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#1
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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 |
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#2
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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 |
#3
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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. |
#4
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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 |
#5
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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 |
#6
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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. |
#7
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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 > |
#8
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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 |
#9
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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 |
#10
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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 > |
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