Marks69BB

I'm thinking about changing out my hyd flat tappet for a new hyd or solid roller. My info is in my sig. Since my 454 peaked at 303 RWHP at ~3500 RPM, I want to sacrifice some low end torque for high end (~6000RPM) HP and my heads will come alive with a new cam. What would I need to change out (rods, rockers, pistons, valve springs, etc.) and what would you estimate would be the total cost? If I sound like I'm a rookie when it comes to this stuff, I'm still trying to understand how much needs to be changed when going to a new cam. Thanks in advance for the replies! :cheers:


[Modified by Marks69BB, 3:47 PM 1/9/2002]

Vetterodder

I'm kinda curious about why your hp peaked at only 3500 rpm? If that wasn't a typo, I'd suspect that you'll find a LOT more power at higher rpms. Did you get readings above 3500?

79er

Here is the Comp Cams extreme energy K-kit cam that would give you the power range you want. The kit comes with Camshaft, Lifters, Timing Chain/Gears, Valve Springs, Spring Retainers and Locks, and Valve Springs. It comes with all the stuff you should change out when putting in a new cam. One other thing I would also change out the rockers and pushrods but you don't have to.

Parts# from Jeg's Summit will have it to.
249-K11-246-3 Extreme Energy K-Kit, XE274H $ 396.99
Grind: 274
Lift: .552''/.555''
RPM Range: 1800-6000


[Modified by 79er, 8:24 PM 1/9/2002]


[Modified by 79er, 8:25 PM 1/9/2002]

Don Schuette

I have the XE274 kit and it really works well. It does "come to life" around 1800 and doesn't let up until I let off the pedal or it hits the rev limiter at 6,000. Nice moderate lopey but not too bad. The vacuum is a little light but still runs the headlights and the like.

It will work well with some more cubes, like you have on the 454, as well as your 4 speed like I have. However, the 3.08 might be a little tight. You might check with Comp Cams if you decide to look at their Extreme Energy line a little harder. What is your compression on that crate motor?

Good luck.

Don

Bob Turner

Mark,

I second Don Schutte on the XE274 for the BB!!! Based on what he told me AND what I read in Chevy High Performance, this is the cam I am going with as well.

In the Chevy high Performance build-up, they got 480hp with the following specs:

454
9 to one compression
Performer RPM intake
Demon 850
Comp Cams XE274H
headers(I am assuming this because of the dyno)

They didn't state if they had the following on the motor. They probably did NOT:

Roller rocker arms
2.19" 1.88" valves

The only thing you will have to do that is a pain with this cam (or larger in the XE series) is break the cam in WITHOUT the inner valve spring. You will than have to use compressed air, remove the keepers and install that inner spring on each valve (while the heads are on the engine.

DON Schuette can explain this in further detail since he has gone through the painstaking process. I have an email I can send you that Don sent me detailing this procedure (Thanks, Don!!)

Bob :cheers:

mountainmotor

I can't find the rates of the optional 930 Comp spring to compare .The nose pressure on the 924 spring seems a little high for a hydraulic cam but the spring rate is a light 317 exactly what that lobe design needs to live.
Even with the 924 set up at 1.880 installed height I see no reason to remove the inner spring for break in.Just some Valvoline 30 Racing oil and a can of EOS and the certainty that the motor is ready to turn over a few times and bust off right away a guy should be good for the go in my opinion.

Bob Turner

mountainmotor,

Comp Cams recommends removing that spring. I would rather not as well. I wonder if anyone on the forum has broken in the cam with both springs and had good luck with the life of the cam......:confused:

I will probably do it when the time comes....

Bob

Don Schuette

Two points. Mountainmotor, you're probably right as far as being able to get away with not removing the inner spring. However, as Bob mentioned, Comp Cams highly recommends the inner springs be removed; probably just a precaution. My machine shop highly recommended it also.

I did notice that the base of Comp Cams' lifters have a lot smoother/finer finish to them than stock Clevite lifters. This would probably also reduce the chance of flattening a lobe.

Don