This is good advice, much needed. Its a 76 1500 with the US spec Stromberg
CD. I tried the propane trick but with so much fan air moving around it
didn't do anything - or there are no leaks. I'll try the carb cleaner
routine. I suspect the EGR carb port is blocked by the gasket and/or
insulator block. Sure is a pain the put the nuts back on.
The choke control is the water type and I operated it without the water
chamber mounted. I noticed it got richer (as viewed with ColorTune) when I
operated the control manually.
During the rebuild the main needle was reset more flush than before - down.
Maybe I should have left it.
Seems like without a CO meters its basically guessing.
Ps
----- Original Message -----
From: Bob Sykes <stan.part@worldnet.att.net>
To: <alfapete@pacbell.net>
Cc: <spitfires@autox.team.net>
Sent: Saturday, June 26, 1999 2:42 PM
Subject: Re: carb - (ZS tuning problems)
>
> Sorry I missed the beginning of this thread and I'm not sure exactly
> what model car(b) is in question here but I'll give it a shot:
>
> Peter S. wrote:
>
> > Ok listen up out there! Car still runs a bit rough. (recap - ZS carb
> > leaked gas and ran rough - then rebuilt carb and no gas leaks but still
runs
> > fairly rough. Did the following today:
> >
> > 1. compression check - All cyl. at 109lbs.
>
> OK
>
> > 2. Ensured timing was correct and operates smoothly. Discovered advance
> > vacuum pipe was melted and replaced.
>
> Good
>
> > 3. Attached a vacuum gauge. Reads steadily and changes smoothly.
> > Discovered vacuum port for EGR - (top rear section of carb nearest
manifold)
> > appears to be dead (checked good when carb was on the bench). No vacuum
(or
> > pressure) measured. I remember wondering which way the carb-to-manifold
> > gasket should be since it has a notch. I put it where the old was which
was
> > pointed to the front of car and downward. THIS CORRECT????????????
>
> There's a gasket and there's a 3/8" spacer here. The important thing is
> that the notch aligns with a corresponding hole in the carb flange. The
> spacer is not symmetrical, so it's possible for it to be pointed to the
> front of the car and downward and still not line up with the hole. I'd
> check this.
>
> > 4. Ran engine from new gas in gas can instead of cars gas which may be
old.
> > 5. pinched off temporarily various vacuum hoses while engine ran to see
if
> > there was any change. Virtually nil on all of them. Discovered large
> > crankcase breather pipes leaking and replaced with new hoses.
>
> This is good. It's important for the crankcase breather hoses to be
> leak
> free (or will be too lean and impossible to tune). For troubleshooting
> purposes, you can just run a single hose from the rocker cover to the
> appropriate port on the carb. This bypasses the evaporative lines and
> cannisters which could be a source of further vacuum leaks.
>
> > 6. Ensured Choke control operated properly.
>
> Not sure what you did here. ISTR this was a water heated choke?
>
> > 7. Replaced dashpot oil with 3-in-one.
>
> OK
>
> > 8. Used ColorTune. NO color changes when turning idle mixture screw.
Can
> > see/hear no difference at all despite many turns. Always slightly
> > blue/white.
>
> Could be a little lean. Possible vacuum leak. It sounds like you are
> turning
> the *fine* mixture adjusting screw. This will have little/no effect if
> there
> are other problems. As Atwell noted; you probably want to adjust the
> carb
> needle with the "special tool" for more effect.
>
> > 9. Ensured Lucas distributor had gap as specified in manual. Noticed
dist.
> > shaft seems to move somewhat preventing decent measurement. Cap and
rotor
> > are new.
>
> Probably OK. A "points type" distributor and water heated choke are
> mutually
> exclusive wrt to originality. They'll work just fine together, but I
> cannot
> deduce the model year of the car based on these items.
>
> > 10. HT plug wires all measured 6-10 ohms.
>
> Should be OK
>
> > 11. Plugs cleaned and regapped to 25 thou. Splitfire plugs.
>
> I have no experience with these sparkplugs.
>
> > What am I missing? All of the changes had little or no effect to the
> > running of the car though the new vacuum advance pipe does appear to
give a
> > little more power than before.
>
> Possible vacuum leak(s). Did you check for play in the throttle plate
> (butterfly)
> shaft bushings when you rebuilt the carb? This is a common source of
> air leaks
> when the carbs get some age on them. I'd (temporarily) plug the vacuum
> port on
> the carb. Fit the single hose from rocker cover to car (mentioned
> above). Then
> check the EGR valve for vacuum leaks with the car at idle. We're not
> checking
> the control port here (I remember you said this won't hold a vacuum).
> We want
> to make sure the "business part" of the EGR valve is not leaking air
> directly
> into the intake manifold. This can be accomplished by spraying carb
> cleaner,
> WD-40 or other flammable fluid of your choice in and around the EGR
> valve.
> If this causes the idle to change, then you've probably got a vacuum
> leak here.
> You can perform the same test on the throttle plate shaft ends to check
> 4 leaks.
>
> FWIW I'd recommend having a fire extinguisher handy while doing this.
>
> Hope this helps,
> Bob
>
>
> --
> Bob & '78 Spitfires
> (one of them mine for 21 years)
>
|