78mm crank?

yes you have a touch more clearancing, BUT pistons are setup for 82mm
strokes, so while you have less clearancing, with 78mm strokes you
have another problem which is excessive deck height. That solution is
to shorten the cylinders. I find it much easier to get the case
clearanced by a place like RIMCO and you simply deburr and clean, then
you do not have the headache with the piston being in the wrong place.
The 82mm is an easier build than a 76 or 78 IMO. When guys are
building 76 or 78 it's almost always because they are afraid of the
clearancing work, and it's not a big deal, really.

John
Aircooled.Net Inc.

AircooledJohn wrote:
> yes you have a touch more clearancing, BUT pistons are setup for 82mm
> strokes, so while you have less clearancing, with 78mm strokes you
> have another problem which is excessive deck height. That solution is
> to shorten the cylinders. I find it much easier to get the case
> clearanced by a place like RIMCO and you simply deburr and clean, then
> you do not have the headache with the piston being in the wrong place.
> The 82mm is an easier build than a 76 or 78 IMO. When guys are
> building 76 or 78 it's almost always because they are afraid of the
> clearancing work, and it's not a big deal, really.
>
> John
> Aircooled.Net Inc.

Are you referring to the 85.5mm stroker piston and cylinder set or the
stock cylinder set? I was thinking about using stock cylinders with
spacers with the 78mm crank. One advantage of more stroke would be that
I could possibly have more low end torque and that would be good.

Would the Webcam torquer cam give more low end power than a stock cam?

Ton

I think building a stroker 85.5 is a complete waste of time and money,
and have stated this for years. You should increase the bore size, and
if you have $ leftover in your budgeting get an 82mm crank and 5.4" H-
beam rods.

John
Aircooled.Net Inc.

AircooledJohn wrote:
> yes you have a touch more clearancing, BUT pistons are setup for 82mm
> strokes, so while you have less clearancing, with 78mm strokes you
> have another problem which is excessive deck height. That solution is
> to shorten the cylinders. I find it much easier to get the case
> clearanced by a place like RIMCO and you simply deburr and clean, then
> you do not have the headache with the piston being in the wrong place.
> The 82mm is an easier build than a 76 or 78 IMO. When guys are
> building 76 or 78 it's almost always because they are afraid of the
> clearancing work, and it's not a big deal, really.
>
> John
> Aircooled.Net Inc.


I built a 78x90.5 with B pistons, and 5.5" rods. Everything came
somewhat close to where I wanted it with minimal shimming, I can't
remember if I used any shims. I may have shortened the cylinders, and
around the same time I shaved some material off of piston tops too but
it could have been a different engine... LOL.
The longer than stock rods should help it run stronger at higher rpms.
Redline is around 8000.

Jan Andersson wrote:
> I built a 78x90.5 with B pistons, and 5.5" rods. Everything came
> somewhat close to where I wanted it with minimal shimming, I can't
> remember if I used any shims. I may have shortened the cylinders, and
> around the same time I shaved some material off of piston tops too but
> it could have been a different engine... LOL.
> The longer than stock rods should help it run stronger at higher rpms.
> Redline is around 8000.

I'm building a low RPM torquer and I neither need nor want the engine to
rev over 4k RPM. OK, I'll fess up, this is for an airboat and it will
be running it flat out most of the time. Peak HP is of little use to
me, I'm looking for maintainable low RPM power to drive a prop.

The 82mm crank sounds interesting if I can use it with stock cylinders...

Tony

"Anthony W" > wrote in message
news:ViOlk.273$mP.135@trnddc03...
> Jan Andersson wrote:
>> I built a 78x90.5 with B pistons, and 5.5" rods. Everything came somewhat
>> close to where I wanted it with minimal shimming, I can't remember if I
>> used any shims. I may have shortened the cylinders, and around the same
>> time I shaved some material off of piston tops too but it could have been
>> a different engine... LOL.
>> The longer than stock rods should help it run stronger at higher rpms.
>> Redline is around 8000.
>
> I'm building a low RPM torquer and I neither need nor want the engine to
> rev over 4k RPM. OK, I'll fess up, this is for an airboat and it will be
> running it flat out most of the time. Peak HP is of little use to me, I'm
> looking for maintainable low RPM power to drive a prop.
>
> The 82mm crank sounds interesting if I can use it with stock cylinders...
>
> Tony

that engine would be somewhat similar to what folks need in the aviation
field... We just happen to have a very experienced VW guy that knows vw
engines and aviation... Ping Bob Hoover...

Joey Tribiani wrote:

> that engine would be somewhat similar to what folks need in the aviation
> field... We just happen to have a very experienced VW guy that knows vw
> engines and aviation... Ping Bob Hoover...

I already did, now I'm looking for the parts.

The 82mm crank sounds cool if I can get it to work with 85.5mm
cylinders. There's no problem making more power than I can use, the
problem is making that power at a low RPM.

Tony

"Anthony W" > wrote in message
news:QAamk.347$mP.232@trnddc03...
> Joey Tribiani wrote:
>
>> that engine would be somewhat similar to what folks need in the aviation
>> field... We just happen to have a very experienced VW guy that knows vw
>> engines and aviation... Ping Bob Hoover...
>
> I already did, now I'm looking for the parts.
>
gotcha.... smart move!