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104 Camshafts For The 907 Engine

by Greg Fletcher

Performance camshafts, why would you want a pair for your car? More power, it's A Good Thing. There's nothing wrong with the vintage 140 HP stock 907 engine- it was the cat's meow in the 1970's. But if want to keep up on the road these days with the Bimmers and Lexus' you'll need more pep in your step and 104 performance camshafts will help get you there.

The cams, of course, use lobes that push against the valves (through cam followers) to open them as the camshaft rotates. The spring on the valves return them to their closed postion after the lobe has rotated. Cam shafts can have huge effect of how the engine runs and performs. Standard cams and performance cams vary the engine valve timing in different ways. Typically a performance cam will have much more overlap and may tend to run roughly dedending on engine design. Valve lift is quite important here as we will want the valves to open wider at higher speeds (as the engine goes faster and moves the air fuel mixture faster). A fixed cam, like in our Jensen (opposed to an electronically controlled variable cam in a modern car) needs to do it's job over a wide RPM range so it's important you find some the right cam that will feel right for the kind of driving you do. Performance cams would normally give better power a higher RPM rates.

I was recently corresponding with Jensen Healey owner Garry Kemp in the UK about camshafts and what would be the a good choice for 2.2 907 conversion for street use. I'm a bit cautious about too much cam, so I can appreciate many opinions on this topic. Garry is quite knowledable able about 907 engines in general and on rebuilding 2.2 and even 2.4 liter conversions. Here’s what he had to say about it-

"Personally I think the 104 is quite a good cam: not particularly in a 2.0L and especially a low compression engine but if they are in a 2.2L with decent compression (10:1+) they are perfectly easy to get along with. I have seen in the states a bit of confusion about what a 104 exactly is: it should be 272 degrees (at 10thou lash) and 0.415" lift. I think there may be a few reprofiles around purporting to be a 104 but really are just something "close enough". The 107 is a good all rounder but it does tend to run out of breath around 5500rpm : It'll pull up to 7000rpm OK but really its starting to lose its edge after 5500 (in a 2.2 anyway). The 104 however will pull clean and strong to 7000 rpm, it comes alive at about 3-4000 rpm but that's not to say there's nothing below that, it'll tick over just fine at 900rpm and is totally docile to use in traffic. It depends what you're looking for really but I wouldn't discount the 104."

Garry Kemp




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