NMPRA

What would Rocket do?????

Hmmmmmmmmm.
.191 & .017
6.8 P at station 5 & 7 on a Prather PG w/ a 7-5
25,7000 - 26,200
These are general settings for those conditions. Adjust accordingly.

191/17 old dogs do learn new tricks. Haven't run 17 since the SS days.
Another discovery for the Nelson crowd. Don't know if it was intentional or a typeO but the heads are no longer .185. Now, .1875. To .188. If you're measuring the deck don't just ASSume a newer head is like an older one. Like with Lee's 191/17 if you measure your deck at .191 and just ASSume the head is .185 you'll be at .014 not .017.

At .191 deck height you add .011 to get to .017 clearance with the older head.
The newer head you'll add .008 to get to .017
MEASURE YOU HEADS to see which one you have.

rocket wrote: ↑Sat Aug 13, 2022 5:30 am At .191 deck height you add .011 to get to .017 clearance with the older head.
The newer head you'll add .008 to get to .017
MEASURE YOU HEADS to see which one you have.

Didn't know the heads changed, but I haven't bought any new parts in a few years.
That being said, you would need MORE shims for a given deck height with the new deeper heads, not less.

I think Rocket is screwing with us

GaryS wrote: ↑Sat Aug 13, 2022 7:43 pm

rocket wrote: ↑Sat Aug 13, 2022 5:30 am At .191 deck height you add .011 to get to .017 clearance with the older head.
The newer head you'll add .008 to get to .017
MEASURE YOU HEADS to see which one you have.

Didn't know the heads changed, but I haven't bought any new parts in a few years.
That being said, you would need MORE shims for a given deck height with the new deeper heads, not less.

I am severely dyslexic but im pretty sure

191-185 =6
---------
6+11=17
---------
191-188 =3
------------
To get to 17 you add .014.

Yep, Typo. Glad you're paying attention.

FWIW, the head spacing du jour yesterday was even lower than .017. In one case that I'm aware of, .016 was working Saturday afternoon but was still not low enough for Sunday morning.

My backup airplane has a Nelson and it test ran successfully at .190 and .018 with a light prop. I had set up my #1 airplane earlier in the week with a Jett that measured .151 and .012 (pretty low head for a Jett, but my best Jett ever likes those numbers all the time). I decided not to mess with it and it was fast enough but as usual I needled it too fat so the park police cited me for air pollution.

This was my first time at this event and was a real learning curve to say the least(not just engines but how the plane takeoff/flew/landed. My engine book is still in route back to me, but I can tell you for sure that I dropped the head down 3 from 11 to begin with and it ran really good and was competitive relative to speed. Most of my parts are less than 1 year old, so I don't know on the head until I can measure it. I had a 5 under and 8 on top and started with a heavier pitch 7.5, There was little color on the plug and I felt like it cooled off during the heats, so I chose to prop up. For the last 3 rounds I ran a heavy 7.6 and launched around 26K, which was almost 1k off peak. I haven't used a tack in awhile and rarely even push the last button because I just don't even see those RPM's. Congrats to Chuck who was fast all weekend and won both classes, and also to AJ Seaholm who I raced in the flyoff for 2nd. Each of us gave it our best as we battled for 10 laps with a photo finish like a flyoff should be. Both of us were clean even though the lights didn't work at pylon 1, With a storm coming, we chose not to re-fly although it was offered.

Got my stuff back. Measures 193/16.

Doug K

I often take out 2-3 thou for Denver.

Mine was set to 195/17 this time, though I have run as low as 15 head clearance at Denver. Ran a 7.5 all weekend. I think a 7.6 would have worked, but why mess, it was going!

In 426 I didn't change a thing. My notes from a few years ago had me all over the place in testing, and settling back to my normal. Notes day I have .005 shim in it, but no changes since 2019!

Chuck
11H

Regarding conditions in Denver - as a local I don’t normally bother to set my motors for Denver unless we have a local race.

Jett 426: I have a good setting that has worked well in Phoenix and Wichita. It worked fine in Denver (so no change). I had the speed, just not the thumbs!

NQ40: My Wichita and Phoenix setting was 194/19. This weekend in Denver it would get up on the pipe but too soft for my liking. I removed 0.002 and it had the rabid dog growl which I like. But after several flights slightly rich with a solid smoke trail, I was getting distorted plugs (good color though). So I added 0.001 back and all seemed fine. So in the end, I was at 194/18.

So maybe, just maybe I have learned something since I created this thread almost a hundred years ago!

Kurt

Well Kurt, It looks like you became Ray’s straight man.

My setup was .190/.018 to begin with, plug was getting little to no color and occasionally would get a slight pull on the element. It didn't have the rabid dog growl that Kurt talked about but seemed to have plenty of speed. The problem was it wasn't needling like it usually does. I'd start about a half turn open from previous "race" setting, let it warm up a bit and turn the needle in 1/4 turn. Usually this would be in the 22k rpm range but this time it would jump to 24.5+ rpms. After a few seconds it would settle down to the 22k range and I could finish my tuning procedure as normal. In the past I've lowered the head .001 and it fixed this problem, it didn't change anything this time. Is it a tuning or set up issue? I'll anxielly be waiting the experts to chime in.

Things that make you say hmmmm.
Nelson Red
Nelson
Italian cold ?
Italian hot ?

rocket wrote: ↑Mon Aug 22, 2022 6:25 am Things that make you say hmmmm.
Nelson Red
Nelson
Italian cold ?
Italian hot ?

Rocket were they all ran on the same engine and same head/sleeve settings?

SkooterII wrote: ↑Mon Aug 22, 2022 7:44 pm

rocket wrote: ↑Mon Aug 22, 2022 6:25 am Things that make you say hmmmm.
Nelson Red
Nelson
Italian cold ?
Italian hot ?

Rocket were they all ran on the same engine and same head/sleeve settings?

No, it's to show the size difference between the pockets
The element is in. This other than the diameter of the element effects the temperature range of the plug.