[Spridgets] Running rough

corvallis at peoplepc.com corvallis at peoplepc.com
Sat Oct 15 14:36:41 MDT 2011


Distributor advance isn't right; maybe an air leak below 1000rpm?

Balancing SU carbs...billie bob method: Once you rule out air leaks . . . 
1.  warm up engine
2.  Screw up mixture nuts all the way and then down 2 turns.
      up = leaner, down = richer. (this is the nut at the bottom of the
carb)
3.  loosen up throttle shaft couplings
4.  adjust idles so carb air intake is the same, engine running (use
Unisync)
5.  run adjuster nut down until smooth running; or up until rough running
and then back down
6.  adjust idles so they are the same(repeat back and forth steps 4 thru 6)
       Stall indicates other carb is too lean when you push up the piston
pin at the side of the carb (so you'd turn down on its richness adjustment
screw)

7.  do a final idle check on both carbs using Unisync.
8.  tighten nuts on throttle shafts

If you need to avoid blocking holes on face of carb with Unisync base, cut
off both ends of a can. I use and old STP Gas Treatment can (8 oz.) or a
Hunt's Tomato Paste can (6 oz.) Rubber tape around the card end can prevent
air leakage there if that appears to be a problem. . . . bill in oregon
=============================================================
-----Original Message-----
From: spridgets-bounces at autox.team.net
[mailto:spridgets-bounces at autox.team.net] On Behalf Of Robert Weeks
Sent: Saturday, October 15, 2011 11:10 AM
To: Spridget
Subject: [Spridgets] Running rough

Hi All,

I finally got my Midget started but am having a hard time getting it 
running right. I can get the car to idle pretty smoothly around 1000 
rpm. Below that it starts getting rough. The biggest problem I'm running 
into is when I've taken it on test runs up the street. The car sputters 
and looses power above 3000 rpm. Letting off the gas for a few moments 
will clear things up but then as soon as the gas pedal is pressed it 
stumbles and looses power again. Almost sounds like it is backfiring but 
I have a cherry bomb on the car so it's hard to tell.

The car is a 1970 MG. New aftermarket electronic gas pump. New 
distributor with Crane electronic ignition. New sparkplugs properly 
gapped. I'm using Frank's "set it where it runs best" method for the 
distributor timing and was trying to use the John Twist method (see 
youtube for University motors videos) for adjusting the carbs (SUs).

Any ideas on getting this running better would be appreciated. 
Accelerating from idle in the driveway is smooth, but accelerating under 
load is pretty horrible.

Thanks,

Robert
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