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Expert
Posts: 4458
  
Location: Jelling, Denmark | the current cam in my blue a-series is the Kent md296sp which has a duration of 290 degree inlet and 300 degree exhaust but this cam is worn out and I should probably change it. my trouble is then whether I should put in a cam exactly like it or try an other?
I kind of fancy trying the Piper METBP300 (316 degree inlet and exhaust) or the Kent MD310SP (310 degree inlet and exhaust), but I suspect that my cylinder head does not flow enough as the power in my current setup drops off very quickly at 7k rpm as can be seen in the dyno graph here:
http://www.skjulestedet.dk/bilogmc/metropower/20.05.14/rullefelt.jpg |
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Regular
Posts: 112
Location: Hamburg, Germany | did you had any problems with the current cam? not enough power or wrong power curve, like not enough torque to pull out of corners with low revs, or need more revs but the engine doesn't want to rev? need more than 7000 rpm?
changing the cam will demand to change/match anything else, too, like recurving the dizzy, other exhaust manifold.
don't count on cam degrees only, they only tell half of the story.
you may also look at the RE13PP cam, depending on your needs, sold here http://dt-vps.co.uk/calverst.com/cart/index.php?route=product/product&path=57&product_id=85
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Expert
Posts: 4458
Location: Jelling, Denmark | KLAS - 17/3/2016 7:37 PM
did you had any problems with the current cam? not enough power or wrong power curve, like not enough torque to pull out of corners with low revs, or need more revs but the engine doesn't want to rev? need more than 7000 rpm?
changing the cam will demand to change/match anything else, too, like recurving the dizzy, other exhaust manifold.
don't count on cam degrees only, they only tell half of the story.
you may also look at the RE13PP cam, depending on your needs, sold here http://dt-vps.co.uk/calverst.com/cart/index.php?route=product/product&path=57&product_id=85
not really any problems with the current cam no, other than that its worn out and that its a bit of a half assed cam, no low down grunt, and doesn't really rev that high, drops off massively at 7k rpm even though its supposed to rev to 8k rpm according to the specs, but perhaps that is a cylinder head related problem, I don't know.
I would like it to rev higher and have more power really. I don't want low end torque as it has a close-ratio box and a 4.133:1 gearing so it needs revs and I want revs 
A new cam of course means a new rolling road adjustment, I know. and I were planning on getting the rotating parts balanced this year. and since the compression is high enough to handle the longer duration, I think the only worry about fitting a cam with a longer duration is whether or not my cylinder head is the restriction right now, in which case a new cam with more duration wont make it rev any higher.
didn't know that cam you link to no. It sounds like a 280 degree cam like a rally cam. It sounds good. I know some of the other hill climbers use that sort of cams instead of race cams. |
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Elite Veteran
Posts: 925
Location: Thinking of vvc'ing my Roadster Brabus :-) | You could try Crane VP3C cam, 276deg inlet, 286deg ex, but with 490thou lift inlet and 510thou ex lift, This cam comes from the
same group of cams used by David Vizard 'A' Series tuning, he used a VP8C in his drag race Mini.
With the VP3C cam in my 1380 with a single 1 3/4" SU, dizzy ign curve, I got 125bhp. Cam came on song at @ 2500rpm up to 7500 rpm, (5000 usable rpm)
With a mappable ecu/inj, more hp would would be easily possible and better drivability/fuel economy. |
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Expert
Posts: 4458
Location: Jelling, Denmark | Dave 20VTRO - 18/3/2016 3:57 PM
You could try Crane VP3C cam, 276deg inlet, 286deg ex, but with 490thou lift inlet and 510thou ex lift, This cam comes from the
same group of cams used by David Vizard 'A' Series tuning, he used a VP8C in his drag race Mini.
With the VP3C cam in my 1380 with a single 1 3/4" SU, dizzy ign curve, I got 125bhp. Cam came on song at @ 2500rpm up to 7500 rpm, (5000 usable rpm)
With a mappable ecu/inj, more hp would would be easily possible and better drivability/fuel economy.
who sells these cams? do you know where I can read more about them?
125 bhp with the power band you talk about is very good for a cam of that duration, but it does have a lot of lift.
what head was on that engine and what compression was it running? |
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Elite Veteran
Posts: 925
Location: Thinking of vvc'ing my Roadster Brabus :-) | DotMatrix - 19/3/2016 10:08 PM
Dave 20VTRO - 18/3/2016 3:57 PM
You could try Crane VP3C cam, 276deg inlet, 286deg ex, but with 490thou lift inlet and 510thou ex lift, This cam comes from the
same group of cams used by David Vizard 'A' Series tuning, he used a VP8C in his drag race Mini.
With the VP3C cam in my 1380 with a single 1 3/4" SU, dizzy ign curve, I got 125bhp. Cam came on song at @ 2500rpm up to 7500 rpm, (5000 usable rpm)
With a mappable ecu/inj, more hp would would be easily possible and better drivability/fuel economy.
who sells these cams? do you know where I can read more about them?
125 bhp with the power band you talk about is very good for a cam of that duration, but it does have a lot of lift.
what head was on that engine and what compression was it running?
Iirc it was a MG'940' ported head with Rimflow valves, 'Iskey' double valve springs, 1.5:1 roller rockers, Chilled iron cam followers,
I think it was running about 11:1 CR, it was a long time ago (1992).
I bought the cam from Mike Parry of 'Race Technique' in Cheltenham, it was a billet cam, not a reprofiled one.
Mike spent about a year with David Vizard and learned a lot about cylinder head cumbustion processes, He set up a head porting
business mainly for motorbikes as he is now in a wheelchair, Back in the 90's, he developed a ign system for the Honda Motogp
bikes (I think) that added an extra 8bhp, so he knows his stuff. He had a VP8C cam like what Vizard had in his Mini, but it was
too hairy for what I wanted, (powerband from 4500 rpm). I dont know if he's still doing 'A' series porting etc. |
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Regular
Posts: 196
Location: Beds | I used to run the 296 and set the limiter at 7800, it had nothing below 3500 and 5000+ needed for starts but it is after all a race cam. One dyno reported 138HP.
That's with Dellorto 45, miglia spec head, large LCB, straight through exhaust.
The 310 is really fussy about inlet head, and exhaust...if everything is absolutely right it delivers more power but any one thing not quite spot on and it's got no more than the 296 and is peakier too.
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Expert
Posts: 4458
Location: Jelling, Denmark | 1380racer - 20/3/2016 10:50 PM
I used to run the 296 and set the limiter at 7800, it had nothing below 3500 and 5000+ needed for starts but it is after all a race cam. One dyno reported 138HP.
That's with Dellorto 45, miglia spec head, large LCB, straight through exhaust.
The 310 is really fussy about inlet head, and exhaust...if everything is absolutely right it delivers more power but any one thing not quite spot on and it's got no more than the 296 and is peakier too.
ok. well that tells me that I ought to be able to get more revs out of my engine with the same cam also as your 1380 and my engine has the same stroke length.
as far as I can read a miglia cylinderhead has standard mg metro size valves which is good as you produced good power using this size then I also ought to be able to as I am not allowed bigger valves either.
where did you buy your head?
my engine is the same with 3500 and 4500-5000 rpm but does not go on to 7800 rpm like yours. It seems like that the 310 is not the way to go, judging by your description. thank you for the info.
these posts makes me want to either get another 296 cam or something a bit milder but very near it. |
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Regular
Posts: 112
Location: Hamburg, Germany | DotMatrix - 21/3/2016 12:08 AM
these posts makes me want to either get another 296 cam or something a bit milder but very near it.
i would look at more modern cams, like the RE13, or what Swiftune has to offer, SW23T or such a like. not that the older designs like the Kent MD series is bad, but the newer ones usually have more usable power |
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Regular
Posts: 196
Location: Beds | Miglia heads run Cooper S valve sizes (not sure if that's the same). if your regs say standard valves then they were standard for a car that ran a transverse A series...even if it isn't your model.
The head I used was from MED though I believe their expert head grinder subsequently left and started up on his own. I believe it was 38x31 and used 1.5:1 roller tip rockers so had around 0.5" of valve lift. The bottom end could be turned over just holding the crank nose but with the valve gear on it took 20-25lb ft of effort!
Given that Miglias run 1293cc on standard (ish) valve sizes, on a cam design originating in the 1960's their mid-150's HP outputs are simply stunning. That's why they cost so many thousands of pounds!
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Expert
Posts: 4458
Location: Jelling, Denmark | I understand what you mean about a cam with less duration than the one I have now and a powerband of 2500-7500 revs, together with a more professionally modified head. But for now I will stick with the 296sp cam as I am running to high a compression to fit a cam with a shorter duration. So I have ordered a 296 blank.
I appreciate your help and for my next cylinder head I will run a lower compression, enabling me to run a bit milder cam. |
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cam choice
