Question for Alky Mechanics

[14-H]

I've got a question for some of you methanol-burning guru's: What is the experience with alky engines (or any other burners) in running engines that have piston-wrist pin assemblies with snap rings? How many RPMS can comfortably be run with this piston assembly design? How are current alky engines assembled with regard to the piston assembly? Are snap rings used with bearings in the rod and if so, what type of retainer is used to hold the wrist pin in the piston? Thanks. Eddie.

[hydroracer25]

I might have an idea...

Ed,

It actually depends on the wire diameter of your snap ring (circlip), depth of the clip groove, and inertia loading (speed and mass dependent). Yes, with higher rpm's it can become an issue, however there are things that can be done to conpensate for this.

1) use a larger diameter wire snap ring, of course this requires a larger groove
2) change the type of snap rings (ie. other type of snap ring), also requires change to groove
3) place it gap preferably in the "up or down" position. Up being towards the piston crown, Down being towards the crankshaft. This is just something that can/should be done anyway.

Now...my turn...WHY?

Mark

[raceright]

I've got a question for some of you methanol-burning guru's: What is the experience with alky engines (or any other burners) in running engines that have piston-wrist pin assemblies with snap rings? How many RPMS can comfortably be run with this piston assembly design? How are current alky engines assembled with regard to the piston assembly? Are snap rings used with bearings in the rod and if so, what type of retainer is used to hold the wrist pin in the piston? Thanks. Eddie.

Hi Ed
Steel retainer in rod to wrist pin to hold needle bearing's,wrist pin set what I call loose (when set in piston will slide very slowly through without pressure) wire circlip in Rossi,Konig,Konny and Yamato 500's and 700's have seen 14,200 RPM at a max in 500's(kind of risky) and 12,400 in 700's some times cam ground piston's some times not. Ring gap set a little wider from time to time,tighter gap will rise over piston pin on higher rpm engines. Hope this helps
Pat Wright
Top Hydro
Because in the end there can only be one

[David Weaver]

Not a Mechanic, but...

I've got a question for some of you methanol-burning guru's: What is the experience with alky engines (or any other burners) in running engines that have piston-wrist pin assemblies with snap rings? How many RPMS can comfortably be run with this piston assembly design? How are current alky engines assembled with regard to the piston assembly? Are snap rings used with bearings in the rod and if so, what type of retainer is used to hold the wrist pin in the piston? Thanks. Eddie.

...250's are typically running from 12,500 (canoes, I mean runabouts) to over 14,000+ (racing boats, I mean hydro's). I have not had clip fail yet (and yes I am knocking on wood as I write this).

[nicf14]

These clips work great, just don't reuse them. There are $1 a set from Wiseco.

[Dan M]

Make sure you use the ones that are "C" shaped (without the tangs). At high RPM the tangs will fatigue and cause damage.

[14-H]

...250's are typically running from 12,500 (canoes, I mean runabouts) to over 14,000+ (racing boats, I mean hydro's). I have not had clip fail yet (and yes I am knocking on wood as I write this).

How many heats do you put on the engine before you replace the clips?

[raceright]

How many heats do you put on the engine before you replace the clips?

Have had clips fail in 500 when rpm was over 14,000
never reuse them and change them and rod bearing every
time pistons are changed or at end of season
Pat

[ChrisH]

...250's are typically running from 12,500 (canoes, I mean runabouts) to over 14,000+ (racing boats, I mean hydro's). I have not had clip fail yet (and yes I am knocking on wood as I write this).

Dave,

If it it fell out would you replace it or Ellen? This is a mechanics thread you know!!

[Tim Weber]

Ed,

Is it true that you are working on converting a new Sidewinder to alky? I didn't know that Sled had the time.

Tim

[Dave_E71]

These clips work great, just don't reuse them. There are $1 a set from Wiseco.

This is MUCH cheaper than replacing the nikasil, piston and ring, I know...One of the old guys distracted me while the other one reused the clips

How many heats do you put on the engine before you replace the clips?

My 250 had ~60 heats +testing without any failures but I'm not twisting it as hard as David. Around 13,600 for me

Make sure you use the ones that are "C" shaped (without the tangs). At high RPM the tangs will fatigue and cause damage.

If I wasn't so lazy and the garage wasn't so cold, I'd take some pictures on the 500 sitting on the bench that ate one of the tangs. Both top cylinders...

Dave,

If it it fell out would you replace it or Ellen? This is a mechanics thread you know!!

Chris, I'm still laughing

[David Weaver]

Truthfully

Dave,

If it it fell out would you replace it or Ellen? This is a mechanics thread you know!!

Probably Ellen after Steve 77T showed her how to do it. I must conserve my strength in order to chase you, Brandon, Denny, Bruce, et. al.

Ed, I probably get 30+ heats a year out my 250 and change the clips at the end of the season.

[David Weaver]

A contributor

[QUOTE=Dave_E71;99186] This is MUCH cheaper than replacing the nikasil, piston and ring, I know...One of the old guys distracted me while the other one reused the clips

I believe my dad performed the distraction, while Pop recycled a perfectly good clip from his 1970 FA!!

[Dave_E71]

[QUOTE=David Weaver;99240]

This is MUCH cheaper than replacing the nikasil, piston and ring, I know...One of the old guys distracted me while the other one reused the clips

I believe my dad performed the distraction, while Pop recycled a perfectly good clip from his 1970 FA!!

Yep, it was your dad and Pop under the tree at DePue and I think it was the original clip from his FA..... But hey, I made it ~20 yards from the pits before it puked

[alky6]

... How are current alky engines assembled with regard to the piston assembly? Thanks. Eddie.

The assembly is much the same as the mercury 20 ci, 30, 40, etc. except that the needle bearings are caged in a bronze or steel (sometimes nickel plated) retainer instead of rubbing against each other like the Merc. Same goes for the big end rod bearing as the cranks are pushed together. Newer alky engines have no "tails" on the wrist pin clips. Also, most of the alky engines have a 15mm diameter wrist pin (though I believe the twin 350's have a larger diameter).

Hope that answers that one....

-Paul Fuchslin