wise idea to put new cam and rockers in ???

[ross2009]

hi guys
ive nearly built my new lump bottom end is complete going to be a turbo lump
now on to the head im going to have the valve guides done as there a little sloppy and its going to have the water ways welded but while the head is stripped would it be a wise idea to stick a new standard cam and rockers in as i dont know how many miles its done and on the journals there are some nice lines on it ?
whats your thoughts on this ??
thanks

[StuBeeDoo]

Not fitting new would be false economy, particularly as they are a b17ch to change with the head on the block and in the car.

I thought turbos need different cam profiles/timing/duration to standard??

[ross2009]

yeah true standard cams work pretty well with a turbo as i aint having no head work done they still should be pretty matched

[DmcL]

standard cam with gradually retarding ignition timing and gradually increasing fuelling would do the trick. ofcourse thats just summing it all up but in a nutshell thats all there is to it.

tbh unless there is 1mm or more of wear on the cam lobes i wouldnt bother replacing, just set the rockers to the correct tolerance (0.25mm or 0.30mm with engine stone cold) and off u go.

[ross2009]

yeah thats the debatable thing do i use the old one i know a couple of the rockers are worn so may have to replace some of them but still i dont know weather to spend all that money doing it

[DmcL]

if the cam hasnt got like 1mm+ of wear on it id re-use the cam tbh. if the rocker are wearing probably a good idea to replace them. i did all 12 on mine after i broke 2 early last year, been singing up to 7000rpm ever since without any issues. i had some cam wear and replaced it for one with much less wear, maybe 0.5mm at most on the lobes..

could even regrind yours?

[Dave_M3]

Where did you get your rockers Dan?

As all 12 are pricey!
One broke on that engine I mentioned but I'm worried if more would break soon after.

[ross2009]

Well I know from BMW the rockers are are about 20 quid a piece from gsf there 10.50 plus vat so still sort of pricey
So would the cam be ok with the bad lines in the journals??
Does anyone know what sizes the lobes should be ?

[HairyScreech]

depending on how bad your cam is iv got a few here that may be better, infact 4 to be exact, from the cracked porting test heads.

[ross2009]

i dont know what the lobes should measure i mean theres no visable steps on the lobes they look fine i think its just the score marks on the journals that concerns me or is that not really a thing to worry about ?
thanks screech ill keep that in mind

[e30_Turbo]

If you don't have any shoulders on the lobes, unless your rockers are really wide, you should be ok. I've seen both come out of similar mileage M20's.

PPF Z45 is the turbo cam of choice, although more are using N/A 272/288 or even higher for top end power! I and many others used the stock cam to good effect, it'll work and you can upgrade when the time comes.

[ross2009]

as you know mark i aint building it for out and out power
so what ya think of the lines on the journals mark you think theyll be alright?

[e30_Turbo]

You'd need a opinion from someone more in the know really, I've built a few heads but only with parts I've been assured are ok from people that know. The guys that do my machining make race engines for a living and I take what they say as gospel, they do go on about how flimsy the M20 head is though, every time, by the way, they're not to far from you either

I would imagine the journals need to be true, without missing metal or cracks, so any marks in there would need to be checked over.

Who's doing the welding on the head? Welders or mechanic/Garage?

[DmcL]

Where did you get your rockers Dan?

As all 12 are pricey!
One broke on that engine I mentioned but I'm worried if more would break soon after.

i got them from bobby at border motor works in strabane. they arent genuine BMW ones but they are holding up to all the abuse i give them so on that basis id recommend them to anyone haha.

i think they were £12 a peice if memmory serves.

[ross2009]

Ok mark I'll prob take my cam down to our engine builders here and see what they say about it
My dads mate is gonna do the head welding as he's a clever bugger and he's only charging me 70 quid bargain I think considering a normal shop would charge ya about 300

Dan are they febi ones like gsf and euro car parts sell ??

[DmcL]

that at me or is there another dan in here

couldnt tell u what make the rocker are that i got for £12 a rocker. seem to be holding up fine tho.

[ross2009]

Sorry dan yeah that was to you ok I still don't know what to do I'll get the head welded and go from there

[e30_Turbo]

Good plan

If you're dad's mate wants to earn another £70, I have a head here ripe for some welding, that's one thing I've not had done yet, mainly due to cost.

Hopefully your cam is ok and you can start bolting it all up very soon.

[ross2009]

I hope so mark I can always ask him I know he's abit of a clever sod with a welder
I can't wait mate bottom ends complete now so as soon as the heads done it will go bk in I'm gonna have a wrestle putting my new LSD diff in this weekend
Can wait to get it on the rd

[e30_Turbo]

Just receiving your email.

[HairyScreech]

one thought i did have is if the cam journals are really ballsed its possible to machine ~2mm of the journals and then fit a 2mm bronze bush into the hole in the head.

effectively creating a slightly smaller brand new journal that runs in a bronze bushing in the head.

[ross2009]

hmmmm thats a good idea
but then wouldnt it just be easier to maybe get another cam of some one like ya self

[HairyScreech]

yeah, its always possible to find a new used cam, but theres always the potential of the journals being as bad as the cam.

its something in the future that will become more of an issue as good heads and cams become less common.

[ross2009]

where abouts are you in the country screech ?

[HairyScreech]

im down wiltshire way, near the somerset boarder.

[ross2009]

thats abit to far to come and have a little look at them

[HairyScreech]

yep, but i can check them over, take pictures so you can take a look, think iv got two a bit ballsed and two that are fine.

[ross2009]

yeah if ya could mate that would be great how much would u want for one ?

[HairyScreech]

will happily exchange a good one for any of the following to continue the 2.8 work.

a cracked m20 head 885/325i head

a set of m20 2.5 pistons.

a set of m40 318 pistons and rods

a set of 318is pistons and rods

any performance camshaft living or dead from alpina/shrick/catcams etc to measure up.
(living ones can be returned if packed well)

ported or alpina head for testing (also can be returned)

ford cologne v6 group 1 valves live or dead.

[ross2009]

Ok well I've got 4 sets of pistons low comp and high comp for a m20 2 heads don't think there cracked thou
So yeah that would be cool

[e30_Turbo]

I've got some high comp ones going, no use to me.

@ Ross, I'll take that set of low comp ones buddy, can make up a spare engine, got spare crank, bottom end, rods, head, cam, inlet etc anyway.

P.s. Got my MOT this morning! WOOHOO!

[ross2009]

Lol ok mark you go buddy
Hope it passes I've already got my old diff out ready for my new poly bushes LSD