Cam only install question about not pulling heads causing rear of cam to warp
I need advice from you guys. I have a buddy who is a very well respected GM tech. He is telling me that doing a cam only install without removing heads and just sliding cam in the front of the engine causes a slight warpage at the rear of the cam ..
My buddy who I really respect was telling me that GM calls for the heads to be removed when installing a cam for this very reason..
And that because the head bolts are not relieved of tension..the cam as its slid in causes warpage and over time causes problems with cam bearings etc.
He said he's seen quite a few aftermarket cams come into his shop recently ...one where it needed a new block..and another few where the damage was not as extension but enough for him to suggest to me over breakfast ...not to do a "cam only " mod.
I was pretty much thinking of having an expert tuner whose a supporter of this site do my "cam only " mod after I get a look at the new C6 this January.
What do you guys think? Do you who have cam only mods...do anything to relieve the tension on the head bolts during "cam only :" mods.
While we're at it..anybody have any issues with any kind of leaks or valve spring issues..?
I know I'm asking tough questions to answer on the forums but what the hell...we're all adults...just figured I'd throw this out there and hope for cool responses.
JB, I've done cam only installs on 2 LS1s and have numerous friends that have done the same. No issues at all. Your friend is full of it and I'd have to question his status as a well respected GM tech
How does changing out your cam warp the bearings??? I can understand damaging them when you're sliding in the cam. Can you explain in detail what actually happens?
Do you have any idea how much pressure you'd have to put on the front of the cam to warp it? Unless you are installing the cam by ramming it into position with a 3/4 ton pickup I cannot concieve that you would warp the camshaft. I understand there are other issues to consider, particularly the bearings when doing this install, warping the shaft just isn't one of them. Your friend may be well qualified for certain automotive repairs, engine internals however doesn't seem to be one of them.
He has probably never tried it and only goes by a bulletin put out by GM. GM does this some times to insure that dealers dont install a cam wrong and cost more money on claims. Besides GM is in the business to make money right, why not charge to R&R the heads for a cam install?
I appreciate the confidence you guys have in cam swaps....
I didn't get into indepth technical detail with this gentlemen and to be honest ..we didn't spend that much time talking about it.
. We were shooting the breeze,...... I mentioned I was considering a cam only swap and he said there is an issue about not relieving the tension of the head bolts at the rear of the engine while installing the cam causing the the rear of the cam warpage bearing issue or journal problem...(like when you remove the heads during a Head & Cam swap)
This guy knows his sh!t...I have to say I may not remember all the details...I sort of focused in on the main suggestion of not doing a cam without heads.
I'm not trying to say there will be a problem with every cam swap ls1 or ls6...
Just trying to find out if anyone else had heard of something like this happening...
I have done many many cam only cars, never any problems here. Actually if you look at GM's procedure to change camshafts, they intend on having the engine removed. Just shows you that not everything that GM says is the gospel.
If you think about that, it is all wrong. When the motor is under tension (with the heads on), the cam bore should be perfectly round and true. The only time I would expect that to change is when the heads are removed, and the block is no longer under tension. But, that is not the case in either scenario. Witht the heads off, the block isn't in a bind either.
It is the same as when you bore and hone a motor with torque plates installed. You want the same deformation you will see when the heads are installed while you are machining the block.
If it was true that the cam was keeping everything true in the motor you would see cam failures, since the stock cam would always be in a bind from the factory. The stock cam, and any aftermarket cam should turn freely in the cam journals. If it doesn't, there is a bigger problem.
I agree. The block stabilty better not be affected by removing the cam. How can a rotating part of an engine be considered a structural member or component of the block? Sounds to me like another opportunity to refuse warranty work.
If you have an aftermarket cam, you may have caused engine block damage! Sounds like politics at work.
FWIW..I don't believe it was politics. I don't know the specific details of the damage. Like I said earlier...with issues such as this...it often has a tendancy to be involved possibly with improper installation.
Bearing's probably got fuk'ed somehow and caused problems with the block... Thats what I'm taking away from this discussion.
The GM tech manual probably calls for the head removal on the ls1 and ls6 during cam installation.. for some unknown reason to us. Why would GM call for it in the manual?
That I dont think we'll ever find out....
The reason I made this post was I weighing the benefit of spending an extra 2 or 3 grand for CNC heads just so I could avoid a reliability issue down the road (rather than more hp and it didn't seem to make sense 4 me)
Meanwhile... you experienced techs seem to feel is a non issue. I appreciate your opinion and time.
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