<div dir="ltr">All<div><br></div><div>Here in the UK speedos are set to read about 3% high so that any minor variation such as tyres with a different rolling radius does not cause you to inadvertently exceed the speed limit.</div><div><br></div><div>It has been known for people to be fined for going 31 mph in a 30 mph restricted area.</div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, 14 Jun 2021 at 00:40, Len and/or Marge Hartnett via Healeys <<a href="mailto:healeys@autox.team.net">healeys@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div bgcolor="#ffffff">
<div> </div>
<div>John: On a previous long Healey trip with my son, I commented on the
fact that my odo was not in agreement with the GPS. I was confident that
my odo was correct having compared it to official highway mile markers.
His brilliant solution (he is brilliant of course because he is my son
) came up with the following: the automobile is travelling up and
down various hills and mountains whereas the GPS is calculating the
distance on a level altitude. The difference is the added distance created
by going up and down the fluctuating altitude of the highway.
This may or may not be the solution but it sounds logical to me.</div>
<div> </div>
<div>(The Other) Len<br>Fairfield, CA, USA<br>1967 AH 3000 MkIII,
HBJ8L39031</div>
<div> </div>
<blockquote style="border-left:2px solid rgb(0,0,0);padding-left:5px;padding-right:0px;margin-left:5px;margin-right:0px">
<div style="font:10pt arial">----- Original Message ----- </div>
<div style="font:10pt arial;background:rgb(228,228,228)"><b>From:</b>
<a title="banjojohn@cox.net" href="mailto:banjojohn@cox.net" target="_blank">banjojohn</a>
</div>
<div style="font:10pt arial"><b>To:</b> <a title="ryan@jimryan.com" href="mailto:ryan@jimryan.com" target="_blank">Jim Ryan</a> ; <a title="eyera3000@gmail.com" href="mailto:eyera3000@gmail.com" target="_blank">i erbs</a> </div>
<div style="font:10pt arial"><b>Cc:</b> <a title="healeys@autox.team.net" href="mailto:healeys@autox.team.net" target="_blank">Ahealey help</a> </div>
<div style="font:10pt arial"><b>Sent:</b> Sunday, June 13, 2021 3:50 PM</div>
<div style="font:10pt arial"><b>Subject:</b> Re: [Healeys] Speed to RPM
ratio?</div>
<div><br></div>
<div>Jim, you are right. I have used GPS and my speedo is not accurate,
but close enough for me. My point was that the speedo is mechanically
linked, from the tranny, to the engine, and my tach gets its signal from the
coil, which also is directly linked to engine speed through the
distributor. </div>
<div>Regardless of my actual speed, my speedo and tach should maintain a
direct relationship in any given gear.</div>
<div>Thanks again for all the opinions and various charts and facts provided
by the list members.</div>
<div><br></div>
<div>John</div>
<div><br></div>
<div><br></div>
<div id="gmail-m_-4913236380668197417composer_signature">
<div style="color:rgb(87,87,87);font-size:85%">Sent from my T-Mobile 4G LTE
Device</div></div>
<div><br></div>
<div><br></div>
<div style="color:rgb(0,0,0);font-size:100%" align="left">
<div>-------- Original message --------</div>
<div>From: Jim Ryan <<a href="mailto:ryan@jimryan.com" target="_blank">ryan@jimryan.com</a>> </div>
<div>Date: 6/13/21 4:17 PM (GMT-06:00) </div>
<div>To: i erbs <<a href="mailto:eyera3000@gmail.com" target="_blank">eyera3000@gmail.com</a>> </div>
<div>Cc: banjojohn <<a href="mailto:banjojohn@cox.net" target="_blank">banjojohn@cox.net</a>>, Ahealey help
<<a href="mailto:healeys@autox.team.net" target="_blank">healeys@autox.team.net</a>> </div>
<div>Subject: Re: [Healeys] Speed to RPM ratio? </div>
<div><br></div></div>
<div>Am I missing something? I just check accuracy with the GPS on my
phone.</div><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, Jun 13, 2021, 3:25 PM i erbs via Healeys
<<a href="mailto:healeys@autox.team.net" target="_blank">healeys@autox.team.net</a>>
wrote:<br></div>
<blockquote style="border-left:1px solid rgb(204,204,204);margin:0px 0px 0px 0.8ex;padding-left:1ex" class="gmail_quote">
<div>My tach is driven by my distributor gear
<div>Speedo comes off my transmission. Not sure about the relationship
to accuracy. <br><br>
<div>Ira Erbs<br>1959 AH 100-6<br>1967
MGB<br>Milwaukie, OR</div></div></div><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, Jun 13, 2021, 11:50 AM banjojohn
<<a href="mailto:banjojohn@cox.net" rel="noreferrer" target="_blank">banjojohn@cox.net</a>> wrote:<br></div>
<blockquote style="border-left:1px solid rgb(204,204,204);margin:0px 0px 0px 0.8ex;padding-left:1ex" class="gmail_quote">
<div>
<div>Thanks.</div>
<div>I am actually just comparing the tach with the speedometer indicated
speed, which, I believe reads a little high due to tire size. But
the relationship between the indicated speed and the tach should be
consistant since they are both driven by actual engine or output shaft
speed.</div>
<div><br></div>
<div>John</div>
<div><br></div>
<div><br></div>
<div id="gmail-m_-4913236380668197417m_-8612040742838000386m_-7997059852725315655composer_signature">
<div style="color:rgb(87,87,87);font-size:85%">Sent from my T-Mobile 4G LTE
Device</div></div>
<div><br></div>
<div><br></div>
<div style="color:rgb(0,0,0);font-size:100%" align="left">
<div>-------- Original message --------</div>
<div>From: Bob Spidell via Healeys <<a href="mailto:healeys@autox.team.net" rel="noreferrer noreferrer" target="_blank">healeys@autox.team.net</a>> </div>
<div>Date: 6/12/21 12:25 PM (GMT-06:00) </div>
<div>To: Bob Haskell <<a href="mailto:rchaskell@earthlink.net" rel="noreferrer noreferrer" target="_blank">rchaskell@earthlink.net</a>>, <a href="mailto:healeys@autox.team.net" rel="noreferrer noreferrer" target="_blank">healeys@autox.team.net</a> </div>
<div>Subject: Re: [Healeys] Speed to RPM ratio? </div>
<div><br></div></div>That's it!<br><br>On 6/11/2021 4:31 PM, Bob Haskell
wrote:<br>> <a href="http://longstonetyres.co.uk" rel="noreferrer noreferrer" target="_blank">http://longstonetyres.co.uk</a><br>><br>>
Cheers,<br>><br>> Bob Haskell<br>> Austin Healey 3000 BN7/BT7
registrar<br>><br>> On 6/11/21 7:01 PM, Bob Spidell
wrote:<br>>> Note there is a not insignificant difference in
diameters of tires <br>>> with the same nominal size (e.g.
'165/80-15'). The English tire <br>>> site--can't think of the name
offhand--has (had?) a table comparing <br>>> the diameters of
different brands/models of the same size tires, and <br>>> IIRC they
could differ by as much as half an inch. I'd say to measure <br>>>
the actual diameter of your tires, but it's kinda hard when moving;
<br>>> the 'flat spot' goes away--partially, at least--and the tires
'grow' <br>>> some from centrifugal force (anyone seen film of top
fuel dragsters <br>>> launching; the rear tires must expand a few
inches or more?).<br>>><br>>><br>>> On 6/11/2021 3:36
PM, John OBrien wrote:<br>>>> Thanks to all who replied.
These will give me something to work with.<br>>>><br>>>>
John<br>>>><br>>>> On 6/11/2021 4:26 PM, John OBrien
wrote:<br>>>>> Hi Guys and
Gals<br>>>>><br>>>>> I am trying to calibrate my
tach. I installed a Spiyda RVI - RVC <br>>>>> conversion
board, because my tach was acting wierd. Anyway, I am <br>>>>>
still trying to get this setup to read correctly. My question is,
<br>>>>> on my BJ8 with standard 3.9:1 diff. what should my
RPMs be in <br>>>>> fourth gear going 50 MPH , without
overdrive engaged. I'm running <br>>>>> 165/80R15 tires.
I'm just looking for a reference point to compare <br>>>>>
what should be, and what I am
reading.<br>>>>><br>>>>> Any help is
appreciated.<br>>>>><br>>>>>
Thanks<br>>>>><br>>>>>
John<br>>>>><br>>><br><br>_______________________________________________<br>Support
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