Stupid engine question.

[Dan Thomas]

Chill out my friend....

I have the HIGHEST respect for you, your knowledge and lifes experiences. Altho I am kinda suprised you didn't incorporate roller lifters and roller rockers during your modification process... That sir is relatively cheap HP and adds alot of longevity to any motor. My boost power comment was aimed at the 0-360 series.... Heck anyone can add cylinders to increase HP.. That was the radial motors claim to fame,, well that and those pesky oil leaks.

Peace brother...

Roller lifters might be cheap if the engine is done at the Lycoming factory. We buy their factory overhauls and they all come with the roller lifters now, no extra charge, but there's a bunch of machining involved in the crankcase lifter bores to square them up so the lifter won't rotate. That won't be simple in the field-overhaul shops.

There's a drilled aftermarket Lycoming camshaft available that has channels to take oil from the cam bearings to the heels of the lobes. No more dry cam at low RPM or initial idle. I don't know why Lycoming hasn't bought a license from the inventor to incorporate it, or why they didn't do it themselves. I guess they figured the roller lifter would work better and market more easily.

Dan

 

[bigred177]

On avweb today, haha.

http://www.avweb.com/blogs/insider/AvWebInsider_DumbEngineCompanies_202741-1.html

 

[N801BH]

Roller lifters might be cheap if the engine is done at the Lycoming factory. We buy their factory overhauls and they all come with the roller lifters now, no extra charge, but there's a bunch of machining involved in the crankcase lifter bores to square them up so the lifter won't rotate. That won't be simple in the field-overhaul shops.

There's a drilled aftermarket Lycoming camshaft available that has channels to take oil from the cam bearings to the heels of the lobes. No more dry cam at low RPM or initial idle. I don't know why Lycoming hasn't bought a license from the inventor to incorporate it, or why they didn't do it themselves. I guess they figured the roller lifter would work better and market more easily.

Dan

I 'could' be wrong here but.........

In EVERY engine I have built or modified or even blueprinted the lifter bore was square with the cam, ie. exactly 90 degrees. All lifters I have seen whether it was flat tappets or roller were positioned in the block, case, etc perpendicular to the cam. Rotation of the lifter is caused by a crown machined in the face of the flat tappet itself and in some remote applications the very slight taper of the cam lobe. Yeah, I have ground or reground more cams then I am willing to even admit too. I personally built a few lifter grinder/refacers for some aircraft engine rebuilders and as long as the face of the lifter passed the rockwell hardness test after the refacing process they yellowtagged that item. And I am talking 1000's of lifter bodies.

Dan, I would like to see any documentation you have that says lifter bores on Lycs are machined at a slight angle to get the lifter to rotate.

Thanks in advance.

Ben.

 

[Henning]

I 'could' be wrong here but.........

In EVERY engine I have built or modified or even blueprinted the lifter bore was square with the cam, ie. exactly 90 degrees. All lifters I have seen whether it was flat tappets or roller were positioned in the block, case, etc perpendicular to the cam. Rotation of the lifter is caused by a crown machined in the face of the flat tappet itself and in some remote applications the very slight taper of the cam lobe. Yeah, I have ground or reground more cams then I am willing to even admit too. I personally built a few lifter grinder/refacers for some aircraft engine rebuilders and as long as the face of the lifter passed the rockwell hardness test after the refacing process they yellowtagged that item. And I am talking 1000's of lifter bodies.

Dan, I would like to see any documentation you have that says lifter bores on Lycs are machined at a slight angle to get the lifter to rotate.

Thanks in advance.

Ben.

I haven't had a roller lifter Lycoming apart before, but I would assume that the machine work involved is to allow for the link arm between the lifters that keeps them from rotating. There may also be preload springs on the lifter that would require a land be machined to bolt the retainer bracket to.

 

[N801BH]

I haven't had a roller lifter Lycoming apart before, but I would assume that the machine work involved is to allow for the link arm between the lifters that keeps them from rotating. There may also be preload springs on the lifter that would require a land be machined to bolt the retainer bracket to.

I thought about that too but he did say " square them up in the bore".

If there is a market for roller lifters in experimentals I have a good friend in the racing arena that makes high quality stuff and since business is slow on his end producing a roller lifter mod for existing Lycs might be a viable avenue. Tying the lifters together to keep them aligned should be pretty straightforward and properly designed no case mods should be needed. You will need a new 'roller' style cam though. Jus thinkin out loud.

Ben.

 

[Henning]

I thought about that too but he did say " square them up in the bore".

If there is a market for roller lifters in experimentals I have a good friend in the racing arena that makes high quality stuff and since business is slow on his end producing a roller lifter mod for existing Lycs might be a viable avenue. Tying the lifters together to keep them aligned should be pretty straightforward and properly designed no case mods should be needed. You will need a new 'roller' style cam though. Jus thinkin out loud.

Ben.

When I talked to Ed Iskendarian about my cam, I was considering going roller, but at that time there was no roller lifter being made that fit the bore, so I was going to have to redo the bosses, and I didn't have the time or access to the equipment to do it. That was in the days befor Lyc came out with rollers, and yes, there would have been extra cost involved in re-profiling the cam to run roller lifters. I would have liked to, but I couldn't justify doing it.

 

[Dan Thomas]

I thought about that too but he did say " square them up in the bore".

No, I said "square up the bore." The lifter has flat sides on it and the outer end of the bore isn't round anymore; it has flats, too, so the lifter cannot rotate in the bore. Got to keep the roller aligned with the cam.

See the flats? The original lifter bore is drilled or broached so that it's of a larger diameter but flats are left in it near the outside end for the alignment of the lifter with the cam. The pushrod tube seals at the case are much larger and green in color, making the roller-lifter engine easy to spot.

Here's a presentation on the subject:
http://www.aerosportpower.com/docs/007E22338B483021.pdf


Dan

 

[weilke]

How have the roller tappets been holding up in your planes ? Any of them run to TBO yet ?

 

[N801BH]

No, I said "square up the bore." The lifter has flat sides on it and the outer end of the bore isn't round anymore; it has flats, too, so the lifter cannot rotate in the bore. Got to keep the roller aligned with the cam.

See the flats? The original lifter bore is drilled or broached so that it's of a larger diameter but flats are left in it near the outside end for the alignment of the lifter with the cam. The pushrod tube seals at the case are much larger and green in color, making the roller-lifter engine easy to spot.

Here's a presentation on the subject:
http://www.aerosportpower.com/docs/007E22338B483021.pdf


Dan

Good info... Thanks.

Ben.

 

[dmccormack]

IN 50 years of development on the 0- series of aircraft engines all the Lyc engineers could not boost the power by 20% percent..

Ben.

Actually, it's 70 years. The O-145 was the first Lycoming production aviation engine (1939). Initial HP was 55, then increased to 65.

 

[Dan Thomas]

How have the roller tappets been holding up in your planes ? Any of them run to TBO yet ?

All of those we've had, two or three of them, have reached TBO without any trouble. We have three more on the go now. No detectable difference in operation.

Dan

 

[weilke]

All of those we've had, two or three of them, have reached TBO without any trouble. We have three more on the go now. No detectable difference in operation.

Good. I wonder whether it will make a difference on planes flown less regularly.

 

[Capt.Crash'n'Burn]

I 'could' be wrong here but.........

In EVERY engine I have built or modified or even blueprinted the lifter bore was square with the cam, ie. exactly 90 degrees. All lifters I have seen whether it was flat tappets or roller were positioned in the block, case, etc perpendicular to the cam. ...Dan, I would like to see any documentation you have that says lifter bores on Lycs are machined at a slight angle to get the lifter to rotate.

Thanks in advance.

Ben.

AFIAK, the lifter MUST be 90 deg to the cam or you will get binding. I helped a friend of mine, who owns a valvetrain business, put together a Pro Stock engine that used a mid-lifter. The idea of a mid lifter is to get better valve-train geometry while moving the pushrod over to allow for a bigger intake port. The problem with the design is that the bottom pushrod, and top pushrod are pushing on opposite sides of the lifter. This led to several of the lifters binding up at 10,000 RPM. The results weren't pretty. Can you say $80,000 flushed down the toilet??