Chugging Again!

[ham204]

The Sprint is finally idling very sweetly but once I put the engine under load, it starts chugging, as if a plug has gone dead. Idling back it's ok but won't take up speed.

ideas?

It's due for a head recondition and timing chain replacement.

[Jon Tilson]

Oil in dashpots or lead or plug breaking down? Insufficient points gap or duff condensor....you name it, it could be loads of things.

Change one thing at a time....

Jonners

[Flyfisherman]

Fuel starvation

Paul

[ham204]

Fuel starvation

Paul

hmm - that's interesting.

[Flyfisherman]

Mario

Check the bottom of the float bowls for dirt / debris etc - this could reduce the quantity of fuel going to the jets, whilst on tick over its fine but when more fuel is requires it could be resticting the flow - assuming you have SU carbs.

Paul

[ham204]

Mario

Check the bottom of the float bowls for dirt / debris etc - this could reduce the quantity of fuel going to the jets, whilst on tick over its fine but when more fuel is requires it could be resticting the flow - assuming you have SU carbs.

Paul

Could this be the reason? The SU manual says that the gap should be 0.125 but it's more like 3/8 inches. The other one is only slighter better. No adjustment is possible so it seems that the wrong valve/float has been fitted.

[ham204]

Problem solved - PO fitted a washer which, once removed, let the float higher in the chamber. Will check whether this makes a difference to the 'chugging'

[soe8m]

That angle is not good of your float. The base has to be level or a tiny bit going up. I do sand a fiber washer to size to have the correct angle. Also the floatneedles come in sizes. A sprint does need the larger size. There are many parts in su's that look identical but are not and are easily mixed up.

Jeroen

[ham204]

Had the Sprint sent to a mechanic friend as I could not solve the severe tapping issue that it had. Within 30 minutes he phoned and said that problem solved - a shim had fallen out and led to the tapping noise! How the hell could that happen (the shim falling out I mean)? It never occurred to me to have a look around the cylinder head.