I have seen on most of the cam web sites a disclaimer at the bottom that if you have an early evo you may need to notch your pistons even if it's a bolt in cam how do I know if this is going to need done and is it something I can do myself of should I take it to a indi
Looking at the evl 3010 if that makes a diffrence

 

Now, I've never done this, but I've read about it. You have to put it all together, torqued to spec, head gasket you're planning on useing, etc., but with some modeling clay on the top of the pistons where the valves would be close. Then you gently turn the motor over (no spark plugs, and don't force it). Then you take the heads back off and see how much clay got pushed out. What's left is your piston to valve clearance. There's got to be some spec for that, but I don't know what it is.

And if you have to notch the pistons, I'm going with "not a bolt in cam."

 

Dr hess has it I've done several early evos and had to gently grind the top of the pistons till I had the clearance

 

Never ceases to amaze me here, when you think you've read all there is about a subject, a new one comes up. Thinking about a cam for a winter mod, if I wasn't aware of this, alot of cash and more cash to follow by just taking the word of "drop in cam" too literally. Thanks for the posts!

 

You want at least 40(60 is common on a street motor, but you can get away with 30 in a race set-up) thou clearance for.......

valve to valve
valve to piston

Bear in mind, that when you have hydraulic lifters, you need to ensure that the pushrod is bottomed like a solid, or else your reading might make you think that there is clearance that is not really there at all.

 

original poster is correct - the early EVO's (I have an 85) have different pistons. Apparently the tops are flat and have no valve pockets. I'm not sure which ones my 85 has, although I am the original owner and know they are factory original. I think the change was made in sometime in 1985, so your 84 probably does have the early type.

Feel free to correct me.

 

All the warnings I have read say 84 - 86 may need to be notched
So I'm guessing this means I will have to take off my heads , so I can't just cut the old push rods out and use the EZ rods , is a cam change worth all this ?

 

If youve got an `84 thats still got stock pistons in it,its probeply about time for a top end rebuild anyway,put in sme pistons with valve pockets

 

Or don't use a cam that hot.

 

is the evl 3010 that hot
my bike only has 12800 miles on her so did not want to do the top just yet