RCU Forums

RCU Forums (http://www.rcuniverse.com/forum/)
-   Glow Engines (http://www.rcuniverse.com/forum/glow-engines-114/)
-   -   Filled Crank (http://www.rcuniverse.com/forum/glow-engines-114/2970936-filled-crank.html)

MassiveMods 05-13-2005 08:10 AM

Filled Crank
 
What exactly is the stuff called that people fill cranks with ?

exeter_acres 05-13-2005 08:12 AM

RE: Filled Crank
 
Do you mean After run oil?? You can buy it special or use ATF or compressor air tool oil....

I think some even just use 3 in 1 oil.....

downunder 05-13-2005 09:56 AM

RE: Filled Crank
 
Tungsten alloys like Rossi use?

MassiveMods 05-13-2005 10:10 AM

RE: Filled Crank
 
Sorry i should be more specific , like the epoxy resin they fill lightened cranks with ...

tIANci 05-13-2005 10:40 AM

RE: Filled Crank
 
I think you are referring to the epoxy that is in RC car engine cranks. That blob of epoxy allows the fuel to flow better into the crank. One of my pals found some epoxy that works the same, you want to know what it is and use it?

Flyboy Dave 05-13-2005 01:31 PM

RE: Filled Crank
 
Back in the old motorcycle days I would champher the edges or the hole
to give an edge for the epoxy to hold on to, and to remove a bit of weight.

Then I filled most of the hole with cork, and epoxyed both sides to hold the
cork. The weight that was added off-set the weight that was removed, and
it didn't change the balance of the crank. ;)

It's called "stuffing the crank"....it increases the crankcase pressure.

FBD. ;)

William Robison 05-13-2005 03:50 PM

RE: Filled Crank
 
1 Attachment(s)
Here's an example of what FBD was talking about, but this is a factory part.

On the right in the picture is a normal "Sport" crank shaft, with the web milled for balance. The crank on the left is from the "Q40" engine, instead of the open milling it has slots milled from the edges, then an aluminum ring is shrunk on the outside diameter to keep the free volume of the crank case as small as possible.

Bill.

William Robison 05-13-2005 03:56 PM

RE: Filled Crank
 
1 Attachment(s)
I really think you were asking about the inlet port rather than the stuffing of the case.

Here are two more cranks, K&B again. The lower crank is a standard port, the upper one has a "Flowed" port. Many use JB Weld or PC-7 to fill the forward part of the port, allowing it to be shaped for better air flow.

Bill.

MassiveMods 05-15-2005 02:25 AM

RE: Filled Crank
 
Yes thats what i mean, i am interested in the epoxy version so to keep the rotating mass lower and help achieve high revs quickly.

Flyboy Dave 05-15-2005 08:12 AM

RE: Filled Crank
 
Bill....from an old "port grinders" standpoint, I don't see much to be gained
at the inlet port....unless the port is restricted or misaligned somehow, I just
don't see much gain there. In fact, I like the "open" port better.

Now, that doesn't mean I'm right. :D

Dave. ;)

splatt 05-15-2005 10:27 AM

RE: Filled Crank
 

Quote:

ORIGINAL: Flyboy Dave

Bill....from an old "port grinders" standpoint, I don't see much to be gained
at the inlet port....unless the port is restricted or misaligned somehow, I just
don't see much gain there. In fact, I like the "open" port better.

Now, that doesn't mean I'm right. :D

Dave. ;)
Take a look at a 46AX. The crank inlet has a nice pocket machined to match very closely to the case, as compared to the straight cut you see on 46FX.

I am no engineer, but it can't be cheaper to machine that cut in the long run, must be some gain there going for , yes , no, ?

Flyboy Dave 05-15-2005 11:07 AM

RE: Filled Crank
 
A carefully designed "trick" inlet port may indeed be fruitful in an increase in
airlow....modifying a stocker with epoxy....I don't think it would be worth
the effort....especially if the epoxy or J-B weld comes loose. :eek:

FBD. ;)

William Robison 05-15-2005 11:39 AM

RE: Filled Crank
 
Dave:

With the "standard" crank porting there will always be some turbulence induced by the hard angles and the closed forward end. "Filling" the port is to reduce the turbulence. Seems to work.

You are right about its comiong loose at 22K rpm though, definitely some internal modification to the engine.

Bill.

proptop 05-15-2005 02:37 PM

RE: Filled Crank
 
I've seen several engines with the induction port ball milled (I think that's the way they do it?)
The Magnum .52 I have, and the 2 Evo's, and the as mentioned AX...
Several of my r/c car engines have it too...

I did a K&B 40 and .61 years ago with JB weld and it hasn't broken loose (yet anyway:D) maybe because of careful prep.
I roughened the area w/ a Dremel grindstone, after a thorough cleaning w/ acetone. I put the JB weld in and set the crank at an angle to cure. Then I baked it in a toaster oven at about 200* for awhile, then after it cooled, I went in w/ the trusty Dremel and put the radius in there...

MassiveMods 05-15-2005 05:49 PM

RE: Filled Crank
 
.... so does any one know what the epoxy is called ?

splatt 05-15-2005 09:45 PM

RE: Filled Crank
 
I remember something called devcon, but Proptop mentioned JB Weld. It's a brand name

It's a 2 part expoxy. one side black, onw side white. mix it together and it makes a grey base that sets up metal hard.

Flyboy Dave 05-15-2005 09:56 PM

RE: Filled Crank
 
I remember Devcon too....we had that stuff at the motorcycle shop I worked
at....really good stuff too....

....they still make it, but the prices are through the roof. [X(]

http://www.superkleendirect.com/inde...ROD&ProdID=863

FBD. :D

William Robison 05-15-2005 10:00 PM

RE: Filled Crank
 
Devcon is the brand, "Plastic Steel" was the proiduct.

Bill.

Flyboy Dave 05-15-2005 10:04 PM

RE: Filled Crank
 
I remember Plastic Steel as a one substance product in a pretty fat tube....

....available almost anywhere.

Dave. ;)

William Robison 05-15-2005 10:08 PM

RE: Filled Crank
 
Dave:

That was later, the earlier stuff was as Splatt described it - two cans.

Bill.

MassiveMods 05-16-2005 06:19 AM

RE: Filled Crank
 
I had a look at the site provided, it says $194.00 for a tube of this stuff. Can this be right ?

splatt 05-16-2005 08:33 AM

RE: Filled Crank
 
Ouch... spendy

I remember using Devcon on Pontiac V-8 Ram-AirIV Intake Manifolds to build up the near sides of intake runners and blocking the heat crossover. The stuff can take the heat.

JB weld gets soft and turns brown even when used on a glo-engine muffler.

Yet another reminder for me to STAY AWAY FROM CARS(real cars), too spendy

PlaneKrazee 05-16-2005 09:52 AM

RE: Filled Crank
 
:)

MassiveMods 05-18-2005 01:11 PM

RE: Filled Crank
 
Is there really a place called Splattsville ?

splatt 05-18-2005 04:37 PM

RE: Filled Crank
 
No, theres's no splattsville.

I live in Minneapolis, Minnesota.

Minnesota is just to the west of the great lakes. We get about 3-4 good months a year, after that it's winter most the time

One of my racing partners hung the name on me, I just carry it to an extreme.

Our club is www.grassfieldrc.org

Our racing club is www.ncplracing.org

Some good pics between the two if your bored

Be fun to see the other end of the world sometime. Maybe someday..


All times are GMT -8. The time now is 02:09 PM.