Well I was told that to break in my cam correctly I have to run the car at 2000 RPM for 20 min with the outer spring only, then after that install the inner spring.

I have asked around and no one has ever heard of taking the springs off and installing the inner spring afterwards.

Is this correct?

 

Look at the FAQ board, Five7kid has instructions in there.

 

https://www.thirdgen.org/techbb2/sho...hreadid=206726 has engine break-in procedure, but not cam.

If you have a very high lift flat-tappet cam that uses mongo valve springs, the light-spring-only-first process is a good idea. The typical street engine doesn't need that, though.

Use petroleum-based oil for the cam break-in. Crane (and some others, I think) have a break-in additive as well.

I've never wiped out a cam. I've even broken them in with synthetic oil (already had synthetic in the engine, changed the cam, ran it in, changed the oil with a fresh fill of synthetic after that).

 

what is the purpose of the inner spring anyhow?

 

Depends upon the type you're talking about.

True dual springs, to increase the closing force w/o increasing wire diameter.

The dual springs with the flat inner one - to break up harmonics (resonance).

 

Like 5-7 said, removal of the outer spring is really only done when large spring pressures are used. This prevents collapsation of the lifters and whatnot. On the couple that i have done, i have never removed the outer spring.

Also, expanding on 5-7's description of the springs themselves, Most street springs that i have seen aren't true dual springs. Rather, they are outer springs with inner dampers.



The damper spring can be seen here (along with what an inner and outer spring are).

Here's my procedure for a hydraulic flat tappet cam:

Apply lube to bearing journals and cam lobes, also, the fuel pump eccentric, if used and then the distributor gear. I put a drop on the face of the tappet as well. Just don't put any on the sides. Fill the pan with 30w dino juice. I run it for 20 minutes around 2000 RPM. I hover it around 2k, occasionally climb to 3k slowly a few times, then back down. I will also drop to 1500 a few times slowly and back up. Change the oil and put dino juice back in for 500 miles or so. I did that in my engine for my Caprice, a few months ago when i put my Xe256 in. No problems to date, ran the cam now for about 2500-3000 miles. Also did this in my buddies 91 Z when he swapped to his old 327. That was a few years back. No problems for him, either.

 

What about when throwing in a cam that was broken in on another engine (used). Are the same steps necessary? I got a CC306 with about 1500 miles on it im gonna throw in soon, will it still require dyno poo?

 

If its a flat tappet make sure to use new lifters with the cam and break in as suggested above. If its a roller then there isnt any need to run it for 20 mins or so at 2k since they dont need to break in or have lots of lube to do it. You can also reuse your lifters if theyre in good shape. I donno about synthetic, though. Maybe just conventional to be safe.

 

Even new roller cams dont need to be "broken" in...lube um up with that thick stickey jelly stuff and go to town....

i installed on "used" cam in my motor with used rollers..stickey stuff on all journals and lobes and lifters and good to go

 

If it's a roller cam, I just coat everything liberally in 30w dino juice.

 

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I just got me new Crane cam from summit this week and reading the break in info it says directly not to use synthitc oils during the break in. It does not say why but if Crane singled out the synthitics than there must be a good reason.

I am not say five7kid that what u have done does not work but my gut tells me not to do it myself.