924Board.org

datatrain · Posted: Fri Jun 27, 2008 2:15 pm Post subject: Timing set problem, part 3

I followed the advice I found here and after screwing with the flywheel for a while found the timing marks in the dirt. However there are only 2 and not 3 as posted. One is marked "0" the other above it is unmarked.

With the car running I cannot slow it down enough to get the marks onto the corner of the window which I assume is the set point. As soon as I approach the point the idle is so slow I can't adjust it anymore. I cannot bring "0" to the set point so obviously can't go past it either
.
The idle screw is out about 5 turns and has no adjustment left.
Setting as close as I can, I find the throttle is incredibly sluggish to accelerate.

I was originally bothered by vacuum leaks. I'm assuming those are no longer a problem after major replacement of lines.

I had assumed this would be the easy part of the past 2 weeks.

Any suggestions as to what's going on here ?

Thnx
DAve
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

924RACR · Posted: Fri Jun 27, 2008 3:02 pm Post subject:

What about mixture, have you adjusted that?
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

+10
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

datatrain · Posted: Fri Jun 27, 2008 5:32 pm Post subject: Adjusted mixture

Yeah I now have about 1/2 turn of mix adjust whereas before I had a turn and a half. That doesn't give me a big enough gain in RPM.
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

You need to start all over.

The timing, the mixture, and the idle speed all have to be right for any of them to be in the right range. This is a chicken or the egg problem, and you need to reset the idle speed and idle mixture to the initial setup positions to start setting everything correctly.

First fix ALL OF THE VACUUM LEAKS WITH ALL NEW HOSES AND TUBING.

Cutting off the rotten ends is not the same as a new hose, and taking a used hose of questionable condition from your spare parts stash is not a new hose/tubing.

Next, set the idle speed adjustment to 2.5 turns open, and make sure that no one screwed up the throttle butterfly stop. If it has been screwed with adjusted it so it barely stops the butterfly from hitting the end of travel (throttle body wall).

Now turn the idle mixture screw all the way out, then back in 2.5 turns.

Now try to start the car. Odds are the ignition timing will be way off.

Set the ignition timing, then correct the idle speed, then correct the mixture, then go back and reset the ignition timing, then the idle speed, and then the idle mixture.

Go around and around until the engine is idling correctly with the timing set correctly. THEN, you need to go back and work with the idle mixture, and the idle speed until the engine is idling correctly, and does not bog then you come off idle, or idle too fast when you blip the throttle.

When you have everything correct, the idle mixture will end up in the middle of the range (sweet spot will be about 1/2 turn wide) where turning the mixture screw slightly will not result in a significant idle speed change.

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

Rich H · Posted: Sat Jun 28, 2008 4:50 am Post subject:

I have EFI fitted and neglected the vacuum leak problem, had 2 split injector seals, runs alot better now they are fixed!

I found them by squirting carb cleaner on each joint and I could hear it being slurped in by the vacuum. The engine also stumbled a bit as the carb cleaner burned. Vac leaks reduce the movement of the air plate, which in turn leans out the mix.

One that always gets missed is the idle screw o ring. its only tiny (3/8"?) but if its gone (Which it probably has) your idle screw will not work properly at all.

The flywheel marks will be there somewhere, try somethign like POR metal ready.

Other possibilities are fuel supply issues, blocked filter/bad pumps/knackered fuel lines/etc. Has it been standing for a while or been run dry of fuel?
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

datatrain · Posted: Sat Jun 28, 2008 1:41 pm Post subject: Set up

GOHIM, good advice ,I'll go back to the basic set up.

One question... If I back the mixture screw out to the end, is it captive or will it come right out and fall into the housing ? That could be nasty.

Thnx
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR