What to look out for when regrinding cams...

[RAd28]

Hey all,

Uni is finished, and now it's time to get back into playing with cars. High on the list of things to do is a freshen up for my 18RG, so started pulling things apart etc etc... now i decided reground cams wouldn't be such a bad thing. What i wanna knows is... Is there any traps for new players in the reground cam game? As mentioned it's the 18RG with underbucket shims, but i don't know if that's gonna make much of a difference. i'm looking to make a quick streetable car, with aspirations of motorkhanas and hill climbs etc...

any advice is good advice...


cheers


and yes i've searched...

[thechuckster]

I'd suggest talking to Tighe (spell?) Cams - they'd have a good idea of what works.

[RAd28]

yeah, shot them an e-mail a while back, and their price is pretty scary... it was $650 to weld and grind the 18RG cams... but i was thinking they may be able to explain why theirs are so much more expensive...

[oldcorollas]

it's a lot of effort and time to weld the cams properly.... heating, welding, cooling, maybe heat treating after welding... adn then they have to grind them.

maybe the cost of some warranty failures are included in the price

[TERRA Operative]

You're also paying for the 30-something years of experience in making cams too.....

Tighe make some awesome cams. We got a heap custom made up for the Mazda 323 SP20 to our specifications, and a batch got sent to the states.
That batch is now a rather sought after grind by the US 323 boys apparently. People are selling them 2nd hand for more than the original sale price.

[SuperDave]

Yep, Tighe know there stuff.

Kelford Cams are in NZ if you want to see what they want to charge for some work.

[thechuckster]

custom cams will always be pricey - given that Tighe have done a lot of work on 18RG's in the past, see if they have an off-the-shelf item (exchange?) that suits your requirements.

Also, get an engine builder/workshop to order it for you, they probably get a better deal with trade prices.

[RAd28]

OC - yeah, the heat treating bit was part of what i'm looking for... just wondering if one mob do it, and another don't...

TERRA - I'm aware of how long Tighe have been around, my old man used to get cams from them along time ago, but i've heard about other guys doing them alot cheaper, ($30/lobe in one case)... so i'll find out what's the differences in the process...

SuperDave - I believe there's Kelford Kams (not Cams) on the gold coast somewhere... they're a spin off company from Kelford Cams i believe..

Chuckster - I'll have to chase that up... Toyhead auto list exchange cams for about US$130 which is alot more appealing (then again, take into account postage, exchange rate etc and maybe not so...)

Thanks for the advice...

[timbosaurus]

How dodgy is just a straight grind (not welded up), and then using larger shims?

Straight regrinds are usually under $100.

[RAd28]

yeah, that's the debate i was having with OC the other night... i can't see anything wrong with it, but i have no personal experience on the topic... i'm assuming that OEM cams are induction hardened etc, how much penetration does that hardening effect go? if you machine off Xmm will that adversely affect the hardness too much? i wonder if it'd be worth checking...


anyone got a shit cam they'd be willing to donate for the sake of science?

[timbosaurus]

well it happens plenty on pushrod cams like the k motors and 18R... where you just grind the cam for ~$90 then adjust the rocker arms to suit.

But I dont know if that is considered dodge?

[RAd28]

who cares what it's "considered"... i want to know if it acctually has any notable affect...

[w810sc]

How dodgy is just a straight grind (not welded up), and then using larger shims?

Straight regrinds are usually under $100.

The cams I'm using are a straight re-grind. They are very tough and durable. I snapped the woodruff key on the idle/dummy cam when my head ran dry. This was caused by a loose bolt that secured the sprocket that drives the cams.

As long as there is good lubrication on the cam and clearances are right, there shouldn't be any problem.

[jeffro ra28]

Unless your turning massive RPM there is very little chance your valvetrain will become any more unstabble with ground cams and thicker shims providing you have springs up to the task and good valves and guides.

If you have a selection of cams measure the base circle diameters of them all and choose the cams with the largest base circle. I cant remember which cam castings had the larger base circle but they are all different. It would be best to start with the cams that have the largest base circle. With a stock cam ground to about 250 duration at .050" with .430" lift you will require shims in the region of 4-5mm. These can be custom ordered from www.precisionshims.com.au
A set of custom shims from these guys will set you back about $150

Welding and grinding is the proper way and will be expensive.

[timbosaurus]

Well, that sounds like it's relatively acceptable

Whether you weld and grind, or simply grind, you are going to need to reshim the valves anyways. It's just the thickness of the shims is going to be a lot smaller with the weld/grind. So you'd be looking at around $200 for the cams to be reground, versus $650 for weld/regrinds, and (going by jeffro's post) another $150 for the shims either way.

That brings about another question... how much duration could you get out of a stock regrind? Could you successfully grind them to 272's? how bout 288?