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Discussion Starter · #1 ·
Hi,
I am redoing my 454, with cc oval port heads, 10:1cr, roller rockers, single Holley 750 on a Winters intake, with headers. My question is, does anyone have experience with using the Comp 280 Magnum cam? Or more to the point, the bood states that the Crane leak down lifters will reduce the effective duration of the cam to a duration of ~270 to about 2500 RPM.
I want to use this only on the street, and even though the cam is new, I would rather put in a milder cam now, rather than to have to swap cams after the engine is installed.
My big thing is, to have enough vacuum for the power brakes. I know I could use a 2 stage booster, but I would rather not get into that right now.
Bob
 

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Besides 280 is a mild cam for a 454 as it is.
If youre stuck on it wont run bad....just better out there thats all. If those are anything like Rhoads lifters (some hate me but they worked great for me) when warm at idle it should be somewhat tame just a slight rump without drivng issues.
 

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Discussion Starter · #4 ·
What did you find was the best RPM for idle. I'll be using it with a TH400 with a 30% overdrive (Hono-Drive)
Bob
 

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Discussion Starter · #5 ·
I am 73, and only want something that is just barely able to kill me. I know there are a lot of better grinds, but when I bought the cam 32 years ago, when it was state of the art for flat tappet cams.
 

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Discussion Starter · #7 ·
Thanks for the idle info.
I'll be using a Holly carb, but I was a little concerned about having a rough idle against my TH400. I am going to be using the large converter because a high stall is not going to be important to me.
My rear end is a 12 bolt, the ratio is 3.73:1
 

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Comp ratio is also a player as far as idle quality is concerned. With 10:1, I think the 280 will be quite ok in a 454, enough vac for p/brakes without the need for bleed down lifters, which might just drive you crazy with the noise.
And you don't need extra exh duration for a cruiser, which is what it sounds like you want; extra exh duration will worsen idle, vacuum & low end tq & for little or no gain in your cruising driving range.
 

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For a box cam , xe274 will make more everywhere ... And I never use bleed down lifters...

My opinion if your gonna run Hyd flat I like Delphi lifters , cheap and best I have used . I Get them from skip white lol
 

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The ole 280H is 230 duration @.050 .520 110 LSA
FWIW,There was a fellow member here,"Ron454" that used this cam in a 70 SS 454 years ago,with stock 290 heads IIRC..he ran high 11's (like 11.9) with open headers and I believe 3.55 gears.
Not a terrible cam IMHO..based on that.
Are there better? Absolutely.
You are not going to have any idle or vacuum issues with that cam in a 454
 

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I never had any issues with vacuum with that cam in a 350 either.. it is a great cam for all around car.
in a 3000 lb car with 350" and some gear it will go 12.50's pretty ease pull 15 mpg. if you keep your foot out of it.

350" with Ported 305 heads with small valves I get 15" vacuum at 900 rpm

You should like it in a 454.
 

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my .02 on comp 280 magnum it wasn't a chevelle but one of my first builds a 1980 2WD blazer ran fairly decent for what it was with that cam in a 9:1 454 with 049 heads just roller tip comp rocker arms performer 2-0 intake with 1 spacer and 3310 780cfm holley th-350 25000 converter 3.73 gears ran 13.40 in 1/4mile. pulled strong to 5500-5800 rpm. good power brakes. had just enough rough idle to let you there was an aftermarket lumpy cam in it.i had the Rhodes bleed down lifters in it briefly took them out.
 
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