Idle To Low?

[Longboarder]

Yes. I'm saying that there may not be anything 'wrong'.

The basic start settings I would use on a DGV would be Idle mixture screw gently in till it stops and then out one and a half turns.

Throttlestop screw gently in till it just starts to move the butterfly and then in another half turn.

 

Then you start the car with choke and warm it up. (A cam on the choke mechanism lifts the throttle butterfly slightly further open making the throttlestop screw irrelevant when the choke is on). As it warms up and you progressively ease off the choke, the choke cam stops raising the revs and the throttlestop screw comes into play again to control idle revs, fully once the choke is fully off. Don't fiddle with the screws till the engine is up to temperature and the choke is fully off. If the engine revs drop too far as the choke comes off just turn the throttle screw in a quarter turn and start again. Repeat till the warmed up engine runs at about 850 - 900 rpm or a little more and then ease the throttlestop screw back to let the revs drop back to 850 - 900.

 

Now you can play with the idle mixture screw if needed. Screwing in leans the mix, out enriches it. Gently turn the idle mix screw to get the fastest idle. Now ease the throttlestop screw back out to drop the idle to 900. Again try the idle mixture screw either way to see if you can get a faster and smoother idle. If you do then ease the revs back to 900 with the throttlestop screw.

 

Gently rev on the throttle to 2000 rpm for a second or two and let it settle to idle again. Now snap the throttle open for a second. If it revs rapidly then OK. If it stumbles then you are going weak momentarily and need to turn the idle mix screw out a fraction to enrich the mixture (probably less than 1/8 turn) which should get rid of the stumble.

And that's about it.

 

If this procedure doesn't work then report back with what happens.

 

Nigel

[Guest aidankinnell]

Think its pretty much there now.

 

Following the procedure set out by Nigel, the end results are that idle speed went up by 1/4 turn and mixture was enriched by 1/2 turn. Tested on the drive, seemed ok and then tested going up and down the street, no obvious lag or momentary weakness; then it started to rain so the toys went away! Idle is now around 900.

 

If there any further adjustments then I'm sure they will be fractions. Having marked up the starting positions I'm going to remove to marks once the engine has cooled and then remark up once its dry again.

 

Thank you all for the advice.

[Longboarder]

Good. All good fun and now you know how to tweek a DGV webber. Also confirms the carb jets, particularly the idle jet is about right for your car.

 

Nigel

Edited June 20, 2015 by Longboarder

[Guest mcramsay]

My apologies I thought that the car had previously been running correctly and this was a problem had developed, hence me advising not to play with the mixture. At least you got it sorted

[Guest aidankinnell]

Grateful for all the advice!

 

Got the car out in a dry spell, running great

[Guest aidankinnell]

Ok, the problem reoccurred today but much worse than it had been previously! I was dying at every stopping point.

 

Next plan of action, clean the idle jets and take another look at the screw setup.

 

Clearly something not right!

[Longboarder]

Check all the screws again. One may have moved with vibration. Do you have a good pre-carb filter? Maybe some dirt in the fuel and a blocked jet.

 

Nigel

[Guest Gargoil]

Are there any other symptoms, excessive smoking/breathing from the engine for example?

Was there anything else done to the cylinder head when the cam was changed. I mention this because I had a problem like this and it turned out to be excessive wear on the valves. A simple compression test will find out if this is the case.

Edited July 6, 2015 by Gargoil

[Guest zerorace]

Sill question but what air filter are you running as the carb would have be set and jetted for a standard pinto filter if you have a k&n or other hi flow air filter it will be lean not just on tick over but all thought the range check the plugs after a good run for colour the lighter the leaner it is dark grey is good.

 

Just my opinion

 

[Guest aidankinnell]

No other obvious symptoms.

 

I've got a couple of new washable filters on order to prevent any further blockage issues, if that's the problem.

 

Head was cleaned up when the cam was changed, think some valve work was done but I didn't do the work myself.

 

I'm using an ITG filter.

 

Not heading out to garage for a few evenings but will take on board all of the above.