Cam Break in Question

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6T9 GTS

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Here's the situation. I getting ready to put my 416 together here in the next few weeks. The cam that's going in requires dual springs. My question is do I need to take the inner spring out during the break in period so I don't run the risk of flattening the cam? I had a buddy of mine go through three .509 purple shafts for that reason. The cam I got is a Comp XE 275 HL (.525 lift 231/237 dur.). I couldn't find anything on Comp's website about running only the outer spring during break in. Have any of you guys ever run a new Comp cam flat during break in because of running both springs?

Thanks
Kyle
 
No I've never had this problem on break in. Sounds to me like the heat treating wasn't done right. A 130lbs on the seat and 320-340 open shouldn't hurt any cam. Stock springs are 100-110 on the seat and 270-290 open if the springs are worth anything. In some cases you may have to take the inner spring out but you shouldn't have to on a cam like this.


BJR Racing
 
I havent lost any yet (knocking on wood desk..) but I never run the inner springs for break in. Conversly, my machine shop never removes them from their customers' engines, and they dont have a problem either...lol. I always figured why risk it.
 
Are you sure that you have an inner spring. Most of the springs for low lift cams have an outer and a damper ( a flat sorta spring). If you're using Comp"s recommended springs you should have no problem. Just make sure that when you fire it up, you go right up to 2000 rpm and keep it there for at least 10 minutes. It is recommended that you vary the rpm a little up and down 1800-2200. Watch the temp of the motor too, don;t want it to overheat. Make sure its full of water. Let it rip.

don
 
Don makes a point there. You probably have a single spring and an inside damper coil. Like he said, flat.
 
i would suggest using straight 30 weight "racing' oil,
and a bottle of GM Engine Oil supplement, while breaking a new cam in.

The newer engine oils have very little of the zinc high pressure additive in them. I have read this in more than one place, link below was the fastest to find.

Also make sure to use the goop the cam maker supplies on the cam lobes.

http://www.lazercams.com/index.html

TechNote:

Under pressure from the major Detroit automakers, the engine oil manufacturers have removed the zinc additive from engine oil. The really bad news is that this increases camshaft and follower failure rates enormously during the break-in time. If you can find a zinc additive for engine oil, that helps greatly. GM's EOS break=in lube has been a faithful option, too. I have heard that the Valvoline racing oil that's labled "not for highway use" may still have the zinc in it. Napa has made a commitment to keep this oil in stock.

There have been no changes in camshaft or follower materials or heat treatment from ANY of us in the racing aftermarket. The increased failure rates are due to the missing zinc in addition to the usual assembly related problems we've been discussing the last thirty years or so. Keeping open spring pressures as low as possible is now more important than ever.
Click to expand...
 
My question is do I need to take the inner spring out during the break in period
Click to expand...

i would check with who makes your cam... come companies require that you break it in with only the outter springs...
 
The shell Rotella 15w-40 diesel oil is good for cam break in as it has zinc as part of the additive package and you can get it at wal mart. Just dain it after break in and switch to your favorite brand and weight.
 
Thanks for all the input guys! Did some checking with Comp's hotline techs and they said you can run the inner spring. I do have the double springs, when i got the heads back from proting and polishing I had to pull a valve out because I had one hole only pulling 10 in. of vacuum. There is an outer, dampner, and small inner. Turns out when they ported the intake runners the got into a couple of the valve cover bolt holes. Getting the rotating assembly tommorrow afternoon, just in time for spring break which starts Friday.

Thanks
Kyle
 
Use the GM stuff. Cheap insurance. I bould bet your friend lost those cams to, no zinc.. I broke mine on it. Keep up the RPM's and have a hose ready to spray the radiator to keep it cool.
 
dusterdon said:
Are you sure that you have an inner spring. Most of the springs for low lift cams have an outer and a damper ( a flat sorta spring).
Click to expand...

The recomended spring for the XE275HL is a double spring. The XE series of Comp cams has a very fast ramp and it's at the 27x duration they start recomending double springs.
 
6T9 GTS, I am running that same cam (XE275HL) and springs #995 (dual) Comp said to break in with outer springs only. I checked the spring pressure of the outer springs only and they are 85lbs. (closed seat), The springs I had on there Mopar '249' checked 80lbs. closed, so I broke it in with the older springs and switched over to new ones after. Used the Comp break in lube and Dello 400 (diesel oil). All good so far. Good luck, Terry.
 
BJR Racing said:
No I've never had this problem on break in. Sounds to me like the heat treating wasn't done right. A 130lbs on the seat and 320-340 open shouldn't hurt any cam. Stock springs are 100-110 on the seat and 270-290 open if the springs are worth anything. In some cases you may have to take the inner spring out but you shouldn't have to on a cam like this.


BJR Racing
Click to expand...
Ditto to this. Just don't let it idle until after breakin time is done.
 
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