splatt

OK, lets say I've have gotten through the break in process and I've traveled many miles to a race and I find I don't turn my favoerite prop as much as it did at home.

what's the rule of thumb with all those wonderful shims, lots of shims with a big prop, no shims when your under sea level. Whats the deal ?

Ed Smith

With reference to climate.

The higher the pressure the higher the head. The lower the pressure the lower the head. At least I think it is that way round. How much higher and lower is governed by the laws of witchcraft and folklore!

Ed S

daven

My Feedback: (1)

Jesse,

We can talk at the field, so I was hoping you'd get some other responses, but I'll try to answer.

If you break the engine in properly (Another can of worms), and get your spacing where you like them.

As most of you know, I personally like them at .191 and .011

Very rarely do I need to change my spacing from there.

IF things aren't turning up, about the only thing I would do, is add a shim (start with .003). If that doesn't work, I'm going to the backup.

Would like to hear other thoughts on this myself.

bl10

Dave is correct. From my experience a good engine is a good engine and a good setup is a good setup no matter what the weather conditions. As an example my Q500 engine at Winterfest this year was turning a 9.25 at 19500 or so on Friday afternoon. On Saturday morning (8 am and chilly) it would only turn about 18800. What was wrong? Did the engine fairies change the setup overnight? Should I raise the head, lower the head or what? None of the above. Just left it the same and by 1st round it was back above 19K and by afternoon it was back to 19500. I have seen very few of the top flyers worry about changes in performance due to weather. If it runs good at home and is off a little at the race chances are everyone is off the same amount and changing head or sleeve shims is not worth the effort. By the way I was tempted to switch to a 8.75 prop early in the morning at PHX but didn’t and was happy with the results. If my stuff was far enough off that it wouldn’t pull the prop at all I would 1st switch to a different (smaller) prop then to a backup engine. Remember ground RPM isn’t everything, it has very little to due with what is actually going on a 160 mph.

Just my opinion.

Barry

splatt

That's the answer I was hoping for, seems you don't want to go opening the sleeve willy-nilly and lose your fit.

daven

My Feedback: (1)

Jesse,

I have always agreed with that, but there are quite a few top racers that routinely (as often as after every race) completely dissasemble the engine and polish up the piston and head.

So, like most things in racing, everyone has their own opinion.

Lots of people are going fast doing lots of different things.

Find the people with fast equiptment and learn from them. Just about everyone is willing to help other races try and go faster.

daven

My Feedback: (1)

Splatt,

You had your plane dialed in today, nice win.

The wind and cuts were bad today.

diggs_74

I don't know, where the cuts all that bad Jesse? It helped us out a bit... If I only could have passed one more plane we would have had a fly off... Of course, if the dog wouldn't have stopped to crap, he would have caught the rabbit....

Funny thing about these Nelsons... The first 2 heats I couldn't get out of my own way but the engine really started to come on the more laps it got... I thought it was broke in but I guess it had a little "freeing up" left to do..