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Sun Nov 25, 2012 1:57 pm

Hey everyone - I'm doing a basic valve adjustment on my 1971 Invader GT kit car. This is my first time and I'm confused.

Previous owner said it was a 1600cc or possibly a 1641cc engine that had 200 miles on it. She ran great all summer, but when the cold weather kicked in, the vehicle started stalling out when I would slow down. She fires right back up though, but she doesn't sound as nice as before.

So, I cleaned and rebuilt the H30/31PICT carburator and replaced the spark plugs (they weren't even matching plugs). I have not made any adjustments to the carb yet. The vehicle still stalls unless the throttle is held down, but she sounds loud again.

I have everything I need for the valve adjustment. Problem is, the previous owner marked TDC and TBC where it lines up with the aftermarket distributor, but this is not where the pulley indent/cut has been marked by VW. When I try to slide the .006 guage through the intake valves on cylinder 1 and 3, there is NO space. So I loosened the threads to make the adjustment, but they still won't go through. I am now afraid to start the car.

Can anyone help? Is this a common issue? Not sure what to do from this point. :cry: I thank you for any assistance!!

Sun Nov 25, 2012 2:16 pm

Its a 4 stroke so the valves are fully closed at TDC only on its compression/power stroke which is every other TDC. When its at TDC on its exhaust/intake stroke the valve opening overlaps and there will be no gap on either valve. Follow these steps

http://www.glenn-ring.com/tech/valve_adjustment.htm

Sounds like the marks on your distributor may wrong. When the rotor is pointing in the direction of the number 1 plug wire, that should be close to TDC compression/power stroke, #1 cylinder.

You should also invest in a repair manual. It would probably have a picture to show the direction the rotor should be pointing at TDC #1. If the distributor is correctly aligned, the rotor should look like this, at about 4:00 o'clock, if 12:00 is toward the front of the car.

However a previous owner might have put it together 180 degrees out. You can get it to run that way but everything is backwards.

Remember, the most common carburetor problem, isn't.

Do you have a working heat riser on your intake manifold?

BTW, what's TBC? Top Bottom Center?

Sun Nov 25, 2012 2:50 pm

Forget what ever previous owner did or told you because its probably wrong....

There is only two ways to do valve adjustment... One is to roll engine forward (clockwise) to TDC with each cylinder and switch sides, or roll engine backwards (counter clockwise) and do 1 & 2 then 3 & 4 following some very specific written procedures......

You have to find and verify TDC (or BDC) correctly and ignore PO marks until you verify they are accurate....

I prefer the Glenn Ring method... As I can do one side button it up and then do other side... No switching back and forth from side to side... Also there is no guarantee the distributor is installed correctly as in above picture... Only thing accurate is the rotor will be pointed to tower in dist cap that has wire going to #1 cylinder when you start (and subsequently each cylinder you are adjusting)...

http://www.glenn-ring.com/tech/valve_adjustment.htm

Only thing you really need to know is if engine has aluminum pushrods or chrome moly (steel) pushrods...

Aluminum pushrods adjust to .006th...
Steel pushrods adjust to "loose" zero"...

Dale

Sun Nov 25, 2012 3:26 pm

Wow - thank you both for your quick response! I had not heard of the Glenn Ring Method and I think this is what I needed (youtube has been all over the place regarding the proper way to adjust valves).

I did mean BDC (Bottom Dead Centre) by the way. Sorry for the confusion.

Is there a standard way to completely and reliably verify where TDC and BDC are?

Thank you both again for such great info. Hopefully I can solve this tonight!

Sun Nov 25, 2012 3:29 pm

And I'm not sure if I have a heat riser or not. How will that affect the valve adjustment?

Also, how can I tell if the pushrods are steel or aluminum?

Sun Nov 25, 2012 3:57 pm

If you have an old and well worn generator. Beware rotating the engine counter clockwise. The brushes develop a shaped arc in them, and the tip can catch a segment on the stator. Just went through it myself.

Sun Nov 25, 2012 6:43 pm

It is possible to unscrew the pulley bolt if you rotate backwards, or so I've been told. Hasn't happened to me, but it worth pointing out. VW Trends has a nice article about how to set 4 valves, then rotate the engine 360 degrees and set the other 4 (each time it is 3 on one side and 1 on the other.) http://www.vwtrendsweb.com/tech/0106vwt_valve_adjustment/viewall.html

If you forget all the shortcuts and you don't have your book or the internet handy (good thing you already read up) then it is easy to determine what to adjust when. Whatever plug wire the rotor is pointing to when the timing mark is strait up or strait down (generously within 30 degrees of strait up or down) is the cylinder where you can adjust the valves. That cylinder is somewhere around the end of the compression or beginning of the power stroke.

So... rotate the crank so the timing mark is pointed strait down. Pop the rotor to determine what cylinder you can adjust (it will be either 4 or 2.) Set the lash on those 2 valves, then rotate the crank clockwise (from your position facing the pulley) 180 degrees and adjust the other cylinder under that valve cover. Reinstall that valve cover and remove the other one. Rotate the crank the same direction another 180 degrees and adjust the rear cylinder on that side (either 2 or 4.) Rotate the crank the same direction 180 degrees one last time and adjust the last cylinder.

The firing order is 1 4 3 2 so if you start with the timing mark strait down the effective firing order is either 4 3 2 1 or 2 1 4 3.

Sun Nov 25, 2012 7:09 pm

71InvaderGT wrote: And I'm not sure if I have a heat riser or not. How will that affect the valve adjustment?

Also, how can I tell if the pushrods are steel or aluminum?

Aluminum pushrod will be silver/gray in color and NOT magnetic..

Steel pushrods will probably be black and WILL be magnetic...

Dale

Sun Nov 25, 2012 7:59 pm

71InvaderGT wrote: Is there a standard way to completely and reliably verify where TDC and BDC are?

Yes, First take out all 4 spark plugs and remove the valve covers. Rotate the crankshaft clockwise and watch the rockers on the #1 cylinder. The valves should open and close one right after the other, first the exhaust then the intake. Turn it through a number times until you get the rhythm and can see and anticipate the #1 valve action. Then after the intake closes, keep turning the crank another 180 degrees (about), but hold your finger over the spark plug hole and feel for the pressure to keep building then stop building. That should be very close to TDC #1. Look for the marks on the fan belt pulley. You might have a dimple on your pulley that is TDC. It would be straight up on the split of the crankcase when the pressure stops building. Even if you don't have a TDC mark, you'll probably have timing marks like this or the other. You don't have to be exactly TDC to set the the valves, you just need to be around the top of the compression stroke, when both valves are closed.

After you've learned how to tell that you're on the top of a compression stroke, you can do the other cylinders in any order you want. Just make sure each one is on top of its compression stroke using your finger on the spark plug hole and watching the valve action. With an Invader, I'm not sure you can turn the crank, see the valves and put your finger over a plug hole, but on a buggy its usually easy, unless there's a big exhaust system in the way.

This is an intake heat riser tube connected to the exhaust. It takes the heat from the exhaust and warms the intake manifold and carb, which in the winter (or any cool day) can quickly get cold enough to accumulate enough ice to choke it off, due to gas being vaporized. Another problem you might have is your choke might not be working right. A manual would tell you how to check/set the choke, accelerator pump, etc.

Mon Nov 26, 2012 11:30 am

Kevinx wrote: If you have an old and well worn generator. Beware rotating the engine counter clockwise. The brushes develop a shaped arc in them, and the tip can catch a segment on the stator. Just went through it myself.

I this the same KevinX from the Victory Motorcycle boards?

Mon Nov 26, 2012 9:42 pm

Man, you guys are awesome! I had no idea that the forums would supply so much information so quickly.

I will update you as soon as I have the extra hour to do it all. You have no idea how much I appreciate this. Hopefully I can learn how to post some images of the car as well.

Will write back here pretty soon.