The V8 Owners Forum -

I'm looking at cams for my other engine i'm building.

Its a high comp 4.6 with tvr griff stage 4/5/whatever heads.

It will rev to 6500rpm and have all needed provisions to run big cams eg valve cut outs in the pistons, shortended guides etc.

I want to stay hydraulic and i want as much mid and top end power as poss, i don't care about down the bottom end so ong as it does actually run down there!

What do you reckon?

Most of the really big cams are solid. A good hydraulic cam that would fit the bill imo is the H234. I believe a version of this is used in the griff 500 engine so in your slightly smaller 4.6 it might be a tad peakier but nothing like as much to make it undrivable i would've thought. Dont forget though, a griff 500 weighs around 1000kgs. Your Capri probably weighs more like 1200kgs. The lighter your vehicle the easier it is to live with a lumpy cam. See if anyone on here is running an H234 or the slightly milder (but still strong) H224 and get their opinions. Beware of Ian S. though! he will lead down the "stuff the biggest cam you can in it" path, and you will forever be lost!!!!!!!!!

A 218 is a very good cam and it has plenty in the mid range.

Boosted.

How about the "stuff in the biggest cam you can think of but get it ground on a wider than normal LSA so it will idle" path? then you are really lost (you should try my Laverda!)
Mike

Anyway Gav can still use his left leg and shift gears, go on Gav stick a really silly cam in it, you have got fuel injection Haven't you? or is this the engine you are going to supercharge?
Mike

HairbearTE wrote:Most of the really big cams are solid. A good hydraulic cam that would fit the bill imo is the H234. I believe a version of this is used in the griff 500 engine so in your slightly smaller 4.6 it might be a tad peakier but nothing like as much to make it undrivable i would've thought. Dont forget though, a griff 500 weighs around 1000kgs. Your Capri probably weighs more like 1200kgs. The lighter your vehicle the easier it is to live with a lumpy cam. See if anyone on here is running an H234 or the slightly milder (but still strong) H224 and get their opinions. Beware of Ian S. though! he will lead down the "stuff the biggest cam you can in it" path, and you will forever be lost!!!!!!!!!

I love my totally stupid cam, Tom Wilkenshaw European touring car Grp A cam, Ticks over at 800rpm, makes good power, pulls from 1500 to 7000 in top, not very fast untill it comes on cam, but is flexable enough to do it, and if I keep it off cam on the motorway returns remarkable fuel consumption [70miles from full and top up again took £11.00] dont know why?? but it seems to be a superb compromise cam,

kiwicar wrote:Anyway Gav can still use his left leg and shift gears, go on Gav stick a really silly cam in it, you have got fuel injection Haven't you? or is this the engine you are going to supercharge?
Mike

mmmm i see gav is up to something here,
Best i get something planned for the winter

Whoa! Thats a lot of replies! I shall research the proposed options and see what seems to suit me best then!

I think its gotta be the rudest one i can get in there really eh!

I don't know Rover patterns by ref number but I would recommend
about 252 to 255 inlet duration at .05 inches lift on the inlet about 256 to 260 exhaust duration at .05 inches lift as much lift as you can get using a mechanical roller pattern and 110 to 112 LSA, if it is for a blower use the shorter durations here (252, 256) but with 114 deg LSA and stick in bigger exhaust valves than you would normally use with a given size of inlet. and have fun changing gear quickly.
Set up right a mechanical roller cam will only need tappet adjustment about every 6k to 8k miles and will be a real treat, on this LSA it should idle well and kick you in the back as it comes on power.
Mike

I ran a 234H Crane/Kent (same thing) in my 4.6 for a couple of years. I wouldn't consider it too peaky at all. What you have to remember is that what is considered a 'full race spec' cam when designed for and fitted to a 3.5L is much much milder in an engine with 1/3 more volume. In fact. I removed it from my motor because I considered it much too tame. Now have 248 mech which is also perfectly drivable, if a little bit flat below 2K. I made 265 RWHP from my 4.6L with 465 holley/edelbrock/stage3/10.5CR in my car with the 234 fitted.

Russ

Kiwi, roller cams aren't available for rovers i believe?

Russell, how ofter do you need to adjust yer tappets with your present cam? What are you using to adjust them? Adjustable pushrods or rockers?

Gav,

I only check the clearances once a year - it's a real pain in the ar*e on a V8. They don't really move much to be honest but then I don't do big mileages - say 3k max per year.

I have roller rockers and hollow pushrods now but used adjustable pushrods with Crane Hi-revs with the 234 because I hate the idea of pedestal shims - no real logic just seem a bodge to me.

Depending on how much you've had off the heads you might get away without valve reliefs with the 234 also - I didn't but then I've had 1.5mm off the head faces.

If it were me and it's not your daily driver then I'd be tempted to go as big as you dare - it's very easy to change to milder later if you don't like it - you only need the intake manifold and front cover off - but not easy to go bigger later (valve reliefs, valve springs etc).

Russ

Hi Gav
Its the old Buick v6 route! all the tuning stuff for this engine (and there is a skip load) can be adapted to the V8 (well not the heads.... before someone points it out to me ) Buick v6 roller tappets, Buick v6 roller grind on a v8 core etc. (buick v6 titanium valves!! )
If you go visit comp cams website, http://www.compcams.com/technical/CurrentCatalog/
they do custom grinds for virtually every american V6 and V8.
Good luck
Mike

So the roller tappets will fit into a rover block?

You can apparently use chevy roller lifters in the rover block, just dont use the late model oem type with "dog bone" tie bars. You will need the type with the tie bar mounted to the sides of the lifter (most aftermarket ones). To be honest Gav i was looking at this route myself but costs soon start piling up. Consider that the small base circle of the rover cam is not suited to the average roller profile. You need the bigger base circle because the extreme action (open/close rates etc.) of roller profiles demands much higher spring pressure to operate. Bigger base circles (and indeed slightly larger lifter wheels) reduce the mechanical stresses on the parts under the high spring pressures. Like i said i seriously looked into roller cams but in a rover its just not worth all the custom work invloved. The money is better spent on lighter rods, pistons, valvetrain and good efi to enable you to run a bonkers solid cam on the street.