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rough

Posted: 01 Aug 2011 18:48
by gogs
any one know why it only runs smooth on half choke tried carb balance seems ok was thinkink with choke its enrichen it

Posted: 01 Aug 2011 19:37
by saabfast
Logic says its running too lean. Could be the carb setup or an induction leak. Check the rubber carb mountings, they often crack, and the piped connections to the inlet manifold.

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
'81 TR7 DHC
Image

Posted: 01 Aug 2011 20:14
by Beans
Can also be caused by partially blocked fuel line

<center>Image
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

Posted: 02 Aug 2011 00:03
by Hasbeen
Applying choke on an SU is EXACTLY the same as adjusting the mixture. Both lower the main jet, allowing more space for fuel to pass the needle.

However, half choke is a lot of richening of the mixture, so as above, you either have too much air, or not enough fuel.

Hasbeen

Posted: 02 Aug 2011 04:31
by Hasbeen
Gogs how long have you had the car, & how has it been running?

A port & polish, mild cam, good exhaust system, & easy flow inlet filters, or some of these, will change the mixture requirements of an engine, & a 7 engine more than most.

If some of these have been done, you would require richer needles to re-tune for the modifications.

Has anything been changed, or did the car just start running this way?

Hasbeen