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Sir Boost-a-Lot
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21 Posts
Discussion Starter #1
How "crazy" can I go?

I have a mild 351c in my Cougar convertible, mild being defined as 9:1 compression (as far as I know), dual plane Edelbrock Performer intake, Crower Baja Beast hydraulic cam, Edelbrock 600cfm carb, Mallory magnetic breakerless ignition (mechanical advance), headers, and essentially stock 2v heads.

I’m getting some bad vacuum flutter which I think may be a burnt exhaust valve. The engine also seems to be considerably down on power. I’ll probably pull the heads off to give them a once over at the machine shop.

When the motor was rebuilt, it had a Baja Beast stump puller cam installed*, one that I was not very impressed with up top. I’d like something more, but I want to know how far I can go with the cam before everything is mismatched. A nice grind that pulls hard to 6k RPM would be perfect.

The car currently has a stock FMX transmission with stock stall converter too :(, and a 3.89:1 geared 9” rearend. Future plans will be an AOD swap with more stall (maybe 2500 or so)

The car is a street car so I know I can’t go too crazy. I don’t expect to hang with LS1s, but I’d like to make more power over 4k rpm.

My questions are:
1) What cam should I use?
2) Will I need new springs?
3) Is there any minor port work I could have done to wake up these 2v heads?


Thanks for your input.

*Existing cam specs:
Crower Baja Beast
Power range: 1200-3800rpm
Reline: 5200+rpm
Advertised duration: 258/264 (in/ex)
Duration @ 0.050”: 200/210 (in/ex)
Gross lift: .477”/.486”
 

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Sir Boost-a-Lot
Joined
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21 Posts
Discussion Starter #3
Thanks for the input.

What do you think of these CompCams?

Grind: 280H
Duration at 0.050”: 230/230
Valve Lift: 0.530/.530

Or

Grind: XE274H
Duration at 0.050”: 230/236
Valve Lift: 0.562/.565

Or

Grind: 275DEH
Duration at 0.050”: 219/232
Valve Lift: 0.515/.541

Also, do you think I could reuse my valve springs with a 0.530-.560” lift cam?

I'm not sure what brand the springs are but I think it’s safe to assume the engine builder (a reputable one) sized them for the cam currently in the motor (.477” gross lift).

Thanks again. :hy:
 

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74 XB Fairmont
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5,113 Posts
I'd go the XE274. 2V's don't like the same duration in/ex. I tried a cam like that. I reckon the 275DEH has too much of a split. You'd have to change the spring to suit the lift and pressures of the camshaft.
 

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Nitrous Junkie
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98 Posts
Agree with Brenx, run the XE274H and you'll be a lot happier. You will need to change the springs and retainers (std Clevo is junk), and if it has burnt valve, it would be worth changing to single groove valves. They're stronger and more suited to revving to 4000+rpm.
 

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Registered
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1,067 Posts
You have sfa compression, so a 214/224 would be as big as I would go. The cam you had wasn't much bigger than factory standard.
 

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Nitrous Junkie
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98 Posts
Bear in mind though that the XE range of camshafts have valve events designed to increase dynamic compression without needing a high static compression ratio.

You can't compare them with an old TQ20 grind of the 60's...
 

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Registered
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15 Posts
I ran a Comp Cams 280 H Magnum in my Mustang years ago. It had 280 drgrees duration and .535 lift. Used pretty much the same engine listed and it made enormous power Great torque too. It wasn't really well mannered in traffic, but that's not what I had in mind anyway. Had a C-6 with a mild stall and 3.0 rear gear. And even with that it was a beast off the line. Make sure you don't go overboard with the springs though. Too stiff will be a problem down the road and wear your cam lobes too fast or damage the lifters. GET GOOD RETAINERS!! Trust me, the cheaper ones break and you end up with a giant hole in the head and a gash through the cylinder wall and an even bigger hole in the bank account.
 
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