Datsun Cherry 100a running rough and rich

[brightonliving]

Our newly purchased Datsun cherry is running very rough and revs have to be slowly built up. The idle and cruising is erratic and low on power and car is smokey, especially after sitting for a while. Took the plugs out and they show it is running very rich. Gave the carb a blow through (with a by cycle pump ) and nothing appears to be blocked.

The mixture screw does very little to the revs. Spark looks strong. Muffler is shot so replacing that soon. On a side note, what gains would I see fitting a larger stainless exhaust?

What else should I look at?

Also, found this wheel bolt that someone has put in manifold. Anyone know what should go in here and if it could be affecting the mixture?

[mactat2]

Hi, there should be pipe running from where the bolt is to the rocker cover, looks like its been removed and blanked off with the bolt. maybe that is affecting the running? The rocker cover should have two outlets on the top, one on the pas side should be connected to the underside of the airfilter box the one on the drivers side should be connected to the manifold where you have the bolt fitted. If the bolt is a poor fit it could be sucking in excess air! try putting back to standard and see if that helps? :0)

[tineca]

Hi the mixture screw does nothing until the engine is warm on some cars. You could always try a colour tune to help set it up.

[DavidB]

It could be that it's sucking in air from a past-it gasket or an old vacuum pipe. The fact that the mixture screw does nothing points to this.

What's on the other side of that horrible looking bolt? It looks like someone's already had a go at curing it (badly).

[tineca]

Spray all around with wd40 whilst it's running. If it increases revs then you do have a gasket leak.