[Spridgets] SU throttle overrun valves

[Andy Webster]

I bought a cheap but nice looking HIF44 on ebay for my sprite that had the
anti-run-on valve.


I hated that it killed all the compression braking, so bought another, cheaper
HIF44 and swapped the butterflies.

I like the throttle to have a strong return spring also...it seems to help
give the exhaust a nice growl when the car is slowing down or when you change
down the gears.

That valve in the throttle disc can't be good for airflow... give them the A.

on the subject of backfires...is it really bad for the engine to purposely
backfire?
for example, when your heading down hill into a tunnel at 50mph, and you close
the throttle and switch the ignition off for 3 or 4 seconds, then switch it
back on....BOOM!
My dad blew a muffler apart doing this, but do you think it could damage the
engine at all?

Andy





--- On Sat, 28/2/09, Lee Fox <lee.fox at sbcglobal.net> wrote:

From: Lee Fox <lee.fox at sbcglobal.net>
Subject: [Spridgets] SU throttle overrun valves
To: spridgets at autox.team.net
Received: Saturday, 28 February, 2009, 4:42 AM

OK, I'm sure this has been addressed in the past, but can't find a good
answer.

This weekend I'm going to play with my SU HS2s that I have in my 1500 (yea,
not original, but work very well and certainly better than the single ZS.) I'm
changing the needles (from AAX to ABT) to get a little richer mixture at speed
and wondering about the overrun valves fitted to the throttle plates. You
know, those springy things in the butterfly.

Should I remove these and solder the hole or just leave them alone?

The car does come back to idle slowly, so I know they are working. I don't
have any emission controls anymore and don't have to get it smogged. I'm not
going to race it, but it does seem to be a restriction to good airflow.

What's the consensus of the group?

Thanks.

Lee
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