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Cam question?

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noluck

Probationary Member
24
0
Feb 1, 2007
Atlanta, Georgia
I have BC stage three cams. Can a stock valvetrain handle it? The head has been rebuilt.:dsm:
 
to make sure you get the right info and not one of those "well my buddy has"
answers call BC and ask them
 
There was a group buy on ca.dsm.org alot of people picked up and installed brian crower 272's without any issues. Bc 280's are overkill and will need upgrading. I have bc 272's but there not in yet.
 
Shim the springs? What size shim would you use? Is it supposed to tighten the spring so you dont float the valve? I thought it wasnt necessary unless you were going higher than stock redline. The reason I ask is, I just put 272's in my gsx and didnt do anything else to the valvetrain. I wonder what kind of trouble Im asking for by not putting the supporting mods in place first. Oh well :|
 
Even with 272's you would have to shim the springs, and it would still be risky, with 280's...... NO

Don't post info that you don't know about. Stock springs are not an issue with a 272 varient cams & no spring shimming is requiured. Sure an upgraded spring or shimming isn't a bad idea but defently isn't required for this cam size. I would only look at upgrading my springs if my stockers were origionals with high milage. 280's on the otherhand will require upgraded springs, & BC offers an upgraded single spring that will work perfect with the 280's.
 
Our cars have a very light valve train to begin with you will be fine as long as you have the stock rev limiter. Upgraded springs are for better valve control at higher rpm so you don't float the valves. A higher spring rate results in the valve being able to close faster thats all. If your not turning 9000 rpm, and theres no reason to believe your stock valves will fail(recent rebuild)run with them. The only thing i would do is ask the shop that did the head if he shimmed the springs to factory specs.As long as your only in the 5 to 6 thousand rpm range you should be fine.If you want or need to go higher rpm get the springs. you only need to raise seat pressure about 20lbs and open pressure about 60lbs better valve control will help your engine run better. Will you notice? probably not, but your valves will.
 
Don't post info that you don't know about. Stock springs are not an issue with a 272 varient cams & no spring shimming is requiured. Sure an upgraded spring or shimming isn't a bad idea but defently isn't required for this cam size. I would only look at upgrading my springs if my stockers were origionals with high milage. 280's on the otherhand will require upgraded springs, & BC offers an upgraded single spring that will work perfect with the 280's.

I disagree. If you plan on fully using the 272's you are going to rev past redline. Ive personally seen 272's break stock springs. But he was revving the motor above 8k rpm I believe.
 
I disagree. If you plan on fully using the 272's you are going to rev past redline. Ive personally seen 272's break stock springs. But he was revving the motor above 8k rpm I believe.

Then he was running wore out stock springs. . . Research.

I've seen 3 setups run stock springs to the common 8500rpm level (where 272s peter out), w/ zero float.

Broken valve springs due to 272s w/ "normal" ramp rates and 8500rpm rev limit is so very unusual that it shouldn't be a purchaser's concern.
 
I have run stock springs with Web Cams (street grind) similar to 272's to 8500 for years without any problems. Scott Gray ran 272's and stock springs for years to 8500-9000 with no problems. It has been proven many times on high horsepower cars. dsm-onster is right...and for 280's, you need to upgrade.
 
Then he was running wore out stock springs. . . Research.

I've seen 3 setups run stock springs to the common 8500rpm level (where 272s peter out), w/ zero float.

Broken valve springs due to 272s w/ "normal" ramp rates and 8500rpm rev limit is so very unusual that it shouldn't be a purchaser's concern.


Why research when this was from personal experience. I myself would not install 272's on stock valve train. My mechanic blew his valve train on a newly built head and on another guys car when he installed them. He wont even install them on stock valve train if you ask him. Its Jack at jackstransmissions.com and he knows what he is talking about.

Anyways there is a risk of them breaking so I would not just go around saying its ok and they will work perfect. I even emailed BC and they said they would work only if you are staying within the stock redline. Any higher revving gets risky.
 
Why research when this was from personal experience. I myself would not install 272's on stock valve train. My mechanic blew his valve train on a newly built head and on another guys car when he installed them. He wont even install them on stock valve train if you ask him. Its Jack at jackstransmissions.com and he knows what he is talking about.

Anyways there is a risk of them breaking so I would not just go around saying its ok and they will work perfect. I even emailed BC and they said they would work only if you are staying within the stock redline. Any higher revving gets risky.

Of course BC will say if you you want to rev past stock redline, you need upgraded spring. They have to play on the safe side, as otherwise their reputation in on the line. Any smart business will tell you the same thing. I know lots of guys who run/have run 272 varient cams to 8500 all day long with stock spings & not had an issue. Sure if your running them to 8500-9000+ rpms then the stockers probably won't cut it, but a 272 cam shouldn't be run that high in the first place. Personally if I was running 8500 daily on 272's I wouldn't run stock springs, but thats just me, I like to be on the safe side. But it has been done too many times to count without any issues.
 
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