Hello,

After some work, my 1800 is back on the ground and I'm trying to get it running right, but without much luck. Currently, the idle is all over the place. I've looked for vacuum leaks and can't find any so far. When I rev it up, it continues to idle at that RPM rate. Once I put my hand over the air inlet, it will slow back down and remain steady. I didn't touch the idle adjustment or stop screw, either. The machine shop that did the work on the head and manifolds said they didn't, either.

Also, the bottom end oomph has left along with the old oil. It pulls strong, but takes some serious motivation to get there. I had the head worked on, and didn't do anything to the block but pull it to replace the clutch and oil pan. I can't think how the timing could have changed. The fuel pressure is spec at 28 psi, and all the FI things check out to spec. Well, those that I knew how to test.

Any thoughts?

Thanks!

hi there,

i had the same problem as you do for almost over a year. I went wild checking and replacing a bunch of stuff. Here's the catch. Your fuel pressure may seem fine and is able to be adjusted statically. HOWEVER, a cranky old fuel pressure regulator can become sticky dynamically and fuel pressure may surge or drop when after revving the engine. Now, rev the engine to about 2000rpm and then slowly let your foot off of the throttle. If the idle stays stuck high, then the fuel pressure regulator is suspect. If you let off the throttle quickly sometimes the idle will resume to normal. I replaced my fuel pressure regulator and this problem completely disappeared.

let me know how it goes.

-Jeffrey Rothman

Could be weak or broken springs on the centrifugal advance mechanism in the distributor allowing the ignition timing to over-advance at low revs. Check for smooth advance by incresing engine revs from idle to about 3,000 rpm while watching timing marks on crank pulley with a timing light. The timing shouldn't change from the static setting (10 deg ?) until revs are at least 1200 or so. Timing should quickly return to normal static value when throttle is released and returns to idling position.

If the timing wanders around and is out of spec, its best to take the distributor to someone with a distributor graphing machine to set up proper centrifugal and vacuum advance curves.

This would explain the low end power loss too.

I didn't even think of that. I did fill the oil cup up for the first time ever, though. I wonder if that somehow buggered it up. I used 10w oil, for what it's worth. Perhaps I should clean it out and try something lighter.

I havent been able to draw any decent conclusions about the timing because the tach doesn't work. A friend has a multimeter with a tach function tha tI plan to use tonight, though. But based on sound, it seems to be advancing correctly. I guess not coming back down, though.

Thanks for the pointers!

Justin;

I don't know which "oil cup" you are refering to, but the dist has two lubrication points, one, is the felt disc accessible after removing the cap (this lubes the centrifugal advance, whose action can also be checked statically while the cap is off - when turned CCW, the rotor should feel smooth and smoothly return to the non-advanced position), and second, is the shaft lubing reserviour below the points plate (with the turn-to-open cap). Any weight engine oil is both certainly better than none...but the best test of the advance is a functional one with a timing light...a tach doesn't tell you jack about timing.

As far as my thoughts on the idle not settling back down... There is a spring on the throttle shaft which should close it against the idle adjustment screw. It sounds from your description, as though the engine vacuum is holding the throttle open (until your hand over the air intake acts as another "throttle" and shuts off air to the engine). Is this spring in place, the shaft springloaded against opening and rotating freely?

Or...are you reeeaaalllyyy sure you dont have a vacuum leak?

Good Hunting!

Ron,

The cup I refer to is on the outside, with the knurled cover. It does not runneth over, by the way. The second one you describe. I want to know the RPM so I can set the idle, then set the timing from there. I'm just guessing right now.

The throttle plate closes all the way. I am certain of that. I had the "snorkle" off and looked in. Couldn't get even the smallest feeler guage in there, but that could just be because of the curvature of the inlet. Everything appears to move freely and the spring quickly snaps the throttle shut when the cable tension is released.

"are you reeeaaalllyyy sure you dont have a vacuum leak?" Well, preeeeeeeetty sure. I moved the unlit propane torch all over the place, listening for an increrase in idle and was not able to detect anything. I listened and tightened all over the place. No luck. I'll try another distributor this evening to see if that has any effect.

Thanks for the response.

The Bosch FI was too much for me. I way too long getting a dead FI working and then one that had been working for 20 years for me went ugly. After many posts I chose to put in some spare SU's and couldn't be happier. Smooth Steady and responsive. Best of all is that if the engine begins to misbehave, diagnosis is very straightforward. Is it fuel... or spark" With FI ... you just don't know!

When this gets sorted out please send a follow up to what the solution was. I still have a FI 1800ES and can use all the help I can get.