Valve gapping question

[SHOtimer]

Ok, so i'm starting my first valve gap, and i have a question. The Helms says to gap the valves anywhere between: Intake, .006-.010, Exhaust, .010-.014. So should I aim for intake at .006 and exhaust at .010, or should I aim for the middle at intake .008 and exhaust .012. Thanx
Doug

 

[BenSwanson]

it is better to be tighter so aim for the thickest size

 

[gosho89]

Personally I shot for .007 intake and .011 exhaust on all the adjustments I've done, that still allows for a comfort zone so as not to burn a valve if you get to much lift.

 

[rangerj]

Showtimer,

There are several trains of thought on this question. The instructions posted on the SHO Times web site indicate that the middle is the way to go, that is .008 on the intake and .012 on the exaust.

Unless you are using the car for racing, this is fine. In "normal" use the one or two thousandths of an inch in additional lift will not make a noticible difference.

SDPATT, a highly respected SHO enthusiest, SHO owner, experienced SHO mechanic, and engineer by training, likes to go a little tighter. He shoots for .007 on the intakes, and .011 on the exhaust.

He cites his specs in metrics, but I think I read his thread correctly, that is he shoots for .001 tighter than the "middle". SD, if I misinterpreted you, please correct me (and forgive me). You should note that his SHO has over 265,000 miles on it. But, he does the maintainance on his SHO religiously. Do you?

If you are using the car for "all out racing", you still have to allow for heat expansion, but you want as much lift as possible, so the tight end of the specs would be used. If you do this, you can expect more wear and having to do it more often.

IMHO, if it is your "driver", take the middle spec. rangerj

 

[sdpatt]

I appreciate your respectful comments. The Ford procedure that I started with years ago used metric measurements and since the shims are sized in metric dimensions, it makes the calculation straightforward. If you look at the valve gapping worksheet available in pdf format in the Forum's How-to section (old version), you will see that the intake gaps are to be set at a nominal .20mm and within a range of .15mm-.25mm. The exhausts have a nominal gap of .30mm and a range of 25mm-35mm.

The accuracy of your gapping depends a great deal on the precision and steps of the feeler gauges in your set. On the intake, I gap for one feeler gauge below the nominal at .178mm and the exhaust, .279mm. That way, the gap has to be between those numbers and the nominal gauge thicknesses of .203mm and .305mm, respectively.

On another note, one of the purposes of the valve gapping is to ensuer that the shimm surface under each shim is in good condition. I have been using a fresh shim surface whenever possible.

 

[SHOtimer]

Well, no I don't race my SHO, but I do drive it how it was intended. I received it about 10k ago, and from the looks of it am the first one to do this, I appreciate all the feedback, and I have come to the conclusion to shoot for the middle. Thanx for ur help and input it is much appreciated.
Doug