TELEDYNMCS(at)aol.com
Guest
|
 Posted: Sat Mar 10, 2007 8:08 am Post subject: Jab power |
 |
|
In a message dated 3/9/2007 2:59:15 AM Eastern Standard Time, europa-list(at)matronics.com writes:
| Quote: | I would very much like to see your photos when you're back in Tennessee.
Up to now I've had very little to do with Jab's but have lived with a
Lycoming for a while in my Long EZ. The EZ crowd have done a lot of
development and testing with some success.
There are some guys near me who recently bought a Europa with a Jab and
aren't having much luck with it, quite apart from the overheating there
isn't much power either, 300 fpm climb rate! Not a lot of use,
bye for now
Graham |
Hello Graham,
Back in Tennessee now. I'll put together some photo's and shoot them out to everyone who as asked later today.
In regard to their Jab not producing adequate power, there are several things they should check. Most of these are pretty obvious and I might be telling you something you already know, but here goes.
The first thing I'd look at is the intake manifold and make sure it's not leaking air. There are rubber boots that are held in place with hose clamps on the various intake pipes that could be leaking. Also, have them check the distribution block on the bottom of the engine where the intake tubes meet. These are sealed in with RTV and could be leaking. Next, if they haven't already done so, check the valve tappet clearance. Improperly set valves will significantly reduce power and if allowed to run for extended periods will ruin the heads. A compression check will tell them if the valves and or valve seats are burnt and leaking. Next, check the needle jet and make sure it's up to current standards. The Jabiru factory website has the details on this. They should be running a 286 needle jet and the Jabiru "stepped" needle. The engine supposedly dyno's at 127 hp with this set up. Fuel consumption is considerably lower with the Jab needle arrangement compared to the stock Bing needle, too. If they have an older Jab, they probably have the stock Bing needle and jet. Also, have them check the choke spring and make sure the choke is returning to completely off. The choke spring sent on the Bing carby is weak. Some guys replace them with stronger springs, some put a second spring on to help it return. I preheat, so I never have to use choke, but I have noticed when I tested the setup that mine won't return to completely off with just the spring tension. Lastly, check to make sure their prop isn't overpitched. I've found that I can easily overpitch my prop and it won't make sufficient power. I've found it's a fine line between proper cruise pitch and overpitched. An overpitched prop will also make the engine run hotter.
Something is obviously very wrong if they're only seeing 300 fpm climb. This, coupled with the overheating leads me to believe that they are running lean. The color of the spark plugs should tell the story. I'm seeing 1800 fpm from take off (700' msl) to about 6000' agl with two on board and a mid cruise pitch. My oil temps never go above 190F and my CHT's run in the 250F-280F range in cruise, well within the normal operating range.
Anyway, hope it helps!
Regards,
John Lawton
Dunlap, TN (TN89)
N245E - Flying
AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com.
[quote][b]
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
