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Discussion Starter · #1 ·
My mechanic is installing my Comp 262AH cams (from my old stock 2004 2V motor) into a new motor which consists of an MMR750 shortblock with -18cc pistons (dished) with no notches, and a set of MMR Stage II PI heads (stock PI heads, ported with larger valves option). The mechanic is saying that installing the cams according to the cam card info from Comp is causing piston to valve contact. I thought these "baby cams" would drop in without any problems (???). Does this situation seem plausible, or is the mechanic not doing something right? He said he would have to retard the cams to avoid PTV and this would cause a loss of torque, and I should get "new/different" cams. He also said there would be "no guarantee" that he could install the Comp 262AH cams without running into PTV problems!

I've never heard of any problem installing these cams before but maybe I just never really noticed any mention of it on the internet.

Anybody have a similar experience?
 

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Discussion Starter · #2 ·
BTW, I also, at his recommendation, got some Comp Adjustable cam gears for this build, so I guess he should be able to have near "infinite" adjustability for the cam timing.
 

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Discussion Starter · #4 ·
I called them but only talked to a salesman today. He said he's never heard of an issue with my setup and the Comp 262s. I'll have to try to get a tech on the phone tomorrow.
 

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I've never seen or heard of anyone who's had PTV issues with 262's. They're a fairly mild cam compared to most.
 

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Discussion Starter · #7 ·
He should be using 109 degrees as the ICL according to the info that he received in an email (I got copied in the email) from Comp Cams.
 

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Discussion Starter · #8 ·
They should not cause PTVC, what ICL is he trying to install them at? 109? They should clear all say long at 109+

How oversized are your valves?
I asked MMR if they had any specs on their Stage II heads and they provided me with NOTHING. Communication with their customers is not their best attribute.
 

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Maybe the lifter is taking up too much lash when he's timing the cams. This could cause the valve to stay open throughout the rotation, and cause the cam to increase valve lift.
 

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Discussion Starter · #10 ·
Is it customary to use a solid lifter for the purpose of degree'ing cams?
 

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Cone Killer
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My builder welded a lifter to make it solid, he then ground material off the bottom of it and shims it with washers until the lash is zero. I recently purchased one of MHS's adjustable lifters that screws in and out. I haven't gotten it yet, but I'm hoping it works well. If your builder welded the lifter to make it solid, the lifter might be protruding on the rocker too much and causing the valve to be open around TDC. With the valve partially open at TDC, you're going to have PTV no matter what cam you use. Taking the lash out of the system is importent when checking PTV.
 

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Is it customary to use a solid lifter for the purpose of degree'ing cams?
You can use a fixed solid lifter for the purpose of degreeing, but you cannot rotate the engine over with the solid lifter because it will be preloading the valves and cause PTVC. In order to check for proper PTVC, you need an adjustable lifter. Summit sells one by trick flow for like $29.
 

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Discussion Starter · #13 ·
Thanks for the info guys.

I talked to a tech at MMR and he said that they (MMR) do NOT use the cam card specified 109 IntakeCenterLine, but rather they use 112 degrees. He also said that the pistons do NOT have to be notched for this setup, and if anything, because the stainless valves are thinner, that I should have MORE room to put the cams in, not less (even though the diameter of the valve is slightly larger).

Don't quote me on this so to speak as it is not "gospel", but what one person said.
 

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Discussion Starter · #14 ·
Lesson to be learned here: DEGREE the F'ING (aftermarket) CAMS! (or take your chances).
 

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Yeah even an oversized aftermarket valve is going to allow more clearance simply because the stock valve margin is so huge. The margin is much thinner on aftermarket valves. You will be fine at 112. Since you have a centri blower having them back at 112 might end up being a good thing anyways. You will get a bit more usable rpm up top when your centri is shining anyways.
 

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Discussion Starter · #16 ·
Yeah man, the mechanic says to me: "you're going to lose some low-end torque". LMAO. I said, I think I'm going to have adequate low-end. It's not like I'm planning on towing a boat with this thing! Hopefully it will "scream" a little bit on the top end!

I can't wait until this thing is DONE.
I've been planning this project since December 2010, when I placed my order for the shortblock with MMR.
 
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