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| Joined: | 10-22-2015 |
| Location: | Maplewood, Minnesota USA |
| Posts: | 36 |
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Steve,
The very early 907 Mk I intake ports were 24.5 mm tall. Later, they were increased to 25.5 mm as a running change. At the time of the change, the production of the small port head ended and the large port head became the official standard service replacement. Sorry, but no, I don't know the date or engine number of the port change, but I do believe it was within the life span of the Jensen-Healey's 907 Mk II engine.
Tim (or anyone else who knows 907's really well),
When I was at Lotusbits today, Mike showed me stock Jensen Healey and early Lotus 907 heads side by side. The Lotus heads had substantially larger intake ports (a lot more than the 1mm increase mentioned above). The Lotus and J-H heads had the EXACT same part number cast into the head, and Mike thought some later J-H's may have come with the Lotus head, as supplies of the J-H head ran out. Since it appears Lotus changed the port design without changing the part #, it sounds like the large port heads would be legal for me to run. Can anyone else confirm this? The larger port Lotus heads flow better, which would be useful.
Last edited on 11-27-2015 12:27 am by stevegarnjobst