Demon V8 (multiplied 1.5)

Help Support HMEM:

Foketry

Well-Known Member
HMEM Supporter
Joined
Sep 12, 2014
Messages
559
Reaction score
1,189
Location
Modena (motor valley) Italy
Great idea on using the motor brush. Would there by any advantages to making all the electrodes the same way? (Asking out of ignorance, not trying to suggest that there is!)
using the same system for all electrodes is not possible and not necessary
it is not possible because the rotor electrode mills the graphite, it is like a small blade, not necessary because it must not be a sliding contact, only the central one must crawl
 

Peter Twissell

Well-Known Member
HMEM Supporter
Joined
Nov 13, 2019
Messages
331
Reaction score
154
Location
United Kingdom
The other electrodes are not contacts, the rotor arm conductor doesn't touch them, just comes close enough for the spark to jump the gap.
 

awake

Well-Known Member
HMEM Supporter
Joined
Sep 4, 2019
Messages
1,267
Reaction score
534
Location
North Carolina
The other electrodes are not contacts, the rotor arm conductor doesn't touch them, just comes close enough for the spark to jump the gap.
That's interesting. Looking back to the days when I used to tune up my old Dodge Dart, I can remember having to assess whether the electrodes were too burnt and needed to be replaced.

Which raises a question - as best I recall, the electrodes in that old Dart were brass. Wouldn't that burn up rather quickly from the jumping spark?
 

Peter Twissell

Well-Known Member
HMEM Supporter
Joined
Nov 13, 2019
Messages
331
Reaction score
154
Location
United Kingdom
The spark is high voltage, but low current, so the heating effect at the relatively large surface of the electrode is small.
By contrast, arcing at the low voltage breaker points carries several amps and will cause burning if it is not surpressed by a capacitor.
 

Foketry

Well-Known Member
HMEM Supporter
Joined
Sep 12, 2014
Messages
559
Reaction score
1,189
Location
Modena (motor valley) Italy
I tried to anodize at home, with caustic soda and sulfuric acid, I followed the whole procedure seen on Youtube, but with poor results, aluminum does not take color.
I did various experiments with different amperage and voltage, different types of aluminum, no results :(

I brought all the pieces to be anodized by a artisan who in 2 days did a good job
 

Foketry

Well-Known Member
HMEM Supporter
Joined
Sep 12, 2014
Messages
559
Reaction score
1,189
Location
Modena (motor valley) Italy
Radiator from computer, it was necessary to modify the connections for water inlet and outlet and remove an internal bulkhead

IMG_9495.JPG
 

petertha

Well-Known Member
HMEM Supporter
Joined
Jun 24, 2010
Messages
1,755
Reaction score
479
Wow you work fast. Fantastic!
So what is the adjustment you 'lock in' in the engine? Looks like you achieve TDC on piston, match valve position from cam shaft lobe. Then does that mean the camshaft gear gets frozen in that position?
Then what about distributor timing, how does that come into play?
 

Foketry

Well-Known Member
HMEM Supporter
Joined
Sep 12, 2014
Messages
559
Reaction score
1,189
Location
Modena (motor valley) Italy
Wow you work fast. Fantastic!
So what is the adjustment you 'lock in' in the engine? Looks like you achieve TDC on piston, match valve position from cam shaft lobe. Then does that mean the camshaft gear gets frozen in that position?
Then what about distributor timing, how does that come into play?
I followed the procedure indicated by the construction plans provided by Steven H, written in the next post no. 134
in addition to this I checked the timing of each cylinder to check the correct construction of the camshaft (I have not published the photos of the camshaft construction because I have deleted them by mistake)

I also followed this video made by DOC

once the timing of the valves is ok I will make the setting of the distributor but first I have to assemble the heads and check the compression of each cylinder and do a little running in on the lathe, with the spindle that rotates the crankshaft
 

Foketry

Well-Known Member
HMEM Supporter
Joined
Sep 12, 2014
Messages
559
Reaction score
1,189
Location
Modena (motor valley) Italy
Compression test
This is the cylinder with the highest compression
the worst is 4.5 bar the average is 5 bar
I built 7 cast iron cylinders and 1 steel cylinder, there are no differences between them
The compression test was done at around 1000 rpm
 
Last edited:

Peter Twissell

Well-Known Member
HMEM Supporter
Joined
Nov 13, 2019
Messages
331
Reaction score
154
Location
United Kingdom
I wonder what the volume of that gauge and the adaptor is. I expect your compression is higher than indicated.
One way to prevent the gauge volume from altering your compression reading is to pre-fill the gauge and adaptor with oil, making its volume incompressible.
Nice work on the engine!
Re. Iron Vs steel liners, I would expect similar performance as machined. Any difference may show up after a few hours running.
 

Foketry

Well-Known Member
HMEM Supporter
Joined
Sep 12, 2014
Messages
559
Reaction score
1,189
Location
Modena (motor valley) Italy
I wonder what the volume of that gauge and the adaptor is. I expect your compression is higher than indicated.
One way to prevent the gauge volume from altering your compression reading is to pre-fill the gauge and adaptor with oil, making its volume incompressible.
Nice work on the engine!
Re. Iron Vs steel liners, I would expect similar performance as machined. Any difference may show up after a few hours running.
yes, I agree, my pressure control gauge also adds the volume of the tube and the pressure gauge to the volume of the combustion chamber, so the value read on the graduated scale is not correct.
I have always used this for all my small engines and this is my reference. I know that a pressure value below 2.5 bar is not good.
I will follow your advice and will fill the tube with oil to eliminate the air inside and surely the pressure will increase.
 
Top