ok i have a 1972 nova with a inline 250
i need to know how to adjust the valves
thanks

Do you have any kind of repair manual, Chilton, Haynes?

Here's a link it's for a v8, the same procedure applies to sixes. The only difference is the firing order.

http://www.classiccarauto.com/impala/how_to/adjust_valves.shtml

Welcome aboard!

Larry

Larry,
I've read on several different websites that you should adjust the exhaust valve just as the intake valve begins to close. The link above says to wait until the intake valve is almost closed. Will either work? I realize that the valves need to be adjusted when on the base of the cam lobe circle. I guess my question is have I adjusted my exh valves incorrectly? Did I gtet some bad info?

p.s. Also I found it easier to remove the side covers to watch the lifter. The reason being that the lifter body moves a little bit prior to rocker if the lifter has leaked off.
Bear in mind that my level of knowledge is only from what I've read and messes that I've made and had to cleaned up after.

adjust the exhaust valve just as the intake valve begins to close.
Taken literally, this is anything after the intake centerline, or 110° ATDC. Yes, the exhaust valve is closed.

The link above says to wait until the intake valve is almost closed.
This will always be ABDC. Again, the exhaust valve is closed.

If you don't have a good mental picture of the combustion cycle these methods are not helpful.
At TDC on ignition, both valve are always closed on every engine.
At TDC on overlap, both valve are always open on every engine (except those with extremely mild cam timing such as pre-war).

Just to elaborate a little on what Panic has said, since it is critical to both valve adjustment and ignition timing. We are talking about a four stroke motor, and the strokes are, Intake, Compression, Power, and Exhaust. The piston will be at Top Dead Center(TDC) twice, at the end of Compression, and Exhaust strokes. Both of these strokes are pushing the volume, one against a closed intake valve, compression, and the other to an open exhaust valve, exhaust. This is where some confusion occurs when re-installing a distributor. Since the cam turns at half the speed of the crank. The distributor can be at either TDC, so the valve action needs to be watched. Hope I didn't confuse things more.

Larry

153 That's the firing order.
624

Adjust #1 when #6 is in rock position. (That means #6 cyl rocker arms are both moving as you are turning the crank )
Adjust #5 when #2 is in rock position. " "
Adjust #3 when #4 is in rock position. " "

Adjust #6 when #1 is in rock position. " "
Adjust #2 when #5 is in rock position. " "
Adjust #4 when #3 is in rock position. " "

Adjusting it this way takes less revolutions of the crankshaft.

Only time maybe not to adjust them this way is when you have a huge race camshaft w/a lot of valve overlap.

I have never seen it writen this way in any books.

But this is the way I always adjust valves.

Same goes for those V-8 thingys. I have never seen it writen this way in any books.

But this is the way I always adjust valves.
1843
6572 IIRC SBC, BBC?

MBHD

MBHD,
That is the way I also do it. It is so easy to learn this method. And yes, it does work with big cams too. It is easy to see when the exhaust rocker arm is closing and the intake rocker arm is opening, and when the two "pass" each other and are on a parallel plane. That is when TDC occurrs on the sister cylinder. With this method you need not mark the damper - heck, you don't even have to look at the damper - just watch the next-in-line cylinder for rocker arm movement.


6re6

Panic,
So I did it properly, right? The way that I did made sense to me that the exh valve would definitely be closed as the intake valve begins to close due to the next up stroke is compression which means the exh valve ain't movin'.

Hank and FF,
I'll try this method as it makes just as much sense as the one described above with less time and complication. I just never thought of it in this manner. If I'm thinking about this correctly, then it also means that there is no need to pull the side covers, correct?

If you can appreciate, I've spent years adjusting valves on inline 6 diesels that have no siamese ports (728 CI.) The first time I adjusted the valves on my 250 twice I looked at the wrong valve due to siamese port. I guess that I'm saying that I attempt to follow instructions to the tee.
Thanks to all - hopefully all of your explanations are helpful to the guy with the original post.

Yup.
Hank's method uses the least amount of time and engine motion by comparing what any pair of cylinders is doing - less work.

There is no need to remove anything but the rocker arm cover, unless of course your engine has adjustable lifters like a flathead Ford or adjustable pushrods with the adjuster on the bottom end. I mentioned above that you need not look at the damper but I have found that three equally spaced TDC timing marks on the damper will insure that true TDC has been attained with just a glance.

Is there anything wrong with dynamically adjusting the valves?
I have always used this method. I have a valve cover that has been modified with an open top to keep the oil in.

hey thanks guys for all the help you guys rock
ok i have replaced the lifters with new ones and i still have a ticking sound from the #5 exhaust valve what could it be?
cam is ok and rocker arm is getting lots of oil now
could it be my valve has alot of carbon build up?
i am just lost for words on this one

That is my least favorite method.

its messy
you run the risk of getting burned / injured
it beats up your feeler gages
its not as precise

ok i replaced the arms rods n lifters and still have a ticking around number 4 n 5 and they are adjusted correct
here is the strange part it will stop ticking but come back
could this be the oil pump i have around 20 lbs of pressure in park and 12 in drive with a warm engine

ya reckon it might be a bearing, is it a tick or a knock?

12 psi might not be enough pressure to fully pump the lifters up, and cause the ticking noise. Once the pressure gets to 20 or above, does the ticking go away.

it is a ticking sound
and i thought it may be the pump and no it doesnot go away when pressure goes up if i am in the fast lane with the oil to one side it goes away but comes back and goes away it is weird
thanks guys
ps what should my pressure be at idle?