lets say someone aligned the timing marks on the sprockets for thier gear drive with the one on the cam @12 o clock and the crank @12 o clock. Can this engine be timed correctly without tearing the front back off the engine? Could i get it to TDC on compression stroke then rotate it 180 or would it be 360 and drop in the distributor with the rotor pointing at #1? it is a 1970 350. I have been going for a week now. then i remembered i lined them up this way because someone told me to do it that way ( i know it was probably ) i had never heard it done that way before so i tried it. It will make me if i have to tear this apart again. by the way it did start like this after i changed some plug wires around. but it was obviously not right so i shut it down. thanks for any help you can give me.

 

Never heard of crank 6:00 and cam 12:00,
are you sure it wasn't cam at 6:00 and crank at 12:00?
If so, that is TDC firing stroke for # 6 cyl.

 

i put the wrong info down sorry it is cam at 12 crank at 12. thats how screwed up i am with this i cant even tell time right. lol

 

Cam at 12 and crank at 12 is TDC firing stroke for #1 cyl,
you are good to go!

 

This is incorrect; crank sprocket dot is at 12, cam sprocket is at 6!

 

GNKJOY is correct

 

Either way is correct as long as you know the set up.

Cam at 12 and Crank at 12 is TDC firing stroke for cylinder #1.
Cam at 6 and Crank at 12 is TDC firing stroke for cylinder #6.

Many people get confused and install Cam at 6 and Crank at 12 and then drop the distributor
in with rotor pointing at the #1 cylinder and wonder why the engine won't run.

 

IMOP
A – When installing a cam & timing chain, #1 Cylinder TDC, Crank timing mark at 12 and Cam timing mark at 6. That would be dots together as shown in most installation guides (this would be firing position for #6 cylinder)

B – When installing the Distributor, #1 Cylinder TDC, Crank timing mark at 12 and Cam timing mark at 12. (This would be firing position for #1 cylinder)

Is that correct?-?

 

This isn't the first time this subject has been discussed and disagreed upon. I have always done it the way ghkjoy and sstocker31 believe is correct which is crank at 12 and cam at 6 in order to time #1. It's always worked for me. How can there be 2 opposite methods for doing this?
Terry

 

The entire discussion is moot because if one aligns the cam at 12:00 and the crank at 12:00, and you turn the crank one full turn, now they're aligned with the cam at 6:00 and the crank at 12:00! It makes no difference!

As for the rest of the story, when you're finishing up getting everything all back together, just make sure that you rotate the crank to put the #1 piston at the FIRING TDC (NOT at the overlap TDC). Then set your distributor so that the rotor points toward the #1 cylinder; and then rotate the housing so that the vacuum advance points toward the right front tire; insert the plug wires clockwise in the firing sequence and you're going to be quite close!


PS: Two ways to ensure you're at FIRING TDC...
1. There will be compression at #1 as the piston rises (thumb over the plug hole).
OR,
2. The #3 intake valve will be open and the rocker arm is holding it open when #1 is at FIRING TDC.

 

Larry is right. If you just do the timing marks w/o degreeing the cam either location gives the same results. I did find on my last cam though I could only degree it with the marks at the 12/12 positions. Well thats because i was using #1 cyl vlvs to degree the cam. If i used cyl #6 vlvs i'm shure the 12 o'clock crank and 6 o'clock position for cam would be required. But again if just using the marks to set up the cam u are good to go with either method. Just don't be off by a timing tooth as i recall will put like 8.3 degrees off for the cam or maybe like 14.5 degrees off for the crank (awe heck u would need to count the number of cam teeth and divide that number into 360 to figure it).

I think your firing order of intial timing may incorrect if you have problems. Now u can pop the dist cap and make shure the rotor points directly at the #1 plug wire terminal when the balancer timing mark is at 0 to 10 degrees adv. And that rotor points at #6 plug wire when the crank rotates once (360 degrees). Or it could point at #6 first then #1 on the next rotation.
Now to check which should fire on which rotation u need to pop both vlv covers then see which vlvs are rocking open at 0 to 10 degrees adv on the balancer timing mark. The vlvs that stay shut of course are the ones ready to fire and thats the cyl that the rotor cap should point to its plug wire/terminal.

Wehoo, thats a lot for me to type but i hope it helps figure your timing order (18436572).

cardo0

 

thank you everyone for your replies and help i will let you know when i get back in town this weekend and mess with it some more.

 

well i had a friend come over the same one that told me to set the timing marks at 12 & 12 he set the timing but there is still a little poping when the vacume advance is connected. ( he did not have to pull out the distributor either so i guess i was kinda close) if i unplug it from the carb it stops any ideas? My friend said i need a new distributor that has a hotter spark and better plugs. He said rt45 ts . Do you think this will solve the minor poping? He said some cars with big cams do this when they are idiling. It goes away when you throttle up also. i think i am almost there. Then its off to the paint shop. by the way i dont know if i mentioned it but this is a 1970 vette