In our latest installment of the DIY Mini Restoration series, we dive into the intricate process of preparing and assembling the cylinder head for the Bogus 2 Mini build. Our goal is to provide you with a detailed guide to ensure your engine performs at its best. If you need technical advice or assistance, don't hesitate to contact our team at Mini Sport Ltd. Let's get started!
We began by preparing the 7-port head to Bogus 2 specifications. All 7-port heads are modified to customer requirements or can be purchased as raw castings for custom work. Safety gear is essential in the grinding area, which is sealed from the rest of the workshop. Our staff always wear a full-face mask and hood. Contact Mini Sport for your own custom requirements
We then flowed and ported the head with 37.7mm inlet valves and 31mm exhaust valves. All of our 7-port heads come with 31mm exhaust valves or larger. For reference, standard Rover 1275 valve head sizes are: inlet 35.58-35.71mm, exhaust 29.25-29.38mm.
When we screwed in the extra head stud by number-four cylinder, it felt tight. To prevent swarf from entering the bore, we masked the area off before running a tap to clear the stud thread. ARP studs, known for durability, feature an Allen key hole for easy installation and removal.
A BK450 (turbo-type or black top) head gasket is used for its durability in engines from 1275cc to 1400cc, especially under high temperatures and compression. This asbestos-free gasket fits both 9- and 11-stud heads.
The head is carefully lowered onto the block, locating on the 11 ARP head studs. The four thinner rocker post studs were all of the longer length, which didn't pose any issues.
We then used new 1275 pushrods. Always check previously-used pushrods for wear, as worn ends can affect engine tappets. New pushrods and followers can quieten an engine and enhance performance.
It was decided we should use Double valve springs, as specified by Kent Cams (VS2), matched to the valves and cam. The Spring rating is crucial and should be defined by your cam selection.
The spacers were placed under each rocker shaft post to reduce the load angle between rockers and valves, compensating for head and block machining. We checked the Valve lift after installing the rockers.
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Mini Sport 1.5:1 alloy roller rockers (Part No: MSLMS0480) are fitted to allow wider and longer valve openings. These are set up similarly to conventional rocker assemblies, with a valve clearance of 0.016 inches defined by the Kent 286 cam. The head is torqued down in a spiral pattern, bolts checked three times to 45lbf/ft.
A high-lift rocker cover is needed to clear the roller rockers. Mini Sport fits a cork gasket using spray glue to retain it on the rocker box. Avoid silicone gasket sealant as it can damage engines. Replace rocker cover grommets regularly to prevent oil leaks.
To prevent overheating in cylinders three and four, a blanking sleeve (Mini Sport part: 11G176) is fitted in place of the thermostat. If you have a bypass hose on your water pump, block it off as well.
A big-bore exhaust gasket (Mini Sport part: C-AHT381) is used, retaining the standard gasket setup. The gasket is finely trimmed to ensure maximum flow.
Contact us to find the perfect components for your Mini engine rebuild. Or use our Easy Parts Finder to identify the Mini Parts you need!
The water temperature sender supplied with the ETB Digi-Dash2-Lite was not tapered, causing it to foul against the head. Some iron was removed from the head casting to allow proper clearance and tightening. This requires precision to avoid damaging the water jacket.
For additional technical advice or help with your Mini restoration project, contact the Mini Sport team. We're here to assist you with expert guidance and top-quality products.
Explore our range of engine components and accessories to find everything you need for your build. Stay tuned for more detailed guides in our DIY Mini Restoration series!
Don't miss out on the rest of the Bogus 2 Series!
This blog series is your go to for a guide to taking your Mini from a bare shell to a road-worthy classic. Check out the rest of the series for tips and advice from our Mini Experts for every stage of your Mini restoration!
This guide is meant to provide general guidance and a step-by-step approach to restoring your Mini's Engine. It is always recommended to contact a trusted professional if you are unsure about any part of the process or lack the necessary tools and experience. Safety should be your top priority.