mk 1 engine troubles!!

[Jarred]

G'day all.

I'm hoping someone will have a bit of wisdom for me here.

I've got a standard 1.6 with a 32/36 DGV weber and extractors (no exhaust atm), and I'm starting to have a few issues getting her running..

let me explain.

It was all running fine before I put the extractors on, running starting everything was fine, then after I put on the extractors (removed and re-fitted the inlet mani) I went to start her up and it was all sweet. fiddle with the air fuel an idle adjusts to get her right. all good.

then a few days later, I go to start her up and it doesn't hold idle rev smoothly and generally stalls out. I could keep it alive with the throttle, but obviously not a permament fix . I initially thought it was a vaccum leak, so I tightened up the inlet mani studs, and then I worked, but the next day ( or day after) the same problem again.

I figured I'd yank the manifold off, clean it up a bit, etc etc. I ended up using better looking (ie cleaner, better condition) studs off a junker head. I also added another washer (now there are two on each), as I thought that maybe the bolt/stud's weren't pushing the manifold in enough.

So all that's just been finished, but I'm still having troubles, the same things are happening, but I know the manifold and carby are both on tight now. (donno what torque though) I've fiddle with the air/fuel just incase it was that, but it doesn't seem to be, it's still stalling when left to it's own devices. Interestingly though, On start up, for the first 5 odd seconds, it's fine, but then starts getting eratic, and stalls. which makes me think vaccum leak still...

what could be wrong?!
can anyone spit ball with me??
anyone know whats wrong??

Any help, always appreciated

Jarred

[Peter Jones]

Are all the vacuum hose to the brake booster OK?

Pete

[Jarred]

thanks for the quick reply pete

um, just check it, and replaced the dodgy(est) looking piece. the replacement hose is a bit bigger, and is probably too loose, as it didn't fix the problem.

I'm not sure if I have any hose that is the proper size, so I'll look more indepth tomorrow, (i'm helping my bro's fiancee move atm!)

are there any other possible culprits?

[Peter Jones]

How about the vacuum line to the distributor?

[aprr32]

On some extractors the cut out for the inlet manifold is too small and when you bolt everything down the inlet manifold doesn't sit flat on the head.As you can imagine the air leak is enough to make idling impossible and running almost as bad.The anwer is to grind out the extractors so the inlet manifold fits in and sits flat.

[Golf Loon]

^^^^^^^^^
Yeah i have seen that too.
Or grind a pieec off the inlet manifold if that is easier

[ontarv]

def sounds like vac leak
but most times vac leaks will run alright at revs
did you put a kit though carby before you put it on
if you didn't put one though it
it could be that you distrubed some crap in the fuel bowl
and blocked a jet ??

[Antdragonist]

sounds like what was happening to mine a LOT after i put twin carbs on. some days she would even idle at like 100revs lol (impressive - mildly, but definately not what i wanted lol)
in my case i put it down to the intake manifold, and possibly one of my carbies, i reckon there was an air leak somewhere along the line or somethin. and the vacuum line to the dissy (as has been mentioned by others) was at one stage not even connected i think, and i had the same problems after clearing the line and setting up a new hose on it.
but yeh i dunno, also seemed like whenever someone would tune them in itd go right back to doing it a couple days later.
the last place i went to must have set the idle up around 1500 after i serviced it with them (it was easily noticeable as soon as i turned it over) and i havent had any problems with it since then though.

[gldgti]

get a tin of WD-40 and start her up. spray the WD-40 around the carbie, and the interface between the manifold and head and listen for changes in the idle. if you notice that the revs pick up when you give it a heap around the manifold/head interface, you can be sure the leak is there.

[jaffa]

Jets

Hi Jarred

I'd be checking the jets, particularly the idle jet, as it may have picked up a bit of garbage when you ran it the first time. It would explain why it runs OK for a while when first started as it will start rich from the accelorator pump or choke. The good thing is that the jets on webers are usually easy to access, though not familiar with that particular one.

[gldgti]

Hi Jarred

I'd be checking the jets, particularly the idle jet, as it may have picked up a bit of garbage when you ran it the first time. It would explain why it runs OK for a while when first started as it will start rich from the accelorator pump or choke. The good thing is that the jets on webers are usually easy to access, though not familiar with that particular one.

good point

to access the jets on the DGV carb, you need to remove the air filter, and then the top cover of the carb. this also removed the float, so should be sone carefully. in the base of the flaot chamber are the 2 main jets, and the idle jet is screwed into the back of the float chamber - you dont need to remove to top cover to get out the idle jet, you can remove it using a stubby screwdriver from the firewall side of the carb.

when i was running the DGV, i was using a .5 idle jet.

[Jarred]

alrighty, thanks for all the help guys.
I didn't want to start pulling aprt the carb for two reasons a) they're tempremental buggers and b) it worked fine before the extractors went on.

so what I ended up doing was ripping off the extractors, bolting them upto the old exhaust manifold, got out my grinder and went at it, trying to make the extractors fit the profile of the old exhaust manifold, and so far so good.

well it didn't work straight away, cause the carb was tuned way out, and was pretty difficult to retune with the extractors on (a real lack of back pressure is becoming apparent I think) but I got that sorted. My only real issue, is that with no choke setup at all, it does make it very difficult to start! it used to be alright, but yea, I donno, we'll wait and see after I get my exhaust made, and I'll put some new plugs in and try and do the timing (how's that done??) and then I'll give it a real go at tuning it, if I suck at that, I'll take it somewhere/to someone i thnik..