driversdomainuk 8 Posted April 3, 2006 Hi Finally decided to bin the idea of an Mi16 engine for my 205 as I have spend quite a bit on getting the original 8V sorted in to a reliable state. However, there are still a few things need sorting: 1) New cam 2) Bottom end rebuild (which you will know from previous postings) Questions: 1) Don't really want to fork out for new cam and bottom end rebuild at the same time - so which should I do first (i reckon on new bottom end to start - but does it really matter?) 2) Type of cam - Would a Piper BP300 be too mad, although I am running 45 webers and is used for hillclimbs mainly. Cheers Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 3, 2006 ok, to make things easy what shall I do first - bottom rebuild or cam?? Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 3, 2006 BP300 is as i am sure you know a 300 degree jobbie! Share this post Link to post Share on other sites
veloce200 3 Posted April 3, 2006 forged pistons? or cast. I would also consider CatCams. Their profiles are measured at .1mm or 1mm rather than Piper or Kent which vary their measuring point buy usually .2mm. Part number 4900343 looks like a good bet. very similar overall - I'm assuming the piper is measure at .2mm. CatCam has more lift which is what you need on this engine. Same LCA at 106 deg which would probably work well with more than 11.5:1 compression. Cheaper than Kent and Piper. PM me if you want a price, recently a dealer courtesy of Mattsav. Share this post Link to post Share on other sites
Anthony 1,000 Posted April 4, 2006 I'd personally rebuild and uprate as required the bottom end so that you know it's going to handle the power and abuse safely. "To finish first, first you've got to finish" and all that.... Share this post Link to post Share on other sites
petert 554 Posted April 4, 2006 Part number 4900343 looks like a good bet. Way too much lift for the standard springs. You'll get spring bind. The 4900342 (very similar to the Grp A cam) is a better idea, unless you're forking out the big dollars for double springs, spring bases, retainers etc. In fact, Catcams recommend doubles for that one too. I thought spring bind occured at 0.460", so you'd need to check! You'll still need 11:1 minimum CR however. Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 4, 2006 Way too much lift for the standard springs. You'll get spring bind. The 4900342 (very similar to the Grp A cam) is a better idea, unless you're forking out the big dollars for double springs, spring bases, retainers etc. In fact, Catcams recommend doubles for that one too. I thought spring bind occured at 0.460", so you'd need to check! You'll still need 11:1 minimum CR however. Should have said, I would be getting the cam kit with springs included..if I am going to have to shell out more with increasing CR I may forget it and just buy a mild kent cam and be done with it!! Share this post Link to post Share on other sites
veloce200 3 Posted April 4, 2006 Should have said, I would be getting the cam kit with springs included..if I am going to have to shell out more with increasing CR I may forget it and just buy a mild kent cam and be done with it!! No point getting the milder versions of kent as the std one is pretty hot! If you are planning on changing springs then you've got to take the head off so a skim is easy and cheap. You'd be better of in all respects with std cam and a skim than an uprated cam and no skim. Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 5, 2006 already had the head skimmed last year Share this post Link to post Share on other sites
Mattsav 1 Posted April 6, 2006 If you doing hillclimbs then you need a decent powerband which your not going to get with a 300deg cam. 4900342 gives a nice wide powerband and is ideal for your application. When it comes to cams less is often more. 5bhp extra at peak power is worthless if you lose a big chunk of mid range torque. Share this post Link to post Share on other sites
hengti 2 Posted April 6, 2006 I'd personally rebuild and uprate as required the bottom end so that you know it's going to handle the power and abuse safely. "To finish first, first you've got to finish" and all that.... agree w/that presumably you'll be revving higher with the cam; it'd be a shame if the bottom end let go as a result and trashed everything before you got round to rebuilding it! Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 6, 2006 I have been told a rally cam is ideal for hill climbs..... Would this be worth considering? Share this post Link to post Share on other sites
Guest Chris Astley Motorsport Posted April 22, 2006 Personally i would go for a piper 285 or kent PT22 if you want something a bit more driveable and arent gonna rebuild the bottom end! If you want something a bit bigger then choose the piper 300 you mentioned or a kent PT27. If your interested i could supply you with either in kit form? Chris Share this post Link to post Share on other sites
TB_205GTI 1 Posted April 23, 2006 I have been told a rally cam is ideal for hill climbs..... Would this be worth considering? Maybe.. "Rally cam" doesn't say anything about the duration and the lift, so maybe it will Share this post Link to post Share on other sites
Guest Chris Astley Motorsport Posted April 23, 2006 The piper 300 is a rally cam Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 26, 2006 I have already had my head skimmed 3k ago - this was as I had the HG replaced. Would this be classed as a skim good enough to increase the CR (I have no idea how much they took off) How could I check the current CR..?? Share this post Link to post Share on other sites
Dom9 2 Posted April 26, 2006 They probably didn't take enough off the head face to get your CR up to the required level... Only real way to check it now is to measure the size of the combustion chamber with a burette and some fluid... Then doing the calcs with the HG thickness, cylinder volume and piston bowl volume etc... Share this post Link to post Share on other sites
petert 554 Posted April 26, 2006 How could I check the current CR..?? Give it a compression check. If you haven't got 240+ psi with the current cam I doubt you've got enough for a big one. You can also measure the height of the head against either a std. head, or one that has been milled a known amount. Share this post Link to post Share on other sites
driversdomainuk 8 Posted April 26, 2006 ok, so what would happen if I fitted a BP300 cam with current CR (if its normal) Share this post Link to post Share on other sites
veloce200 3 Posted April 26, 2006 ok, so what would happen if I fitted a BP300 cam with current CR (if its normal) rubbish bottom end, poor fuel consumption, poor specific torque - generally probably not a good idea Share this post Link to post Share on other sites
