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aircraft pushrods

M

mwood7800

Well-known member
if anyone needs to know, there is a company in Oregon that will make your pushrods adjustable (like a harley). they charge 10$ a rod. the company is Smith Brothers at 800-367-1533
 
I use Continental tubes on my O-360 Lycoming. The have a spring that keeps them tight. Use the rubber grommet that goes on GPU tubes and you'll have no oil leaks. Learned this from Dick Hoffman.

Ken
 
Ken you were talking about the shrouds or the pushrods? I think I have the same set up on my IO 540 , This year I manage to find some stainless springs for my shrouds.
 
My mistake mike. I misread the post. I was refering to the tubes or shrouds.

I'm fortunate enough to have a friend that rebuilds Lycoming Engines and when we rebuilt my O-360 he just gave me a box of push rods to play with untill I found a set that was within spec.

Ken
 
I have had several friends that run aircrafts that have had push rod length issues. I told them to have an automotive pushrod manufacture make them a custom set well they said no way the wanted high quality aircraft air worthy pushrods. Well here is the funny part I took one of their old push rods and smashed it with a hammer to drive the tip out and found they were made from cheap seamed tubing they split right down the tube seam. So I talked them into upgrading to a chrome molly seamless tube pushrod. Well I checked all of his valve train and found his motor was so wore out in order to have the correct lifter preload it needed 10 different length push rods. So the easiest and cheapest way to fix his problem was to buy stick of .090 wall chrome molly seamless tubing. Then I made a pushrod length checker and check the required length of each of his pushrods. Then I popped the ends out of his old pushrods most of them were not even spot welded in then installed them into the piece of tubing I cut to length. Now he has a much higher quality pushrod that is the exact length needed to put the correct lifter preload on his lifters. His motor runs noticeably better with absolutely no valve train clatter like he had before. All this cost under $60.
 
Careful Dave,

Next thing you know you will have an R&D program going for Lycomings, then we will see some real performance out of them. Excellent post.

jim
 
Thunder- So when are you moving to Texas so I can think about having my next Lycoming done right. LOL

I had always figured they could put fine threads one end of the rod and the tip to come up with some sort of length adjustment so rods could be fine tuned. Maybe the issue of locking the tip in place is the issue, but seems like it could be done.

Guess it might run the cost of a new TI0-630 up another $1,000, but seeing what they ask for a new one, you probably wouldn't notice the extra grand. LOL

Good idea Thunder, thanks
 
the adjustable ends smith is adding to my tubes sre the same ones that have been in my harkey for 7 years, My bike often sees 6500rpm so my lycoming at 2700 should handle them fairley well. and make my life a littlr smpler.
 
Jim, I think he secretly really likes working on 'em.

I'd like to see him build one some time and use a few of the tricks he's learned for those Monster LT1's ..... that would be some motor 8) .

BF
 
I was planning on getting some of those adjustable ends from Smith Brothers and make my own chromoly pushrods when I finish my 520. It does make it real nice to be able to run the proper lifter preload without needing a box of different length pushrods, esp. when you mill the cases down alot.

Larry
 
Just think you can set all your preloads within .005 if you wish! Allot of air boaters are missing the boat on this little tid bit. Trust me guy's allot of people don’t think its critical but here is a simple test. On a standard automotive rocker arm stud, 1 turn is .042 of travel. So go out and back the rocker arms off in you truck 1 turn and watch how shity your motor runs and wouldn’t rev and clatters or turn em 1 turn tighter and watch it pop and bang. 90% of all hydraulic lifter run on a .050 preload I have been told aircrafts run looser to compensate for massive expansion however after cases have been ground or a valve job has been done or parts have been interchanged allot of airboat motors fall out of this range. So if people paid a little more attention to this detail you would be surprised how much better allot of these motors would run.





I love a good challenge. I have built a few nasty aircraft motors but I hate having a limiting factor that no matter what you do you can’t over come it. And that is being air-cooled the more horsepower a motor makes the more cooling it needs and an air-cooled motor will not make big horsepower and remain a drivable reliable motor. I know Lycoming is building water-cooled motors now and once those trickle down to us airboaters I may build one because then you can modify an aircraft motor and make big reliable horsepower however I’m sure the run out’s will be 10K or more.
 
Waterthunder, what do you think i should set my adjustable pushrods at when I go back togeather, the books says somewhere between 28/80
 
Cool you found us some book numbers if your manual states between .028 and .080 then they are just like an automotive lifter and are based on the.050 preload range so I would set them up at .060. When you install these new push rods use a molly lube on the tip's for break in because the pushrod tips are the last place to get oil.
 
I also made custom pushrods, I found a bunch of them at a buddy's house. They were longer than mine by about 1/4". I figured what lenth I needed them and poped out one end. Then trimmed them on a lathe to the right length, installed them and now no more clacking!
 
That's the best way to do it find zero lash then add .050 length for lifter preload. I just like up grading the pushrod to 4340 chrome molly seamless tubing because the pushrod is sooooo loooong in these aircraft motors I'm sure there is some push rod deflection at max RPM's but not near as much as car motors because they only turn 3,500RPM and run a much smaller lift cam but every little bit helps.
 
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