To tap or not to tap
 

Just wondering what the general thought is regarding a pressure tap on a diesel. I've got a paw .35 and would like to know if I should pressure tap it or not. Is this a try-it-and-find-out if I need it kind of thing, or is there some principal I'm overlooking? I've also heard that because the exhaust is so thick that it is a bad thing to get back in the tank (from the pressure tap line).

Thanks for any advice in advance.

RE: To tap or not to tap
 

most diesels have very good fuel draw - I have never had a problem - even with the top of the tank below the mounting lugs on a paw .49 just my experiance.

RE: To tap or not to tap
 

thejc,

Just to clarify, that means you dont use any pressure tap on your diesels, right?

Anyone else have a preference?

Thanks in advance again for any responses

RE: To tap or not to tap
 

As it happens, I have a PAW .35 which I tapped for pressure. Can't remember exactly why, but what happened was a real mess in the fuel tank after a few flights. Unless you absolutely need it I wouldn't reccomend it. With the smaller carbs diesels seldom have a problem with fuel draw.

Max

RE: To tap or not to tap
 

My paw 40 now has a MVVS twin needle carb and I did tap for it. As pointed out the smaller
bore stock carb not needed,

RE: To tap or not to tap
 

Maxtenet
Did you do anything to the muffler with the hole in it (i.e. patch)? Is it ok to run with the hole if you dont need it (how messy)?


Dieseldan
How do you like that twin needle, and how did you do it (does the mvvs bolt/screw right on/ any tapping needed)? Does it really help transition or what?

Anyone,
What do you do with the extra vent line/tap line comming from the tank if not connected to the tap nipple?

Thanks all!

RE: To tap or not to tap
 

I ran a dieselized Tower 40 for a while with muffler pressure. On the bench I would get an occasional drop of oil going through the pressure tube. I flew it quite a bit since mounted on a CL airplane. The muffler was below the tank except when inverted or doing outsides; never had any problem. I used silicon fuel line for the muffler line and it worked fine.

Jim

RE: To tap or not to tap
 

Luftman,

Leave the vent line open to atmosphere or you will create a vacuum. As far as patching the hole, I just put a small sheet metal screw in it.

Max[8D]

RE: To tap or not to tap
 

Luftman.One of the MVVS carbs I used (I do not remember if it was in the 40 or not) was a few
thousandths off ( to big to plugin) I took the carb apart and chucked it (the body) venturi up in my drill
press and filed it smaller (no lathe) till it fit, installed with the O ring of course and tightened the screws to lock it. It transitions better idles great very much like my irvines and as I said
before run pressure. One of the carbs was too small in diameter so I did a wrap with shim
brass and used copper kote the red stuff for a good seal , Did not want to use JB weld so
I could remove it, So if too big or too small thats the adaption. I have used OS 10 size carb
on the smaller paw s doing this. I know some of you have mini-mats or some other sort
of lathes/milling combos so it would come out a little neater.

RE: To tap or not to tap
 

Max,
I read (SMALLnet, I think) about someone installing a catch box for the sludge. Install it between the muffler and the tank. Empty it after every flying session (or sooner if necessary).
I don't use muffler pressure so I have never tried it.
Hope this helps.

George

RE: To tap or not to tap
 

Thanks for all of the replies. I think I'll go without the pressurized tank unless it (the engine) wants it.

With a vent line for the tank is there any noticable ether loss for say a 250cc tank (25-30 min run) in your collective experiences? I mean, does the bottom of the tank (last part) make it run a bit hotter/worse, or is this only a factor on really hot days, or never?

Thanks

RE: To tap or not to tap
 

You might want to put a one-way valve on the vent line. I think Foremost sells a gasoline one-way valve that should be fine. Black and white plastic as I recall.

Jim