Ok I got my new test stand done today and here it with engine running on it.







I tried to test the exhaust timming mod today to. the best i could get was 7380 rpm which is down from the 7440 that I had been getting.

I had a static thrust of 13lbs 10 oz.

I dont know how acurate all this is as i discovered some problems.

1st my engine would not hold a steady top end rpm. it kept kind of searching and you could hear it do it to.

2nd I dont know how accurate my tach is after droping and repairing it. I have one of them laser tachs on the way to check against.
I am of the opinion that these hobby tachs suk pretty bad and are very general and not very accurate at all.

3rd I could not get a steady idle and it changes every time i run it. I discovered here that when i chenged the throttle shaft out from the old carb it lets it vibrate around and wear some slots into the edge of the butterfly valve. as you can imagine the larger they get the worse the idle. now i know why it changes ever time i run it also.

4th when i was dissasembling my engine again i discovered my spark plug was loose. what can i say but DUHHH!!!

I need to get thses four things ironed out before I am willing to make a good determination on the exhaust timming change test.


Ok also when looking at my rings it has spots in it that are shinney and other spots that are not and have a good coat of varnish on them. It seems to me if the rings are contacting all the way around the ring face should be shiney all the way around where it is in good contact with the cylinder wall.

This really makes me wonder how good of a seal i have with this ring cylinder combo.

Aviator1977 said it well in another post that this is a very basic important starting point. Its got me thinking on how do we figure how good a seal we are getting? I then remebered my airplane training and i havent had to do this for years but i think we could build some leakdown testers and check it that way. If you are unfamiliar with a leakdown test i will have this procedure later and we can all know where e are at cylinder seal wise. you can see how it works here to http://en.wikipedia.org/wiki/Leak-down_tester

At this point I have what i feel to be to many inconsistencies in the testing procedure that I am contemplating stopping this thread and starting all over on a new one. I guess the best way to look at this thread is it was a good education on getting a good consistent testing set up. I also need to purchase a new carburetor to. I think i will get a couplke just to have some on hand to.