21-11-2018, 03:31 PM
I fitted a HC head to my Ruby - this head is reputed to be the best all-round in the development of the ideal head, but you could get a similar increase in compression ratio on a later LC head by "wedging" this (5-degree angle). I have had this done on one and it will be fitted on my Swallow saloon engine shortly.
I can't honestly say that changing from a LC to HC was really that noticeable, ok, the changeover was part of an engine re-build and I didn't drive the car for several months whilst this was all in progress so I may have forgotten what it was like before.
However, the one modification that did make a really noticeable difference (to me) was the fitting of flatter tappet blocks - the valves open & close quicker, which mean they are open longer, giving a better charge and evacuation, that really helped performance, the engine has a purposeful grunt (so it seems to me!), the engine is noisy under load (always was), but once cruising speed is reached, the engine is quieter as less revs seem to be required at any given speed. Going up hills is not the trepidation it once was!
Fitting the tappet blocks requires the tappet guides to be cut down (in the tappet chamber) as after grinding they end-up being slightly shorter than before and there is insufficient space to adjust the tappet gap before fouling the guides. Simple enough to cut down (Austin helpfully provided a guide line to cut...!), but it will be necessary to whip the block off to do this, a methodical approach to removing, cutting and re-fitting each individual guide meant I was doing each one in 20 minutes, so the whole operation, could be done in a day, but two is better, particularly, if you are using a silicone gasket for the joint between the crankcase & block to allow this to settle over night before giving the nuts the final tighten.
I can't honestly say that changing from a LC to HC was really that noticeable, ok, the changeover was part of an engine re-build and I didn't drive the car for several months whilst this was all in progress so I may have forgotten what it was like before.
However, the one modification that did make a really noticeable difference (to me) was the fitting of flatter tappet blocks - the valves open & close quicker, which mean they are open longer, giving a better charge and evacuation, that really helped performance, the engine has a purposeful grunt (so it seems to me!), the engine is noisy under load (always was), but once cruising speed is reached, the engine is quieter as less revs seem to be required at any given speed. Going up hills is not the trepidation it once was!
Fitting the tappet blocks requires the tappet guides to be cut down (in the tappet chamber) as after grinding they end-up being slightly shorter than before and there is insufficient space to adjust the tappet gap before fouling the guides. Simple enough to cut down (Austin helpfully provided a guide line to cut...!), but it will be necessary to whip the block off to do this, a methodical approach to removing, cutting and re-fitting each individual guide meant I was doing each one in 20 minutes, so the whole operation, could be done in a day, but two is better, particularly, if you are using a silicone gasket for the joint between the crankcase & block to allow this to settle over night before giving the nuts the final tighten.