Alex

I have the correct 3 bolt long shaft oil pump for the 731. It was the oil pump for the MD266 which required that I drill an extra hole in the back of the block to mount it, if I were to use the MD266. I chose to stay with the 731 and not drill the block.

Having installed as many as six 731 cams over the years all ST not regrinds, I'm a fan. I suspect it depends on what you expect from the cam. I first installed one in a blue printed 1275 Cooper S in a stock class auto cross car. I guess that was 69/70 and the lifters on the 510 looked like they were shot with bird shot. Fresh rebuild new cam new lifters seemed like the right move to me. 10 to 1 CR, mildly ported head twin 1 1/4" SUs 3.65 CWP. I was more than pleased with the result. Was it a 643 NO, but I had no expectation of it being one. A few years back the SW5 was all the rage now it's coming out that when used with 1.5 rockers they kill lifters and cams. I'd say one of the best all round cams would be a 997 cam if offered in 1/2 inch lobe. The MG metro cam gives a good result. Being a combo of 731 and 997 specs what is it Vizard says suck it and see.

Steve

I ran a 731 in a 1275S motor back in the 60s, I found it was better than the stock cam- but even then, there were better aftermarket grinds available. Even in Australia...
BTW the 731 (or spider drive 800) was the cam fitted to Mk2 Cooper S used by the NSW Police in the late 70s. These also got a pair of HS4s, Ramflo foam filters, and some factory attention to the head porting. 

I remember getting a letter from Downton Eng. in the early 70s about my questions of use for the 731. To paraphrase, the answer was that they found no application for a 731 for which there wasn't a better cam.

If anyone is looking for a Kent 731 cam, I have one in excellent condition that I removed from a Cooper 998.  It is 3/8" lobe width and pin drive.  Stamping on end of cam is KC 731.   My email is in my profile.  Feel free to make an offer.  Pictures upon request.

Paul (mowog)

"the 731 profile cam, probably one of the most versatile profiles ever put out by B-L.  It will pull fair top-end RPM with usable revs round to about 72-7500, depending on your engine size.  What it costs at the bottom end is those few RPM you never use just past idle.  If you use the cam right and everything is set up properly, your engine should go, foot flat on the boards, from as little as 1500 RPM.  Mind you set it up wrong and it will be a pig, but there again, that applies to most things, although cams with less duration are not so fussy.  If you can't get a 731 to pull from 1500 revs, then chances are 9 time out of 10, you have done something wrong, so you have nobody to blame but yourself.  If you are going to use your vehicle for the road with the occasional bit of competition work, or even just solely for fast-road work, then the 731 or its equivalent in spider-drive is a hot favorite." - David Vizard from "How to Modify Your Mini" (page 76) [the C-AEA 800 is the 731 in spyder drive]

"970, 1071, 1275 c.c Engines

I have lumped all these engines together because basically one can consider them as being identical from a camshaft tuning aspect.  The 731 makes an excellent general purpouse camshaft" - Clive Trickey

There are two types of oil pump, small bore and large bore (other than the obvious pin, spider & spade drive options) - did you get the right one for your block ?

I agree with you. I've had this cam in my 1275 S engine forever. I recently removed the engine to freshened it up and I'm reinstalling it back it. I was going to install an MD266 cam but I would have to drill holes in the back of the block in order to match an oil pump so I chose to put the 731 back in instead.

Opinion on the 731 does appear to be very divided, with some loving them and some hating them - a bit like the SW5 I guess.

A couple of years ago I asked Uncle Dave about the abrupt change of mind between HTMYM and TBLASE and he basically said that it was great for small bore stuff but better cams were available for large bore.  I often wonder if an element of this was based on KC's declaration that only 30% of 731s were ground correctly...

I had one in a 998 Elf (that was thrown together and timed dot-to-dot) and it went like stink - must have been one of the good ones !

Here's what Vizard says about the 731 cam.

"The 731 cam has long been considered a 1/2 race cam, but it simply doesn't produce results in a 1275 motor ... I have foundthat the 731 cam really only comes into its own in 850s and 1000s and even then its not really a sparkling cam." Vizard quotes a unnamed 'well-known' engine builder as follows, "Install a 731 cam, lose all the bottom end power and gain almost nothing at the top end."

My first Cooper S which I bought in 1972 was alleged to have a 731 cam. To my untrained eye it went like a scalded rabbit, so my experience is contrary to what Vizard says.  

Thank you, that's exactly what I needed to know.

Full lift on #1 inlet 110 ATDC according to Vizard.

Does anybody know what the cam timing is for a 731 camshaft or where I can find it. Getting ready to time the cam and having a hard time finding what it should be timed at.

Thanks

Angel