Standard cap head bolt to fit TVR Speed 6 engine. 14 per engine. Note the 2 doweled holes in the Speed 6 engine use the same bolt but with less thread. We do offer a longer bolt for these 2 positions to utilise the deeper threads that are normally left unused. The longer bolt TVR E6022 +10MM has to be cut to suit individual applications but does typically allow a further 7-8mm of thread to be used to maintain correct torque on cylinder head. This extra thread is important as cylinder 1 and 6 have slightly higher compression ratios due to the way TVR manufactured the standard cylinder head. In effect this means that the cylinders with the highest compression ratios have the weakest head bolt arrangement??