From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Cracking issues discovered in Goshawk cast iron cylinder heads.
| Identifier | WestWitteringFiles\I\June1922\ Scan38 | |
| Date | 28th June 1922 | |
| To H.{Arthur M. Hanbury - Head Complaints} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} ORIGINAL HsE/LG28.6.22. GOSHAWK CYLINDER HEAD. Further tests have proved that heads made in cast iron are liable to crack in the same manner as those made in semi-steel. 6-Goshawk-11 which has just returned from France, arrived here with a cracked cylinder head - this is the second head which has failed on this car. We have now had a total of 6 cracked heads on cars running on the road. Two on 4-G-11, two on 6-G-11, and two on 3-G-11. Of these cracked heads, all of them have had cracks round the exhaust valve seating. Four of them have had longitudinal cracks causing external leaks on the sparking plug side. One of them has had longitudinal cracks causing external leaks on the inlet and exhaust port side. The present head on 4-G-11, we do not know whether there are any external leaks at all. We have carried out several tests here and have at the present time four cylinder heads which we have boiled dry without cracking. We have changed these heads over to different engines and find that on any engine they can be boiled without cracking. On the other hand, we have taken two new cylinder heads and on the first tests, we have cracked them. The heads cracked before there was any apparent signs of shortage of water, although the car had been boiling in one case for 20 miles - in the other case 23 miles. In the first instance 2 1/2 galls. of water had been lost, and in the second case 3 galls. of water had been lost. We are now having several cylinder heads annealed and shall be testing them shortly. We feel that the cracks must be caused due to casting contd:- | ||