We recently took on a Jaguar E-Type with a problematic head gasket, experiencing normal faulty head gasket symptoms – white smoke and an over-pressurized cooling system. Overall, the car wears an older restoration, and comes equipped with a number of modifications, including power from a later-model XK engine punched out to 4.5-liters with forged pistons, hotter cams, and more.
Upon disassembly, it became apparent some questionable repairs were undertaken at some point in the past. Note the threaded insert.
So… earlier Jaguar engines utilized shorter head studs. Beginning with the 4.2-liter engines, longer studs were added, and threaded into the (stronger) base of the cooling jacket, while the shorter studs remained on the four front and rearmost studs. The problem with these long stud engines begins when corrosion in the cooling system occurs, which is almost inevitable in any older vehicle. This particular XK block had two broken studs, that had rusted to such a point, they lost their integrity. The engine builder’s fix, was to leave the remnants in the block, and add two shorter studs to the deck. Not a kosher fix, in my opinion.
Conveniently, Jaguar placed. a freeze plug at the base of each stud. Through this hole, we were able to file/grind the old stud flat and center punch it for drilling. The drill bits for this application are 12″ long, and we use a specially made drill guide (not pictured) to keep the drilling perpendicular.
All drilled out.
Extended Heli-Coil tapping and insertion tools are unavailable. So we make them.
Going in.
And, the new Heli-Coil.
All new ARP studs installed.
It turns out the heater block plug for later XK engines utilizes a British Leyland thread, and a suitable replacement is unavailable. We ended up making one out of chunk a of 6061 aluminum.
The modified head was resurfaced and received six new exhaust valves before reassembly.
Valve clearances were set on the work bench. So the head is ready to be torqued down before we double check the cam timing.
We also made a few changes to the Weber induction system, including a new fuel line with braided German hose and T-fitting borrowed from an Alfa 2600, as well as redesigned throttle return springs. More to follow on this project.