Unleaded Swap: Fitting New Barrels, Pistons & Unleaded-ready Replacement Heads on a VW Type 1

We had overhauled a 100% stock 1584cc Type 1 bottom end (re- machined surfaces/crank and fresh bearings throughout), hence we decided to top it off perfectly with new barrels, pistons and heads.

No engine overhaul is a cheap procedure, and when you’ve sunk a lot of time, effort and cash into the overhaul of a bottom end, it kinda makes sense to treat the top end to some love, too. Sure, it’s perfectly acceptable and possible to hone barrels and de-coke pistons/fit new rings and then have your heads chemically cleaned, fitted with new guides and valves etc but, to be perfectly honest, we didn’t have the time to sink into all that labour, and the price of buying new compared very favourably to paying the labour charges at an engineering shop!

We picked up an engine overhaul kit, which included a fresh set of Mahle 85.5mm barrels and pistons and a pair of very nice, fully assembled 040 1600cc cylinder heads with 35.5mm inlet and 32mm exhaust valves.

With a fresh set of pushrod tubes thrown into the deal, the fitting was easily tackled in a couple of hours – i.e. many hours were saved over the lengthy task of overhauling ageing cylinder heads!

Fitted to our overhauled bottom end, this motor should provide many years of reliable service now. Here’s our guide to installing the parts including the required torque settings etc.

Removed Heads, Barrels & Pistons From Old Block In this case, we had a freshly overhauled short block, however this is what you would be left with if you were upgrading a 1300 or overhauling a 1600 once the old heads/barrels/pistons are removed.

New Unleaded Ready Heads
 The heads we chose are brand new castings with new hardware (valves, springs etc) throughout. They are unleaded ready and will provide years of service!

The pistons were slipped back into the barrels ready to be installed

After everything had been cleaned/degreased, the pistons were slipped back into the barrels ready to be installed. A piston ring compressor makes it simple to slot the pistons home. 


We assembled all four like this – just far enough into the barrel to cover the rings whilst allowing to slide the gudgeon pin in. Note the arrow and size (85.45/1584cc) machined into the face of each piston.