Cylinder Head / Valves

On Friday May 4th 2007, the final version of the “Merlin F85” heads were dyno tested. The heads were fitted to a 5 litre engine, which had been converted from a 3.9, using our 5litre stroker kit. The heads performed very well, we obtained 353ft lbs of torque. Also, the torque exceeds 321ft lbs between 2500 & 5500rpm. These figures were obtained using 10.5:1 compression, and our new “Tornado” camshaft, 224/231 degrees @ .050” lift, .508”/.512” lift. The cylinder heads are much stiffer than the standard Rover unit, which can distort easily, and the rocker gear is not very stable. Two extra rocker pedestals are supplied for each head. Rocker covers are supplied, complete with bolts. Valve guides are manganese bronze, and the valves are stainless (1.73 & 1.45”). The exhaust seats are very hard, and will withstand most fuels including LPG. As supplied, the heads are good for .520” lift. Use an PP-BYRC9YC spark plug to begin with. Exhaust ports are raised slightly. Regular inlet manifolds fit.
SMALL BATCHES MADE AT A TIME SO ALLWAYS A WAITING LIST. PLEASE ASK FOR AVAILABILITY

The modified guides have their tops shortened for a higher lift cam and have their noses modified for better gas flow.

Packet of Iske shims to go under the valve spring. 1.25”O.D. and .625” I.D. Contents- 16 of .010”: 16 of .015”: 16 of .020”: 16 of .030”

The fitted length for each cam varies, check the sheet supplied with each cam.

For Merlin Heads only

ARP

ARP Head Studs ensure more consistent torque values, enhance cylinder head sealing, and help prevent damage to the threads in the block. The kit comes with aerospace-quality hex nuts and parallel ground, hardened washers. Tensile strength of 190,000 psi. (14 per head) Torque 65 ft lbs using ARP Moly lube [BY100-9903].

The washers are machined from 4130 chrome moly steel, heat-treated and parallel ground. They will not bend or gall. The washers will promote accurate torque readings and more evenly distribute stress loadings. Also good for main bearing caps, rocker arm stands, etc. Note: washers are a must when using aluminium heads. Chamfered side of washer should be toward the head of the bolt.