Originally Posted by
Cougar429
O/K. I'm going to have to defer to the more experienced for this one.
As posted a while ago the Eagle IV 60 is installed in the F-15 with a Perry pump and carb setup. Tried to get it flying a few weeks ago and although would idle all day, full throttle would surge and/or die, regardless of pump and carb settings.
Back home I pulled the Perry carb and reinstalled one of the originals, (have a pair of these). There were two completely different carbs and I opted for the two-needle MK-X and was able to get much better response. Have not tached the top end yet so no numbers.
Had to go back through the notes as the carb suffered what appears to be a common problem, fuel leakage past the HS needle. I checked the setting before adding a piece of fuel tubing and lacking the optional gasket found an O-ring that fits in the housing with very slight compression when the housing is installed. Will try and check that in the next few days.
NOTE: The HS is out only 1 1/2 turns, while the LS is below 1 turn out. I can reduce pump volume, but already have over 2 full turns in and suspect I will then get into feed problems, especially with the nose up attitude.
The second carb I had in spares is an odd duck. There is an air bleed, but no needles at all. Where both would sit in the MK carb allan head cap bolts are fully seated. I can upload a pic later. So far I have not been able to identify this one so no ideas of what it requires, not if it would work better with the pump setup.
Anyone with some info on that one or if I also need to modify the LS needle on the -X? I have fuel tubing on the LS as well, but did not reverse the nut to place the groove on the bottom. Engine is side mounted, so any HS leak drips down to the bottom and would hide any leak there.
Things may have been much easier if the bolt spacing were identical to the YS 50 heli engine. That is designed to work with a pressurized tank and would have eliminated the pump completely, (although made fueling/defueling more difficult).
That 'odd duck' carb sounds like it's an E-Z Adjust model that somebody has set up for use with a remote HS needle valve. Fox used to sell a remote needle setup. Dub Jett still does. Many Asian engines have remote HS needles too........and one of those could have also been used with that carb.
The E-Z Adjust carb has an air bleed trim in front for the idle, and a HS needle on the left side in the spray bar assembly. The throttle arm is held onto the throttle barrel on the right side of the carb with a cap screw (in the location where you'd find the LS needle on a MK-X carb). My guess is that you're seeing that arm retaining cap screw on the right side, and another cap screw (hopefully a short one) threaded into the spray bar on the left side as a plug in place of an HS needle. IF they used a screw on the left side that was too long, the tip of it could have damaged the spray bar when seated.
If the spraybar is undamaged (and it probably is unless some rube forced a long screw in there), then you could either run that carb with a remote HS needle valve assembly, or replace the left side screw with an HS needle for an E-Z Adjust carb. We can look up the part # for you if you want to go that route. Bet that needle would be easy to find on eBay (unlike the 26063 L side needle that I need for my 2-jet carb equipped B-Frame .40).
This is just a guess based on your description. A pic or two would make 100% identification much easier. I have no experience running an E-Z Adjust carb with a pump, so I cannot comment on its suitability for your application.