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Author Topic: hesitation under load  (Read 7870 times)
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gatewright
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« on: September 08, 2012, 07:40:47 PM »

can anyone advise on my problem, 1978 ,1600 beta coupe, starts and idles perfectley but falters during mid revs trying to accelerate, its ok if you floor the accelerator but doesnt like normall throttle pressure, i have checked timing (electronic ign) changed leads, rebuilt carb, and today fitted an electric fuel pump but still the same although a strange thing happened when caught in heavy traffic today the temp gauge went to just over half way which during normal use it doesnt go to but the hesitation was all but gone during the period the car was hot but returned as the car cooled ?. does auto choke give this sort of problem ?.
Alan   
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MattNoVAT
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« Reply #1 on: September 08, 2012, 08:06:04 PM »

I had similar issue, I replaced the gaskets between the inlet manifold and the plastic spacer and the base of the carb.  Air was getting in where it shouldn't.  As the engine got hotter things expanded and sealed up the gap and when it cooled it went back to hesitant running. 

Also, it's worth checking there is nothing blocking any of the jets.
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1981 2000 Coupe S2/FL
1976 1600 Coupe S1

Understeer is when you hit the wall with the front of the car. Oversteer is when you hit the wall with the back of the car. Horsepower is how fast you hit the wall and torque is how far you send the wall across the field once youve hit it.
gatewright
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« Reply #2 on: September 08, 2012, 08:30:11 PM »

Thanks Matt, but have renewed gaskett and thoroughly cleaned carb and all jets, Im getting to the point when i feel i should take it to omicron or someother
expert as i am running out of ideas   
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MattNoVAT
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« Reply #3 on: September 08, 2012, 08:41:50 PM »

Do you have vacuum advance fitted?  Check the pipe is connected and there are no splits in the pipe.
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1981 2000 Coupe S2/FL
1976 1600 Coupe S1

Understeer is when you hit the wall with the front of the car. Oversteer is when you hit the wall with the back of the car. Horsepower is how fast you hit the wall and torque is how far you send the wall across the field once youve hit it.
gatewright
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« Reply #4 on: September 08, 2012, 08:56:53 PM »

will check that out tomorrow. thanks 
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VXdeMayo
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« Reply #5 on: September 08, 2012, 09:50:59 PM »

Dear Matt and all,
this is a similar problem to what we are having with our VX HPE "Lulu".
This has prompted me to ask should you have the Volumex top alloy air inlet chamber actually touching the underside of the bonnet? The reason I know this is we have recently bought one of Mark's replacement under bonnet covers to replace the old manky one, and ever since then the 4 studs with their nylock nuts which hold this inlet chamber onto the top of the carb, have left four deep impressions in our new cover. So is there a possibilty that the carb assembly might be being distorted by the weight of the bonnet pushing down onto it, thus letting air in, and distroying the vacuum?

We have suffered from frequent hesitation and stuttering when under light acceleration, usually around 1600 - 2000rpm , normally in 2nd or third, BUT if you give it the beans then acceleration is smooth and progressive (although not as good as I have expected).
The trouble is around town you are most of the time "off throttle" or just feathering to keep up with normal traffic. So the stuttering is frequent and annoying. Any wise words from anyone would be welcome. (By the way we have pretty much checked everything else, both carb and ignition etc and substituted to try to track this gremlin down.
What do you guys think??
best,
Chas and Anne. Huh?
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"Baldric - I have a cunning plan" (Oh - ah, maybe not)!
MattNoVAT
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« Reply #6 on: September 08, 2012, 11:10:11 PM »

Chas,
I personally doubt that the bonnet & liner is pushing down sufficiently to distort the intake assembly and cause your issue.
To confirm this I would simply try popping the bonnet thus releasing any potential pressure on the intake a go for a short spin.  Maybe put two small pieces of wood above the two bonnet catches to stop the bonnet from closing.

As you know the VX is much more complicated set up than a 1600 carb!
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1981 2000 Coupe S2/FL
1976 1600 Coupe S1

Understeer is when you hit the wall with the front of the car. Oversteer is when you hit the wall with the back of the car. Horsepower is how fast you hit the wall and torque is how far you send the wall across the field once youve hit it.
credders
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« Reply #7 on: September 09, 2012, 07:54:51 AM »

i seem to have a similar problem so let us no any findings please.
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gatewright
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« Reply #8 on: September 10, 2012, 09:01:43 AM »

Over the weekend i changed the coil, checked all settings,replaced leads car starts on the button, revs really well when not moving but as soon as i apply any load on the engine it splutters and misses almost impossible to pull away if uphill, but if i floor it opening second choke it goes well,
I have serviced all parts in carb  thoroughly cleaned carb, accelerator jet works fine.
Alan
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MattNoVAT
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« Reply #9 on: September 10, 2012, 09:13:37 AM »

Have you set the distributer correctly?
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1981 2000 Coupe S2/FL
1976 1600 Coupe S1

Understeer is when you hit the wall with the front of the car. Oversteer is when you hit the wall with the back of the car. Horsepower is how fast you hit the wall and torque is how far you send the wall across the field once youve hit it.
gatewright
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« Reply #10 on: September 10, 2012, 09:52:02 AM »

set distributor to 10 degrees btdc.
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HFStuart
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« Reply #11 on: September 10, 2012, 08:52:43 PM »

I had this issue on my Spider. It was sorted by adjusting the timing on the rolling road. Try a few degrees either way from the standard setting.

Also make sure the centrifugal advance is working correctly and progressiveley  - if one of the springs has come off the weights in the dizzy it can produce the same effect.
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gatewright
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« Reply #12 on: September 11, 2012, 08:53:02 PM »

I have booked the car in for rolling road tune and and i suspect carb work at Atspeed tuning in rayleigh, the have previously
sorted problems on my cortina gt and appear to be experts with webers,will let you all know of my findings,
thanks for the helpfull advice.
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capriblu
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« Reply #13 on: September 12, 2012, 11:50:01 PM »

I bought my first Beta , which I still have, over 22 years ago and it has always (until a few weeks ago) suffered a slight bit of "fluffiness" at mid range engine speed and at the transition point at which the second choke would open.  I never had quite the same level of problem with several subsequent Betas that I owned - all carburetted and with Bosch electronic ignition.  Swapping carbs never seemed to shift the issue to another car.

I have recently completed work to recomission my 1980 2l coupe, my first Beta, including repairs to the head.  Annoyingly the hesitation that I remembered still existed.  I remembered that slight retardation of ignition timing from "nominal" (turning dizzy a few mm clockwise) would reduce the severity of the hesitation but not eliminate it completely and I found this still to be the case.

In an effort to get the car running more smoothly I had the Bosch distributor (2000 car no vacuum advance) refurbished and rebuilt with an integral trigger unit to replace the Bosch black box unit. I also replaced the coil with a conventional 12V unit (i.e not a ballast resistored unit).  The spark is definitely much stronger.   The hesitation has completely gone!

I'm quite certain that the work to improve the ignition set-up on my car has been the reason why the hesitation problem has gone away.  The hesitation issue does seem to be very prevalent on these cars and was often mentioned in contemporary road tests.  I suspect that there is a mid range throttle opening position/engine speed combo that provides a relatively leanish mixture setting and which may, in combination with a weak spark, lead to the apparent very slight misfire/hesitation 
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!980 2.0 Coupe - Owned since 1990
credders
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« Reply #14 on: September 13, 2012, 08:58:14 PM »

that all makes sense, sounds like mine. i was convinced it was a fuel problem and swapped to a carb i had off my old strada 105TC but the carb didnt have a take off for the vacuum advance and the hesitation was still there but wasnt sure if it was to do with not having vac advance connected or maybe a leak between carb n manifold, ive had the carb off so many times n used the same gasket now thinking that could be it. previous owner changed plugs,leads,cap n rotorarm he must of thought electrical. can you upgrade the std dizzy with a better trigger system n keep the vac advance?
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capriblu
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« Reply #15 on: September 14, 2012, 11:44:59 PM »

The Bosch distributor for electronic ignition whether it is variant with vac advance or without can be rebuilt/refurbd and have a small but powerful trigger unit (c20mmx 30mm x 10mm) attached to the body of the unit at the point where the wires from the pickup unit exit.    Following recommendations on here (and elsewhere) I approached H&H Ignition services for advice.   I had my distributor rebuilt with trigger unit attached (to replace original control unit - Bosch black box) and supplied with new powerful 12V (non ballast resistor) coil.  Total cost was about £140 which I though was vgvfm.
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!980 2.0 Coupe - Owned since 1990
credders
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« Reply #16 on: September 15, 2012, 07:25:12 AM »

Yes. Value for money. You can spend more than that on the rolling road only to have to spend the money on the ignition anyway.
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archigraphe
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« Reply #17 on: September 15, 2012, 09:30:22 AM »

I've resolved this problems on my 2ltr coupé  with a new gas filter, a new plug cable, and to repare the old connection of the "etouffoir de ralenti" on the carb.

But my tiing had more advbance and I heard that in the exhaust..
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credders
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« Reply #18 on: September 23, 2012, 08:21:31 PM »

any news from the rolling road session ?
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mangocrazy
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« Reply #19 on: September 26, 2012, 08:09:14 PM »

The Bosch distributor for electronic ignition whether it is variant with vac advance or without can be rebuilt/refurbd and have a small but powerful trigger unit (c20mmx 30mm x 10mm) attached to the body of the unit at the point where the wires from the pickup unit exit.    Following recommendations on here (and elsewhere) I approached H&H Ignition services for advice.   I had my distributor rebuilt with trigger unit attached (to replace original control unit - Bosch black box) and supplied with new powerful 12V (non ballast resistor) coil.  Total cost was about £140 which I though was vgvfm.
Hi - pardon my ignorance, but what did you need to send to the H&H Ignition people for them to do the work? Is this their website or have I got the wrong people?

http://www.h-h-ignitionsolutions.co.uk/
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1980 Lancia Beta Spider 2000 (S2FL)
2002 VW Transporter T4
2017 KTM Duke 690R
2008 Aprilia SL1000 Falco
1992 Ducati 888 SP3
1988 Honda VFR750F
1980 Yamaha RD350LC
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