262XP Day

[.404]

Am I doing it wrong?

Well does sinusoidal really describe it? I've often wondered.

 

[Hedgerow]

You all know the math for this is not terrible and it's all laid out in Bell's book pretty well. There are also a couple of websites that have port opening/duration calculators if you have an affliction with calculators or excel.

Not afflicted with those...


Nope....



Not at all...

 

[blsnelling]

They are all roughed in. Now to get the top dead on in height, and make the depths all uniform.

View attachment 417947

My hands hurt just thinking about that much grinding in one day!

 

[Mastermind]

My hands hurt just thinking about that much grinding in one day!

Still going.

All right angle work now. Getting the tips of the fingers just exactly the right height, and tightening the corners of the mains.

 

[blsnelling]

Tedious work.

 

[drf255]

Love it bro. Keep going.

 

[drf255]

So a bigger finger and no bridges?




Sent from my iPad using Tapatalk

 

[drf255]

They look more like bananas than fingers to me.

 

[drf255]

Well does sinusoidal really describe it? I've often wondered.
View attachment 417948

Looks like red is the real world length, so sinusoidal may be appropriate.

Long rod lengths should make it peakier.

 

[Mastermind]

Not just fingers.......fingers and bridges.



This is the swarf from the transfer work so far. For visual reference that tool is 7" long with the burr.



I'm taking my lovely wife out for Sushi. She's been fasting and this is a great way to break her fast.

Later.

 

[drf255]

Nice!

4 bananas per jug!

 

[cheeves]

Not just fingers.......fingers and bridges.

View attachment 417960

This is the swarf from the transfer work so far. For visual reference that tool is 7" long with the burr.

View attachment 417961

I'm taking my lovely wife out for Sushi. She's been fasting and this is a great way to break her fast.

Later.

Too much!!!

 

[skippysphins]

Looking great

 

[skippysphins]

Sushi now I'm hungry

 

[Tor R]

Not just fingers.......fingers and bridges.

View attachment 417960

This is the swarf from the transfer work so far. For visual reference that tool is 7" long with the burr.

View attachment 417961

I'm taking my lovely wife out for Sushi. She's been fasting and this is a great way to break her fast.

Later.

Randy,
Without doing the base&squish, just by doing finger and bridge, how much gain do you think that modd would bring?

And second, how close to perfect do you think the timings are on standard 262?

I also have a third question, do your guys now and then shave off the lower transfer a bit, or would it not mather at all?

 

[srcarr52]

Well does sinusoidal really describe it? I've often wondered.
View attachment 417948

Yes it does, the red line is pretty close to a sine wave, it's just 1/2 the cycle.

Also note that a rod length of 2x the stroke gets the closest to a sine wave where anything else yields a larger velocity near TDC (less dwell). Although almost all engines are below 2 rod to stroke ratio.

 

[.404]

For visual reference that tool is 7" long..........

Hehe heh tool.....

 

[rattler362]

This Thread has got to be one of the best of all-time so many great minds in one place at the same time and some great pic's and explanations now Carry on men I shall hush

 

[weedkilla]

Clearly a guide to finger ports.

 

[Marshy]

I must like over thinking but does the distance from crank centerline to rod bearing have more affect on dwell than rod lenght?

The length of the stroke does not affect the dwell time. The rod's length in relation to the stroke does. The shorter rod will have less 'dwell' time at tdc, but the long rod will have greater acceleration (not to be confused with velocity) back down towards bdc.
The longer rod engine will have less time to fill the cylinder due to the fact that while its piston is still hanging around at TDC, the short rod engine has already beguns its travel (and suction) downward. This is advatageous for low to mid engine speeds. Once the short rod engine reaches high RPM the stress of that short rod pressing against the cylinder sidewall (termed: sidewall load) can have ill effecs (cracking sleeves, overheating, power loss due to excessive friction). Piston speed is merely a factor of the length of the stroke itself and RPM.

I've been doing some reading lately because a little while back there was another discussion about rod length and dwell times and I was overlooking the dynamics of how the rod length effects over a given crank angle. http://www.arboristsite.com/community/threads/finding-the-con-rod-length.274140/