Idle musing

[tinweevil]

What follows below is a purely hypothetical question, an exercise for the grey cells only. So please don't jump on me for being sooo stupid and naive, I know it ain't realistic. I wish it were tho.<br>
<br>
I've been asked to overhaul two Stag lumps, both of which have been laid up for years. I'll probably tap this mine of wisdom about something or the other on them later. Anyway, this got me thinking about the old 8 pot and the eternal question of weather Triumph ever planned a 32 valve version. I concluded years ago that they did not, it can't be done. Here's why:<br>
<br>
Imagine you have a Stag block with a sprint head on one side and an exactly mirrored head on the other. Picture in your mind the three main timing gears, crank and 2 off cam. Run an imaginary chain round them and rotate this lot in your mind. All three timing gears rotate the same way, clockwise or anti-clockwise, I can't remember and it doesn't matter. On the standard head all is well because the cam lobes are travelling from exhaust rocker to inlet cup. On the bass ackwards imaginary head the cam is rotating the same direction but the positions of the buckets and rockers means the exhaust opening would follow the inlet opening. I'm pretty sure about this but the only time I've ever attempted drawing it out has been in the pub on the back of beer mats. Somehow I doubt my drawing were up to much.<br>
<br>
So why am I asking this? Because after at least 14 years of drunken pub coversations it still bugs the hell out of me from time to time. But more to the point I thought with the number of people on this forum with more motor industry knowledge and experience than I'll ever have someone might have come across the solution. Triumph can't be the only ones to want to economise on timing gear this way and 2 valves per pot seems pretty rare these days. Even on a Ford. I'm pretty sure there are other single overhead cam and rocker straight engines now.<br>
<br>
I've mused a few theoretical and all highly improbable 'solutions' over the years: A cam layshaft (might as well use 2 cams), improbable chain paths with the reverse cam on the outside of the chain (would be less improbable with double sided belt), cam over exhaust valves (fine except the cam timing wheel sticks out the wrong side of the head). All unworkable I'm sure.<br>
<br>
So to sum up in one question; has anyone ever come across a V format multivalve engine that uses only two cams plus rockers?<br>
<br>
Go on, you can laugh now.<br>
<br>
Any vestige of creadbility shredded, Tinweevil.<br>


<p>1978 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/704">Dolomite Sprint</a><!--EZCODE LINK END--><br>
1968 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/705">GT6 II</a><!--EZCODE LINK END--><br>
1972 Spitfire IV<br>
39 anorak points on the Nicholas scale<br>
</p><i>Edited by: <A HREF=http://p206.ezboard.com/bthetriumphdolo ... nweevil</A> at: 25/9/05 4:50 pm<br></i>

[LewisK]

far as I know, several Stag engines have been built with mirrored Sprint heads. Someone on the forum here had one built, at a cost of 5000 alone for the mirrored head casting, but it did make 400BHP before the timing chain gave up the ghost.<br>
<br>


<p></p><i></i>

[LewisK]

someone in NZ solved the timing chain issue by installing a duplex system by milling the covers thinner and adding some extra depth to them...

<p></p><i></i>

[tinweevil]

Woa! :-) Links???<br>
<br>
Tinweevil

<p>1978 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/704">Dolomite Sprint</a><!--EZCODE LINK END--><br>
1968 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/705">GT6 II</a><!--EZCODE LINK END--><br>
1972 Spitfire IV<br>
39 anorak points on the Nicholas scale<br>
</p><i>Edited by: <A HREF=http://p206.ezboard.com/bthetriumphdolo ... nweevil</A> at: 25/9/05 8:59 pm<br></i>

[alun n]

I enquired at Zeus Engineering (F1 castings inter alia) who are local to me and that is where the 5k cost came from but I'm not aware of it having been done...links please...<br>
<br>
Tinweevil, I don't have beer fueled inspiration to hand but wouldn't the problem be solved by ensuring the mirror cam turned the opposite way (OK, improbable chain path and inelegant timing cover) and also fabricating the cam to be a mirror item too?

<p>1973 Dolomite Sprint<br>
1974 Dolomite Sprint<br>
1977 Dolomite Sprint (Pageant)<br>
1977 Dolomite Sprint (White)<br>
1979 Dolomite Sprint<br>
1979 Dolomite 1850HL<br>
1980 Dolomite 1500HL<br>
1998 Lotus Elise<br>
1999 Alfa Romeo 166 2.5 V6<br>
1999 Alfa Romeo 166 3.0 V6 (Didn't sell, still for sale!)</p><i></i>

[2F45T4U]

Nah... far to complicated! You have to go back to your rootes, thats what the yanks did! one cam and push rods all the way <!--EZCODE EMOTICON START :lol --><img src=http://www.ezboard.com/intl/aenglish/im ... /laugh.gif ALT=":lol"><!--EZCODE EMOTICON END-->

<p></p><i></i>

[davepoth]

I'm not sure if it will provide the answers, but the Volkswagen VR6 engine uses two cams to run 24 valves, although in an unconventional way.<br>
<br>
Also, Honda have a normal V6 with 4 valves per cylinder, but I can't find too much info on it.

<p></p><i>Edited by: <A HREF=http://p206.ezboard.com/bthetriumphdolo ... avepoth</A> at: 25/9/05 11:13 pm<br></i>

[LewisK]

I'm afraid the archieved post appears to have been lost, but I'm certain a member from here had it done.<br>
<br>
Hopefully, they'll pick up on the thread <!--EZCODE EMOTICON START :D --><img src=http://www.ezboard.com/intl/aenglish/im ... /happy.gif ALT=":D"><!--EZCODE EMOTICON END--> <br>
<br>
Or maybe it's all a product of my diseased mind. I've looked at doing it myself, we just about have the facilities in the uni to do it, maybe it'll be my final year project <!--EZCODE EMOTICON START :rollin --><img src=http://www.ezboard.com/intl/aenglish/im ... s/roll.gif ALT=":rollin"><!--EZCODE EMOTICON END-->

<p></p><i></i>

[tinweevil]

Hi Alun,<br>
Having the 2nd cam running in the opposite direction is the ideal solution, no engineering is needed in the head, just (!) manufacture the reverse head. (I am making the rather huge assumption that regular rockers could be assembled onto a shaft to achieve whats needed). The problem is how to make the cam turn the opposite way. The only way I have come up with is for the chain to run below rather than above the gear, sort of like a video tape round the drum. <br>
<br>
Dave, thanks for that. I'll have a look at the VW VR6.<br>
<br>
Tinweevil

<p>1978 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/704">Dolomite Sprint</a><!--EZCODE LINK END--><br>
1968 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/705">GT6 II</a><!--EZCODE LINK END--><br>
1972 Spitfire IV<br>
39 anorak points on the Nicholas scale<br>
</p><i></i>

[alun n]

Well I have a brand new unused unskimmed fully fettled cylinder head if you need any dimensions...<br>
<br>
Still think you'll need a mirror cam too.<br>
<br>
As for turning the cam the other way I too thought about running the chain beneath but you'd need at least two extra tensioners, so how about a simple gear box similar to that used to make cars steer the wrong way that bolts onto the end of the cam flange? Would it take the torque?

<p>1973 Dolomite Sprint<br>
1974 Dolomite Sprint<br>
1977 Dolomite Sprint (Pageant)<br>
1977 Dolomite Sprint (White)<br>
1979 Dolomite Sprint<br>
1979 Dolomite 1850HL<br>
1980 Dolomite 1500HL<br>
1998 Lotus Elise<br>
1999 Alfa Romeo 166 2.5 V6<br>
1999 Alfa Romeo 166 3.0 V6 (Didn't sell, still for sale!)</p><i></i>

[davepoth]

Quick search on google, and this 2.2 Peugeot 607 runs contrarotating balancer shafts off the crank. Probably worth a look. If this link works...<br>
<br>
<!--EZCODE LINK START--><a href="http://66.249.93.104/search?q=cache:Icu ... n&start=19" target="top">66.249.93.104/search?q=cache:IcuRsJ5_nukJ:www.newcarnet.co.uk/perf_indepth.html%3 ... <!--EZCODE LINK END--><br>
<br>
Although thinking about it, some kind of gear drive might be possible, maybe even within the same space as the normal duplex gear. Take a look at my crap diagram.<br>
<br>
<!--EZCODE IMAGE START--><img src="http://myweb.tiscali.co.uk/dpothecary/chain.JPG" style="border:0;"/><!--EZCODE IMAGE END--><br>
<br>
If I have all the directions right, I think the gears in this arrangement will reverse the direction of rotation without causing an eccentric motion. I have no idea how to mount it though.

<p></p><i>Edited by: <A HREF=http://p206.ezboard.com/bthetriumphdolo ... avepoth</A> at: 26/9/05 11:59 pm<br></i>

[2F45T4U]

why would you need to run it the opposite way? <br>
<br>
The way im thinking of it is as a straight 8 with 4 valves per cylinder and obviosuly all cams operating the same way and when you open it up to a V the cams still turn in the same direction. Why would that not work?<br>
<br>
<br>
My idea is far superior though. you do away with the cams and you make it all solenoid/electronic powerd. So the time the valves are opened and closed can easily be changed by the few alterations of a simple computer programme. Ok so its lotus's idea and its patended but it does seem rather simple really.... in a complex way<br>
<br>
<br>
Adam<br>
<br>
<br>


<p></p><i></i>

[davepoth]

It would be fine in a straight 8, but for a V engine, the cylinder heads have to be mirrored so all the inlet valves are in the middle and all exhaust valves go on the outside.<br>
<br>
Solenoids would be great, but you would need to have them work flawlessly for 100,000 miles in 200 degree heat while covered in oil.

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[davepoth]

I realised I just invented the planetary drive. Do you reckon I can patent it before anyone notices?<!--EZCODE EMOTICON START :o --><img src=http://www.ezboard.com/intl/aenglish/im ... rassed.gif ALT=":o"><!--EZCODE EMOTICON END-->

<p></p><i></i>

[2F45T4U]

yer I think it has potential. How about for some gear box reduction gears? Get me a patent for the gear box part while your at it <!--EZCODE EMOTICON START :p --><img src=http://www.ezboard.com/intl/aenglish/im ... tongue.gif ALT=":p"><!--EZCODE EMOTICON END-->

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