Engine Update

Man, I got to work faster. I can almost see the end of "Ball" season.
This is great for the kids, but it sure eats loads of time out of my
life. I am not sure who has more fun, them or me!!

Anyway, had a game canceled last night and no practice either!! Dubb
time!! First task, make a better metal jig to torque the jugs down to
check deck height. Fix: a 6 inch long piece of 1.5 inch steel square
tube. Drilled holes for two head bolts 4 3/8 inches on center. Holes
slightly bigger than head bolt threads.

Perfect!!

Used large nuts and large washers for spacers to take up slack.
Torqued diagonal head bolts in jig and measure deck height under square
tube. Came up with .037 minimum and .040 max measuring all four
cylinders. Compression ration came out to be 8.2 to 1 using:

85.5mm cylinders
69mm crank
50cc chamber size
..037in deck height

By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
smiling.

Ordered parts this morning and will work on the heads to rid them of
the sharp edges in the combustion chamber while I wait on the parts to
come and for either rain or canceled ball games again.

So far so good, I think and I hope to be ready for installation in the
near future.

PS
SEND RAIN!! LOL

TerryB wrote:
>
> Used large nuts and large washers for spacers to take up slack.
> Torqued diagonal head bolts in jig and measure deck height under square
> tube. Came up with .037 minimum and .040 max measuring all four
> cylinders. Compression ration came out to be 8.2 to 1 using:
>
> 85.5mm cylinders
> 69mm crank
> 50cc chamber size
> .037in deck height

Not enough deck


> By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
> smiling.




That's too much deck, you're wasting energy. To lower the CR from 8.2 to
below 8, you could get two birds with one stone by unshrouding the
valves by making the combustion chamber around them bigger. Allowing
better flow in and out. Combine that with a deck height of around .057
(.20spacer) and you get the best of both.

> PS
> SEND RAIN!! LOL

You can have ours.

Jan

Jan Andersson wrote:
> TerryB wrote:
>
>>Used large nuts and large washers for spacers to take up slack.
>>Torqued diagonal head bolts in jig and measure deck height under square
>>tube. Came up with .037 minimum and .040 max measuring all four
>>cylinders. Compression ration came out to be 8.2 to 1 using:
>>
>>85.5mm cylinders
>>69mm crank
>>50cc chamber size
>>.037in deck height
>
>
> Not enough deck
>
>
>
>>By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
>>smiling.
>
>
>
>
>
> That's too much deck, you're wasting energy. To lower the CR from 8.2 to
> below 8, you could get two birds with one stone by unshrouding the
> valves by making the combustion chamber around them bigger. Allowing
> better flow in and out. Combine that with a deck height of around .057
> (.20spacer) and you get the best of both.
>
>
>>PS
>>SEND RAIN!! LOL
>
>
> You can have ours.
>
> Jan


Why not stick with 8.2 C.R. ? After all 7.5 allowed you to run 87
ocatne RON....

J.

P.J. Berg wrote:
> Jan Andersson wrote:
>
>> TerryB wrote:
>>
>>> Used large nuts and large washers for spacers to take up slack.
>>> Torqued diagonal head bolts in jig and measure deck height under square
>>> tube. Came up with .037 minimum and .040 max measuring all four
>>> cylinders. Compression ration came out to be 8.2 to 1 using:
>>>
>>> 85.5mm cylinders
>>> 69mm crank
>>> 50cc chamber size
>>> .037in deck height
>>
>>
>>
>> Not enough deck
>>
>>
>>
>>> By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
>>> smiling.
>>
>>
>>
>>
>>
>>
>> That's too much deck, you're wasting energy. To lower the CR from 8.2 to
>> below 8, you could get two birds with one stone by unshrouding the
>> valves by making the combustion chamber around them bigger. Allowing
>> better flow in and out. Combine that with a deck height of around .057
>> (.20spacer) and you get the best of both.
>>
>>> PS
>>> SEND RAIN!! LOL
>>
>>
>>
>> You can have ours.
>> Jan
>
>
>
> Why not stick with 8.2 C.R. ? After all 7.5 allowed you to run 87
> ocatne RON....
>
> J.


If he stayed with 8.2, he would still need to modify the engine because
there's not enough deck. It's not safe to run deck that tight.

Jan

P.J. Berg wrote:
> Jan Andersson wrote:
>
>> TerryB wrote:
>>
>>> Used large nuts and large washers for spacers to take up slack.
>>> Torqued diagonal head bolts in jig and measure deck height under square
>>> tube. Came up with .037 minimum and .040 max measuring all four
>>> cylinders. Compression ration came out to be 8.2 to 1 using:
>>>
>>> 85.5mm cylinders
>>> 69mm crank
>>> 50cc chamber size
>>> .037in deck height
>>
>>
>>
>> Not enough deck
>>
>>
>>
>>> By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
>>> smiling.
>>
>>
>>
>>
>>
>>
>> That's too much deck, you're wasting energy. To lower the CR from 8.2 to
>> below 8, you could get two birds with one stone by unshrouding the
>> valves by making the combustion chamber around them bigger. Allowing
>> better flow in and out. Combine that with a deck height of around .057
>> (.20spacer) and you get the best of both.
>>
>>> PS
>>> SEND RAIN!! LOL
>>
>>
>>
>> You can have ours.
>> Jan
>
>
>
> Why not stick with 8.2 C.R. ? After all 7.5 allowed you to run 87
> ocatne RON....
>
> J.


.....and you know those silly americans, all so afraid of cam degrees and
compression

Jan

Jan wrote:
> P.J. Berg wrote:
> > Jan Andersson wrote:
> >
> >> TerryB wrote:
> >>
> >>> Used large nuts and large washers for spacers to take up slack.
> >>> Torqued diagonal head bolts in jig and measure deck height under
square
> >>> tube. Came up with .037 minimum and .040 max measuring all four
> >>> cylinders. Compression ration came out to be 8.2 to 1 using:
> >>>
> >>> 85.5mm cylinders
> >>> 69mm crank
> >>> 50cc chamber size
> >>> .037in deck height
> >>
> >>
> >>
> >> Not enough deck
> >>
> >>
> >>
> >>> By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
> >>> smiling.
> >>
> >>
> >>
> >>
> >>
> >>
> >> That's too much deck, you're wasting energy. To lower the CR from
8.2 to
> >> below 8, you could get two birds with one stone by unshrouding the
> >> valves by making the combustion chamber around them bigger.
Allowing
> >> better flow in and out. Combine that with a deck height of around
..057
> >> (.20spacer) and you get the best of both.
> >>
> >>> PS
> >>> SEND RAIN!! LOL
> >>
> >>
> >>
> >> You can have ours.
> >> Jan
> >
> >
> >
> > Why not stick with 8.2 C.R. ? After all 7.5 allowed you to run 87
> > ocatne RON....
> >
> > J.
>
>
> ....and you know those silly americans, all so afraid of cam degrees
and
> compression
>
> Jan


Afraid, You bet! This is my first real engine build. I am just trying
to build the engine to be reliable and economical. I don't need lots
of HP and did not plan on going that route "This time". Now, with what
I learn this time round and continue to learn here and other places, my
next engine will not be so timid, but it will not be a whole hog
either. As I have said before this is the second time to build this
engine, the first time was pure stupidity on my part and I am very
lucky it did not go up in smoke.

I am just not ready to make mods to the heads that you speak of as I do
not fully understand what needs to be done and I do not have a manual
yet that shows/talks about it. I need lots of pics and lots of
How-To's before I would feel really comfortable doing it. I also don't
have a set of heads to practice on other than a pair of 40 horse heads.
And I just would not feel right cutting those up as someone out there
may need them someday. 40hp heads are getting scarce and so are single
port heads.

I know Jan is speaking good sound information and has the experience
behind him. I on the other hand am just beginning to crawl in this VW
engine arena. Some day I plan on just plunking down a big chunk of
moola on a Sweet Jake Raby engine!! Turn Key, that is!! Now that is a
real dream.

I think you would better off without the shims. My engine is pretty
close to your measurements and because of the tight deck, you get
a swirl effect in the combustion chambers. Efficiency goes way up
and this is what Jake has been repeatedly telling everybody. I can tell
you that it does work. I can't believe how efficient my 1600DP is
now and it does not run hot.

My heads were 48 and 48.5cc so my CR was just a tad higher
than your numbers and coincidentally, my tightest deck was .037".
I went with it since my RPM is limited to 5500.

If your nervous about the .037, then get the case decked a few
thou... but don't kill that engine with shims.


Raymond T. Lowe
--
E-mail=fullname,no initial-at-telus.net

"TerryB" > wrote in message
oups.com...
> Man, I got to work faster. I can almost see the end of "Ball" season.
> This is great for the kids, but it sure eats loads of time out of my
> life. I am not sure who has more fun, them or me!!
>
> Anyway, had a game canceled last night and no practice either!! Dubb
> time!! First task, make a better metal jig to torque the jugs down to
> check deck height. Fix: a 6 inch long piece of 1.5 inch steel square
> tube. Drilled holes for two head bolts 4 3/8 inches on center. Holes
> slightly bigger than head bolt threads.
>
> Perfect!!
>
> Used large nuts and large washers for spacers to take up slack.
> Torqued diagonal head bolts in jig and measure deck height under square
> tube. Came up with .037 minimum and .040 max measuring all four
> cylinders. Compression ration came out to be 8.2 to 1 using:
>
> 85.5mm cylinders
> 69mm crank
> 50cc chamber size
> .037in deck height
>
> By adding a .040 spacer I will have 7.5 to 1 CR. I can see Jan
> smiling.
>
> Ordered parts this morning and will work on the heads to rid them of
> the sharp edges in the combustion chamber while I wait on the parts to
> come and for either rain or canceled ball games again.
>
> So far so good, I think and I hope to be ready for installation in the
> near future.
>
> PS
> SEND RAIN!! LOL
>

Raymond Lowe wrote:
> I think you would better off without the shims. My engine is pretty
> close to your measurements and because of the tight deck, you get
> a swirl effect in the combustion chambers. Efficiency goes way up
> and this is what Jake has been repeatedly telling everybody. I can
tell
> you that it does work. I can't believe how efficient my 1600DP is
> now and it does not run hot.
>
> My heads were 48 and 48.5cc so my CR was just a tad higher
> than your numbers and coincidentally, my tightest deck was .037".
> I went with it since my RPM is limited to 5500.
>
> If your nervous about the .037, then get the case decked a few
> thou... but don't kill that engine with shims.
>
>
OK, I'll bite. What about shims will kill the engine? Details Details

TerryB wrote:
>
> Raymond Lowe wrote:
> > I think you would better off without the shims. My engine is pretty
> > close to your measurements and because of the tight deck, you get
> > a swirl effect in the combustion chambers. Efficiency goes way up
> > and this is what Jake has been repeatedly telling everybody. I can
> tell
> > you that it does work. I can't believe how efficient my 1600DP is
> > now and it does not run hot.
> >
> > My heads were 48 and 48.5cc so my CR was just a tad higher
> > than your numbers and coincidentally, my tightest deck was .037".
> > I went with it since my RPM is limited to 5500.
> >
> > If your nervous about the .037, then get the case decked a few
> > thou... but don't kill that engine with shims.
> >
> >
> OK, I'll bite. What about shims will kill the engine? Details Details

More prone to leak oil because there's one extra mating surface between
cylinder and case.
A realllly thick shim might throw a cylinder off center in the case
bore, it's the last few mm of the "skirt" of the cylinder that centers
it. Mind you, I'm talking about shims thicker than 3 quarters stacked
together. Not a problem for you.

Jan

His CR is pretty good where it is. Shims will lower it into the realm
of Berg, Briggs & Stratton, etc. Tighter deck = more quench =
more violent swirl of the mixture = more efficiency. And the better
the mixing, the less chance of uneven flame travel. Had a Berg
inspired engine once. Ran good and cool but I'd hate to be the
guy stuck behind me in traffic sucking in the half-burned exhaust.


Raymond T. Lowe
--
E-mail=fullname,no initial-at-telus.net

"TerryB" > wrote in message
oups.com...
>
> OK, I'll bite. What about shims will kill the engine? Details Details
>