A75-8 ENGINE CUTTING OUT DURING CLIMB

pdb9809 · Post by **pdb9809** » Tue Oct 09, 2007 20:01

Hey Group,

I have a 1941 65CA with a brand new O/H'd engine, new Slick mags, harnesses and plugs. During climb out (500-800 AGL) the engine starts to quit. I lower the nose and start thinking about looking for a place to land. In the meantime I've applied carb heat, and the engine begins to recover. Makes for an unpleasant flying experience. I've managed to return to the depart airport both times. On the ground the runup at full throttle is fine.

The carb (Stromberg) was overhauled 6 years ago and only has about 225 hrs since O/H. I beginning to think the float level is off. I have to pull fuel lines and check for partial blockage and flow rates to the gascolator.

Was wondering if the group has any other suggestions.
Thanks,
Paul in Atlanta

Post by **joea** » Tue Oct 09, 2007 20:32

Agree with your ideas and would check fuel flow first, then float level second.

marklamon · Post by **marklamon** » Tue Oct 09, 2007 23:59

Vent for the fuel tank? I had a Stearman do that. Dag burn mud dobbers made a home in the vent line. Let us know what you find.

gusc · Post by **gusc** » Sun Nov 18, 2007 20:44

Mark,

Mud dobbers caused the totaling of my beautiful Stinson 108-3 on takeoff.

They had only blocked one vent, if I had used the other tank for TO it would have been a non-event at cruise!!

Mikek · Post by **Mikek** » Sun Nov 18, 2007 21:32

pdb9809 wrote:Hey Group,

Was wondering if the group has any other suggestions.
Thanks,
Paul in Atlanta

Have you found anything??

Mike K.

pdb9809 · Post by **pdb9809** » Tue Nov 20, 2007 13:06

Hi All,
Discovered what the problem was. Did a flow check on the fuel line where it hooks up to the gascolator, came out to somewhere like 140 liters per hour (enough to power a small turbine). I pulled the carb and checked the fuel level. It appeared a little low, so I had the engine overhauler look at the carb. He installed a C75 venturi (1 1/2 inch vs 1 1/4 inch) and a No. 46 Main Jet (49 is standard). During reinstallation of the carb and mounting the gascolator, a 1/4 inch long 6-32 screw fell out of the outlet side of the gascolator (above the screen). I believe it's been there since I finished the restoration on the plane. Makes sense as the engine was starting to quit during R/H climbing turns only. The screw must have worked itself loose and during turns was partially blocking the flow out the gascolator into the carb. Stranger than fiction.

Thanks all for the suggestions.
Regards,
Paul

Mnflyer · Post by **Mnflyer** » Tue Nov 20, 2007 14:32

Hi Paul that is stranger than fiction, glad to hear you found the problem and I bet you are relived. Good flying

marklamon · Post by **marklamon** » Tue Nov 20, 2007 20:03

pdb9809, Glad to hear you found the problem.

If your engine is a A-75-8 the correct venturi is the 1 1/4" with a stromberg carb. In fact the A-65-8 carb needs no modifacations as per Cont service letter M47-16 (page 9).

The change between the A-75-8 is basicly different pistons (waffle under the head for added cooling) and drilling the rods or using ones with holes drilled in them allready (again cooling). The bore and stroke remain the same while the the timing is changed to 29'btdc RH, 32'btdc LH, and a increase in rpm allows the engine to develop 10 more horsepower.

The volumetric efficiency of the engine remains unchanged. Therefore no changes in mixture (jets) nor CFM (venturi) are required. It may run but it will not be correct as per the Type Certificate Data E-213. Mark

http://www.aeronca.com/ServiceLetters/cont_m47_16.pdf

http://www.airweb.faa.gov/Regulatory_an ... ight=e-213

National Aeronca Association Bulletin Board

A75-8 ENGINE CUTTING OUT DURING CLIMB

A75-8 ENGINE CUTTING OUT DURING CLIMB

Re: A75-8 ENGINE CUTTING OUT DURING CLIMB

A75-8 CUTTING OUT DURING CLIMB