are dollys relieable

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davepoth
Posts: 856
Joined: Tue Jan 20, 2004 9:46 pm

Re: timing

#16 Post by davepoth » Wed Dec 14, 2005 12:56 pm

A heavily machined head is a very likely culprit for the pinking. When you take a lot off of the head the compression ratio goes up (cylinder gets smaller, but the piston still sweeps the same amount of the cylinder), which would mean that the ignition would need to be retarded quite a bit to avoid pinking. The only real solution to that is a replacement head, as extra thick head gaskets can be unreliable.

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katey ansell
Posts: 8
Joined: Thu Dec 08, 2005 1:52 pm

timing

#17 Post by katey ansell » Thu Dec 15, 2005 12:00 pm

ahhh rightio, just been informed that when we changed the head gasket, dad pulled out a thick one and we replaced it with a thin one because it was all we had. The ignition timing is at TDC, instead of 10 degree's before TDC, we also tweaked springs and the distributor, to try and prevent what i've been told is more commenly known as pinking<!--EZCODE EMOTICON START :) --><img src=http://www.ezboard.com/intl/aenglish/im ... /smile.gif ALT=":)"><!--EZCODE EMOTICON END--> WE are also unsure on what octane rating your optimax is in the UK, i probably should have mentioned that i'm from Australia before hand which would explain the bigger radiator and low temp termostat, but our optimax is 98 octane, and there's a new optimax that's jsut come out which is Optimax extreme with a 100 octane, which is about 2 hours each way from where i live if i wanted it, which is why we tried octane booster. We, my dad and I would also liek to know what is the actual height of the cylinder head from base, as we are both unsure, and both still learning, my dads a spitfire enthusiest and knows the ins and outs of a ducks arse about them, but dolomites are our new toys and we still are unraveling mysteries, particulaly on my dolly <!--EZCODE EMOTICON START :D --><img src=http://www.ezboard.com/intl/aenglish/im ... /happy.gif ALT=":D"><!--EZCODE EMOTICON END-->

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Carsreunited
Posts: 1673
Joined: Sun Aug 17, 2003 6:45 pm

Optimax

#18 Post by Carsreunited » Thu Dec 15, 2005 3:02 pm

Optimax here is 98RON as well. Most people will use standard 95 RON unleaded though as unless you ar doing alot of motorway miles or rev the nuts off of your car constantly, the valve seat recession seems minimal. One of the board members can verify that.<br>
<br>
I use optimax plus an octane booster/lead replacement additive on my race engine but the compression ratio is 11.5:1. Timing is also more advanced at around 28 degrees.<br>
<br>
Sprintparts are a wealth of knowledge and are your side of the world. Might be worth getting to know them.<br>
<br>


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algtj
Posts: 1298
Joined: Wed Sep 21, 2005 7:17 pm

Re: Optimax

#19 Post by algtj » Wed Jan 18, 2006 9:12 pm

I have just used 100 octane aviation fuel in my 1500, whilst burning hotter than 95/98 ron fuel (unleaded) I can report no adverse effects. I have to say it runs even better than normal and it has lead too! Get an account at an airfield near to you and you might find it cheaper too.<br>
<br>
Al W

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KLJ895W
Posts: 265
Joined: Mon Sep 22, 2003 9:30 pm

Re: Optimax

#20 Post by KLJ895W » Thu Jan 19, 2006 4:48 pm

To get the most out of that you need to up the CR and/or advance timing, but a bit of lead every so often has to be good for an iron headed engine.<br>
<br>
David

<p><!--EZCODE LINK START--><a href="http://www.triumphowners.com/570" target="top">1980 Sprint</a><!--EZCODE LINK END--><br>
<!--EZCODE LINK START--><a href="http://www.triumphowners.com/569" target="top">1980 1850HL with Sprint gearbox, propshaft and axle</a><!--EZCODE LINK END--><br>
1972 VW Camper Van</p><i></i>

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