valve cover removal/replacement

[Baltimore Sailor]

I've searched the forums and found some information, but I still have a few questions. I have fair-to-middling access on the carb side of my A4, and I'd like to have a look at the valves. Is it just a matter of removing the cover and there they are? Are there hazards to look out for when removing the cover? Does the carb have to be removed to get access, or can it be done without doing so?

I have the A4 manual, but didn't see anything about valve adjustment. However, the picture of the engine makes it look like there's a lot of stuff in the way. This may be something I'll wait for layup to do, but I like to find out as much in advance as I can.

Thanks!

[Kelly]

Here's a picture of the valve cover with the carb and manifold removed to improve access.

I would think that you would have to remove the carb, especially if you are thinking about adjusting the tappets (gaps given in the Moyer manual and the yellow A4 maintenance guide).

As for the manifold, I'm not sure. Without, access is much improved but removal may not be necessary. If my memory serves me, the two bolts holding on the valve access cover are long (3-4 inches ?).

Good luck,
Kelly

[Tom Alessi]

I'm doing the same job. Do have the same picture with the valve cover off?
Tom

[wlevin]

What made you want to adjust tappets? Are there specific noises or other indications that this needs to be done?
Bill on Otter

[David Masury]

You can remove the valve cover and adjust the valve clearances without removing the manifold. Taking the carburator off is easy and should be done first.

Previous posts and Don's manual speak of slightly bending the valve cover to help keep it sealed when you replace it. It is only held in place by two bolts and the extra spring in the cover keeps the ends tight to prevent oil seepage.

David

[msmith10]

David is correct. Just remove carb. As for why to check valves, I checked mine this year because the engine is 30 years old, compression is going down, and it was clear from the unblemished paint on the valve cover edges and bolts that this had never been done. After adjusting clearances, my engine ran much smoother and compression increased. Correct procedure is as follows:
A: VALVE ADJUSTMENT PROCEDURE:

1) Set the engine to number one TDC, just as you would for ignition timing. The TDC
position of the No. 1 cylinder is most easily found by holding a finger over the spark plug
hole in the first cylinder (at the flywheel end), while manually turning the flywheel
counterclockwise. As soon as compression is felt, stop turning and look at the position of
the roll pin in front of the crankshaft. Continue turning until the roll pin is perfectly
vertical. The piston will then be at TDC.

2) Check/set the valve clearances in cylinder number one by loosening or tightening the
top of the adjustable tappets (.010" for intake valves and .012" for exhaust valves). In the
first cylinder, the exhaust valve is at the front, and the intake valve is in the direction of
the reversing gear. The clearance is proper when you can insert the appropriate feeler
gauge between the valve stem and the top of the tappet, feeling a slight resistance - or
drag - on the feeler gauge.

3) After setting the valves in the first cylinder, set the valves in the rest of the cylinders
in the normal firing order (1, 2, 4, and 3), being sure to rotate the engine 180 degrees
between cylinders.

NOTE: The arrangement of valves in each cylinder is as follows: The valve at each end
of the engine is an exhaust valve. Then working in from each end toward the center,
there are two intake valves, and then two exhaust valves (in the center of the engine).
From the flywheel end of the engine, the arrangement of valves works out to be:
exhaust/intake (cyl #1), intake/exhaust (cyl #2), exhaust/intake (cyl #3), and
intake/exhaust (cyl #4).

[Baltimore Sailor]

3) After setting the valves in the first cylinder, set the valves in the rest of the cylinders in the normal firing order (1, 2, 4, and 3), being sure to rotate the engine 180 degrees between cylinders.

Do you mean that one just rotates the flywheel 180 degrees to the next cylinder, then another 180 for the next, etc? So you'd start with the roll pin vertical for cylinder 1, pointing down for 2, up again for 3, down for 4?

[msmith10]

That's correct. You can put your finger over the spark plug hole (sequentially) as you are rotating the engine (counterclockwise), and feel compression build up as the pin gets about 90 degrees ahead of vertical just to reassure yourself. In other words,you will feel compression build up on cylinder 1 as the roll pin gets to about 90 degrees before vertical. Continue to rotate until the pin is vertical, adjust valves. Move on to cylinder 2, same as before, but crankshaft (and roll pin) rotated 180 degrees, adjust valves, etc.
As long as you have good access, this is an easy job. Be sure to have a new gasket for the valve cover plate. If you don't have one, you can make one (as I did) out of cork gasket sheet.
Also, be sure to have a couple of clean rags available to lay in the bottom of the valve chamber as soon as you take the plate off. There are oil passage holes in there that you don't want dirt, pieces of gasket, etc, falling down.

[Kelly]

I just wanted to get back to the question, "why adjust the tappets?"

I didn't want to do this going in, it's just that in taking apart and cleaning/painting everything, it was "now or never" to take a look and adjust if necessary.

As it turns out, they needed to be adjusted. In buying a used boat with a used engine, you never know exactly what went on in the previous 10 to 40 years.

Now I know the clearances are as they should be.

(Side note: taking off the manifold allowed me to find the old paper towel ballooning into one of the passages in the block. Nice surprise!)

Kelly

[HOTFLASH]

Valve Tappet Adjustment Q's

As soon as compression is felt, stop turning and look at the position of the roll pin in front of the crankshaft. Continue turning until the roll pin is perfectly
vertical. .

I too have my valve cover off, and have reduced compression, so I should do the same.

What and where is the "roll pin"? I have the utility crank. Do I have to take the flywheel cover off to see the roll pin?

Also, looking at the valves, just where is the "top of the adjustable tappets."

What is good way to slightly bend the cover?

Is there anything else to look for in there?

Mary

[HOTFLASH]

"Roll Pin"

OK, Silly Me, I figured out what the "roll pin" was. I have been using it to find TDC, but did not know what it was called! I still wonder about the other Q's.
Mary

[Baltimore Sailor]

Actually, I don't know what the "roll pin" is either. I'm assuming it's something visible on the front of the engine, but I haven't done any timing or valve work yet, so it would probably be a really good idea to know exactly what I'm looking for there.

Thanks!

[HOTFLASH]

Roll Pin Description

I am doing this from memory--so size estimates may be a little off, and are based on my late model A4.

Assuming you do not have fresh water cooling, and you can see the hole in the center of the fly wheel cover, you would be able to see the roll pin. Look in, and you will see the center--like the butt end of an axle--of the fly wheel. I think what I am calling the butt end of an axle is actually the end of the crankshaft--not sure about that. On mine it looks like a circle about the circumference size of a penny, maybe a nickel. Thru the end of the "axle" perpendicularly (is that a word?) is the metal "pin" the size of a fat pencil, sticking out about 1/3 inch on both sides of the axle-end. That "pencil" is the roll pin. Looks a little like an arrow through a head--remember those? If you have a hand crank or utility crank, the crank has a cutout on the business end so it can slide onto the "axle" end, around the roll pin making the crank not slip, but be fixed on the "axle" so the crank may turn the flywheel and crankshaft.

I finally realized that was what they were talking about by looking at the engine overhaul manual. I did not know that protrusion had a name and the name was "Roll Pin".

If you have fresh water cooling, a pulley is attached where you would put the hand crank. I do not know about how to remove that.

Hope this helps.

Mary

[Baltimore Sailor]

Thanks! I have raw water cooling, so all this is visible. I figured that was it, but I've figured some pretty dumb things before!

[baileyem]

Roll Pin

Hey guys,

You are correct in describing where the roll pin is and what it is there to do. A roll pin is simply a pin that is not a solid, single piece but is formed by rolling a piece of metal into the form of a rod (pin). It is intended to be driven into a hole that is slightly smaller than its original diameter. It will compress, due to its compressible, rolled form and hold itself in place by the friction created as it trys to expand to its original diameter. They are very effective and can normally be driven out rather easily. They can be purchased in any good hardware store.
End of lecture.

Mike