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Posted by: ThePaintedMan Jun 4 2013, 05:18 PM

Okay, so I just need a logic/brain check here. I've been doing valve adjustments the Cap'ns way since I got the car, but Rich suggested I try a go/no go method to see if I can figure out what is causing my backfiring problem.

Basically, I need to get one valve open as far as possible, making sure that the OPPOSITE valve is as closed as possible. In this case, #1 exhaust and # 3 exhaust.

So if I'm looking at #1 exhaust and it is open (the rocker has play in it) then the #3 exhaust should be closed solid, correct?

Rich, sorry to post this for all to see, I'm just looking for an answer quickly so I can get this buttoned back up before it's dark. Thanks for your help!

Posted by: The Cabinetmaker Jun 4 2013, 05:44 PM

No. If the rocker has play, it's closed. When the rocker moves toward the center of the engine, it's opening.

Posted by: ThePaintedMan Jun 4 2013, 06:50 PM

Shoot, I said that wrong. Yes, when the rocker is fully compressed and isn't moving back up in either direction the engine is turned, the valve is fully open.

What is interesting, and as it appeared to me, is that when I was at TDC for the cylinder (#1 in this case), the opposite cylinder's valve did NOT appear to be fully open. Ie, if I kept turning the engine, there appeared to be more inward movement of the rocker, as if it was not at the peak point of the lobe. I don't understand how this is possible, and it's probable that I was just "seeing things" but it's what I think is happening.

Posted by: The Cabinetmaker Jun 4 2013, 06:58 PM

You need to take a good look at a cam.
#1 intake being fully open does not mean the opposing valve is fully closed.
The lobes are not opposite of each other.

Posted by: ThePaintedMan Jun 4 2013, 07:40 PM

and if I had the ability to attempt a teardown and rebuild, I would. But looking at a picture of a cam, it only has one lobe per cylinder.

http://www.socalautoparts.com/images/product/ENG_6210.jpg

In my head, it is as follows: An intake valve on the #1 cylinder is fully closed at TDC, then the intake valve on #3 should be fully open, at the peak of the lobe, no?

Posted by: Dave_Darling Jun 4 2013, 08:53 PM

There are four lobes on the camshaft. The forward pair of cylinders share two cam lobes (one intake, one exhaust) and the rear pair share the other pair of cam lobes. Intake and exhaust are offset from each other, but the intake lobes of the front cylinders are guaranteed to be 180 degrees apart from each other.

--DD

Posted by: The Cabinetmaker Jun 4 2013, 08:59 PM

This thread is full of brain farts. I just reread my post. I am full of it. Not sure what I was thinking. If one is fully closed, the opposite is fully open.

Posted by: messix Jun 4 2013, 09:05 PM

time to buy a Camry.....