Unleaded

[80sprint]

Lots of questions today guys. Seems i do not know as much about Sprints as i thought.<br>
<br>
How do you tell if a head is converted to unleaded ?<br>
The valve seats i take it , but what am i looking for?<br>
<br>
Mike

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[djw113uk]

Is it the head that needs to be converted? <br>
<br>
We have covered pushing 50k miles in two years in a sprint, with just one valve burning out.. the seats were fine. (valve died due to bottom end burning oil according to engine expert)<br>
<br>
That is running bog standard (as cheap as can be found) (typically supermarket) unleaded with no additive. Lots of 70mph motorway miles from bristol to devon etc. It was the bottom end that died, again! 3 we have seen now have burnt out the ring grooves on the pistons, leaving 3 piston rings in 1 large gap.<br>
<br>
Now onto our Mahle forged piston bottom end to see if that will cope any better.<br>
<br>
Will be LPG soon (- we hope), that has killed two straight 6 heads so far ( valve seats -6mm recession) and guides - 1No broken up leaving wobbly valve). The previous sprint only did about 8k on gas before deer incident and head gasket blowing.<br>


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[80sprint]

I have been running inleaded with no problems before but now the head is off i was wondering how you tell. I think the head has had work done on it before but not sure if the seats were worked on.<br>
<br>
Mike

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[algtj]

I thought that as the Sprint head was alloy, hardened valve seats were already fitted and so unleaded can be used with adjustment of the timing.<br>
<br>
Anyone?

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[redrichie]

Mine has always ran on unleaded, just need a slight adjustment to the timing. I was lead to believe that what Al says is true. If you are worried you could always throw some redex additive in there, but reading an article in PC about the whole unleaded thing, it says that cars that have been used for years with leaded will build up a memory of lead on the valve seats, and can be used on unleaded safely for many miles. They obviously gave no figures of how many "many miles" is, and put the usually disclaimer at the bottom of the article "blah blah blah, consult an expert".

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[george]

aloy heads use inserts and were also fitted to saab (17...) so dare say they already hard enough to cope with unleaded u.s vehicles of the time fitted rotators at the bottom of the vale springs to keep the vale spinning round to stop ression<br>
the 6 cyl trimuphs i think from memory were machined into the head cut from the cast iorn ? so these would require seat inserts to give longevity

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[80sprint]

I can see the inserts in the head but is there a way of telling if they have been changed to a harder material.<br>
<br>
I will run it as it is either way but it's more out of interest.<br>
<br>
Mike

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[Howie]

I was wondering the same question about the head on my rebuilt sprint engine. I have no history on it and the PO did'nt know much either. But there is something which makes me think it might have been rebuilt to unleaded spec and that is it has been painted green on the front end. The head does look new. A bit of a long shot I know but all the unleaded pumps are green. <!--EZCODE EMOTICON START 0] --><img src=http://www.ezboard.com/images/emoticons/alien.gif ALT="0]"><!--EZCODE EMOTICON END--> <br>
<br>
Perhaps i'm clutching at straws or just a bit mad.<!--EZCODE EMOTICON START : --><img src=http://www.ezboard.com/images/emoticons/ohwell.gif ALT=":"><!--EZCODE EMOTICON END-->

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