Question on "Backside" Method for Valve Adjustment
 

I tried the "Back Side" method for adjusting the valves this weekend. I got all of the lower exhaust valves adjusted to perfection - wow, what a great way to do this.

However, when I switched to the upper, intake valves, I can't seem to find a way to easily slip in the feeler gauge. I'm going to try again when it's daylight as holding a mirror, flashlight, and drop light seemed to be nearly impossible.

I'm open to any suggestions. Otherwise, I may revert to the standard way for the upper valves.

I would prefer to use the back side method as all of my valves needed adjusting and were loose. It's much easier to get the measurement right with the back side method.

The engine is in the car so space is limited.

Thanks.

I had to remove the engine tin to be able to do the top side from below.

Get a good headband flashlight.

Trouble/drop lights are a PITA in tight quarters unless they are set up well with magnets and swivels.

OK - This may be better info. I did mine on top the old fashioned way. Must be a line of sight/attack thing with the back-side method.

I have a 930, so maybe the engine tin is different, but I did not have to remove it (wasn't in the way at all). I inserted the feeler gauge blades between the intake lobes and rockers from underneath the car.

valve adj. back side method
 

I am preparing as well to do a backside method valve adj. (first time)...
I bought from our host the 2 gauges to be used in the process and they are 12 inches long...I assume that this will help with the inserting because they are bendable...
Am I wrong? I was led to believe that this is the easiest method...

The inserting on the backside method is easier because you are checking the distance between round cam and round(ed) cam follower on the rocker.

Picture two beer cans standing side by side and sticking a feeler gauge between them. Would be easy to get the feeler gauge in between them as you are guided by the arc in the cans to the center.

The traditional method is like two cans end to end. If the gauge is fatter than the gap you are not guided to the gap - AND it won't fit. It is hit and miss and you can't be certain immediately you are not just missing the gap rather than the gap being too small. Even when the gauge is thinner, it's tough to hit the sweet spot to slide it in. ou know immediately on the backside method it it's go or no go.

Feeler gauge blades are flexible as they are steel and thin. As they get fatter, they flex less. Not the reason the backside method is easier.

Great Info - Thanks! This makes perfect sense as I was thinking that I could probably access if that tin wasn't there. But 10pm came and said save it for tomorrow.



I hadn't heard of the 12" long version but I'm going to look into this. My only issue that I had was that other sizes kept wanting to pop out of the mix of feelers. I finally taped up so that only the .003 and .0025 were out. I used two different feeler gauges. I think that a 12" feeler might just be right.

Although I only got the lower valves done, it was pretty easy. I also bought a special tool that has a screwdriver inside a 13mm wrench that made it easier. This tool however, won't work for the upper valves unless the engine is out of the car due to space.

Thanks all!

The long blades will be nice because they will be easy to hold on to and move around (easier than the small blades), but there really isn't any bending going on - you measure the exhaust from the top and the intake from the bottom and it is almost a straight shot with the blades.

More good info. I just ordered the 12" feelers and when I remove the tin, I will re-measure the bottoms and do just like you say.

Thanks.

Where would I find a "How to" doing the adjustment this way ?

Thank you

The Back Side Method is written up here on Pelican Tech Articles:

Pelican Technical Article: 911 Valve Adjustment - The Backside Method

Popsicle sticks -- Black Tape ---

Tape the No Go on one end and the Go on the other in between the two sticks.

This provides a little more reach without the flex and it keeps both gages handy with a simple flip.

To get real creative you can make a handle out of metal and rig a small led lights so you can see what you are doing as well.

That's the ticket. Use a different color tape for your "go" and "no go" ends and no need to read the etched label on the feeler.

The backside method is great. The hard part for me was getting the cinch bolt tight without letting the adjustment screw turn.