2L CU Air Cooled Erratic Idling Speed

[mgbman]

Hello everyone, I wonder if you could help me with this one. When I start the van I notice that once the engine has warmed up it idles ok but revs rise slightly and then fall and a few seconds later rise and fall again and continues in this pattern. The revs never stay steady. Engine does not stall.

Engine has done 145,000 miles and lacks power up inclines but can still achieve 70 mph on motorway.

Compressions test showed 120 120 120 110

Engine tends to pop and misfire quite a lot as well.

Carbs are standard Solex PDSIT and looking pretty grubby and i feel long overdue for a clean and tune.

I am planning to check timing as well at some stage and I noted that the engine has no timing scale.

[ajsimmo]

Hello everyone, I wonder if you could help me with this one. When I start the van I notice that once the engine has warmed up it idles ok but revs rise slightly and then fall and a few seconds later rise and fall again and continues in this pattern. The revs never stay steady. Engine does not stall.

Check throttle is returning to fully closed, and that there is no vacuum signal from left hand carb vac pipe at tickover. You should just have vac on the retard pipe only until you slightly open the throttle, then the advance port in left carb opens sucking on pipe to dizzy and advancing the timing by about 12 degrees! Any advance will raise tickover speed, so could be rising and falling due to timing moving due to incorrect carb adjustment.

Engine has done 145,000 miles and lacks power up inclines but can still achieve 70 mph on motorway.

Compressions test showed 120 120 120 110

Not too much wrong with it then.

Engine tends to pop and misfire quite a lot as well.

Timing, lean mixture (carp in carbs blocking jets) or air leak.

Carbs are standard Solex PDSIT and looking pretty grubby and i feel long overdue for a clean and tune.

I am planning to check timing as well at some stage and I noted that the engine has no timing scale.

They're a tenner at Brickwerks http://www.brickwerks.co.uk/index.php/t ... ngine.html

[The Bobdogs]

Don't know about Carp in the carbs, but I tried keeping Perch in the ashtray......

[Bexyvan]

Watch out for the pike in the glovebox too : rofl

[ajsimmo]

Perhaps the last mechanic fishing around in there was a chubby fella who couldn't tuna carb?
Or maybe last time he bought petrol he filled it to the bream?
Alternator belt got too much tench on?
Idle problems can really give you a haddock.

OK I'm done.

[lefty67]

Perhaps the last mechanic fishing around in there was a chubby fella who couldn't tuna carb?
Or maybe last time he bought petrol he filled it to the bream?
Alternator belt got too much tench on?
Idle problems can really give you a haddock.

OK I'm done.

thats reely clever

[danmetallic]

^^spam?

[jason k]

have you tried plugging the wires from the digital idle stabiliser together?