max RPMs and the Amphi

T

tommyintpa@aol.com

Guest
<font FACE="arial,helvetica"><font SIZE="3" FAMILY="SERIF" FACE="Calisto MT" LANG="0">When I drive my waterbugs on the road I just can't make myself drive the cars
flat out, wound up, peddle to the metal for an extended length of time. But
in the water I find that I am standing hard down on the pedal. Without a tach
I have no idea of how tight I've got the car wound up. They don't sound like
here screaming like they do on the road. Will someone out there with a tach
please tell me how many rpm's an average stock Amphi will be turning flat out
on level ground and the same car in smooth water flat out. Thanks in advance

Tommy in Tampa Red - 67 & White 64</font>
 
D

David Chapman

Guest
Flat out in the water is 3300 RPM (You have to sit in the back or water
comes over the hood and slows you down before max revs are reached) On the
road you get power up to about 5200 RPM (somewhere over 70mph depending on
your tire size) at that speed the limiting factor is valve bounce - the
inlet valve springs don't have enough time to shut and take the next gulp of
air so the engine is strangled. The engine can be tuned with Spitfire parts
so it can reach 6000 RPM (or even more) but you need a different cam that
then doesn't run as well at low revs (Explains the trend in modern cars to
variable valve timing).

At least one manufacturer in the 1960s produced an aftermarket rev counter
(probably for a VW) that is the same size and fits the same way as the Amphi
clock, it has a similar layout to Amphi speedo so doesn't look odd and is
much more usefull !

One other recently discovered fact, the cars with the lip at the bottom of
the bodywork (normally but not always post 1966) are lighter than the
earlier cars, this is because the panels with the lip are made of slightly
thinner steel, this means that with everything else equal (unlikely) the
later cars will be slightly quicker on land and water.


David Chapman in the UK



> here screaming like they do on the road. Will someone out there with a
tach
> please tell me how many rpm's an average stock Amphi will be turning flat
out
 

StephenChu

New Member
<font FACE="arial,helvetica"><font SIZE="3" FAMILY="SERIF" FACE="Calisto MT" LANG="0">When I drive my waterbugs on the road I just can't make myself drive the cars
flat out, wound up, peddle to the metal for an extended length of time. But
in the water I find that I am standing hard down on the pedal. Without a tach
I have no idea of how tight I've got the car wound up. They don't sound like
here screaming like they do on the road. Will someone out there with a tach
please tell me how many rpm's an average stock Amphi will be turning flat out
on level ground and the same car in smooth water flat out. Thanks in advance

Tommy in Tampa Red - 67 & White 64</font>
I installed a Veglia tach in place of the clock in 1968. Max speed in water is 3400 RPM.
 

lvflyer

New Member
Flat out in the water is 3300 RPM (You have to sit in the back or water
comes over the hood and slows you down before max revs are reached) On the
road you get power up to about 5200 RPM (somewhere over 70mph depending on
your tire size) at that speed the limiting factor is valve bounce - the
inlet valve springs don't have enough time to shut and take the next gulp of
air so the engine is strangled. The engine can be tuned with Spitfire parts
so it can reach 6000 RPM (or even more) but you need a different cam that
then doesn't run as well at low revs (Explains the trend in modern cars to
variable valve timing).

At least one manufacturer in the 1960s produced an aftermarket rev counter
(probably for a VW) that is the same size and fits the same way as the Amphi
clock, it has a similar layout to Amphi speedo so doesn't look odd and is
much more usefull !


One other recently discovered fact, the cars with the lip at the bottom of
the bodywork (normally but not always post 1966) are lighter than the
earlier cars, this is because the panels with the lip are made of slightly
thinner steel, this means that with everything else equal (unlikely) the
later cars will be slightly quicker on land and water.


David Chapman in the UK
Dave - What manufacture or how would I find this particular tach OR a different one (newer,etc) that would fit right in the same place as the clock? Or to keep originality, somewhat, put a new, inexpensive tach maybe under the dash on the left side of the steering wheel?
 

lvflyer

New Member
Thank you strandweiss62 - I looked up MotorMeter but it looks like I cannot purchase this gauge. Where do you think I can purchase one?

Also, since we are talking about gauges, my fuel and temp gauge is not working. My car is NEGATIVE ground and I believe I need to do the "thin wire swap" for the gas gauge to work but I am a little nervous doing that. Where would I purchase a new working NEGATIVE ground one if I do not attempt or mess up mine up trying to do the NEGATIVE ground conversion? I contacted Gordon Imports and they sell the gas/temp guage BUT it comes as POSITIVE ground and would have to be converted also.

I purchased the car that was restored very well and the gauges are in great condition but the restorer did not do the gas gauge NEGATIVE ground conversion and the temperature needle sits all the way to the right when the car is turned off and goes all the way to the left and stays there when the car is running.
 
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strandweiss62

Active Member
I bought my used MotoMeter Tach on Ebay, but had to search for a long time. They come in serveral diameters.

The temp gauge works with positive and negative ground. Seems the sending unit is defective. It's a very special part with an electric heated bi-metal switch inside. Or there may be a short circuit in the wiring.
 

lvflyer

New Member
Thanks for the info strandweiss62. So you think it is a short vs an open in the circuit? If I "short" the wire that goes to the top of the sending unit to to ground with the engine on or off (?), should the temp gauge needle deflect right or left if the wiring from the sending unit to the gauge is OK?
If I cannot find a problem in circuit, must I purchase the sending unit from Gordon Imports?
 
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strandweiss62

Active Member
If you disconnect the wire from sending unit the needle should stay right.

As far as i know there is no alternative replacement for the sending unit.
I bought it from Gordon, but repaired my old one. That is tricky.
 
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