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Cuda
01-03-2007, 05:32 PM
I know someone told me before what to try adjusting to get the flat spot out that happens when the secondaries open, but I have searched and can't find what it was. It was some simple adjustment to try.

maddad
01-04-2007, 11:05 AM
Cuda, if the flat spot is from a lean out as the secondary opens, you can increase the preload on the air valve return spring. The extra preload will keep the air valve closed a bit and draw more fuel from the secondary fuel jets. There isn't a lot of adjustment, but if not enough to fix it, you'll at least know the jets need to be bigger.

CHACHI
01-04-2007, 11:28 AM
Cuda, I get a flat spot with my 350 Mag if I bury the throttle at too low of an RPM. If I get to the higer end of the primarys before burying the stick...no problem.

Ken

Cuda
01-04-2007, 05:13 PM
Cuda, if the flat spot is from a lean out as the secondary opens, you can increase the preload on the air valve return spring. The extra preload will keep the air valve closed a bit and draw more fuel from the secondary fuel jets. There isn't a lot of adjustment, but if not enough to fix it, you'll at least know the jets need to be bigger.
Is this the air valve return? The refer to it as the power piston in this article.

http://www.carcraft.com/howto/57178/

maddad
01-05-2007, 09:15 AM
Cuda, that power piston sits on that spring and vacuum controls how much tapered needle is in the seat. The spring I refered to controls tension on the air valve door for the secondaries. Keeping that door barely open will increase the draw on the jets and richen things up at the transition, to a point. Sort of an easy way to see if jet or needle need to be addressed. There is a locking screw and adjuster where the shaft comes out of the body. More than one turn of adjusting should be fixed by jet instead.

mrfixxall
01-09-2007, 09:09 PM
I know someone told me before what to try adjusting to get the flat spot out that happens when the secondaries open, but I have searched and can't find what it was. It was some simple adjustment to try.


Timing a little off, or the choke pulloff is weak and not holding the secondary flap closed...when you stick the throttle down the choke pull off is designened to hold the secondary blades closed until the engine looses vacume then it will open and start to let fuek into the secondary..if its too weak or mis adjusted it will suck open to fast and let too much fuel in and cause a flat spot..