bad vibrations. maybe carbs/ignition??

[phatmendus]

hi,

I have an elan plus 2, and at the weekend the car started vibrating really badly at low revs, but at higher revs it smooths out, my original thoughts were engine/gearbox mounts, but they are fine. On closer inspection there is something suspicious going on in the engine. it runs ok although the tickover is rough and it will konk out after a while, but if i disconnect the HT lead from 1 or 2 cylinder it hardle makes any difference to the running of the engine. I have a good spark and have swapped plugs round, and the problem stays on 1 and 2. Also I have done a compresssion test, and all cylinders are fine. I am thinking perhaps there is a carb problem, it is on dellortos and it seems it is running rather rich anyway. I have checked all the jets and cleaned the carbs out, but the problem is still there.

If anyone has any ideas I would be really gateful, as I am stuck. Maybe its not the carb??? Maybe the timing has gone out or something? I really dont know. And it really is a significant vibration, can an engine not firing correctly really have this effect?

Any help would be great.

thanks in advance

Simon

[worzel]

Hi Simon

If removing the plug leads does nothing in effect it's probable that the throttles aren't properly synchronised between the carbs.

The quickest way to test this is to get hold of a flowmeter or similar and check each intake on the card ram pipes. Or, if your hearing is very good use a tube.

John

[elansprint]

Simon i had a pin hole in the float so the needdle valve was not closing same symptoms as yours obviously very rich, could be butter flies totally closed or idle jets screwed in too far but this would be lean. Where are you located i have a synchrometer.

[phatmendus]

hi, thanks for the replies. I am in North Hampshire, not too far from basingstoke. The whole thing is a bit stange as the vibration appearing was quite a sudden event. I know there is defo something up with the front carb, even though i forked out almost 300 quid for some chap with a rolling road to set them up and tune them a few years back. DOH! anyway, if any one can help that would be great. Im replacing the engine mounts today to see if that solves the problem, as the old ones have had it, and it just feel to 'physical' whislt driving to just be the carbs.

thanks

Simon

[elansprint]

Simon afraid i am in Northants are the floats brass or plastic the webers are brass & you can feel the weigt of fuel wher it had leaked in the float with the carb top off. soon solved with a bit of solder
Ian

[phatmendus]

right, so i have solved the vibration issue. it was a pair of knackered engine mounts. even though they hadnt fallen apart, it is now obvious after replacement that the engine was around an inch lower than it should have been !

in terms of the Carbs, the floats are plastic on the dellorttos, i have checked them and they are still working ok, i.e no leaks. I have the feeling that the have just been really badlty tuned by the 'expert' but i am still reluctant to mess with them after forking out all that cash on them!

thanks for the offer of the manometer though, i may take it to Miles at fibreglass services to get him to tune it correctly and slove all these issues.

Simon

[collins_dan]

I had the same experience with engine mounts. They looked fine installed, but once removed, I could see they were shot and I can feel a marked difference. Dan

[robertverhey]

Thanks for this, I have a steadily worsening resonance in my T/C motor at 2000 rpm. Fine above and below that. I have looked absolutely everywhere to try to isolate the source. Maddening. So I'll be whipping out those mounts on the weekend for a look

Robert

[elansprint71]

Glad you sorted the engine mounts- modern rubbish rubber?

Invest in a Colortune glass spark plug, brilliant bit of kit.

[robertverhey]

For the record

My mounts were fine, however the alternator adjustor strap had snapped. Amazingly, the pivot bolts were tight enough to hold the alternator in place and keep the belt tight..

All sorted now, and no more vibration!

Robert