Adjusting valves

[Dtown66bug]

Hi, I just read advice on adjusting values everytime I change oil on my '66. I just posted a blurb about starting her after 20+ years sitting is a garage. Should I clean and adjust the valves before attempting to start?

Thanks, John

[exprof]

cleaning them won't hurt, but you should definitely check the adjustment

[fatalifeaten]

Definitely adjust them.

[Blue Baron]

You can't clean the valves. They're inside the combustion chamber. But adjustment is vital, and easy to do.

Here's a great explanation from thebugshop.org that explains why it's so important:

Setting valve clearances

I'm not going to tell you how (look in your Muir book that you just bought, there is a great de*****ion there), I'm going to tell you why. Valve clearances are important to the valves because they insure that the valves will "seat" (close) completely when the plug fires, and do this under all engine operating temperatures. I can't explain why, but the guys who made the engine determined that if the clearance were about 4-6 thousands of an inch when the engine was stone cold, the valves would seat no matter what the engine temperature and also stay open for as long as they could to optimize flow. Some books say 4 for the intake, 6 for the exhaust, some say 6 and 6, depends on the year, etc. A safe bet is always 6 thousands (.006" for both). But let me help you understand what the bad side of misadjusted valves is.

If the clearance is to too great your valves will:
1) "chatter" more. (you can always hear that sewing machine sound even with properly adjusted valves, but it will be louder if the clearance is too great.)
2) close too early in the cycle. They won't be open the maximum amount of time that they can be to allow the exhaust gas to escape and/or the fuel mixture to enter the cylinder. This is not likely to cause any major problems unless they are way off, but in any case your engine is not running at its best.

If the clearances are too small (or none), then your exhaust valve will never close completely and allow a small amount of gas out into the manifold during ignition when they are supposed to be shut tight. As this super hot gas violently rips past the smooth sealing surfaces of the valves, it will cause deterioration of the seating surfaces in the head and on the valve and may cause your engine to overheat and run poorly. More importantly, if the exhaust valve doesn't get its due time to rest firmly against the head casting, it can't transfer all the heat built up in it to the head. Hot valve = burnt valve. In any case, your heads will not last long. On the intake side, this will compromise the compression of the fuel mixture and cause the car to run poorly as well as the deterioration effect of "open during ignition" for the exhaust valves.

This valve adjusting is the "fine tuning" of the whole 4 cycle internal combustion process. Too tight (ie.: not enough clearance) is far worse than too much. Keep the valves adjusted and the engine will run at its best all of the time and your heads will last a lot longer.

The first time you try to adjust your valves, you may get frustrated or at least a big cramp in your neck, but stick it out. All good VW owners had a horrible first experience but will tell you that they can now do it with their eyes closed. It gets easier. It may seem tedious the first time you do it, but the good thing about doing it every 6-8k miles is that you will get pretty good at it. Make sure that the engine is "overnight" cold when you make the adjustment.

[trev0006]

Thanks for the great writeup, we are working on my brothers car and this helped.

You can't clean the valves. They're inside the combustion chamber. But adjustment is vital, and easy to do.

Here's a great explanation from thebugshop.org that explains why it's so important:

Setting valve clearances

I'm not going to tell you how (look in your Muir book that you just bought, there is a great de*****ion there), I'm going to tell you why. Valve clearances are important to the valves because they insure that the valves will "seat" (close) completely when the plug fires, and do this under all engine operating temperatures. I can't explain why, but the guys who made the engine determined that if the clearance were about 4-6 thousands of an inch when the engine was stone cold, the valves would seat no matter what the engine temperature and also stay open for as long as they could to optimize flow. Some books say 4 for the intake, 6 for the exhaust, some say 6 and 6, depends on the year, etc. A safe bet is always 6 thousands (.006" for both). But let me help you understand what the bad side of misadjusted valves is.

If the clearance is to too great your valves will:
1) "chatter" more. (you can always hear that sewing machine sound even with properly adjusted valves, but it will be louder if the clearance is too great.)
2) close too early in the cycle. They won't be open the maximum amount of time that they can be to allow the exhaust gas to escape and/or the fuel mixture to enter the cylinder. This is not likely to cause any major problems unless they are way off, but in any case your engine is not running at its best.

If the clearances are too small (or none), then your exhaust valve will never close completely and allow a small amount of gas out into the manifold during ignition when they are supposed to be shut tight. As this super hot gas violently rips past the smooth sealing surfaces of the valves, it will cause deterioration of the seating surfaces in the head and on the valve and may cause your engine to overheat and run poorly. More importantly, if the exhaust valve doesn't get its due time to rest firmly against the head casting, it can't transfer all the heat built up in it to the head. Hot valve = burnt valve. In any case, your heads will not last long. On the intake side, this will compromise the compression of the fuel mixture and cause the car to run poorly as well as the deterioration effect of "open during ignition" for the exhaust valves.

This valve adjusting is the "fine tuning" of the whole 4 cycle cars internal combustion process. Too tight (ie.: not enough clearance) is far worse than too much. Keep the valves adjusted and the engine will run at its best all of the time and your heads will last a lot longer.

The first time you try to adjust your valves, you may get frustrated or at least a big cramp in your neck, but stick it out. All good VW tires owners had a horrible first experience but will tell you that they can now do it with their eyes closed. It gets easier. It may seem tedious the first time you do it, but the good thing about doing it every 6-8k miles is that you will get pretty good at it. wheelsbrakesbmw Make sure that the engine is "overnight" cold when you make the adjustment.

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[Blue Baron]

Is this an advertisement with an embedded link? Because not only is it off topic, it doesn't make any sense.