exhaust "Y" too long??? also rudder pedal reinforcements?

11 posts in this topic

Posted

I need advice.. My 1990 KF2 does not have any reinforcements on the rudder pedals. THere are no cracks in 700 hours but they are not reinforced. How critical is this????

Also my new "Y" header pipe from my 582 BH is about 1 " longer than the old one that was on the plane. I cant make it fit without interfereing with the cowling support tubes that hold the engine cowl.....Has anyone seen this before??? Maybe I have an old 532  Y pipe????Ill try to get some photos tomorrow.

I looked at a model IV classic kitfox and it has a completely different engine mount... that is probalby what I need if it will fit a model 2 kitfox. then the exhaust if clear of the engine mount....puzzled in Washington..

 

Mark

exfaa@outlook.com

 

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Posted

How much room do you need to get back?  I know they had a tighter bend (smaller radius) on the connecting elbow to alleviate some of this.  Header length can be important, especially on a tuned exhaust as it can change the power band, so you do need to exercise some caution and sort it out.

My Model III did not have the reinforcement either.  No problems at 150 hours.  Only significant load might be when braking.  However many folks have accomplished and it is probably good insurance.

Do you have the side mounting or bottom mounting on your crankcase?   Friend has a Model 2 with original 582 and no issues with exhaust clearance, so maybe if you can get some pics and measurements I can check against it.  My Model 3 was side mounted, but I think his is bottom mounted.

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Posted

mine is a botton mount.....Ill try to post some photos later today....this is a photo I took before I removed the old engine. You can see how close the elbo on the exhaust comes to the mount. IN fact KF factory shortened the elbo to clear the mount... Im thinking the only real way to fix this is get a newer mount that holds the engine different and allows for clearance....

The bluehead is Daves install from Eastern Canada. He has the later mount for KF4. THe cowling support tube is not in the way. YOu can also see where Dave welded and extension to the header pipe and claims to gain 700 more RPM which could be true.....IF I try to run my elbo on the outside of the cowling support, I would have to hack up my cowling something terrible to make it all clear and fit. Still tryhing to figure out exactly what KF changed because Daves cowl and mine Look the same, the radial engine look cowling,,..

8 Daves mod to 582 exhaust to get more power.jpg

DSCN1442_LI.jpg

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Posted

I assume you are using the shorter (unmodified elbow) as the extended one wouldn't work for your application.

 If able let me know what two lengths you have and I will try to confirm on a local model II

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Posted

Another option might be to also look at if those side cowling tubes even need to be there.  I know the Model III and later did away with them, though dont know if there were any modifications to the fiberglass for added support. 

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Posted (edited)

Mark - I had a thread about the different cowl/582 engine mount differences a while back on the TKF forum. If you are registered you might find the info and pics helpful. LINK

Also, you can see the different KF engine mount p/n's (and all other part #'s too) listed on the Packing Lists from the KF3 and KF4-1050 kits I listed in the Classifieds HERE . Attached is a quick screen shot from the KF3 records.

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Edited by dholly
Add pic

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Posted

Re: rudder pedal reinforcement, I say critical. My experience below.

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Posted

If the pedals were cracking at the little arm attached to the rudder cable, why reinforce the base of the pedal?  Granted, that is also a weak spot but I don't understand how it addresses the original problem.  Am I missing it?  :)

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Posted

The KItfox Service Bulletin was originally directed at crack failure between the main torque tube and rudder pedal upright, but mine was not the first to fail at the cable arm to upright point of attach. It may be more difficult to see than the triangular gussets, but I also reinforced that area with a strap wrap. IMHO, both are necessary and should be a priority before next flight. My failure occurred during landing in a x-wind where every bit of rudder was important and I was -very- fortunate not to wreck my plane.

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Posted

Thanks for the info guys... Im going to try to just buy a whole new rudder pedal setup from Kitfox factory if they have one.. If not, Ill look for a used on and add the reinforcements, that way I dont have parts all over the place ripped apart.........I inspected each weld very carefully and they all look fine for now however I dont want a built in problem so will do something about it soon...

 

Mark

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Posted (edited)

Mark,  I have a pair of pedal torque tubes that are factory fresh and powder coated, but I have not looked at them to see if they have the reinforcements added.   Check Kitfox for prices and ask if they are reinforced, and then get back to me on this.  EDMO

Edited by EDMO

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