Some of the people on these forums are professionals that do this kind of thing day in and day out for a living. All your doing is quoting a manual. If you want to measure guide clearance precisely like your mission statement then you will ignore that manual and do it like I said to.

 

I formally take back my question.

 

lol, sorry 95Blackhawk, I am sure your guides will be fine. Didn't mean to turn your thread into a pissing contest. It just bothers me when people quote manuals or copy and paste tech info from websites and then put down good advice from people that know what works. I bet that RX7 goes like hell with a 383 in it! I also just noticed your running AFR heads, the clearance numbers for the guides in them is most likely not the same as the ones GM lists. I would call AFR and get some numbers from them if you were still worried about it. You can ask them how to measure them too since no one here can agree on how it should be done.

 

The method outlined in the GM manual is a "screening" method... it gets you in the ballpark, and may indicate that you have valve guide wear problems. Unfortunately, its precision is compromised by simple geometry. How far is the dial indicator away from the top of the guide? What is the length of the guide? What is the effect of barrel distortion (wear) within the guide? How does it compensate for variations in valve stem diameter? What happens if the wear is eliptical and the major axis is not parallel to the axis of the dial indicator?

Its probably an OK method for screening the average mass-produced engine, under the pressure of the piece-work rates paid to dealer mechanics.

 

I couldn't agree more injuneer. The only thing different than just grabbing the valve and wiggling it back and forth by hand is that you have stuck a dial indicator up against the side of it so it gives you a number. This number is in no way a precise measurement of anything except how far the end of the dial indicator moved. That's why they make ball gauges. I mean really, that is the tools sole purpose.

 

I think I will go get my teeth out of the Polident.

Seriosuly, it's nothing to get upset about, just a minor difference of opinion.

Rich

 

Exactly.


This is how a tech in the field could get a rough idea of what the guide clearance is like. But to say that it's a valid way of measuring true guide clearance is foolish. Injuneer pointed out exactly what I was going to say about the inherent inaccuracies to trying to measure clearances that way.

Realistically, techs at the dealership never go this far into the motor, I get the heads complete from all of the local Ford, Honda, Toyota & Lexus service departments because they don't have the tools, equipment to even take them apart these days.

This is the industry standard gauge for measuring guide clearance.

 

You know this forum is for sharing information, and all to often information gets shared along with ego inflating. I applaud Jake for stepping up and giving just the facts. He has consistently shown that the information he shares is from personal experiences or fact. All too often we (myself included ) have posted information not from fact or from certified sources, but rather from memory, non factual events or from just trying to build up our ego's. So I think we should be more like Jake, there may be less threads, but what will be there will be something that a newbie or someone coming from some other car world can step into and use right away. Stepping down from the soap box now............

And yes if Jake is the only one posting that is fine by me!!!!!!!!!!

Have a great day.

 

I will "assume" the heads are on the car. No mention one way or the other but I, like many on the board, change springs with the heads on.

If the heads are on the car, Jakes way is the only way.

If we are speaking to a GM Service manual, I seriously doubt this is the case. If we are speaking to a Haynes Book. .

With the lack of "detailed" information that the OP provided, this response is not very helpful.

Ding, ding, ding we have a winner here.

The GM book most likely is only going to screen the issue with the heads on using the method like Jake said. I doubt GM would have the "average GM certified mechanic" to pull the heads, take them apart and do the precision inspection and measuring down in the guide, which is the best method, like many of you guys have pointed out. Those guys are mechanics, not precision machinists and it would be better to just warranty out the motor if the screening showed a problem just like Machinistone said.

I write service manuals for a living at the manufacturer level and I keep things to a "screening level" as well. I cant go into "precision" levels because it would be over the heads of most of the folks turning the wrenches. The manufacturer service manual is considered the "gospel" for 75% of the situations when its required to be referred to especially if warranty is in the equation. Us "gearheads" and racers have no need for it.

Is the SM always correct? By and large yes, when its looked at in the proper context the way the manufacturer intends. Are there more precise ways to diagnose issues outside of the SM? Absolutely and the precisionist for the most part, has no need to even refer to it at all.

The OP unknowingly, did not post the additional detailed information, that could have helped to reach the best solution to the problem. No big deal, I have done that plenty of times. At least all the angles on the topic have been covered and now everyone can get over getting butt-hurt.

Nonsense. It was a good question to be discussed and not one I recall ever reading in the past.

 

Actually....You can lower the piston with the valve on top of it until it is low enough to insert the ball gauge.

 

If thats true, I stand corrected.
But how much of the lower part of the guide will still be unaccessible?

Still that ball guage tool is not a conventional tool that the avearge gearhead or GM mechanic will have funds for or access too.

 

To me, the basic premise is that reasonable people can hold differing views and reasonable people can debate those differing views without becoming disagreeable.

Reasonable people should be able discuss those differences without becoming so entrenched in their view that other differing views are summarily dismissed, sometimes in offensive, inflammatory ways. Effective communication also includes the ability to recognize and fairly consider the differing views of others. Maintaining objectivity is important in achieving those.

One characteristic I admire most about ShoeBox (and I'm sure we'll all agree he's one of our most well-respected members) is his communication skills.

He doesn't paint himself into a corner. He doesn't become so entrenched in his positions that he arbitrarily excludes all other possibilities; take as an example the recent head bolt discussion. His skill in that area is worthy of emulation. Taking that approach also prevents 'Box from having to scramble to fabricate excuses. Fabricated excuses which would be designed to allow him to be able to retreat from some previous post or position. In psychology those fabricated excuses are identified as a Defense Mechanism.

However, what we shouldn't lose sight of is: In order for any poster to receive satisfactory responses to his question, effective communication is essential.

Jake

 

OK all,

Just to let all know, I decided to put the springs on and not worry about the play. Only one of the guides showed any real play so I will not worry about it knowing these heads will be off after a few thousand miles (1-2 years). Further, I indend to replace the springs after every season so again, I can check.

Thanks all.

 

If its anywhere near this bad you're in trouble.

 

/\
Yup that guide is plum shot.