Keith Warren Posted November 8, 2011 Report Share Posted November 8, 2011 Help or advice I have converted my CP 150 to EFI system with a single butterfly system from EFI Conversions, although the system works well I have had problems at low speed, it snatches below around 1500, Dave from Emerald says it's down to the single butterfly and the profile of the standard camshaft, overlap of 70 degree, I was looking at the ones on offer from Piper (fast road) Kent (high torque or Moss (road 83) all have more lift slightly less duration and a lot less overlap, looking at the profiles I would like one between the 125 and the 150 cam. Has anyone tried any of the above or got experience of camshafts? Thanks for any help Keith Quote Link to post Share on other sites
Tom Fremont Posted November 8, 2011 Report Share Posted November 8, 2011 (edited) Can't help you Keith , but must say I'm surprised that the EFI would have trouble with the P.I. cam . I've got one with triple Webers that behaves sublimely at all speeds and loads . I also have a 0.504" lift 292 duration ( 82 degrees overlap ) cam on Webers and got it set up with great difficulty , so I know that " too much cam " can occur - I just didn't think the P.I. cam fits into that category. FWIW, snatching is attributed to excess fuel ( per John Passini's Weber guide ). Edited November 8, 2011 by Tom Fremont Quote Link to post Share on other sites
rpurchon Posted November 8, 2011 Report Share Posted November 8, 2011 Help or advice I have converted my CP 150 to EFI system with a single butterfly system from EFI Conversions, although the system works well I have had problems at low speed, it snatches below around 1500, Dave from Emerald says it's down to the single butterfly and the profile of the standard camshaft, overlap of 70 degree, I was looking at the ones on offer from Piper (fast road) Kent (high torque or Moss (road 83) all have more lift slightly less duration and a lot less overlap, looking at the profiles I would like one between the 125 and the 150 cam. Has anyone tried any of the above or got experience of camshafts? Thanks for any help Keith if you want a cam inbetween the 125/150 you want one from a mk1 2.5 pi saloon exactly in between.part no 308788 i had newman cams make me one but i asked for 260" cam lift instead of the original 238" the car drives nice,good at low revs pulls from a 1000rpm up to 5500rpm where i have rev limiter set. timing 25 65 65 25. cam lift .238 duration 270. overlap 50 richard Quote Link to post Share on other sites
Nick Jones Posted November 8, 2011 Report Share Posted November 8, 2011 I have two Triumph 6s with EFI (Megasquirt MSII ECU) on plenum manifolds. A 2L Vitesse with a homemade inlet and a 2.5 PI saloon with the original throttle bodies and plenum but with the throttles removed and a single TB at the plenum inlet. Both run the 308788 cam mentioned above in its original, lower lift form as their original factory fit. This is a very good general purpose cam, but won't give quite as much mid-range or top end power as the CP cam. Both cars will pull smoothly from 1000 rpm or less. The Vitesse tops out at about 6K now, the PI has not been on a RR. It is true that plenum type inlets can be fussy at idle/low rpm when used with "big" cams. However, I'd not really think that the CP cam would qualify. What certainly is true is that is a tricky area to map for best driving manners, as acceleration enrichment seems especially critical here, and a nice throttle action with a quadrant to slow the motion near the closed position makes a big difference. What is also true is that the ignition timing in this area also makes a big difference. The engine will accept loads of advance at low rpm and high vacuum (low load) and give strong torque as a consequence - which actually makes it difficult or impossible to drive smoothly. Less advance works much better. Was the mapping of this area done on the road or rolling road? I've found best results come from doing it on the road and I've spent alot of time on it as it has a such a big impact of the driveability of a car in everyday use. Nick Quote Link to post Share on other sites
Keith Warren Posted November 9, 2011 Author Report Share Posted November 9, 2011 Nick / Richard Thanks for the replys regarding the cams, I was thinking about the 2.5 PI cam Chris Whitor grinds one to have more lift, it was set up on the rolling road, James from EFI Conversions tried setting it up at Harrogate this year but when I rebuilt the engine I fitted a light weight spider flywheel, so was impossible to set up, as soon as I got home changed back to standard and could see an improvement, but take your point about setting up on the road, that's problem two. Last week went out in it when I got back could detect a misfire, removing the rocker cover found one of the roller rocker tips had broke off with the roller, pin and a small section of alloy missing, so engine front off now and cam removed. Thanks for now Keith / Quote Link to post Share on other sites
rpurchon Posted November 9, 2011 Report Share Posted November 9, 2011 Nick / Richard Thanks for the replys regarding the cams, I was thinking about the 2.5 PI cam Chris Whitor grinds one to have more lift, it was set up on the rolling road, James from EFI Conversions tried setting it up at Harrogate this year but when I rebuilt the engine I fitted a light weight spider flywheel, so was impossible to set up, as soon as I got home changed back to standard and could see an improvement, but take your point about setting up on the road, that's problem two. Last week went out in it when I got back could detect a misfire, removing the rocker cover found one of the roller rocker tips had broke off with the roller, pin and a small section of alloy missing, so engine front off now and cam removed. Thanks for now Keith / the chris wittor ones are regrinds.newmans are new and were £10 cheaper. richard Quote Link to post Share on other sites
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