AMB

Forgot about this one was talking to Davis today and I had committed to him for a
ST90 and head some time ago Looks like I need an other plane-- will be here before the first Jan we were talking Dec delivery

AMB

It appeared here in Florida on friday they suggest a 13x6 or 12x8 for break-in davis
head is massive nicely dished slightly on piston side , will break in on 0 nitro
some castor.Less than a half hour should do it then diesel time

AMB

OK ran 2 tanks 0 nitro + 3% castor held 10200 on 13x8 zinger (ringed engine)
Slapped on the davis head my starter is weak so did not even try. with tongue
in cheek used chicken stick with very little break in I had my doubts that I could
hand start, I kept turning in the screw finally a 1/2 turn from bottom a pop about
10 more flips and off it went after about a minute we got a sag and turned out the
screw about about 1 turn out and adjusting needle same prop 13x8 (biggest I have now) running 10,000 we now only have maybe 20 minutes or so total. I had to
quit do the getting other things done around here as this beds in rpm will get
better will pick up a 14 " inch prop ANY SUGGESTIONS FOR OTHERS?? LET ME
KNOW. ONE OF YOU GUYS MUST HAVE THE SAME SET-UP Transition a little
ragged but have not even touched low end and needs more running in anyhow\\
an other tank of davis abc now at 10200 with occasional spurts to 10300
had to put foot on back of test stand looks like that Band D little portable work
stand with test mount clamped to top it almost went over due to thrust

PeteJoMan

My Feedback: (1)

Dieseldan, The head you received from Davis, is your engine a G or an S 90. The reason I ask is I have a G90 and the engine is going on a TF corsair.(the engine is already fully broken in) I want to turn a 3 blade prop in the approximate scale diameter of 15 to 16" and was wondering if the engine will turn it without overheating.Thanks, Pete

AMB

I was turning a little better than 10000 on the 13x8 (wood zinger) my guess better
than 9k with a 3 blade 15x6 maybe 7 the comp props will run about 500rpm faster
than wood zingers you may need to run a 15x7 maybe 15x8 2 blade for thrust
Davis has some real numbers on this best check with him for the gospel.you should\be able to balance prop load by compression adjustment for best run and
avoid over heating over compression is the major cause of over heating in diesels
HOBBSY I think you have one of these your thoughts...

AMB

I run mainly wood zingers no 3 blade comp props theory ok but you need real numbers

AMB

It is G-90 (forgot to tell tell you)

AMB

Pete a few minutes ago put the ST 90 g series on the bench red max fuel (first can I found in the room) 14x8 zinger air temp 58-59 2 flips and a fire 3 or 4 more stayed running did not
touch compression screw warmed up gobs of thrust my tach needed a new battery but it
was certainly more than 9000 pulled throttle back halfway still mucho thrust hummed
loud hum but a hum.My guess will go a 15" prop but only had the 14s did not mess with
the 14x6

fox35

My Feedback: (9)

I'm running an APC 15/8 on my ST90 w/Davis head.

I think it would like a 16/8 better, but that is too big for the GP Cub ARF on floats.

My MVVS 90 deisel definately likes the 15/8 Graupner 3 blade better than the 14/7.

I'm beginning to get the impression that deisels like to run bigger props at lower RPM, just like four strokes.

AMB

yup bigger props lower rpms less fuel thats why I run them.Now I don't know how many
irvine 39s the new red one are out there but a diesel head would be nice (hint Bob Davis)
it would match my family of 46s and 53s,