702roadrunner

Any rotorheads in the Las Vegas area, or anywhere else that can help a fellow rotorhead tune my Nikki, I think I'm running too lean? I checked my spark plugs and there's a little white starting to build up on them. But my exhaust smells really strong like it's running rich. Also I'm getting loud backfires between shifts on high revs.

t_g_farrell

iTrader: (1)

You are probably lean at idle and rich in the secondaries.

Jeff20B

iTrader: (13)

You need stronger ignition like DLIDFIS and some new exhaust gaskets.

The idle will smell rich, yes. Kind of normal.

The main primary circuit might be a bit lean, but without a wideband, who knows.

Stock primary jets are 91 or usually 92 for FB carbs and usually 93 or rarely 94 for SA carbs.

I'd mention idle air bleeds but that's getting ahead of ourselves.

702roadrunner

Thanks for the reply. I've been wanting to convert to DLIDFIS (read some of your posts) just been busy at work. I also was thinking of adding a bung to my exhaust for a O2 sensor and install an AFR gauge somewhere on my dash. I'll take the horn off my Nikki and check the jets and air bleeds just to see if the PO hadn't swapped them out. I already did a rebuild on my Nikki and replaced the needles and seats before I read your posts on this, so I want to get back in there to put the OE's back in ( still have them).

702roadrunner

How would I go about correcting this?

t_g_farrell

iTrader: (1)

Like Jeff said, check you jets and make sure they are correct. Then you just need to diddle with
the AF adjuster and the idle rpm adjustment. The 2 screws lower near the AP I think.

702roadrunner

I already turned the AF screw clockwise until the engine started to stumble, and then I turned it back a quarter turn, then I turned the idle screw clockwise until I got the rpm's down to around 650, and still the backfiring persists. If the timing is off would this also call it to backfire? What are the optimal timing settings now that I converted from points ignition to '81+ electronic ignition.

t_g_farrell

iTrader: (1)

Theres 2 ways to set timing, at idle or at about 4K. Using the pully marks for the
timing initially at idle should be fine. Also check to make sure the trailing is within
spec as well. I set my timing at 4k (full advance) to about 27 degrees. Makes for
kind of a lumpy idle but really runs well up top. YMMV, timing is very engine specific.

Backfiring can be caused by timing or it can be caused by too rich a mixture at
WOT.

702roadrunner

Thanks. I'll set timing at full advance, right now its at 20 deg at idle. Hopefully I'll get rid of the backfiring once I convert to DLIDFIS.

702roadrunner

Please help with timing, I think I did it wrong. When I'm facing the engine from the front of the car, is ATDC clockwise from the the timing mark or counter clockwise.

702roadrunner

Figured it out and got it timed. Set it to factory timing, but still won't pass smog check for Nevada. HC's at idle are too high at 1044 ppm, the limit is 500 ppm.

Qingdao

iTrader: (3)

It can't be that hard to hook up your air pump or run a little Propane to clean up your system. Why not put one or the other on then take it off when you're done with the smog?

If I lived in a **** state like that; that's what I'd do. Have a stocker engine and exhaust and every couple of years swap it out and go do the test. Then swap it back when I got home. The SS would be none the wiser.

702roadrunner

The air pump is already hooked up, so maybe it's not working. I'll check it out and then go back and get the smog check redone.