Cost of CAMs

[project.r.racing]

Maruha F-cams for NA8 , HLA friendly, new and not regrinds. new tappets not required, $840 delivered to my door.

yeah, but shame they don't make them for na6....

drop a BP into your engine bay, that'll solve the problem.

have you tried Yahoo Japan and eBay USA?

[NitroDann]

Hey Mate.
Yeah i am another one bothering you

Just wondering your thoughts on requiring lash caps for a B6?
Do you need these with Hydraulic Lifters?
Camtech have told me to run there Stage 2, basically 265Deg cams, i will need lash caps.

Does this sound right to you?

I can not seem to find a great deal on MX5/Miatas and Lash Caps.

I know you are running solid lifters, how much would i be looking at to do that?
Would that negate the need for Lash Caps?
Again, Sorry if these are dumb questions.

If you have a minute to explain, it would be much appreciated.

Thanks
Name withheld.

PS- AWESOME write up on E85 and tuning.

I just recieved this PM from Dweezle yesterday. I decided as the answer would answer a few questions here I would type it up here for peoples.



Ok so heres a generic picture of a lobe with the parts labelled.

Ill first explain what is done when regrinding a cam.

What we want when we are after bigger cams is greater lift, and greater duration, with possibly a great ramp rate (definately if we go to a solid lifter).

Firstly we can see the base circe (heel) is the non lifting part of the cam, the lifter runs along this part but its only there so that the lifter isnt free airing then suddenly gets smashed by a cam lobe. The nose is where the action happens.
Essentially the entire nose area outside of the base circle is very much like the are under the curve, the bigger this is the more air/fuel is let in and the more power we make. If the nose is taller it will lift the valve open more, this is more lift. If its wider rather than pointier it will have a greater duration. The next image shows what a billet big angry cam would look like (exagerated to make the differences obvious).



Lets start with lift, lift is the Lobe Lift minus base circle RADIUS. you can obviously see that it isnt measured from the centre of the base circle to the tip of the nose. Its the DIFFERENCE between the top and the bottom.

Next is duration, we can see that my new lines start further down the sides of the cam, this is obviously the exact instance the cam starts to lift the valve and the exact moment it closes the valve.

Remember that the cam moves half as fast as the crankshaft, this is because this is a 4 stroke engine. this cam above, lets say its the intake cam, only needs to open once per 2 revolutions so its dríven at half the crankshaft speed. So for this reason the measured duration is doubled.
Eg, the above cam seems to have a duration around 150 degrees, but the crankshaftmoves twice as fast as the cam, so from the crankshafts perspective its open for 300 degrees. So this is a 300 degree cam. (BIG!)

Now we can look at ramp rates, see how my redrawn cam here has a 'wider' nose, obviously it opens the valve much faster and harder than the first cam, this is called ramp rate. if it had the same ramp rate as before it would have a pointier top, and would be open at maximum lift for a shorter duration of time.

The stock hydraulic lifters cant handle a big ramp rate, they work exactly like a shock absorber and a big ramp rate it like hitting big bumps hundreds of times a second, they 'pump down', which means that they move away from the lifter totally by maybe 1 mm or more. thos in effect reduces the lift height and destroys the valvetrain pretty fast.
This is why we go to solids, we can use a bigger ramp rate, get maximum lift for longer, and the whole time the valve is open it will be open slightly more, 5% average more over that time is 5% more power, period.

Now lets look at a regrind



You can see that the base circle has been ground down, and a lift is Lobe Lift MINUS Base circle RADIUS, the total lift has been increased, we can also see that it now has a nice wide top, compared to the original cam. This is where the welding comes into it. Mind you; you can easily use your imagination to see how the duration and ramp rate can be changed simply by removing more base circle.

Ok heres the lash caps bit...

There is no way to move the cam closer to the lifter (the lifter is directly below it 8 one thousandths of an inch away), so with the base circle radius smaller there is now a gap, so to close this gap we have to shim the lifter closer. Solid lifters dont self adjust like hydralics do (hydralics just push out further like a shock absorber) so we have to add a shim to increase their height, they dont adjust at all they are solid.
But when we remove so much material to make a huge cam the factory hydraulic lifters just cant adjust up that much, so we use a lash cap. it sits on top f the lifter and takes up that 1 or 2 mm that have been ground off. Just as a solid lifter has shims, so can hydraulics.

Dann

[geofiz]

Dann,

Excellent write up. Keep sharing the knowledge.

[PaulF]

So I'm guessing the main advantage of a regrind as opposed to brand new cams is that it's cheaper. What are the disadvantages of going for a regrind? I presume that if you buy new cams you're not likely to need solid lifters or shims/lash caps?

[Dweezle]

Got this back from crow cams.

"We don't have castings or grinds for this motor..try Clive Cams "

Guess they do not do anything for us 1600ers..

[NitroDann]

The advantage is that they can make them to just drop in.

But really if your gonna do cams do it properly. Go solid lifters. A properly designed solid lifter cam grind with the EXACT same rpm band and driveability and idle will always make much more power than a hydro cam.

Lash caps are 2 minutes extra work when changing cams. Actually less id say.

Dann

[gslender]

Spoke to ... MaruhaMotorsCo in Japan

Thank you so much for your email.
Unfortunately, NA6(B6) camshafts are re-grind type.
This sales way is Trade-in base.

Then we need your returning of the stock camshafts.
But this is not easy from oversea's customers.

So we don't accept any orders on B6 cams from overseas
customers now.
We are very sorry for this inconvenience.

Fail again !!

[NitroDann]

Easy, there are some stock cams for 100 dollars on the site right now, send them first.

Dann

[Dweezle]

Now who on earth would want a 1.8???
We all know 1598cc is the exact right amount :-D

[Matty]

So I'm guessing the main advantage of a regrind as opposed to brand new cams is that it's cheaper. What are the disadvantages of going for a regrind? I presume that if you buy new cams you're not likely to need solid lifters or shims/lash caps?

Yeah, the problem with a regrind is you are reducing the base circle, which means either the HLAs have to expand more (maybe more than they are physically capable of) or you have to add shims or spacers, which is another potential failure point (if it's a shim on top the cam could flick it out).

The other issue is that the smaller your base circle, the more side load you put on the lifter as the cam rotates. This increases its wear.

on the flipside, a new billet cam with the same base circle will be larger overall, so will need more space inside the head to fit (so you might need to remove material from the head) and may need a larger lifter diameter or it could hit the edge of the lifter.

[NitroDann]

On a B series, over caps and mushroom head (wider head) lifters are not possible with a big cam. Possibly you could machine the lifter bore to a larger diametre, but that really doesnt help the people with questions here, they are unlikely to touch that with a 10 foot pole.

Also shim over buckets arent possible with the hydraulic lifters. All factory Solid lifter B series engines (for the uninitiated, many have solids stock) are shim over type. My worked head has shim overs, as does my 10,000rpm AE86. Shim overs are only a problem in engines with too little spring pressure/too much valvetrain weight/poorly designed cam for the head geometry.
Mind you the shim unders ARE better. But for the truly hardcore (how my next one will be) you go to a shim under with a longer valve so it doesnt need a shim, then you get the actual lifters theemselves ground down so the clearance is right. Zero risk of failure even at stupid stupid RPM, and on top of that, this is the lightest possible setup.

Dann

[noobee]

re: cost of cams
last set I bought was $100,(80 for regrind + 20 for nitriding)for a 1600 datto so comparable to danns single pulsar cam,
whats the difference?.......over 25 years,lol.
Then that was about one third of a weeks wage for a machinist(me).nowadays,the pulsar cam is less than one eighth so regrinds are getting cheaper!
A good new cam was then a weeks wage,now around half a weeks wage for 2 cams,so even cheaper(relatively).
as an aside,we used to do occasional mild regrinds here in our toolroom on a small cylindrical grinder(base circle only and shoulder blend,no cam grinding machines here) with good results and only a couple of screwupsfrom overgrinding(we put them in the bin,not in the cars).
a book called Tuning For Speed by Phil Irving(one of Australias great engineers,and when alive a genuinely nice bloke)
has good explanations,its an oldie but a goodie,should be required reading for anyone who wants to start playing with engines.
Mick

[project.r.racing]

A good new cam was then a weeks wage,now around half a weeks wage for 2 cams,so even cheaper(relatively).

I wish my wage was $1600-$2500 per week so I could claim that!

[zoomzoom]

I have had Crow cams for the B6 in my car for about 3-4 years now. At the time they were available through crow ground onto brand new blanks that were available from mazda. I don't know if they are no longer available or the guy that got a quote from there earlier in this thread got quoted BP by accident, which does not have blanks available.

Cheers,

Tim

[gslender]

I have had Crow cams for the B6 in my car for about 3-4 years now. At the time they were available through crow ground onto brand new blanks that were available from mazda. I don't know if they are no longer available or the guy that got a quote from there earlier in this thread got quoted BP by accident, which does not have blanks available.

Cheers,

Tim

I think you are right. Crow Cams list on their website new performance cams for B6-ZE engine for ~$300 per cam bank.

I'll contact them and confirm specs and price.

G