Valve Adjustment ??

[R C Cola]

Anyone heard of setting the intake valves at . 008 instead of . 010. ?

My mechanic said it improves power, does no damage, and is within factory specs of plus or minus . 002. Overheating problems ? Other concerns ?

Thanks R C

 

[1stgen4evr]

8 10 +/- 2

If you are going to go that much closer, you had better be **** sure of the reading. The 2 thousandths fudge factor will keep you safe at ten. Keep in mind that there are plus and minus machining tolerances in all the engine parts as well as the block itself that will accumulate high and low in a given engine. You might be well able to do it on one and not on another. We have a new engine that somehow had accumulated inteferrence that had the valves striking and the pistons touching the head. That engine would definitely not been able to run the tighter valve lash. Fact is, it died from a spalled camshaft. You have GOT to have some clearance.



1stgen4evr

James

 

[bmoeller]

I'm with James. The spec is there for a reason.

 

[dpuckett]

It says in my Chilton book, and I believe the FSM, something to the effect of: "Don ot adjust the valves to closer tolerances than specified, as extensive engine damage can result. "



Keep em at . 010 and . 020. If you want more power, better MPGs, etc, there are safer ways to get it, that cost less in the long run.



Might be time to start learning to do your own work



Daniel

 

[BushWakr - RIP]

For what it's worth... mine have been set that way for some time now... . that of course is no guarrantee that you'll be ok.

In my opinion the real dangers lay in your upper rev limits... . if you plan to pull very high revs then you need to go to the heavier valve springs for a reason...

JMO here... .



pb. .

 

[JLEONARD]

Your mechanic may be right about the factory specs of +/- . 002, but you still need to use . 010 as the "nominal". In other words, use the . 010 feeler gage.

The problem with feeler gages is that everyone's "feel" is different, so one person may be actually setting the gap at . 009, an another at . 011, even though both are usuing the same set of gages.

Now get a different set of gages and the variation gets larger.

Also, you are setting the gap "cold" so when the engine is "hot" the clearance is correct after the steel expands.

So, how cold is "cold"? 50 *F, 90 *F? There's another variable.



Best off setting them at factory "nominal" to be on the safe, conservative side.

While your mechanic may be right "in theory" that you "may" get more power, in the practical sense its such a small percentage. (my guess 1 or 2 %)

As others have said, there are better ways to make hp than risking the integrity of your engine.

Jay

 

[BushWakr - RIP]

As I recall the valve set should be done with the engine at roughly 100*F...



pb. .

 

[JLEONARD]

As I recall the valve set should be done with the engine at roughly 100*F...



pb. .

That would minimize one of the variables.



Jay

 

[Paychk]

FSM states "Adjust the valves when the engine is cold, below 60°C (140°F)"

 

[BushWakr - RIP]

Another tid bit here is the 1st gen cams have a pretty decent exhaust valve lobe on the cam. . the intake is not as aggressive and because of that you should use a tad more care on that one for settings... . you'll find that by going with a "TIGHT 10/20" you should be just fine



pb.