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[Dave Leonard] Hey Rusty, Thanks trying that injector switch. Now I don't have to bother removing my intake manifold. :-) It also helps that some dead-beat e-bay seller never sent the injectors I bought. (grumble). My setup is with the same injectors and behaves exactly the same. Idle gets pretty bad below 1400 and the MSD injectors seem to do a little better job. Recently I made a change that improved things somewhat that you might try if it applies.

I has previously set the idle stop screw very loose so I could manually close the idle as much as I wanted. I finally gave up and set the screw at some place that thought would reliably prevent the engine from quitting when pulling the throttle all the way back. This was at about 1200 RPM. Low and behold, the idle at 1200 (against the idle stop) was much better quality that I could previously achieve.

My theory is that the butterfly valve was vibrating under the play in the throttle cable, but stable when against the idle stop. At that RPM the opening is very small and it is easy to see why any variation could wreak havoc with the idle. Just a thought.

BTW, I have looked at my fuel pressure under idle. It goes from 42 with the engine off to about 32 at idle.

Dave Leonard

I'll probably order the new plastic diverter thingies that go in the block, so I can install the '88 NA square plug injectors as primaries. I don't suspect that will change anything mixture-wise though. I sure wish I could install the MSD injectors in the block, and I may have to look at that again.

Also how is the fuel pressure ? If it is too high, maybe it is running very rich on both the large and small injectors. Does you fuel regulator have a MAP reference so that it reduces fuel pressure at lower power settings ?

The fuel pressure is 42 psi when the engine is not running, and the regulator does have a MAP reference.  I've never really watched it while running to see if it changed though.  I just scribbled that on my note for today.

My engine is now running pretty good and idles very well at 1000 RPMs. My only rough spot is somewhere around 1500, it stumbles occasionally. Mainly when the engine is hot.   Now if I could just get my temperatures down another 15 degrees I’d have it made.

Pity I can't trade you 15 degrees for a better idle :-)

Hey Tracy, how well does your engine idle below 1500? Porting the engine should have some effect on the idle quality, and since Bruce ported both of our engines, I would suspect they'll be the same. Also, is anyone with a ported engine getting good idle at 1000 or less? I can live with 1500, especially when I go to the 2.85 gear drive. The bigger problem now is that I can't get the B controller to idle at even 1500.

Cheers,

Rusty (FD goes on Auto Trader this week)