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Collection, Preservation and Display of Old Lawn Mowers

1960's Atco 21" rotary

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Hi All,

New here, looking for info on Atco rotary, 1960's green/cream model. It has an Aspera (I think) 4 stroke engine and Dellorto

carb.

Picked up this mower a while ago, it looks to have done very little work and is complete and original. Started work on it as a lockdown project with my teenage son...but its giving me a headache!

Mechanically is good. no wear in the bore, electrically fine with a good spark. The carb has been stripped, ultrasonically cleaned and blown out with high pressure air more than once... but .. it wont run (well not as it should)

It will run for a few seconds if primed with fuel straight into the carb inlet, and, strangely it will run (flat out) if I cover the air inlet 90% with my hand.

- maybe that suggests an air leak but from where?

Any ideas anyone?

 

Forums

hortimech Wed, 13/05/2020

It is an Aspera LAV35 engine and I would peer very closely at the inlet manifold to engine block gasket, they were prone to leaking.

wristpin Wed, 13/05/2020

As per Hortimech's reply but the issue was not just the gasket, but also a warped flange on the manifold.The original gasket was very thick to insulate the manifold from the heat of the cylinder block but that gave rise to over tightening. Check with a straight edge and correct by rubbing over a sheet of abrasive on a true flat surface or even with a file initially in bad cases.
The carbs were just not supported enough hung out on that long manifold.