460/660/395xp hybrid?

[Rich Fife]

Make up some crank stuffers for funsies?

I'm too lazy. Lol

 

[Loony661]

Make up some crank stuffers for funsies?

I would think crank stuffers would be too much - the case volume is already reduced compared to the cylinder volume above it. The velocity coming from the carb into the case is going to be huge, to feed it up top.

 

[drf256]

Rich, the only crank I’ve ever welded was on a solo 681. I tried to do a dip 180* apart on each lobe, just to prevent warpage. Mine was out very little also. I used 309 SS filler cause it bonds everything.

Looks like you hit one side of the pin. I tried to copy what Falicon used to do.

 

[Rich Fife]

Rich, the only crank I’ve ever welded was on a solo 681. I tried to do a dip 180* apart on each lobe, just to prevent warpage. Mine was out very little also. I used 309 SS filler cause it bonds everything.

View attachment 444894View attachment 444895

Nice... that looks good! ideally I would've welded in two spots per side but the clearance for the bearings is .015"... so I only went with 1 on each side.

 

[Rich Fife]

Nice... that looks good! ideally I would've welded in two spots per side but the clearance for the bearings is .015"... so I only went with 1 on each side.

In hindsight, I probably should've chamfered the pin and crank hoke a bit, then I could've welded it "properly".
Live and Learn.... here's to hoping all stays well. Ahahaha

 

[drf256]

With your skills, a full circle crank would be easy for you.

I agree that you wouldn’t want in this case because of case/displacement mismatch.

If you offset that pin to gain stroke, I think you’d need a smaller pin and rod end to clear the case.

 

[Rich Fife]

With your skills, a full circle crank would be easy for you.

I'm sure I could... I might... I have pre hardened 4140 that I could use.

I agree that you wouldn’t want in this case because of case/displacement mismatch.

Right, its grossly over matched.

If you offset that pin to gain stroke, I think you’d need a smaller pin and rod end to clear the case.

if I found a 45-46-47mm-ish cylinder that would bolt up, i think that would be the ticket! especially if it were a 37.5mm stroke... no case mod would be needed And i think there would be room to play. But, the big end of the rod would be danger close to the case.

 

[Rich Fife]

Here are a couple more progress pics from the other day... rough measurements before and after on the crankcase...
Before: 2.650" / After: 2.730" = a difference of .080"...
I didnt do the math to see how much volume we gained... ... I'm thiiiiink I have the numbers wrote down on a sketch pad so I should be able to figure the volume increase. I wish the cases were a bit thicker in this area... I would've preferred to open it .125"... but, I'll take it for what it is.

 

[Rich Fife]

The other half. Dialed in and machined. Look at this area in the 3rd pic... we only have .028" of landing for a sealing surface... perhaps I got a little too greedy!

 

[Rich Fife]

Next up was opening-up the top side... just a little... my fingers were crossed that I wouldn't punch through the case....
First, I had to bolt the case halves together, take measurements, make a plate with a hole in the center, level and get my center...

 

[Rich Fife]

What's that saying??? Oh yeah, "you don't know until you know!" I had that inner voice saying back off on depth... buuuut I wanted to push the depth to allow a 56mm piston to recess into the case... well, best case scenario... if it doesn't recess into the case I just gain case volume. I am hoping the bottom volume isnt so far apart. I machined the raised section on one side and then interpolated the bore... Either way, it looks like I'll be spending some time tig welding the case.

 

[Maintenance Chief]

Well that sucks! You could just jbweld it this early in the build to make sure it doesn't leak?

 

[Rich Fife]

Well that sucks! You could just jbweld it this early in the build to make sure it doesn't leak?

I thought about that... but, I'm going to wedge thin aluminum on the backside, try to melt it in and then hit from the front in hopes I can blend... if that fails, JB weld it is.

 

[Rich Fife]

You always have to find the good within the bad...
After patching the "oops" I mocked up the cylinder-n-piston... and I learned a few things...
1st... I don't have to open the top of the case as much...
2nd... the depth of cut that I removed from the case isn't needed if I remove it from the bottom of the piston... who knew!? Lol
3rd... clearancing the crank and going a bit extra was a bit too much... instead of opening it up to 2.730"... (from 2.650")... I'm going to open the other case to 2.680"...
4th... if I remove "x" amount of material.from the piston skirt my intake lands at 77*.
With everything listed, this is where my numbers will fall without machining the cylinder... 102* exh, 137* x-fer, 77* int... 35* of Blowdown and .035" of squish.
I miiiight take .010" from the base..

 

[drf256]

I thought about that... but, I'm going to wedge thin aluminum on the backside, try to melt it in and then hit from the front in hopes I can blend... if that fails, JB weld it is.

Think the case is Mg.

 

[Rich Fife]

Think the case is Mg.

Definitely... it welded up but, I'm going to use my 460 case for the final assembly.

 

[Rich Fife]

I pulled apart the 460, cleaned the case and got to work.
1st pic are supports for when I clamp on the case... just trying to minimize deflection.
2nd pic a top shot into the case.
3rd pic shows the hump has been removed
4th and 5th pic show the 54mm bore at a depth of .220" as well as a 56mm bore at a depth of .075"...
I have a few areas that I have to relieve which should help yield more case volume.

 

[Rich Fife]

On the 046 case we opened up the crank case to 2.730... this time we went to 2.690" trying to find a balance between case volume and adequate webbing thickness.

 

[Rich Fife]

I wanted to remove .188" from the piston skirts... that would've brought my measurement from the skirt to the top of the piston to 1.700"... I used a Dewalt grinder... why? Because it's much faster. Lol
As you can see, I was at 1.715"... close enough. This brought my intake to 78*... I can live with that.

 

[Rich Fife]

The 1st pic, shoes the skirt is at the top of the intake roof...
The 2nd pic, you can see what remains of the old husky keyway
The 3rd pic, is my timing mark. It's set at 29-30* BTDC... I think the older saws were set at or around 30*... I need to do more research though.