Classic American cars

Gavin’s 351ci Small Block Ford Windsor for his superb AK Cobra Replica

Gavin had a hankering for a Cobra Replica and after much research went for an AK version. After looking around for a while he eventually found one in Rugby, a high quality car with mile deep silver paint and laquer with black leather interior.

The original builder of the car obtained his 351ci V8 Windsor and 5 speed manual gearbox direct from the USA, unfortunately it has never performed well and after several people tried to get it to run properly Gavin got in touch with Probuild American. It was obvious to us almost immediately that this engine has serious problems which can only be rectified by a complete strip down, examination and analysis of the parts. Work in progress.

Strip down of the 351ci Windsor is going well, numerous problems have shown themselves including definite overfueling, there is a strong smell of petrol in the engine oil. Unfortunately overfuelling is particularly bad for an engine that has not been ‘run in’, petrol bore wash takes all the lubrication away and this leaves piston and bore rubbing together giving rapid wear and heat build up. Luckily for us the bores and pistons are still in excellent condition, pistons will need a clean and the bores will be honed.

Big end and main shell show evidence of particles of metal in the oil system, some of it has become embedded in the soft layers of the shells and some particles have eaten the shell. The crankshaft should be ok with a clean and polish of the journals.

Two other problems are the balancer/damper and the flywheel, the balancer has been rubbing on the timing cover and has worn a small portion off the balancer and the flywheel has cracks in the face, both items will have to be replaced and that means all the reciprocating parts will have to be balanced again as a unit.
The camshaft is an old grind and is also worn on the lobes, almost no two lobes give the same lift, probably due to not being ‘broken’ in correctly when fitted but probably not a new unit fitted when the engine was rebuilt in the States.


Rust in the lifter valley and on pushrods and lifters indicate condensation in the engine, we know the engine stood for some considerable time and this has not helped things. One intake manifold gasket had failed blowing between the exhaust riser for inlet manifold warming and the adjacent intake port.

The rebuild begins with a thorough cleaning of all the parts, when that task is completed you can go on to test fitting of the crankshaft.

All of the reciprocating parts on this 351 Windsor have been balanced for 28oz balance by Real Steel in Uxbridge, to do a proper job of balancing an engine you need to balance the crankshaft, con rods, pistons, flywheel and bolts, clutch cover and bolts, front damper, front pulley and bolts and the lower timing chain sprocket and you need to know the weight of the rod bearings and the piston rings, all of this has been done on this engine.

Remember, if you change the crankshaft on any engine you should have it all balanced as no two crank’s are the same. A crank fitted that has not been balanced with the rest of the engine will wear out bearings very quickly due to vibration and harmonics.

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