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23/10/2004 22:24:35   James Ross   Hi there,

I hope that you guys can help me out as i'm at the end of my teather now.

My 1974 96 V4 developed troubles almost a month back & hasn't been right since (having only weekends to work on it due to work). I replaced the electronic ignition & coil with a decent brand (Lumenition), new Magnecor HT leads, new spark plugs, distributor cap, rotor.

My dad messed around with the idle & mixture on the carb to try to sort it but no avail.

This week I have done the timing (dynamically) with a Gunson timing light (with the vaccum pipe off the distributor) & a Gunson colour tune to get the fuel mixture right.
I have set the idle at 850 RPM but think this is a little high.

Today it has been running fine when the engine is up to normal temp. but this evening once it had cooled down the car had trouble starting, runs badly and would have stalled if i didn't keep pressing the accelerator & the choke almost right out.

All timing changes etc. were done when the engine was warm.
Carb float level is okay & all jets seem to be clear.
Have also put a new replacement fuel filter to the carb...running out of ideas now!

Any ideas to help me, before I go & buy a Trabant instead?

Will attempting to lower the idle down to 500 RPM & alter the mixture to fit solve my problems?

Many thanks in advance!

- James

P.S
Carb is an evil FoMoCo thing - maybe setting fire to it & buying a Webber would be sensible?
 
24/10/2004 11:04:26   Alistair   James - let's see what the rest of the guys think but here's my initial thoughts...

800-850 rpm idle is right, don't try to set too low.

Did you plug the vac hose when you disconnected it to set the timing? Doesn't normally make a difference, but can occasionally.

When you say runs badly, is it missing or is it something else? Have you tried disconnecting the plug leads individually to see if there is just one that's causing the trouble?

Does the car use any oil? If so, it could be valve stem seals allowing oil to drain into a bore and fouling a plug. It's worth checking the condition of each plug, both when cold and hot.

That said, it certainly sounds more like fuelling trouble than ignition. Poor running when cold could be down to the choke - is it operating OK?

I'd recommend you ditch the FoMoCo asap and get a Weber when you can find one at a reasonable price. In the meantime though, you should be able to get the crappy Ford carb working better than you describe.

Perhaps if you could beg/borrow/steal a spare carb to try that it could help pinpoint the problem. I have some spares in the garage but I'm quite a way from you.

Another thought, have you checked all the crankcase ventilation hoses & breathers etc? Sometimes if they get blocked with crud or the rubber collapses you can get all sorts of wierd problems. Are all the seals OK on the carb, air filter etc?

Good luck...  
24/10/2004 12:12:03   James Ross   Yes it does say in some of the manuals that the fomoco should be about 500 but i've set it to 850rpm in the hope that it would stop it stalling when it's cold, sadly not.

I didn't plug the vac hose when I did the timing, I suppose I could give it a whirl & try that.

Car doesn't burn any oil.

Have taken the filter box to pieces & cleaned it so I can eat my dinner off it. All the crankcase hoses seem to clear too & not collapsed or broken.

It doesn't sound like it's missing any beats, as once it's warmed up it's nice & smooth like it used to be.

I haven't taken the HT leads off one by one as it seems to run okay when warm but I could try that to eliminate it.

The mixture was running rich which threw a load of carbon onto the plugs, but that's all been altered now & both mixture & plugs are fine. I've never had oily plugs thankfully.  
24/10/2004 15:17:51   Senor Burt   Try setting the timing and mixture 'by ear'. Turn the distributor while the engine is running until you get to the point where it runs smoothest. Do the same with the carb idle mixture screw.
You should be able to get them set so it runs right like this. If it doesn't work, then there is obviously some other problem.
Did you fit the electronic ignition etc before or after the problems started? If before, suspect one of your new components.  
24/10/2004 19:31:20   James Ross   I originally tried setting it by ear last week & when I tested it this week with the timing light & colour tune I was pretty close. Sadly it still starts badly.

I fitted the new electronic ignition after the problem developed in order to cure it, which sadly it didn't. :-(

Everything new that i've put on I have changed back to the old ones to make sure that there were no troubles but still this poor running remains :-(

I don't think that there's much more left to change on the engine, so hopefully get there soon!  
25/10/2004 12:24:48   Richard   What have you set the timing to?
Try new ht leads.
Have you put the filter to the winter position?
Is the auto choke working as it should?  
25/10/2004 13:46:36   James Ross   Timing has been set dynamically to the "6" as the Haynes & autobooks say (with the vacuum pipe taken off).

Already have new HT leads (Mangecor 8.5mm with 10yr warranty)

Filter is in the winter position (it's not carb icing, been there & done that with my old 2CV)

Mine has a manual choke fitted - am currently away during the week, so will have to look at the weekend, maybe the choke plate gaps need re-adjusting?  
25/10/2004 15:30:16   Senor Burt   Well..... a brief glance at my Haynes manual suggests:-

Difficulty cold starting:

Clogged jets - clear
Loose main jet plug - tighten
Choke flap not closing - check mechanism (just take off the air cleaner and check whether the choke flap is closing sufficiently( IE almost all the way))
Weak mixture - Adjust (You've already done this though).

It might be a good idea to use the colurtune whilst starting from cold. This will tell you if the mixture is richer with the choke on.
It's easy enough to strip these carbs down and clean the jets etc out with carb cleaner spray. Sometimes you can get blockages right inside the carb which don't respond to this treatment.
A good S/H FoMoCo should be cheap if you need a replacement. Webers more expensive, but a far better carb.  
25/10/2004 15:42:08   Senor Burt   Just seen James's ad asking for a Weber carb.
For anyone who thinks an adaptor plate is a good idea for fitting a twin-choke carb - don't bother. You get little or no performance enhancement for a lot more noise and fuel consumption. Either get a single-barrel Weber or a proper manifold.  
25/10/2004 17:56:16   James Ross   I have taken my FoMoCo to pieces as I first thought that it was a blocked idle jet causing the problems, sadly cleaning it all didn't make any difference.

One thing I didn't check was the choke plate settings - do you follow the same method (in the haynes manual) for a manual choke as you would for an automatic?
(Think the example in the book is a particular sized drill bit, to measure the gap it's supposed to allow)

I think I could do with scrapping the FoMoCo & getting a Weber if it doesn't respond when I get back home this weekend.  
25/10/2004 20:39:56   Alistair   I'm afraid I'd disagree with Burtie Boy on the twin choke Weber/adaptor plate issue. If the rest of the engine is standard, then you don't really get any significant gain from a 28/36DCD on a pukka 4-bolt manifold than you do using the SAH adaptor. This may not be the case with other (bigger) twin choke carbs, but is with the DCD.

A 28/36 + adaptor will improve economy by about 10% (the progressive nature of the carb sees to this) and they run SOOOO much better, smoother, cleaner pulling from low revs and bags more mid-range torque.

 
26/10/2004 02:17:38   ian banks   When you took the carb apart did you check if there was any damage to the float?, or perhaps leaking needle valve. You might also have a look at your fuel pump ,check it is actualy delivering enough juice.  
26/10/2004 13:14:55   paul   I havnt had carb troubles on a saab, but i have experience of them on other cars. A friend had a webber that started running very rough after 6 months of working fine, tried changing/tuning main/idle jets and emulsion tubes, cleaning all jets, checking float levels etc, didnt work. Sent it away to get cleaned and the guy dismantled it to pieces, cleaned ALL the crap off it and replaced ALL the gaskets etc. since then it has run perfectly. Try getiing your carb down to as many pieces as possible and either cleaning it yourself, or pay a pro to do it...  
26/10/2004 14:12:49   steve h   Dump the carb..

Sounds like you are wasting your time flogging a dead horse. I have found after 120k or so the interior of a fomoco starts failing apart, especially inside the main jet tube. I run a 28/36 DCD which is crap for tickover when cold but beautiful when warm, and a weber somethingorother that Halfords were chucking out, which is fine but ordinary. Both infinitly better than a fomoco.

Bite the bullet.  
28/10/2004 18:06:06   James Ross   I think i'm going to have to bite the bullet Steve & swap for a Webber (assuming that this is the problem), my beastie has done about 122,000 miles & think it's still the original carb as i'm only the third owner.

I have tried taking it to pieces, cleaning as many jets as possible, & the float seemed to be working and was set to the correct level. I think there is enough fuel getting into it as when I took it apart their was petrol in the float chamber & it only has trouble when starting (rough as a bag of nails) but fine once it's warmed up.

I'm back home tomorrow, so hopefully (if the weather stays fine) i'll be able to have a fiddle with the choke mechanism & if still no joy then i'll swap it, though I think i'll swap it for a webber anyway (as that was my original intention when I bought it a few months back).  
28/10/2004 22:12:42   john wyatt   James, you should be able to pick up a replacement carb for your 96 without much bother I recently fitted an old fomoco carb from my 96 onto next door neighbours 1300mk2 escort and it worked fine, I have had a few V4's and have put up with "poor" running when cold i.e. for the first few minutes it may not idle even with choke, I am also presently on an adaptor plate with at 32/36 weber and it works fine these carbs were used on lots of fords and Rolf at Svenska saab klubben will probably sort you out with a twin bubble manifold  
31/10/2004 07:53:29   ian   bought a nikki on e-bay for bens v4 for 25 quid when we couldnt get his fomoco to behave...bolted it straight on and made pucker linkage and what an amazing difference..the car really flies now and is using less fuel  
31/10/2004 19:13:26   James Ross   Somehow by magic, I have gotten the old beast going again and it's back to it's normal smooth state after much shouting (and blood spilt). Though I think i'm going to still swap the carb as the FoMoCo is clearly on it's way out sadly :-(
Hopefully it'll keep it going until I get chance to do the swap, thanks for all your help & advise too guys :-)  
01/11/2004 10:30:52   James Ayres   Ahh, ...by magic... the joy of owning a classic - it's pure magic. On another day it's a beast of the Apocalypse, but today, it's magic!

Adieu fellow Magicians...  
01/11/2004 18:04:11   James Ross   That's very true, but just as the car started to work again the brand new timing light, I bought only a week or so ago, decided to completely stop working! (So i've had to send it back) Swings & roundabouts....  


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