396/375 cam for street 454?

[Chevy454]

Nuch: go with the GM blueprint cam made by Crane...us Pure Stock guys have already done the leg work and tried the other brands, and the GM/Crane piece is worth the money...the part # from GM will be 12364057...from Crane it's part # 19038.

[Stefano]

Yeah, what he said, same cam.

[nuch_ss396]

[ QUOTE ]
Nuch: go with the GM blueprint cam made by Crane...us Pure Stock guys have already done the leg work and tried the other brands, and the GM/Crane piece is worth the money...the part # from GM will be 12364057...from Crane it's part # 19038.

[/ QUOTE ]

Rob,

Thanks for the input. Just one other associated question
for you. I have heard a number of opinions about the solid
lifters for these cams and which ones to use. I've been
told that the NOS GM lifters are the best by far. Man, they
do go for major bucks on eBay.

I was informed that the aftermarket lifters aren't ground
properly on the bottom face ( rides against the cam lobe ).
What's your take on this issue?

Steve

[nuch_ss396]

[ QUOTE ]
It should work great!!! You can't beat that cam for the money...you will have lots of power and that super "solid" sound! Next motor I build will be a BB with oval ports and that cam....good luck!

wilma

[/ QUOTE ]

Tom,

Would you have the oval post heads incorporate the use of
the bigger valves as well? What size valves are we talking
about here anyway? BTW, what casting ( head ) would you
recommend?

Steve

[WILMASBOYL78]

As for valve size we are talking 2.19 Intake and 1.88 Exhaust....heads choices for stock GM are open to discussion, depending on your preference for open or closed chamber dsign and what kind of piston/compression ratio you are running. I like the 290 closed chamber head..it has very good flow potential and can help make decent compression. There is probably more power potential with open-chamber design, but your pistons have to be set up to work with the larger chambers. The 820 casting would do a good job. All of these heads benefit from some "massaging" on the exhaust side to improve flow. Use quality valve train parts and make sure you check valve to piston clearance during assembly. The oval port heads will perform better on the street and provide crisper throttle response and more low end TQ....Weiand makes an oval port dual plane manifold "Stealth" that looks a lot like a factory hi-rise and even has the choke setup....this manifold or the Edelbrock Performer RPM are good choices..add the Airgap if stock appearance is not imporatnt. Good luck..wilma

[nuch_ss396]

Tom,

A couple more questions if you don't mind.

With those valve sizes, would some porting need to be done
for flow? If so, how much? Got any target numbers?

If open chamber heads are used ( Like the #820 ), what
compression ratio should I be after? 9:1 or so? What if
the closed chamber heads are used?

Again, it is an interesting topic to be sure.

Steve

[Chevy454]

Steve: the Crane/GM lifters that come with the blueprint cam are fine...I've tried regular Comp and Crane solid lifters, and had no problems...(knock on wood)

[WILMASBOYL78]

Depending on what you start with you will definately have to machine for larger valve seats for the 2.19 and 1.88 sizes. As for porting I think some mild blending and smoothing to improve std flow will be fine. The exhaust side on the BB heads responds well to some improvement. I'm no machinist but any compentent shop should be able to help.
As for compression..10.0 will do the trick..maybe a little more???. Depending on piston configuration and other factors you can use pump hi-test with modest timing. You may have to experiment a little with total advance...not sure if combustion chamber style will impact how much compression you can get away with..but at 10.0 to 10.5, I don't think it will be a major factor. Will check with one of my engine buddys for his thoughts. Most of the aftermarket suppliers like Edelbrock offer their performance heads with some style of open-chamber design. This design is superior to the original closed chamber head for the way the head flows and allows for "better breathing". Some might say that you can even make more horsepower with less compression. This is important if you want to run your car on pump gas...any engine that performs really well, usually has the right combination of parts and technology. hope some of this helps...

wilma

[nuch_ss396]

[ QUOTE ]
... This is important if you want to run your car on pump gas...any engine that performs really well, usually has the right combination of parts and technology. hope some of this helps...

wilma

[/ QUOTE ]

Tom,

What you finished your last post with sums it up in a
nutshell.


I would prefer to run on pump gas, and get a brute of an
engine in the process. But, I want it to appear stock.
The L/78 cam with the oval port heads sound like an
interesting combination. I'd love to test drive one of
these before I build it. BTW, I have a 402 +.040 ( L/34 )
just sitting here waiting for such a project.

Steve

[Jim Ferron]

Just a couple notes, my brother has that cam in his 454 and it's fine...maybe a little small. Second, I'm not so sure 820's are the head to use...781's or 049's are the perferred OC smog head, I believe the intake runner are the big difference..Dirt cheap as well, couple hundred bucks a set.
Third, certainly you don't have to change the valve seats to go to the bigger valve no matter which of the three heads you use. Just hog out what's already there.

What will be VERY inportant will be to unshroud the valves in the combustion chamber. You'll see with the big valves, when they are open, they come very close to the wall of the chamber. ANY machinest will/should know to use a grinder to remove material around the edges...to allow for better flow with the big valves.