Engine Trouble

[Space puppy]

I am having trouble with my 0320 H2AD Duel mag single drive. left mag loses 4-500 rpm. right mag 50-75 rpm drop. both mags on I get 2300 rpm and runs fine. I am using fixed pitched Senench prop recomended by vans. only one time did it run with small equall rpm drop. I flew 1.8 hr. this day and when I returned I checked both mags and still 50-75 rpm drop. two days later at run up the left mag. showes 4-500 drop. I have replace both coils and condensers new wire harness clean plugs checked timing still the same drop. rebuilt engine by A&P now 4.8 hours on it. the A&P has run out of ideas. anybody with any ideas would be apprecated. Jerry Jones.

[Mike S]

Jerry, welcome to VAF, sorry I cant help with the mag problem, but I would be surprised indeed if there wasnt someone out here who will be able to assist you.

Glad to have you aboard

[Mark Burns]

Originally Posted by Space puppy

I am having trouble with my 0320 H2AD Duel mag single drive. left mag loses 4-500 rpm. right mag 50-75 rpm drop. both mags on I get 2300 rpm and runs fine. I am using fixed pitched Senench prop recomended by vans. only one time did it run with small equall rpm drop. I flew 1.8 hr. this day and when I returned I checked both mags and still 50-75 rpm drop. two days later at run up the left mag. showes 4-500 drop. I have replace both coils and condensers new wire harness clean plugs checked timing still the same drop. rebuilt engine by A&P now 4.8 hours on it. the A&P has run out of ideas. anybody with any ideas would be apprecated. Jerry Jones.

Hi Jerry,
Have you moved all the spark plugs from one mag to the other? If not I'd try that first. It could be a bad plug. (even if it tested good)
If that's not it then I would borrow a high tension lead tester and check the spark plug leads.

If you don't find anything with these two tries then I would think it's the mag and re-examine it.

Good luck with it.
Mark

[hgerhardt]

Is the timing the same R&L? If it's different, one or both of the point gaps is wrong. If it's the same, check e-gap.

Heinrich Gerhardt

[mahlon_r]

Could be a bad condenser. If the plugs, leads and points check, try swapping condenser positions, in the cap, and see if the problem follows.

Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

[osxuser]

Smooth 400 RPM drop or rough?

[Norman CYYJ]

Do you have an EGT and CHT on each cylinder. If so check the EGT temps running both mags. Then check the temps with the left one off and see if there is a major change in any of the temps then do the same for the right mag. It should show the problem area. If all the temps change with one of the mags off in a big way the timing is probably out. If only one cylinder shows a problem then it is probably a plug or lead or a bad distributor cap in that order.