DR1665
Well-known member
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.
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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