7MGTE cams - when to and when not to replace the stock bump sticks?

[MorGo]

BTW the last 7M-GTE head I ported make 550hp/1,2 bar.HKS 272 cams and big turbo and so on.. Why only 1,2 bar just because the automatic box;with hard box somewhere near 2 bar.. :-)
In highway you just wait someone to pass.. wastegate straight under the car is too noisy to my ear but still;it is cool to scream past the trucks and buses..

[tig321]

I'm thinking again about a set of cams, nothing crazy mostly just something with more duration and a little more lift. I'd like regrinds due mostly to cost but the hang up of course is making up what's lost when ground. I've seen the lash cap option and of course thicker shims but I've come across a couple others, and I'm wondering if any of you might have some input.

One alternate option was done by Jens lyn on his 6mge with ITB'S. He welded a small amount of metal inside the caps where it contacts the valve then milled it down. He might have used shimless buckets, I'm not sure, those pics are down and I haven't had a response to my pm as of yet.

The other I read in an old post by suprarich on supramania (SIP Racing) He said he has used makeup shims under the bucket so standard shims could be used up top.

Any thoughts on these methods? I like the Idea of welding under the caps as it would add very little weight,without lash caps or shims to come off, just wondering about distortion and I assume it would be hardened material and may crack?

http://www.celicasupra.com/forums/sh...light=jens+lyn

[boxh34d]

Yeah, still figuring out (well, Andrew really) how best to make up base circle reduction due to grinds with a 7M. Since my turbo upgrade is progressing, I should be able to play with cams shortly.

That 6M / 7M hybrid was sure a lot of work! The machine time on the pistons alone would be mind blowing.
Interesting use of the beemer throttles though.

[oldeskewltoy]

get the cams hardwelded, and then ground to size... The last thing you want to do is drop a valve or seriously damage the engine because of some band-aid solution.

[andrew_mx83]

Hey lee sorry ive been a bit slack with doing the prototypes for the shim under setup, ill get on it for you mate

[tig321]

Shim under set would be nice. I welded one of the caps today to see how much it would distort...too much, not worth the trouble. Will likely just do lash caps, used on many engines, some from the factory. I read one guy posting how he regularly hits 8500rpm in his vauxhaul (racing) In another post some time later he said he missed a shift, hit 10500 and broke 2 springs. The valves still had the lash caps on them. Somehow that makes me feel better.
I'm not building a racing engine, won't see redline frequently. I just want to see what a set of mild performance cams and a modern turbo will do for me. If it doesn't work out, Oh well, fiddling around with cars is just a hobby.

[boxh34d]

Hey lee sorry ive been a bit slack with doing the prototypes for the shim under setup, ill get on it for you mate

Andrew, don't stress about it. Still nowhere near ready for that yet and so I'm in no hurry for the parts. I reckon I'll be down your way sat 16th, so I might catch up with you then if you're free.

[amichie]

How much are the regrinds versus buying new cams? My BC264 cams were only about $600 aud and all clearances were within about 2 thou compared to the stock toyota cams.

[andrew_mx83]

Sounds good lee, txt me a few days before to remind me and ill put some time aside.

Amichie, grinding is about $11/lobe, pretty cheap. Then there is the range of profiles available rather then being stuck with "stage 1" etc

I figured welding the buckets would be no good and they are indeed hardened on the tit underneath. In moments of desperation i have ground these down a whisker if i didnt have a shim thin enough. Note there is also some variance in the thickness of the 7m buckets without a shim installed as well.
Tig321, Let me know if you are interested in a shim under setup, im aiming to have them under $500/set with shims. They will be factory toyota shimless buckets modified to take a captive titanium shim underneath. I feel this option is much safer than lash caps as there is a lot more meat holding the shim in place plus it will lock in with thermal expansion as soon as the engine is upto temp.

[boxh34d]

How much are the regrinds versus buying new cams? My BC264 cams were only about $600 aud and all clearances were within about 2 thou compared to the stock toyota cams.

Amichie, grinding is about $11/lobe, pretty cheap. Then there is the range of profiles available rather then being stuck with "stage 1" etc

Yeah, as Andrew said, grinding is quite cheap, and means that you can select a profile for your needs / goals rather than only having the choice of the 3 standard grinds that most aftermarket companies do.
Of course you're limited by the lobe size with how much you can grind off, and of course, then you have to make up the reduction in base circle somehow. This could be cheap, or really expensive.

I really didn't like the specs from the easily available cam suppliers, so went with grinds. I'm not an expert (far from it), and they obviously work for people, but I feel that they are far too generic, and not at all tailored to a specific build or requirement. A solution made for 75% of people will obviously work well for those, but not so well for the other 25%.
Of the profiles I was interested in, there was only a couple of advertised manufacturers that had something close, and they were all hardweld and ground, and around $1200 a set, plus freight taxes etc. There may be options out there, but I couldn't find them so went with straight regrinds due to availability and price.

[dnegative]

Get the lobes built up with hardfacing and grind them to whatever you want?

[amichie]

The other dissadvantage with regrinds is the lift rate is going to be lower because the lobe is smaller. Max lift rate occurs when the cam pushes on the outer edge of the bucket.