erik58

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Hello- I've converted a os fsr? 46 to diesel with a davis head with a just engines piston &cylinder kit it isnt broken yet it has about a tank of fuel run thur it.I would like to know if I should put a shim under the head to reduce the compression it is backed all the way out and the compression is a tad too high. should I wait till its broken in or throw the shim in. thanks Erik 58 once you got diesel you never go back

Hobbsy

My Feedback: (102)

Go ahead and put the shim in now, the compression may increase as it breaks in and you'll need to reduce it anyway.

Burna Tire

Finish the break-in on glow then do the conversion,I wouldnt use the shim unless the piston is hitting the head.

AMB

You should have put the shim in when you put on the Davis head, also on the glow break in you should run at least 3tanks or
20 to 25 minutes on glow before conversion,however some of my irvine 53s only had 2 tanks before conversion my TT61 with a davis
head never saw any glow fuel you do want enough adjustment on the head screw so you can back it out enough to get the diesel
miss then turn in just enough till it smooths out and adjust the needle and compression for best running also it has to heat up for a minute or so before you hit the "steady state" of smooth running. remember as you increase your prop load the compression must
be reduced you are timing the engine to its load this way.whats nice about the diesel besides the power increase and reduced fuel
consumption is unlike a glow engine where you are messing with nitro % and adding or reducing compression by adding or taking
out head shims you can match the prop to the engine by changes of the compression screw simple/// If you decide to just go as a diesel and not go back to glow for a complete break in no harm, it will just take longer some of the guys have noted increases in rpms
that took a SEASON of flying for max rpms, most people when first running diesels overcompress, and on overleaning the needle it
will SLOW down just the reverse of glow overall you will very happy with the results you have a great combo martin

DarZeelon

Erik,


I cannot find the listing for OS FSR engines, in the JE replacement ABC sets.
The FSR is a .45, I believe; not a .46 (these are SFs and FXs).
Is it an OEM OS piston+sleeve set? If so, you probably paid dearly for it.

If it is a non-ring tapered-bore set (the piston is 'pinched' at TDC), follow this [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]break-in thread[/link] and do it with the glow head, as Burna Tire suggested.

If it is a ringed set, from any make, it needs a slobbery rich break-in, a description of which can be found in several threads in the "Glow Engines" forum.

Only after the break-in is completed, should you change to the DDD head, with the shim.
It will make your task much easier.

erik58

My Feedback: (4)

hello-Darzeelon I used a just engines piston & liner set it was cheaper than the oem with the shipping from the UK I have only run it a tankful made the shim and not run it yet (home &work[&o])I'll let you know my results when I get the time. thanks every body for the info Erik once you go diesel you never go to glow

AMB

Hi Dar and Erik all my 2 strokes are on davis heads (and a couple are AJs since Davis did not make heads for them) regardless of glow or diesel use the head shim, Mr Davis makes a specific remark to move the head shim to the diesel head when installing
as far as how much break-in on glow I have 4 irvine 53s with davis heads 2 were squeaky tight at the top the other 3 just a little
bit the not real tight 3 saw 3 tanks the other 2 saw 5 or so the MVVS 40 and 61 with Davis heads were broken in on glow by the book
the ST40 and ST 90 ringed davis heads only saw 2 or 3 tanks rich with short lean outs and on with diesel heads run rich for a few tanks
they are all fine an other case in point the old irvine Q40 and irvine 40 diesel are the SAME engine only difference is the head ( I have
them both) and of course that engine never saw glow fuel there is a davis head on the Q40 I did put 1 tank of glow thru it to to see how it did but really did its steroid thing one the diesel head
and now Dar sorry I missed your call Alligator farm in Israel ????I thought only here in Florida Sandy says Hi

DarZeelon

Martin,


Yes! In Israel.

There are about 250 alligators, crocodiles, gavial and caiman.

This is [link=http://www.hamat-gader.com/hamatGader/rightbar/taninim.html]their web site[/link]. Sorry, no English...

Thanks for filling me in, Erik.

erik58

My Feedback: (4)

uuuummmm- gator is good eatin