like to be close together in the middle and then you should be right on the money.

ray14
Dirt Full Roller

Total posts: 67
posted October 03, 2002 09:17 AM
the dot on the cam sprocket should be pointing down towards the crank and the crank dot should be pointing up inline with the top dot,u get the motor on tdc and then turn ur cam sprocket to get the cam in time with the crank. thats how i do it an never had any problems.unless you want to get techinical with the timing an use a degree wheel.

sideways
Dirt Freak

Total posts: 273
posted October 03, 2002 04:58 PM
The cam "sprocket"dot(on top dead center on #1)should be pointing up and the crank dot also pointing up.When they are "lined up"#6 is on its compresion stroke. hope this helps

Wheels47
Dirt Maniac

Total posts: 127
posted October 03, 2002 06:13 PM
Sideways I've never timed and engine that way--can you explain how it would work. I've always time the 2 marks pointing at each other. Cam dot down and crank dot up. This gives you top dead center on #1 cyl. Hmmm that could work and have #6 up I guess but if you do it with dots together it is very easy to do do distributor timing also.

Just my 2 cents worth--Wheels

6pack
Dirt Maniac

Total posts: 128
posted October 03, 2002 06:24 PM
If you line them up "dot to dot" and turn the crank one revolution the dot on the cam sprocket will be at the top. The crank turns twice for every turn of the cam.

carscomefirst
Dirt Full Roller

Total posts: 45
posted October 03, 2002 06:50 PM

With the cam dot down and the crank dot up a sbc is TDC compression stroke on #6 and TDC exhaust on #1. If you try to time your dist like this you will be 180 degrees out. With both dots up it will be TDC comp. #1 and TDC ex #6. As far as cam timming goes it really doesn't matter. 6 of 1 or 1/2 dozen of another.

ray14
Dirt Full Roller

Total posts: 67
posted October 03, 2002 11:11 PM
all i know is that i put mine dot to dot and done it for years i have no problems with the timing.but u can also do it with top dot up and bottom dot up thats what i have heard an sean it done but i will not do it. i have a stupid question,say ur ehgine has no heads on it it sitting on stand ur putting timing chain in it #1 is at tdc how the heck u going to say its on exhaust when that piston is at tdc it is on compression stroke.might be wrong but thats how i do it

intimidtr3
Dirt Full Roller

Total posts: 32
posted October 04, 2002 03:56 AM
Thank you all for the help.I think I confirmed what I thought and continue on with putting it together.Much appreciated.

6pack
Dirt Maniac

Total posts: 128
posted October 06, 2002 10:17 PM
It's a four stroke engine; intake, compression, power, exhaust. Piston comes to the top on the compression stroke and the exhaust stroke.

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