Idle musing

[tinweevil]

Yeah, sorry but the chain has to run over one and under the other. I think the idea of having a timing wheel below the cam sprocket with a meshed gear up to the cam is the least unlikely of the solutions so far. After all, the gears would take much less load than those in a gearbox. A belt could be used instead of a chain if the crank oil seal could be moved inboard of the sprocket (and copious other mods acheved).<br>
<br>
I had an opportunity to look at a stag block today, the bores are offset but only by a very little amount. Looking at my spare sprint block there probably is room for the bores to move fore or aft but very little before the bore would intrude into the water jacket. Especially tricky as I think the block is overbored and lined isn't it? I suppose both heads could be manufactured to fit the smaller bore? Kerching goes another 5 grand.<br>
<br>
I also looked at a crank, the journals point north, south east and west (didn't note exact order of those) unlike the sprint that points north, south, south, north. This means that both heads would require custom cams.<br>
<br>
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></i>

[davepoth]

I doubt even BL would have been stupid enough to offset the unmirrored side, allowing them to use the 1850 head, so it would only be the (by now not especially similar) mirrored head that would need to be changed, I reckon. Anybody got stag and 1850 heads to compare?

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

[Carsreunited]

You are more than welcome to borrow my Stag head. You can do the head gasket while you are at it!<br>
<br>


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

[alun n]

If you can get it off?<br>
<br>
Why don't we do it TVR AJ8 style and junk the chains altogether?

<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>

[Carsreunited]

God how spooky is that????<br>
<br>
I'm picking it up a week on Saturday.............<br>
<br>
<!--EZCODE LINK START--><a href="http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... %3AIT&rd=1" target="top">cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=4577787348&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1</a><!--EZCODE LINK END--><br>
<br>


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

[Jon Tilson]

the engine life between major overhaul is about 40k miles...<br>
Dont ever crash it. They only come in 2 halves and you have to get whichever end matches the damaged bit.<br>
Jonners

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

[alun n]

Yeah, but what bargain fun in between...slightly jealous!<br>
<br>
I only had someone chelt the elise with a tow bar whilst reversing and ended up with a new front half and complete respray. If you worry about that sort of thing best not drive at all; why else do we pay insurance?

<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>

[Mark Larmour]

Why make a mirror casting for the head?<br>
<br>
Take 2 Sprint heads, cut the front off the head where the chain runs. Seal the front of the motor to try and keep the oil where it should be, inside the crankcase.<br>
<br>
Spin one head around and fit to the RH bank, make a new camshaft for the RH head then use an external belt drive to the camshafts. Couldn't be easier, so if someone has a lazy $20,000 I am prepared to have a go for you.<br>
<br>
Then again, you can buy a second hand 32 valve Lexus V8 for around $1000 which will produce more horsepower, rev like hell, probably weight less and be super reliable.<br>


<p><!--EZCODE LINK START--><a href="http://www.sprintparts.triumphowners.com">SPRINTPARTS</a><!--EZCODE LINK END--></p><i></i>

[SprintV8]

The Lexus engine is a bit too long.<br>
<br>
But with some Mod's here and there I supose it could me done over here there around the £550+ mark and you can use the Supra 6 speed manual gearbox.<br>
I did some research earlier on but stopped when the lenght was going to be a issue.<br>
<br>
You may want to look at this regarding the Stag engine<br>
<!--EZCODE AUTOLINK START--><a href="http://www.hotrodders.com/forum/boogere ... <!--EZCODE AUTOLINK END-->

<p>1980 Dolomite Sprint V8 (Rover 3.9/4.2 engine and gearbox needed I have the need 4 more speed.)<br>
1997 Vauxhall Calibra 2.0 16v SE8<br>
2003 Suzuki GSX1300R (The Yamaha R1 is indicating 190mph When the Busa flies past)<br>
This space is available for advertising, contact user for rates.</p><i></i>

[alun n]

<!--EZCODE LINK START--><a href="http://www.rst-v8.co.uk/">Surely...there is only this direction to take?</a><!--EZCODE LINK END--><!--EZCODE EMOTICON START :D --><img src=http://www.ezboard.com/intl/aenglish/im ... /happy.gif ALT=":D"><!--EZCODE EMOTICON END--> <br>
<br>
Oh oh...they can fit one to the Elise too...wish I hadn't just bought another house...

<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>

[tinweevil]

This is still rattling round the grey cells.<br>
<br>
I was thinking that because the stag and sprint cranks are so different you'd have to have two custom cams made. However, reading up on that tasty little v8 that Alun posted the link to has made me think a bit more laterally.<br>
<br>
Why not get the big end journals on a sprint crank elongated to take two ends? This would make for a more lumpy engine as the bangs would not be so evenly spaced. But the upside is that I'm certain a standard cam could be used on the standard head. It may be possible to use the standard cam on the reverse head too, if the cam is running backwards the pot firing order would be different on that bank. I think it'd work. Hows that animation coming along Lewis? The capacity would then be stag bore by sprint stroke instead of sprint bore, stag stroke. No more worries about the offset bores. Probably a problem with the valves tho. Hmmm, that probably knackers that plan.<br>
<br>
It may be possible to get over the original major stumbling block too, that of the rotation of the cam needing to be reversed. If the rocker arms on the reverse head were longer and reached across the cam then the rotation can be the same as in the standard head. Theres a lot more to it than that, the cam needs to move left a bit (in my picture above) and the pivot point would need adjusting too so that the valve lift is the same. This would be an almost entirely new head design rather than the reverse sprint head originally mooted.<br>
<br>
One last note, the Toyota Soarer has a V8 32 valve engine and the cam belt only drives two of the cams. Hopefully this week I'll see inside a rocker cover and find out if its chained or cogged across to the 2nd cam. Only other way is one of the gearboxes Alun and Lewis were talking of.<br>
<br>
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></i>

[2F45T4U]

Would there be any point in only running 2 cams? Surely the complications and expenses involved in coming up with and then building such a contraption would rule it out over a quad cam design....<br>
<br>
And with quad cam you dont have to mirror the valve timing like you have to with a single cam and fingers.....<br>
<br>
<br>
<br>
Adam

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

[davepoth]

But then it wouldn't be a stag sprint engine. Might as well just stick in a helicopter jet turbine engine and be done with it...<br>
<br>
<!--EZCODE LINK START--><a href="http://www.ntpapull.com/Videoclips/Gard ... tone-1.wmv" target="top">www.ntpapull.com/Videoclips/Gardner%20S ... <!--EZCODE LINK END-->

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

[tinweevil]

Triumph must have had their reasons for making the sprint the way they did. Perhaps the cams were a very expensive item back then. As well as simplicity quad cams have other advantages too like the inlet and exhaust profiles can be different. Cams are hard things to turn though, they take a lot of power. Perhaps Triumph went the way they did for the Sprint because its a more efficient way to move that many valves. With valves at 8 different positions in their cycle rather than 4 there is a better chance that one is closing at the same time as another is opening balancing forces.<br>
<br>
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></i>

[davepoth]

I think the main reason is that the bonnet would have been a whole heap higher with two cams running in it. Take a peak at a saab 900 16v lump to wee what I mean.

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