Well i have finally got the new cam installed and i'm ready to begin the process of putting the engine back together. I believe i have the #1 cyl at TDC on the compression stroke but need some clarification/confirmation. The timing chain sprokets, timing cover, dampener, and intake are all removed. The pushrods and rockers have all been replaced so i also need to be sure i'm at the proper starting point to adjust the valves, of which i have Lars' paper on proper valve adjustment . I removed #1 spark plug and began to turn the crank, my wife was at the #1 spark plug hole with a finger covering the whole, as continued to turn the crank she felt a puff of air forced out the #1 plug hole, this is the compression stroke, correct? I brought #1 piston up to the top and stopped. I placed the dampener on the crank temporarily and it was at TDC, I also installed the distributor it aligned at #1 also, so all indicators are i'm at TDC on the compression stroke, unless i've missed/forgotten something ! Am i good to go or do i need to start over?

 

Yes, and verify by making sure both (#1 intake & exh.) valves are closed.

YBnormal...drive a vette

 

stupid questions , with the rocker arms and pushrods removed will the valves still open and close while turning the crank? How will i know whether the valves are open or closed?

 

By lining the dot on the cam sprocket and crank, you should be good. The dot on the crank will alway point up at TDC if you have a stock sprocket. There are other sprocket that have preset advances on them, so follow there directions if that is the case. So saying that, If you turn the crank and one revolution the sprocket dot will be up, but the cam dot will be on top. ie exhaust stroke. One more time for compression stroke. Dot to dot. You can follow this with the push rods to.

 

With both dots together, you are at #6 TDC firing position.

With crank dot up and cam dot up, you are at #1 TDC firing position.

Without the valvetrain, you will get a puff in the #1 spark plug hole at #1 TCD firing position but you also get a puff in the #1 hole while it is at the #6 TDC firing position so that is not a good indicator.

Line up the dots together first to be sure the gears are timed correctly then rotate the crank 360 degrees to where both the crank gear dot and the cam gear dot are both on top and that is #1 TDC firing position.

Hope this helps.

-Mark.

 

Never heard of that. I'm confused.

 

Just went and looked at every manual I have and it says to line the dot together.

 

My last cam swap I thought they had to be lined up too, with the crank sprocket dot at 12 o'clock and the cam sprocket dot at 6 o'clock. But after we looked at the instructions for the cam and got it all figured out the cam dot was supposed to be at 12 and not 6. Maybe it depends on the sprocket / cam ??

 

Guys,
this is a common misconception. The timing gears I have seen all come with the dots set up to align together while the cam and crank are at #6 firing position. Some have advance/retard tam timing indicators but they will all align together while the cam is at #6 TDC Firing Position.

The crank does not care if it is #1 or #6 because #1 and #6 are both at TDC with the crank gear dot facing up. The crank throws for #1 and #6 are in the same plane. The cam gear determines which cylinder (either #1 or #6) is at TDC firing position.

When we assemble the engine we align the dots together. This is so we are sure they are timed properly. The only hang up is the assumption that this dot-to-dot is #1 - It is not #1 TDC firing position, it is #6 TDC firing position.

I got fooled once on this one myself so I have it carved into my memory now. You can check this the next time you have your engine apart and see for yourself.

-Mark.

 

i had the same decision yesturday......

i put both dots up (12 o'clock)

w/ dist @ #1, fired right up.

and yes my timing set instructions wanted both together

i set TDC on 1 before i took the engine apart

stock timing set was also w/ both dots up ? go figure?

 

stingr69,
just read the instructions i got with the timing set (Edelbrock) and states to align the dots (crank @ 12 and cam @ 6)
What you say does make sense however i do have 1 question, if i align the dots as stated in the instructions and then rotate as you have stated, the distrubutor should return to the #1 tower, correct?
As i stated this is very important to me to get this right because i have to adjust the valves next and when i put the engine together the first time adjusting the valves correctly wore me out! It took me 3 tries before i finally got it right and was able to get the engine fired up. Look forward to your response. Thanks

 

Just did mine yesterday.
Set dots 12 crank/6 cam o'clock to install and turn to 12/12 o'clock for TDC. Confirm in lifter valley with lifters in place both lifters should be down and as you approach TDC nothing should be moving if exhaust begins to rise as you approach TDC you are on # 6. Sounds more confusing than it really is.

 

Dot-to-dot will throw the dist 180 off. Please ask me how I know this.

 

72,
You seem to have understood what I have said. The dots are there to help you get the cam timed to the crank properly. This #1-#6 stuff is shown in most Chilton's manuals. I have one here for the Camaro and it shows up in the "Engine and Engine Rebuilding" section. As others have said, "Ask me how I know". We been there, done that, used the T-shirt for a shop rag.

The distributor needs to have the rotor pointing close to the #1 tower when both dots are at 12:00 (both dots pointing up). If the timing cover is usualy installed by that time so this will not be visible.

If you have the engine at #1 TDC firing position (as opposed to #1 TDC exhaust position) the distributor rotor needs to be pointing close to #1 tower on the distributor cap. If you have the engine at #1 TDC firing position, the valves will not be anywhere close to moving off their seats. The #1 TDC exhaust position will have the valves rocking a bit off the seats. If the exhaust valve looks open, just rotate another 360 degrees and see if they both look closed.

If your distributor is not pointing the right way, just pull it out and rotate it so it does point at #1 when it is sitting all the way down on the intake manifold. The only hangup is that the slot on the oil pump driveshaft has to be lined up pretty close to the tang on the bottom of the distrbutor shaft for it to drop down all the way on to the intake. if you have the oil pump slot pointing close to the #5 cylinder intake pushrod, the distributor should drop all the wat down with the rotor pointing forward close to the #1 tower position. Use a long screwdriver to set the angle of the slot and adjust as needed. The vacuum canister is usualy pointing close to the passenger side front tire. The actual ignition timing setting will dictate exactly where the canister points on your car but this is typical.

As an aside, you might want to try to set the balancer mark at about 8 degrees before #1 TDC and then line up the rotor with the #1 tower. That would get the timing very close for easy start-up. Maybe that would help you get it to fire up quickly.

Hope this helps.

-Mark.

 

this should be more clear in timing set inst.

set timing sprokets dot to dot (this is for #6)
THEN turn crank 1 full rotation to get to #1
THEN start on rockers

it has been unclear why they go dot to dot.this is to
insure that you are not a tooth off either way........

they never state to turn crank 1 full rotation to get to TDC

this is where the confusion is


R

 

I'm clear now.