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I may be able to pick up some Maruha cams for my car although I had not originally planned on any engine modifications to my stock engine internals.

A few questions I am hoping some opinions on:

- Can I keep such an upgrade (new cams) relatively simple and without need to pull the engine to get a power bump?

- Are there some other key things I should do on the head if installing new cams?

- Any suggestions on a good shop in Melbourne that could do this work?

Please note I have an Megasquirt2 and ITBs already installed.

Treat the cam upgrade like an extended edition 100k service. The head will need to be pulled so look around at different head gasket thicknesses, consider ancilliaries like coolant reroutes etc and get it all done while things are easy.
Sounds like you're on your way already with itbs and ecu, the cams will help engine breathe but don't go too large a duration if it is a part time cruise mobile. Easy to go too large and never get to hit warranted revs to enjoy gains. 265-ish duration for a streeter, 272/288 if you spend time at track events.
Research the solid/hydrolic lifter options and shim measurement process as unless specific mx5 shop is used they might require input from you on specifics. Maruha site is good for info if you can 'transrate' it a little better.
Pity you're not up this way as it would be a nice x to work on.

As above, ECU tune etc sounds like you have sorted.

Cams (i'm assuming they're the mild cams, not the custom race ones) will work fine on an untouched head, but will be better with some work.
From what I understand, head work (on mild cams) will give you a little bit more peak power, but more importantly will allow you to have a broader powerband (ie: more power at less revs)

the more aggressive the cam, the more likely you need head work to let it breathe.



As far as install, if they're a hydro grind, then it's as simple as remove stock cams, plop in new ones and put the rocker cover back on.

If they're for solids, then you'll need to also buy suitable solid lifters, install cams, measure clearance, remove cams, buy/install shims/lash caps of the correct thickness, then reinstall cams, check clearance again, hope it's right, then put the rocker cover back etc.

Also, depending on cam specs, the head lifter bosses may need grinding to accommodate rotating cam lobes. Some do this in car, but care is required.

Thx for the quick replies everyone. Sounds promising that just installing cams may be of benefit and possibly not too much work??

The cams I am considering the Maruha 'F-cam set with pulley HLA adjusted'.

http://www.maruhamotors.co.jp/miata/par ... fornb.html

No idea if they are a 'hydro grind':(. But it appears that they create no clearance problems?

I believe they mean "hla adjusted" to be that the standard hydrolic lifters adjust the lash, and as hks suggested, be a straight drop in replacement. No head removing or setting solid lifter lash etc.
They have a reduced base circle diameter on both cams meaning the cam lobe diameter is smaller overall allowing a lift of over 9mm without the lobes interfering with head.
The difference between standard cam base circle 36mm and maruha cams smaller 33.6mm in' and 34.2mm ex' base circle diameters would be within the standard hydrolic lifters lash adjustment range.
Basically drop in without clearance issues or messing with lifters.
I have 9mm lift on the standard 36mm base circle lobe and they come close enough to trim the lifter bores of casting dags but maruha account for larger lift with their smaller diameter.
My wallet opened in expectation upon reading OP as I began thinking stronger valve springs, solids, Gates belts and adjustable cam gears etc.

HLA = Hydraulic Lash Adjuster

HLA Adjusted would just be Maruha's own strange or mistranslated way of saying they're suitable for use with HLAs, or Hydraulic Lash Adjusters.



Basically HLAs work by self setting the lash using oil pressure.
They have a hollow inner, which when the engine starts and oil pressure rises it pumps them up until they just touch the cam lightly.

Solid lifters by comparison are a single piece, and you need to add small shims to bring the gap to the correct spec (too tight and they wear the cam, too loose and the cam slams them and wears quickly)


There are pros and cons for both.
HLA are easy and low maintenance, and allow for simple cam changes. But at the expense of their ability to deal with aggressive cams.

Solids can deal with very aggressive cams, but at the expense of being a lot more fiddly to initially setup.



There's a bit more to it, but that's the basics.



(also worth noting the HLA tick is often caused by the HLA getting clogged with old oil/dirt, which means it doesn't pump up fully, or as fast as normal)

With a aftermarket ecu and quads, you are handicapping their potential if you put in basic cams that would work with the stock ecu and airbox.

project.r.racing wrote:With a aftermarket ecu and quads, you are handicapping their potential if you put in basic cams that would work with the stock ecu and airbox.

If I didn’t consider the Maruha cams what cams would you suggest (while still wanting to avoid doing a whole lot of other work)?

lucmor444 wrote:If I didn’t consider the Maruha cams what cams would you suggest

Custom regrinds.

talk to the grinder, tell them your goals, and they'll tell you if they have a grind to suit them.


If you're in Melb I know of 2 grinders.
One has done a fair few B6/BP engines.
the other I'm pretty sure they've done B6/BP stuff, but I mainly know them from their work on MGB racecars.


edit: 100% disclosure. I've not personally used either of their work, but I know a local business that uses the MG ones a lot, without issue.

hks_kansei wrote:

lucmor444 wrote:If I didn’t consider the Maruha cams what cams would you suggest

Custom regrinds.

talk to the grinder, tell them your goals, and they'll tell you if they have a grind to suit them.


If you're in Melb I know of 2 grinders.
One has done a fair few B6/BP engines.
the other I'm pretty sure they've done B6/BP stuff, but I mainly know them from their work on MGB racecars.


edit: 100% disclosure. I've not personally used either of their work, but I know a local business that uses the MG ones a lot, without issue.

Thx - are you able to advise who they are (via pm if you prefer)?

lucmor444 wrote:

project.r.racing wrote:With a aftermarket ecu and quads, you are handicapping their potential if you put in basic cams that would work with the stock ecu and airbox.

If I didn’t consider the Maruha cams what cams would you suggest (while still wanting to avoid doing a whole lot of other work)?

I didn't suggest not to use Maruha. I'd brought off them twice before.

But using a set of 250ish duration and 9mm-ish lift cams that work within the normal parameters of a stock engine and ecu. Then you are not getting the full potential from all your other mods. They offer more than the ones you exampled.

Thx for the clarification project.r.racing.

Think about whether its worth spending more than you think and getting less that you think you will. An old car thats fun to drive anyway and then add a lot of labour and it starts to look like burning a hole in the pocket. A sports exhaust makes the car go much faster- well thats what the ears say anyway. Good shops in Melb - yes there are but get proper estimates and then see whether its attractive.

Mr Morlock wrote:Think about whether its worth spending more than you think and getting less that you think you will. An old car thats fun to drive anyway and then add a lot of labour and it starts to look like burning a hole in the pocket. A sports exhaust makes the car go much faster- well thats what the ears say anyway. Good shops in Melb - yes there are but get proper estimates and then see whether its attractive.

Excellent thoughts. I will tread carefully and am not committed to anything. I think I am realistic in not expecting any significant power gains by what I may be considering so I may end up leaving things well alone.

The input of the more experienced is much appreciated and I am intending to remain realistic in both expectations and more importantly expenditure.