911 Valve Adjustment - The Backside Method
 

Greetings Friends,

I just read the tech article on valve adjustment and was wondering about the pros and cons of the "Backside Method" of adjustment. I would welcome anyone's input that has used this method.

I would like to pose another question if I may tap the terrific resources of this forum. I'm wondering if using ramps by backing onto them would be an acceptable way to raise the rear end to change the oil...or would that prevent the oil from coming out completely due to being higher in the back than the front.

This is on a 1975 911S with a 1978 3.0 engine.

Thanking you in advance for any help you can provide,

Bruce

Can't give pros and cons. I have only used backside since I couldn't learn the feel of the Porsche gauge. I like it.

I'd keep the car level when changing oil. But I'm CDO, so it makes sense to me.

The backside method is real good for checking the valvle clearance, but it takes some trial and error to make the adjustment. The nice thing is that you can check the clearance before you make any adjustment and you will probably find several valves that don't need adjusted at all. It's also a lot easier if you have 2 people since you have to be on the opposite side of where you make the adjustment to make the measurement. So if you're adjusting an exhaust valve you make the measurement from the top of the engine and then crawl underneath to make the adjustment. Having the extra set of hands keeps you from having to go from underneath to on top several times if you don't get it right the first time.

One tip - push the valve down lightly with your hand at least once before trying to slip the shim in.

Babak

If you were truly OCD, wouldn't you have used spell check? LOL

I have tried this 'gay' method, and it is awesome! For the longest time, I wondered if my normal method was too tight; especially the exhaust. It turned out the the intakes were a little loose, and the exhaust were alright.

I have managed to learn to 'not' have to insert the feeler blades from above. I just bend them a little.

I still don't understand what's so hard about the tried and true, and IMO, more precise method?

I put the letters in order, nice and neat, like they ought to be.

Try it both ways. If it works for you, use it. The backside method is great for checking which valves need adjustment, as well as double checking a new adjustment, even if you like the "factory" method.

I like the backside method myself. Though now that the cat shield is in a box and not on my car and in the way, maybe I will have better luck with the factory method next spring.

my feelings exactly. why try and reinvent the wheel? so much easier and more exacting than the go-no-go method. you wanna be right on, or are you content with close enough?

You don't need to raise the rear to change the oil. There's enough clearance to drain the oil tank and the engine with the car on the ground. If you do need to raise it I would do it so it's level. Put the front up on the ramps and then jack the rear up and put it on jackstands. Just make sure you have a real big oil pan. A properly filled 911 is going to drain 9 to 11 quarts of oil. If the oil has been checked and topped up when the engine is cold or not running then it could have a lot more in it.

The "Backside Method" was developed to allow a person to adjust their valves with confidence the adjustments are correct before reassembling valve covers, sheet metal, etc.
There has been example after example of Porsche enthusiasts adjusting valves and finding after putting everything back together that little ticking noise from one or two valves set loose.

The "Backside Method" does not require a special .004" feeler that is often destroyed with normal use.


No risk of the small screws and nuts that hold the feeler shim to the handle falling into the engine.

Further the "Backside Method" doesn't require the user to learn the "magnetic" feel of a proper adjustment.

The Go, No Go process does not require "feel", the gauge either slips in to the gap or it doesn't.

The range of adjustment is 0.0035" to 0.0042", Go to No Go.
This means the loosest any valve can be set with this method is 2 ten thousands over the .004" factory setting. Well within factory specs.

Using the original process, there is no method to check the settings.

For the professional mechanic that may do valves several times a week the traditional method usually works fine.

For the rest of us, the "Backside Method" provides a means to check yourself.
The traditional method does not.

Wow, this sounds like the common attitude of "eveyone is a winner" nowadays, and why there are a lot of 7th place trophies on display in today's environment.

The backside method is, as you point out, imprecise. You seem to ignore the
fact that you can miss a bunch more on the too tight side, which can probably do more longterm damage.

I'm no pro mechanic, but I had the feel the second time I did mine. The "special" gauge you describe is pretty damned cheap in the grand scheme of things. And it's the replaceable shim stock that gets "damaged".

I think this falls under the category of "any job worth doing is worth doing right".

Where is the "official" write up of the backside method? I have never done it.

Mister Ed,
Apparently you don't understand what I wrote. Try reading it again.
The "Backside Method" is well within the factory specs.
Setting the valves at .0035" will not hurt the engine in any way.
.0035" is well within the factory specs.
Congratulations on getting it correct the second time.
With the backside method you would have got it right the first time.
The "Backside Method" also checks the adjustment.
How do you check your setting?
With just a little care, the valves can be set even closer than .0035" to .0042".
Seriously, I could care less what method you use.
The "Backside Method" has been used by folks around the world with success the first time and they could check their work before putting everything back together.

I didn't say it took me two times to get it right, it's just that the second time at it, the muscle memory was pretty well burned in.

How did I check it? Hmmmm.....I had a .004 feeler stuck in there.

I can pretty much guarantee I'm better than within 17% of where I should be, which is the range of "slop" you provided in the backside method.

Oh, and it should be mentioned there are .004 feelers around that are better than Porsche part 9191, or whatever it is. Although, I've used it a couple of times. I can't remember any nuts or screws falling off into my engine though? :confused: I'll take the precision of the traditional method over a go/no go method any day. We're not playing horseshoes. Good luck to you, though.

Ed,

"How did I check it? Hmmmm.....I had a .004 feeler stuck in there."

That's part of the problem. How much pressure did you have on the feeler?

Could you slip the feeler back in the gap without loosening the adustment?

Can you really guarantee the adjustment, without checking by another means, (dial indicator)?

Have you bothered to check your work with a dial indicator?

Ed, I'm afraid this "discussion" will come to no fruitful end.

I'm sure you do a good job on your valves, as do folks using the Backside Method.

The backside method is and has always been presented as an alternate method to the traditional method.

Again, no need for "special tools", no need to learn the "feel", and a positive method to check the adjustment.

The traditional method has been and is used with great success for all thse years.

The "Backside Method" is an alternative for those of us with ordinary feeler gauges, that may adjust our valves once or twice a year, and do not have confidence in the "feel".
Plus, I can positively check the adjustment with the Go and No Go feelers.

The bottom line here, use whatever method works best for you.
This is not a contest.
All my best,

Both ways are a pain in the are...
 

I have tried both ways and gave up and opted to just take it to a mechanic and pay the $300. I do all the other repairs myself, but when it comes to that I don't even hesitate or feel guilty.

I wasted tons of time trying to do the backside method on my stock 89 3.2. I don't know about other engine bays, but mine has sheet metal at the bottom of the top valve cover which gives me no access or line of sight to the bottom (from the top).

The only way I could of done the backside method would of been to remove the sheet metal (I don't know how involved this is) and remove the cat... Yes... I did try bending the feeler gauges and insert them from the same side I was adjusting the valve. This resulted in a very damaged and unusable .003 feeler gauge.

I reverted to the traditional .004 feeler gauge method and was done in no time. I could see how the backside method would of been interesting if my engine was out! I wouldn't recommend it on a stock 89 3.2 setup.