Chris’s Fiat 850SC motor


This is a sad story of a ’71 FIAT 850 Sport (100GBC 903cc) motor build, a local country mechanic has put together some bits to make a motor without the care and attention this special build needed, dialling in the aftermarket camshaft would have been a good start, upon just kissing the piston with the exhaust valve for about 1000klms it finally made a noise misfired and the motor got its chance to be built properly!

In that short time (1000 klms only)the aftermarket oil pump ground itself to death, top compression rings stuck in pushing compression through to the sump, a lightly score to all big end journals and great wear to the rockers and big end bearings from lack of oil pressure, a massive amount of corrosion to the water ways and parts….besides driving badly with a peaky cam grind, it was gutless with the feeling of draging.

Update 12/2017- To carry on from November stripping and assessing the little motor for cause and damage , After being supplied the new valves and having the updated A112 head machined,was cleaned up and reassembled…….. Now to look at the Block!

Update 3/2018- Back onto this beauty…… All block parts striped away and put through the bath, Crank measured and cleaned ,lightly linished ready to fit in block .

Update 4/2018-  New Bearing shells checked for use on Crankshaft and Rods, supplied Camshaft , is now back to the original “Sport” grind and checked for scoring and bearing size, linished and cleaned crankshaft and camshaft ready for assembly!… Block degreased, scuffed back and cleaned with thinners for priming and painting, dry…..painted the block in Fiat Grey, whizzed up gasket surfaces ,blown dry and onto assembly, replaced piston rings after checking gap in bore and cleaned out the grooves to pistons, reassembly piston rings and push into bore , camshaft with replaced faced followers oiled and fitted, the new oil pump has chewed itself to death with lack of oil as the aftermarket pump has a pick-up too close to the bottom and then restricts flow and volume , replaced with a second hand factory original, but shaved housing to raise oil pressure and insure les bypass, now the fun bit…upgrade sump with a PBS 2pce alloy type!!……100GBC bottom end Complete!

ARP head stud kit in with Hylomar spray on the head gasket ,this motor has a good chance to be reliable now!…head back on and tensioned twice, linished rocker shaft and replaced chewed rockers, cleaned and tappets done ,Intake manifold/Rocker cover cleaned fitted as is Thermostat housing ,Flywheel and clutch kit .…..Finished!!!

Update 5/2018- Finished, packed and sent!!!






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