Yeah, I know, another camshaft recommendation
 

Looking for camshaft recommendations for a 455.

1974 455 with stock bottom end, no forged internals. Currently has 4X heads, I have a set of 6X-4's I plan to build, as well as change cam. Car is a 1968 Firebird 400 HO 4 speed M-20, 3.55 rear end, but will be switching to a 3.23 ratio. LBM manifolds, stock points ignition. Quadrajet carb on Performer intake

I know that 6X-4 heads are a common swap, so what are you running? I am open to all ideas from experienced builders. Thanks in advance!

Stick a RAIV cam in it.

Or hydraulic roller equivalent.

Hard to go too far wrong.

When you say “ A stock bottom end” does that also mean it has not been rebuilt since it was born in 1974?

It came out of Pontiac Hearse, low miles, had a re-ring & bearings, crank polished.

HFT cams...

I am not getting the warm and fuzzy’s about a motor that got used so little as it likely did in a Hearse yet needed bearings and rings .and a crank polish.

Have you driven this motor in a vehicle?

My concern lies in if the Rods where checked and the oil pump replaced.

From what I understood from the guy I bought it from said when it was torn down, he found the bearings be in perfect condition. So I was told, it has great oil pressure.

Hard to go wrong with a RAIV style cam in a 455, I have the Crower version listed for sale in the classifieds here.

I run a 455 with a RAIV cam and 7K3 heads with Rhoads lifters and makes good power and is a perfect street motor in my opinion.

Leave the the 3.55's and do the 6X-4 swap. Some of the 4X's are good heads but will take more $$$ thrown at them than the 6X. The RA IV cam is a proven winner.

I think this might be what I'm looking for.

https://butlerperformance.com/images/F221284671.jpg

This is a running engine, it did get a new 60psi pump Melling.

I agree with the RA IV cam. Degree it in 4 degree advanced.

Which 041 cam ?

Quite a bit of difference between the Butler Ram Air IV "041" Reproduction Camshaft using Comp lobes and the Crower 60919 cam that many use as a 041 replacement !

Evaluate the seat durition.......

Butler: 276 / 290
Crower: 304 / 316

(for conversatio, presume they are both rated at .006" tappet lift )

They both have the same .050" duration. But given a engine with a lower static compression ratio could one be considered the 'better' cam ?


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Crower 60919

When pairing a camshaft with a lower static compression ratio, you should generally aim for less valve overlap.

Valve overlap and low static compression are a highly mismatched combination.

Valve overlap is designed for high-RPM scavenging, where exhaust momentum pulls in the fresh air/fuel mixture. However, this action requires high static compression to offset the pressure drop. When paired with low compression, the engine struggles to build cylinder pressure at low engine speeds.

Butler camshaft: 57 degrees overlap
Crower 60919: 80 degrees overlap

http://www.wallaceracing.com/overlap-calc.php
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Here’s what HO racing use to recommend for a 10 to 1 street motor.

With under 9 to 1 things change fast!

For interest, and further conversation....

Note the comment "Use Advertised Duration Numbers" here:
http://www.wallaceracing.com/overlap-calc.php

That brings up the topic at what tappet lift is the cam rated at for the advertised duration. It will make a difference in input, and why in my original post I presumed 'for conversation' they were rated at the same lift.

Since Butler is using Comp Cams lobes his numbers will be rated at .006" tappet lift. When it comes to the Crower 60919 cam, that specific number has been open to speculation. But for conversation, I seem to remember it was rated at .005" tappet lift. I recall a phone conversation with a Crower tech rep and he stated it didn't matter ! But then said it was 301 degrees at .005" tappet lift. My old catalog states 304 degrees on the intake.

Further, note the conversation in this related thread and specifically the comments from Jay S in his post #13 here:

https://forums.maxperformanceinc.com...ighlight=60919

To further muddy the water it is my understating the factory 041 cam is rated at .004" tappet lift. Because cam lobes have unique ramp speeds, there is no fixed mathematical formula to convert duration from 0.004" to 0.006" tappet lift.
One source states you can estimate the change by subtracting roughly 8 to 12 degrees from the 0.004" advertised duration. Some sources suggest even more than 12 degrees.

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Steve,
What is the .050" numbers for those cams?

I have the Crower 60919 @t 231 @ .050"

So 276 -231 = 45 which is a very aggressive lobe.

Stan

Stan,
I'm presuming this is the Butler cam under consideration:

https://butlerperformance.com/i-3164...tegory:1459636

The stated 231 degrees at .050" is the same as indicated for the Crower 60919 in my Crower catalog.

Keeping in mind here, my information provided in this thread does not represent any endorsement It's not based on personal experience and is offered for general interest only.

Condidering Harvey Crane's Hydraulic Intensity formula.
This is the duration at .050" subtracted from the duration at .004", where the SAE has decided that hydraulic durations begin and end.

Again, similar to calculating the overlap we need to keep in mind at what tappet lift is the cam is rated at.

To muddy the water further, this one from Tilden Technologies is always a good one for a camshaft debate.....


"A quick opening and closing cam will provide better low end performance than one that is slower opening."

Substituting the term "quicker opening" for "smaller intensity", Harvey Crane states, "In practical terms if two cams with similar lobe designs have the same duration at 0.050 lift, maximum torque and horsepower will be almost identical. However, the cam with the quicker opening will have a smoother idle, better off-idle response, superior low speed drivability and a broader power curve."

Which one is the "slow" camshaft :)



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Steve,
My understanding is that the Crane version was the closest to the Pontiac 041. I have Cam Dr data for the Crane cam I got from Ken C / H-O.

Stan

The Crane example mimics these numbers:

60919 approximate duration average 286*/295*@.006”

RA4 grinds (SPC-8 Melling all ground by CMC)

292*/303*@.006”.

Subtracting the 231 duration at .050" tappet lift supports that Butlers cam is more aggressive with the lower intesity number.

When searching the numbers will vary all over the map but here are some examples for a hydraulic flat tappet cam....

Key Intensity Guidelines (in Crankshaft Degrees)

60 to 70°: Mild to factory stock. Lazier ramps, easier on the valve train, excellent longevity.

50 to 55°: Moderate street performance. Good mix of vacuum and power without requiring extreme spring pressures.

40 to 45°: Aggressive. Yields quicker throttle response and more area under the lift curve for top-end horsepower.

Below 40°: Highly aggressive (often seen on racing or solid lifter profiles); this territory can cause valve float or severe wear on a hydraulic flat tappet if spring pressures aren't perfectly matched.

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CROWER 60243 284* / 290* 63* Overlap w/ .479" .494"
@.050 228/235
284 -228 = 56 intensity

A fwiw. That Crower 60243 is one that Cliff Ruggles would often recommend for a 400 combo with a lower static compression ratio. 9:1 or less.

In lieu of the Comp XE274 HFT which is a good alternate touted by some.

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