Push rods too long

[Spirit of Pappy]

I'm overhauling a Continental 0-300 for my Starduster. Had to buy a refurbished case from Divco. Now the standard push rods are too long. I am certain the hydrahlic piston in the lifters are dry and bottomed out. There are only longer rods available no shorter rods.
Any ideas?

Thanks in advance

Don

[GAHorn]

It’s common to find .030 (over-length) pushrods on engines which have been overhauled previously… but shorter ones are available. Have you measured the actual length of the ones you have?

[dstates]

I have 4 used pushrods that when I overhauled my engine I had to replace with longer ones. I believe I have the length measurements for them. I would be willing to sell them if they are of help to you. I'll look this weekend and see what length they are.

Doug

[Bruce Fenstermacher]

Don, when the hydraulic pistons are flat you can push in on the rod with your thumb and move then what feels like a 1/4". If you can't move the rod and hydraulic with your thumb, something is not right.

PN 537870 is the same push rod used on all these engines: All models of the following engines: A65,A75,C75, C85, C90, O-200, C125, C145, O-300, GO-300.

SA before the PN = Superior Air Parts, a PMA producer of parts for a long time.

Airpower says they have 20 SA537870 rods in stock at $40 each. https://www.airpowerinc.com/SearchProducts?q=537870

Aircraft Spruce claims to have at least 8 SA537870 rods at $52 each https://www.aircraftspruce.com/catalog/ ... -16406.php

Fresno has them at $26 https://www.fresnoairpartsco.com/product/pushrod-10/

I just removed 7 of them from an A-65 the owner might want to part with. But you have lots of options.

[cessnut]

What are you getting for clearances? Like Bruce mentioned, if the hydraulic unit is properly bled down, you can feel the spring compress when you push the rod in.

[Bruce Fenstermacher]

Rereading Don's post, he says STANDARD rods are to long. I think we all read standard was too short. My question is, how does he know he has Standard rods? He may, what I just removed I only suspect are standard but they are not marked. In my case replacing the 7 that exceeded .110" of lash with .030" over fixed the problem.

If he does have standard rods, and they are too long, I don't think shorter was ever made.

[n2582d]

I too haven’t heard of shorter than standard length pushrods. Where do you find them George?

My immediate thought, on reading the original post, was that Divco screwed up on this “refurbished case”. The Overhaul Manual doesn’t list anything in the table of limits for cylinder deck height. Figure 8 shows a width from centerline to outside of rocker cover to be 15.75” and fig. 9 shows 12.25” from case centerline to exhaust port centerline but those are “installation drawings”. I don’t think they are to be used as data on a rebuild. More relevant perhaps is the 1.679 +/-.002” given in fig. 7.

IMG_1849.jpeg

For what it’s worth, the IO-360 Manual lists the crankcase half width to be between 4.559” and 4.565”. My guess is that Divco milled too much material from the case mating flange prior to line boring/honing or perhaps removed too much from the cylinder base surface. AirWorxs talks about taking around .002” off the case mating surfaces prior to line boring at 8:20 here.

How kosher would it be to remove some material from the valve end of the rockers? If they’re nitrited I would think that’s not a good idea.

[GAHorn]

That’s a good question, Gary…. In the automotive world, pushrods are mfr’d using a hollow tube…with a “ball” welded ..(or formed and inserted) …onto the end…(drilled of course)… The tube can be made any length whatsoever….

Of course, milling any case beyond OEM spec’s… likely involves obtaining another “basis of approval”…. which DIVCO might…or might not… have….

[cessnut]

Gary,
That was my first thought as well, but it seems they would have had to remove an egregious amount of material to eat up all of the .030-110. At that point wouldn't you have trouble aligning the sump and the accessory case?
I would like to have the OP measure the rods. In the few little Continentals that I have messed with I have not had the need for a pushrod shorter than standard, usually the other way around. I wonder what the valve grind situation is.

[n2582d]

... At that point wouldn't you have trouble aligning the sump and the accessory case?

That's what a rat tail file is for -- make the sump and accessory case mounting holes into slots. Seriously, that's a good point ... very unlikely to find that much material removed from the crankcase center flange. If the cylinder mounting pad/deck were milled the sump and accessory case alignment wouldn't be an issue but, again, it's unlikely that much material would be removed from there either. I was wondering if Don accidentally got a C-125 case. But, even if that were the case (no pun intended), I've never heard that the case half width is any different on the C-125 than the C-145/O-300. I emailed Continental to ask if they had a case half dimension like the one shown in the IO-360 Overhaul Manual. Kyle Blackwood (CMTechnical@continental.aero) wrote back, "I don't have data for crankcase dimensions. Make sure the lifters are bled down or move rocker arms to different positions, the foot of the rocker arm could be a different thickness." If one elects to start swapping rockers, don't mistakenly swap exhaust and intake rocker locations. See Continental Service Bulletin M77-19.

[GAHorn]

The other items that come into play on this is the valves, rockers, and valve SEATS. If the cylinders are out-of—spec….

[Bruce Fenstermacher]

I am also in the thick a of new cylinders on an A-65 project, which has required 7- .030" rods. In my reading, likely in the '1948 Overhaul Manual, I seem to remember it said that if you don't have the minumum required .030" lash, consider fresh valves, seats or, , grind the tip of the valve stem to required lash. I could have been dreaming this though.

Bottom line was the valves and seats have been ground to the limit (or probably to (far) was different valve and seat or grind the valve stem.

Back then parts were plentiful. Valves were $2 and seats another $1 and nearly every airport or town had a "engine" machine shop.