Finding 3.0 TDC

[mountainman]

Hello All-

This is my primary vehicle and I need to fixed right away. I did a search on this forum and on the internet and still haven't found what I am looking for- how to find TDC with the timing cover and heads on?

I am trying to torque down the heads and I don't have the timing cover off and the specs call for me to have the crank in position A then position B by using the marks on the cam gear... well, I can't see the timing gear.

Any help on this one? I'll be out in the garage all night trying to figure this out.

Thanks in advance for your help.

 

[Spott]

Pull the spark plug and stick something long (like a piece of coat hangar wire) into the cylinder. Then you can feel the motion and position of the piston.

Spott

 

[mountainman]

So I am kind of an idiot when it comes to timing... and I don't know after which stroke to find TDC. Is it after the compression stroke? Oh, I also have the valve covers off and the spark plug out. I can see exactly when the piston is at the top but what TDC do is considered TDC?

 

[martin]

tdc is when piston number one is at the top and both of the valves for that cylinder are closed.

 

[RonD]

With push rod engines you can torque the heads down with cam(or crank) in any position, because the valve train isn't active until you install the push rods and rockers.

The "A and B" position are for tightening the rockers
Top Dead Center(TDC) means the #1 cylinder piston is at the top of its stroke and both intake and exhaust valve are closed, this would be at the end of the Compression stroke and start of the Power stroke.
The crank pulley has a TDC mark BUT.....the crank goes around twice for each one rotation of the Cam.....when the crank pulley is on TDC it could be the start of the Power stroke or the start of the Intake stroke.
So with valve train disassembled you will have to install the push rods and then watch them rise and fall as you manually rotate the crank.
Tighten rocker when push rod for that valve is down, it takes a little longer but not as long as pulling the timing chain cover.

 

[mountainman]

With push rod engines you can torque the heads down with cam(or crank) in any position, because the valve train isn't active until you install the push rods and rockers.

The "A and B" position are for tightening the rockers
Top Dead Center(TDC) means the #1 cylinder piston is at the top of its stroke and both intake and exhaust valve are closed, this would be at the end of the Compression stroke and start of the Power stroke.
The crank pulley has a TDC mark BUT.....the crank goes around twice for each one rotation of the Cam.....when the crank pulley is on TDC it could be the start of the Power stroke or the start of the Intake stroke.
So with valve train disassembled you will have to install the push rods and then watch them rise and fall as you manually rotate the crank.
Tighten rocker when push rod for that valve is down, it takes a little longer but not as long as pulling the timing chain cover.

Yes Sir- you are spot on! I was all discombobulated last night-
So here is my real issue that I need to get on right away:

When I torque the rockers down, using the procedure you listed above, I have no gap on these rockers. I had the heads gone through, and I installed new pushrods, using the old lifters. Even when I rotate the crank, just to make sure I didn't have it in the wrong spot. The way I see it there is no adjustment, but then why do the manuals say there should be a gap there?

I still can't get this and I have to get this running by the end of the weekend... I am just about to get out the BFH and make this stuff work. Ugh.

 

[alwaysFlOoReD]

I'm not familiar with the 3.0, does it have hydraulic lifters? If so, that would be a reason why there is no lash.
Another possibility is the heads were shaved and took away some slack, same could happen with new valves.

Richard

 

[RonD]

Solid lifters or over head Cam will have a gap.

Hydraulic lifters will not, the spring in the lifter is not strong enough to hold open a valve spring, but it is enough to keep "tapping" noises to a minimum.
After final torque on rocker you should be able to spin the push rod with your fingers, on closed valves, it should have pressure but still spin.
This is general info, I have never rebuilt a 3.0l

Make sure to use lots of assembly lube on the valve train, it's the last place that the oil will get to on startup

 

[mountainman]

Thanks guys- you are a big help!!
And the manual is of no help here- it says that there should be a gap of a couple thousandths. What for? That is what kept throwing me off. And I must have been hung over and half asleep during that auto shop class and missed this part of engine theory. And that $hit was years ago. Enough excuses-

So to reiterate, there is no lash because of the lifters being hydraulic, which take up all the slack. The head was shaved because it had a warped face, and the valves were done. Not sure, but probably seats and seals. So because the heads were relieved slightly in height,and the valves and seats ground, it could cause there to be less of a gap at the rocker upon reassembly, or no gap at all.

But why does AutoZone, AllData, and my mechanic buddy who read his "book" all say the same thing- that there should be a gap when there isn't one due to this engine having hydraulic lifters and no adjustments on the pushrods or rockers? My thought is that if the engineers called for a gap that is down to THOUSANDTHS of an inch thick, then why is there no gap? Was there something in re-doing these heads that caused this and will this cause an issue when I get this truck running? I don't have unlimited time or money to throw at this truck as it is my work truck and I really need to get it back into service, so I can get back to work.

I am grateful of your guys' help- thank you.

 

[huh?]

disclaimer = huh? has never worked on 3.0l and info that follows comes from haynes manual for 1983-1992 rangers:

chapter 2 part C 3.0L v6 engine section 5...

step 12: use lifter bleed-down tool to bleed down lifter, check clearance between valve stem and rocker arm

step 14: adjust clearance by using longer or shorter pushrod(available from your dealer)