I am looking for longer pushrods for a C-90, I heard that there are pushrods available which are 0.03" longer.
So I´m looking for a part number and where to buy.
Yes I changed all cylinders. The rocker arms were changed too and I noticed that they were machined where they touch the valves. I checked the dry tappet clearance and I was right on the upper limit.
The engine run great for the last 35 hours since the new cylinders were installed. It still runs good with a very slight vibration in cruise, but at idle power there is a kind of popping and I suspect that the valve clearance has increased some. Not sure but longer pushrods would bring me into the middle of the tappet clearance limits. At this time I don´t know the pushrod length but would say they are standard. I got new ones with the cylinders and they were exactly the same length.
One more point: I just changed from straight mineral oil to W100.
Checked my continental books and they show only one push rod part number for all C model engines the rocker arm being machined is were you got the increase in the valve gap but if your hydraulic lifters are working the gap is zero so as long as you are within spec they are good the popping at idle could be caused by a rich idle circuit the stromberg carb will tend to run a little rich and the extra fuel goes in the exhaust and when next valve opens you get a second explosion in the muffler hence the poping sound
The pushrods do come in various lengths. I believe they come in .030" increments. It's been awhile since I did a Continental but I did have to get longer pushrods to obtain the proper clearances.
The longer pushrods are getting harder to get. Robert Weber had an old guy who used to make them for him but the guy died. We have talked for years about making a washer type shim the you could put under the cup in the tappet body to raise the cup doing the same thing as the longer pushrod. The adjusable pushrods in my Shovelhead looked like they would work.
How about going to an adjustable pushrod. There are kits available to make your own. Might have to get a field approval or Continentals approval but would be better than a shim in the lifter which would need some kind of approval also,,,unless you're Experimental.
Shovelhead,,,right on!
Steve where in the parts manual did you find the listing for oversize push rods i have went threw both c75/0200 overhaul and parts manual for said engine and can't find any thing said about longer push rods at all also went threw A65 manual and nothing said there either. I think the large valve gap is caused when the cam follower and rocker arms were rebuilt do they not machine the face of the follower and the valve face on the rocker arm witch would make the valve gap wide and as far as adjustable push rods they are a oil passage to the rocker arms so oil has to flow threw them Oh went on harry Fentons site also no longer push rods there either
New rockers are over 300 bucks each, five years ago they were 100.00 . We need one of the repair facilities that overhaul rockers to come up with an off center rocker pin bushing that gets them back to original specs.
Ok, I ordered the oversize pushrods. I am confident that this solves the problem. Will report back when they are installed, might take three weeks or so.
Here is an update: I got the oversize pushrods and installed them. Meanwhile I flew about two hours or so and all seems normal. Engine is smooth again and no strange sound.
However the .03 oversize pushrods are more like .012 - .015" longer than my other pushrods and this is kind of disappointing because now I am still near the edge of the dry tappet valve clearance tolerance. And they were expensive with all the side costs! May be I have to look for .06 oversize pushrods!?