20valve head

[Gaz]

Originally Posted by 20vcqdriver

The bore is slightly larger on a 7A 82.5mm compared to 81mm for the KV but the main issue is the pistons. The 7A pistons are as shown and completely different to the KV which has a small bowl. The 7A normally runs a 10.3:1 compression ratio so you will have a KV with 20v head and low compression and possibility of valves hitting the piston. Cheaper to get a whole 7A with larger capacity which it needs to compensate for the loss of torque at low revs.

what if i wanted to put a 20valve 7A head on my 2.5?

or could i just take a complete 7 A engine and fit my crank and pistons? and have some head work done to the 7A ? would that be any easier?