Printable View
Garry is lucky in a way,, its a lot easier to get these things to make more KW/NM at higher revs,, its really hard to get more at 2600rpm,, and yes, on the highway 400 revs in top is a lot to overcome.
I have this fantasy about running defender TC gears,, that would bring 100kph at 2600rpm,, still with the ability to tow faster (not very often) but it would make the 80 - 100 range much less work.
hmmm.[bigwhistle]
Hi
Apparently LR used a few differtent factory cams, so it's hard to find an "original" spec.
I have compiled a list of mild cams below ad the crow 371771 looks like a good choice, especially given the feedback from here [thumbsupbig]
Steve
Cam Exhaust Duration Intake Duration Exhaust Lift Intake Lift crower 50229 260 258 0.446 0.43 Piper 285 278 278 0.445 0.445 Crow 371613 264 254 0.408 0.382 Crow 371771 262 258 0.405 0.395 Kent H180 262 262 0.44 0.44 CamTech CT37 262 260 0.399 0.399
hi guys,
thanks for the responses.
that chart is interesting - such a confusing topic, though.
i emailed camtech for their recommendation and the information provided seems to conflict with their website.
a cam of the same spec 274/274 (aside from lift, but one is quoted at 1.6 .472 and the other 1.5 .442 ratio - not sure how to calculate this) is described by email as "Smooth idle, enhances throttle response and low end torque. RPM RANGE 1400-4600" but on the website "Fair idle, strong mid range and top end. Recommended for modified engines. Min 9.5:1 comp ratio, 3.08 + diff ratio. RPM RANGE 2000-5500". very different!!
the crow website gives slightly different figures to those in the chart but perhaps the cam design has been updated.
i am wondering if perhaps the best thing might be to just get a stock cam from tr spares in sydney.
after all that, i found some factory specs here -
RR camshaft specs - The V8 Owners Forum -
and plugged the info from the scan into here -
Camshaft Technology and Calculations
which tells me the stock 4.6 cam is 264/264
10.57mm lift is 0.416"
seems very close to the stage one cams often suggested, and pretty much directly between camtech CT37509 and CT37524 any difference would be lost without a degreed crank sprocket?
perhaps therefore ER5250 may be the one.
according to the LR spec sheet and that calculator, the 4.0 cam works out to 285/285 but with 0.391" lift.
the email from camtech includes a chart specifically for 4.6 which suggests 274/274 with .472 lift is their mildest recommended cam. i had read the kent's lift at 0.44 was already at the limit for stock springs, etc?
confusing !
however, i have just noticed that despite having similar durations, the timing varies considerably across the cams... but i don't know what the implications of that are. even more confusion.
Quote:
Originally Posted by mpwdhc
Thats my info as well,, the reason I replaced them at build time.
G'day Guys,
When I did my 4.6 conversion of my D2 I fitted the Crow 371771 but was really unhappy with it. It made the car very sluggish and a 0-100 time of 19 sec [bigsad]. I rang Crow about it to ask if the cam had any advance or retard ground into it, and no. I mapped the cam out on a degree wheel to check proper timing and it was fine. One thing Crow said to me was "they work well in a 4.2 Commodore" so I'm thinking that the Crow cam is more a generic grind than Rover specific.
I was so unhappy with it I pulled it out and fitted a new stock 4.6 cam. Wow what a difference, back to what it should be 0-100 in 11 sec.
I still have the slightly used (about 1000km) Crow 371771 around but I didn't want to sell it on and make someone else unhappy.
I have heard that the Kent is the one to go for.
Anyway just my 2 cents worth, others may have had better results with the Crow than I did.
very interesting FisherX!
i suppose the next question relates to the quality of the cams sold by TR Spares (Syd)
Having just put one of these in my engine - this is something I didn't want to hear [bigsad].Quote:
Originally Posted by FisherX
Hmm I also spoke to Crow and confirm the 771 cam grind profile is common across a range of engines - he also said that the new cam has to be dialled in correctly (well I just followed the LR Cam installation instructions but apparently that is not good enough) and that the ECU will need reprogramming to take into account the new cam - well we know that the is not really an easy option for the Bosch Motronics ECU. I am going to use Megasquirt not the OEM ECU in my engine so I may not have this issue a I can tune the ECU accordingly - well supposedly if I can work it out.
Anyway the guy I spoke to is going to check with one of their client engine builders/tuners to see if they have issues and get back to me - but as usual the initial response is that we have never heard of this issue before.
Garry
General consensus is anything much above 0.43" at the valve may result in the retainer clouting the guide. It was around that in mine so I machined down the guide and seal area slightly for my higher lift cam. Springs are actually OK, you just run out of clearance there well before the springs would bind. Plus a"bigger" cam can overpower the stock springs...= floaty.Quote:
Originally Posted by Pedro_The_Swift