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evo 8 cams prep discussion (with pictures)

DR1665

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Oct 19, 2005
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I'm posting this here because modifying cams for use in a vehicle other than the factory intended isn't something you do every day. Additionally, my research into this project suggests it's fairly simple to do, although there are all manner of opinions on the subject and minimal imagery to help the more visually-inclined among us to fully wrap our brains around what we're doing. I want to make sure other people have the confidence to try this, as I certainly don't have a whole lot, given the mish-mash of opinion and speculation found on the web up to this point. I will be updating this thread as I proceed, which might take a couple months overall.

To clarify: This thread is about how to modify Evo 8 cams for installation in a GVR4/DSM in the same orientation as they were designed for the Evo - NOT backwards, as some people have done. That is, if you've seen pictures of Evo cams with (2) slots cut for the CAS, that's someone running the Evo EXHAUST cam in place of the DSM INTAKE cam. This thread is about modifying the Evo 8 cams to be installed in a GVR4/DSM in their engineered INTAKE/EXHAUST capacities.

Note: These initial pictures are meant to illustrate the extent of modification necessary and prompt discussion of options for measuring/indexing for machine work. The comments along the way represent my thoughts AT THAT TIME, which I hope will help others understand how I came to finally figure this one out. (Getting tired of people who are experts in telling others WHAT to do, but can't explain WHY you do it that way. Let's crack this nut and empower people to not only explain how to do this mod, but understand the theory behind it so they might apply the knowledge to other cams/platforms.)

INTAKE: (L) Evo 8, (R) GVR4 - CAS-SIDE
Cutting the CAS slot doesn't look to be too complicated, although there doesn't appear to be a quick/easy reference point for the slot. In this picture, the cams are resting on the #4 lobes, so they are more-or-less "indexed," but notice the GVR4 CAS slot is *almost* perpendicular to the #4 lobes. Shouldn't be too hard to get it close enough.


INTAKE: (L) Evo 8, (R) GVR4 - TBELT SIDE
Again, cams are "indexed" on the bench. Looks like the cam gear dowel pin is advanced 15-ish degrees. I am still trying to decide if I would prefer to relocate the dowel pin on the Evo cams, relocate the hole in the GVR4/DSM cam gears, or simply re-mark the gears when I degree-in the cams at final installation. Thoughts?


EXHAUST: (L) Evo 8, (R) GVR4 - CAS-SIDE
As expected, the Evo exhaust cam has the CAS slot cut in it. No modification is needed here as far as I can tell.


EXHAUST: (L) Evo 8, (R) GVR4 - TBELT SIDE
Again, cams are "indexed" on the bench and it looks like the dowel pin is off by 15-ish degrees.


BASIC COMPARISON SHOT: (L) INTAKE, (R) EXHAUST
Evo cams have the bolts in them. Notice how the cams look almost identical side-by-side. You can also see how the dowel pins are off between the two sets.


SURPRISE: CLEARANCE ISSUE ON INTAKE SIDE
This might just be me, but there is a casting mark on the Evo intake cam which comes into contact with the head (the protrusion closest to the camera), preventing full rotation. Should be an easy fix with a Dremel (with extensive precaution taken to collect shavings - I've done this before), but it's worth mentioning, as I've not read about this elsewhere.

Note: Lifters/rockers removed, cams generously lubricated with Lucas assembly lube (sticky, slippery green stuff), cam caps tapped flat, but only finger tight. This is an experiment to see how markings line up. (Also, Jesus, I need to chase some threads...)


OBLIGATORY SHOT OF 195/2000 "IN-PROGRESS"
My plan is to get the engine assembled, refurb/replace the wire harness for it while it's on the stand, and get it ready to go back in the car before I put the engine bay back together (it's completely stripped at the moment). I'm hoping to have 195 back together in time to break it again in March at a rallyx.


As you can see, I bolted-up the GVR4 cam gears to the Evo cams as-is just to play around. I went into this process looking to see how things lined-up right out of the box. With both dowels pointing up, the GVR4 marks line up and the cams even look like they might work, but I know it's not right.

Appreciate any feedback on how the more seasoned engine builders would go about measuring the Evo cams for modification. What would you use as reference points - for the dowels, the CAS slot? Would you re-locate the dowels, the dowel holes in he GVR4 gears, or just re-mark the gears?

I picked up these cams for $40 shipped cross-country. I know they aren't likely to deliver the sort of gains from a 264/272/FP3X/Piper setup, but I don't think people should have to feel their only options for cams in an old GVR4/DSM are the $300-$500 grinds everyone and their brother are running. Let's keep this discussion on-topic.

Thanks. More info and pictures as I progress.
 
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toybreaker

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Apr 30, 2006
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Cool project /ubbthreads/images/graemlins/applause.gif

Brian, I'm thinking the easiest way to re-index things on the cam gear end is going to be to re-drill the cam gears.

I'll have to check and see if there's enough meat to be able to use offset inserts, but it *might* be possible to provide a limited amount of advance/retard with offset bushing inserts.

An easier solution would be to use aftermarket adjustables after they are redrilled with the correct clocking.


Note that the gear pilots fairly tightly on the nose of the cam, so a jig would be a handy thing to have to insure dimensional/clocking accuracy.

A suitable jig can be made on a lathe and then precision drilled with the two locations. A dowell can be pressed into the original clocking, and the then you can thru drill adapter an into the gear in the new location accurately.

Also, before you get too deep into this, let's make up a set of solid lifters so we can get accurate lift/duration numbers for each cam set.

If you can give me a couple of days, I'll see what I can do on that end.

It'll give us the capability to get the centerlines of both cam sets down, and make the proccess repeatable for others following in your footsteps.





p.s. your garage is way the fawk too clean right now

... sh*t aint natural

Please take a pic of where you piled everything so things feel more to home /ubbthreads/images/graemlins/devil.gif




edit any locals have an evo cam set available so I can spec out a few things?
 
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DynastyLCD

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May 12, 2006
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Harwinton, CT
food for thought: click

i have the same gears, looks to be a quarter turn difference between the locations of the dowel pins.

question: could you simply run above cam gears, on the evo dowel pin hole, with the DSM timing marks?
 

jepherz

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KC, Missouri
I will say that I've tried to machine the cam gears for a miata, which appear to be made out of the same brittle powder casting as the 4g63 cams. I have also seen the cam gears pretty easily shattered by using a hammer at junk yards. Machining them was basically impossible to do correctly as they were so hard and brittle. The material wants to crack rather than actually cut. Just keep that in mind if you are trying to drill them. If you are going the route of modifying the gears, you may have better luck just re-marking them via a file.
 
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DR1665

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Thanks for the all the feedback, gents.

@John - The garage is a veritable crime scene most of the time, but I did do a little cleaning weekend before last. Had to make room for the mini fridge I got for Christmas and clear some space on the bench to do some wire work in the near future. /ubbthreads/images/graemlins/wink.gif

The Fidanza gears Phil (DynastyLCD) linked are a pretty solid deal. Under $200 for the set, and it looks like they come drilled for both Evo/DSM, which would be super convenient over all, but I would really like to come up with an easily repeatable process for those who want/have to stick with the stock gears. I'll gladly trade the 5-6hp I'd get from a set of adjustable gears if means I help others pick up 10-12 with a cheap cam mod.

I really, REALLY like the idea of the jig. I have the facilities to get such a thing made. To confirm, you're suggesting something which mates to the end of the Evo cams like the factory gears, but with (2) dowel holes in it. The Evo cam would be bolted into the jig, indexed via original dowel, then you'd just drill through the jig with a specified bit to a specified depth, swap/replace the dowel, and be done with it, yeah?

Maybe we make such a thing here in Phoenix, source/mark the proper drill bit, and make it available for anyone who needs it. They do this with the "Liquid Nitrogen Freeze Death Ray" over on Rally Anarchy. Whomever uses it hangs onto it until someone else needs it. They cover shipping to the next user. It's an honor system. In this case, it would be awesome to have someone send a kit in the mail, clamp it in a vice, chuck up the drill bit, and knock it out in a half hour.

If you can send a set of solid lifters my way, I'll make sure to get speccies on these things at the shop. Might need a little instruction on doing so, but we're going to be hosting some disadvantaged local kids at the shop on Thursday nights starting pretty soon, so I'll be at the shop weekly to work on this stuff.

I will also make a post on AZAWD to see if anyone local has a spare set of stock Ebo gears we can borrow for a spell. Good call.

@Phil - It does look like those gears are drilled for the Evos as well. Could you check with Fidanza/XPSI and get us some answers, sir?

@Jeff - Good call on the gears. I might have a spare set somewhere to play with somewhere in my unnaturally clean garage. Last thing any of us want is compromised cam gears under tension spinning at 3000rpm!

Thanks again, guys! Feels good to make some progress and help others out.
 

desant78

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Jun 23, 2010
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Clarksboro, NJ
Keep up the effort its great to see this get done.

How about, as a food for thought idea, create a jig for the actual cam gear? Assuming other manufactures made gears with two.holes, the second hole on the stock gears shouldn't compromise the gears.

A smart insert, that is a tight tolerance to the hole for the bolt. This will have a lip on the said insert, with two holes. On that fits over the evolution pin, and one a specified angle, but equal distance. Then one simply drips the hole. This process also assumes you know the angle, which I suppose you could use a mill but I feel you trying to stay away from tools like that.

Imo drilling the gear will be easier than drilling a new hole and fitting a pin in the cam.
 
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CutlassJim

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I'm with Jeff on the cam gears. Redrilling the stockers is a PITA because they do break very easily. When I was using the Evo intake cam in my exhaust position I used the Evo cam gear as well. It's actually 90 degrees offset not 15, Unless you mean 15 minutes then you are correct. The ramp rate is the same intake/exhaust and opening/closing so using them mixed up isn't the "wrong" way to do it like a lot of people think. I had this exhaust cam with an HKS 264 intake cam and the car RIPPED all the way to 7500rpm unlike the stock cams (on a 20G)

The best way to do this in my opinion would be to machine a slot into the Evo exhaust (DSM intake) cam exact to the original slot via a machine shop or someone who has the proper tools. A lathe and end mill and a precise way to measure degree's is a must. The Evo intake cam (DSM exhaust) drops right in. Both with Evo cam gears.

This is worth it if you get the cams for cheap, which is very easy to do. $50 for cam's plus say $100 in machine work is a VERY good price to pay for the performance you get from this. It just needs to be documented so people KNOW what NEEDS to be done and don't ask a million dumb questions only to be answered by a million people who haven't even attempted this.

Bad picture I know but it's the only one I have of the cam cover off. The exhaust cam gear is an Evo unit with only 4 spokes and the intake is a DSM one with 5.

DSCF2327.jpg


Different angle? Not much better.

DSCF2316.jpg
 

DynastyLCD

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Quoting DR1665:
@Phil - It does look like those gears are drilled for the Evos as well. Could you check with Fidanza/XPSI and get us some answers, sir?




i have the same gears on my stroker motor, they are drilled for an evo as well as a DSM.
 

DR1665

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@Desant78 - We've now got two reports of the factory cam gears being subject to breakage during machining. I like the idea of a small, precision jig which would bolt to the cam gears, indexed with a drill-through to accept he stock EVO dowel. It would be far cheaper to ship and use, but if there is a risk of cam gear failure, I don't think it's worth pursuing. The benefit of this mod is its low cost and OEM quality. I don't want to suggest anyone cheap-out and risk lunching their engine because we encouraged them to compromise a cam gear.

@Jim - Thanks for your input. I'm not saying the way you did things was "wrong," just that I would like to see a write-up on how to install these cams as they were originally designed, intake/exhaust. Like you said, Jim, for the money, these are a pretty good value, so we need to put something together that gives people the confidence to do it right the first time.

You also mentioned the ramp angles were the same either way. Could you advise how you confirmed this? You've done this mod - albeit differently from how this thread will proceed - so I think I speak for everyone when I say we appreciate your insight. I think John is going to pick up some bits to play with at his end. If we can get concrete specifications for our specific application, we could put together a bullet-proof write up with instructions for both routes.

PS: Domestic shorthair. Nice. /ubbthreads/images/graemlins/devil.gif
 

Okayplayer

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Denver, CO
I have already purchased a set of evo8 cams. I also have a spare set of 1g dsm cams with cam gears. I would be willing to hazard a try at putting a new indexing hole in it to see just how brittle they are and if it would be worth the effort. I too believe that it would be good to exhaust the simplest options before putting a new hole in the cam itself. I hear good things about this mod and I would really like to see it be a well thought out process. Excititng times fellas.
 

CutlassJim

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Manchester, NH
Quoting DR1665:
You also mentioned the ramp angles were the same either way. Could you advise how you confirmed this?



With a degree wheel and a dial indicator. The norm with cams is to ramp them up and down as fast as possible so most all cams factory and aftermarket will have the ramp rates at what they consider the limit , obviously a bit more docile for factory cams, and the same opening and closing, intake and exhaust. Our style cams also ramp up very quickly, comparatively, because of the use of a roller follower as opposed to a flat tappet lifter.

A jig for re-drilling the stock gear would be really nice as long as the cam gear takes being drilled alright. I can't say yes or no because I've never tried it but I do know they are quite brittle. Also the accuracy of the jig would rely also on the person doing the drilling. I would say at least a drill press would be a must if not letting a machine shop to that as well.

Carry on sir and if you're ever in NH I owe you a beer of your choosing for your valiant efforts.

Quoting DR1665:

PS: Domestic shorthair. Nice. /ubbthreads/images/graemlins/devil.gif



YUP!
 

turbofonz

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Sep 27, 2006
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Granby, MA
Looking at the Fidanza part numbers... They're identical for DSM or EVO, so evo gears will be fine
 
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