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Origins of 649, Sprint and Super Sprint cams ???
https://www.ausmini.com/forums/viewtopic.php?f=5&t=50912		 Page 1 of 1
Author:  mini7boy [ Fri Mar 06, 2009 8:11 am ]
Post subject:  Origins of 649, Sprint and Super Sprint cams ???
I believe that the 649, Sprint and Super Sprint cams were all designed by BMC personnel and probably in the 1960s, but does anyone know of any information to confirm or explain when these cams came out?

I have read Vizard's rather negative views on the Sprint and Super Sprint cams, but I would like to hear about any successful uses of these cams in race engines in the very early days of A-series racing or competition(probably in the 1960s).

I'd also like to know when 1.5 rockers(either roller or not) came into widespread usage. I know that Speedwell was the first or nearly so to produce 1.5 non-roller rockers, but I have also read that such rockers were poorly received when first offered and that the rockers went away for some years only to return to a successful sales run sometime later.

I realize that many of the users of this forum are probably not old enough to have been around when these cams and rockers were first available, but perhaps there are some oldtimers reading this who can comment.

Any information on these subjects would be most appreciated.
Author:  drmini in aust [ Fri Mar 06, 2009 8:18 am ]
Post subject: 
I was running a 1098 bored to 1220 roady motor with 544 cam and 12G940 head in the late 60s, most racers were using the 648/649. I don't think any 1.5 rockers were commonplace then, at least in Oz.
Author:  mini7boy [ Fri Mar 06, 2009 12:34 pm ]
Post subject: 
thanks, Doc,

part of the curiosity had to do with trying to convince someone else that the 649 cam was not deigned for use with 1.5 rockers because either the 649 preceded 1.5 rockers or the 1.5s were not in wide enough use when the 649 came out.

Maybe you could ask Graham Russell if he knows of the Sprint and Super Sprint cams, He has probably been around the A-series long enough long enough.
Author:  justminis [ Fri Mar 06, 2009 8:51 pm ]
Post subject: 
IIRC, Vizard was critical of the Sprint and Super Sprint cams because of their longer inlet duration compared to the exhaust duration. Said it wouldn't work and developed his Megadyne range of cams, ie 276, 286, 296 that all had approx 10* longer exhaust duration then the inlet duration.

Interestingly however, the other great cam he advocated for, the scatter cam, namely the SPVP4, had much shorter exhaust duration, 278* odd compared to around 305* on the inlet. I know the exhaust is closed early as part of the scatter design, but that is a fair bit early :shock: Was a great cam tho.
Author:  mini7boy [ Sat Mar 07, 2009 1:08 am ]
Post subject: 
justminis,

you remember correctly. Vizard even mentioned Kent grinding some experimental "reverse" cams which featured greater exhaust duration than intake.

The SPVP4 is a very popular cam in vintage racing in the U.S. Not at all the wildest racing cam Vizard/APT/Crane did, but it seems to be pretty flexible about the engine build and is not too fussy.
Author:  TK [ Fri Mar 13, 2009 10:23 am ]
Post subject: 
649 came from Formula Junior, I believe.
That is why they have a dry sump take off (?) Just looking at one that I have on the shelf.
Author:  mini7boy [ Fri Mar 13, 2009 10:58 am ]
Post subject: 
I am familiar with dry sumping, having raced a Formula Ford, but I'm not sure what you mean by a dry sump takeoff or how this could have anything to do with a cam. The 544 is generally described as a FJr cam, but I have never heard of the 649 being mentioned as for FJr. If a given cam, such as the 544, was designed for FJr, it was probably meant for 100cc engines as were used in FJr. Do you have some more information about the 649 vis-a-vis dry sumping? I can easily imagine the inline FJr engines being dry-sumped, but not the Minis. This last sentence is a bit off-topic since there's nothing to suggest that the 649 was designed for either the inline or transverse applications exclusively, nor could I imagine how any cam could be designed to only work in one application or the other.

Do you mean that your 649 has some sort of adaptation, not found on other 649s, that is meant to drive an external dry sump pump? Most of the A-series dry sump pumps are driven off of the front pulley in my experience, but I'm willing to learn something new.
Author:  drmini in aust [ Fri Mar 13, 2009 11:46 am ]
Post subject: 
Factory 649 has a skew gear where the fuel pump eccentric would be on other Mini cams.
It was used to drive the sump scavenge pump. On north/south engines only, I would suggest.
Author:  TK [ Fri Mar 13, 2009 2:10 pm ]
Post subject: 
as Doc said.

PS. the 649 that I have is Genuine BMC and not a copy or regrind.
Author:  TheMiniMan [ Fri Mar 13, 2009 2:46 pm ]
Post subject: 
That "2nd gear" was also used to drive cable opperated rev counters (Tacos) ,,, Hhhmmm yum,,, i might make some Tacos tonight for dinner :-)
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