‘ Swindon has engineered the conversion so it can be sold on the aftermarket’
Swindon Powertrain’ s four-valve heads are identical and are compatible with Porsche’ s late air-cooled flat-six
Like the factory set-up – only much more complex, sophisticated and elegant – the heads are linked together by a housing that contains the camshafts. Two singlepiece cam chests each span the three heads on either side of the engine; it’ s these that are topped with the delicatelooking cam covers.
A single shaft that runs through the cam chests is turned by a cam sprocket at the front of the head, just like the standard Porsche engine setup. A gear behind the front sprocket, but within the chest, turns the exhaust cam. Then a sprocket halfway along the exhaust cam spans across the head to mesh with another gear on the inlet cam. Relatively
A single-piece cam chest spans the triple heads on each side of Porsche’ s M64 engine
‘ Swindon has engineered the conversion so it can be sold on the aftermarket’
complex, maybe, but necessary to double up on valves and cams and contain them to a similar space.
Although the heads were initially destined for a specific car, Swindon has engineered the conversion so it can be sold on the aftermarket. The kit consists of six individual heads, two cam chests, two upper and two lower cam covers, four oil drain back tubes, two cam drive input shafts and gears, two inlet cams, two exhaust cams, 12 inlet valves, 12 exhaust valves and all of the valve springs, caps, collets, followers, shims and non-OEM seals and fixings you need to affix them to an M64 engine. That’ s the air-cooled flat-six you find in 964 and 993 Porsche 911s.
The kit doesn’ t come with pistons because the heads will work with a variety of different bore sizes, from 95mm to 102.7. Swindon does offer a set, but only for the largest bore size.
It would have been easier to engineer these high-rev capable heads to suit a custom intake and timing chain solution, and make them so big they’ d only be suitable for a modified 911 shell. All things a Porsche specialist could have facilitated on a small run of cars. But to make them desirable to anyone with an M64 air-cooled flat six, the heads had to work with as many factory and off-the-shelf components as possible. So, the heads fit a standard 964 and 993 generation 911’ s air-cooled cylinder barrels, using the same cam chain drive and covers, and lubrication system. Even the standard exhaust fits.
Spring 2026 The Engine Rebuilder 39