396/375 cam for street 454?

[goinforbroke]

Was just wondering if a 375hp 396 cam .520 lift 242 duration 112deg, solids.(3863143) would make make a good street cam in a mild 454. Engine is 2 bolt 454, 820 oval ports, cut for big valves and milled to achieve 10:1 with .125 dome pistons. Dual plane intake, 750cfm 4150 holley, 2" headers. Will go in a 72 nova. th350, 3.73 rear. Current cam is a .520 lift crower hyd with 218 duration. Any help would be appreciated.

[WILMASBOYL78]

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

[Chevy454]

I would think it would work...our 10:1 L72 went pretty good with the stock cam (12.7 @ 108+ in a 3800 pound car on skinnys)...where those ovals will shine (mid range) that cam works pretty darn good...

[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

[YenkoYS100]

I had a '62 BubbleTop BelAir with a '71 Vette LS5 454 in it with the Vette 4 speed. Car weighed 4000+ lbs. It had the stock '71 8.5:1 ? pistons in it. It had a GM 375/396 cam in it, 780 Vac. sec. Holley on a C396 Edelbrock dual plane intake, 2 1/8" fenderwell Hooker headers, stock GM ignition, had the #820 heads on it. I think it was 3.08 rear axle ratio? Car ran on regular gas (1980's). You could dog it, shift into 4th gear running 25 mph. Put the pedal to the floor, and it didn't buck, jerk, or anything but start gathering up the speed like a freight train. I loved that car and engine combo. Still kicking myself for selling her. Hopefully she's still in the hands of Delmer McAfee in Odessa, Tx.?

[markjohnson]

Hey Rick, it's strange that you had a '62 bubbletop with an LS-5 back in the eighties in Texas. I remember my my father bought a red '62 bubbletop out of Texas back in 1986 that had an LS-6 454 in it. It had a powerglide though instead of a 4 speed but it also had the big 2 1/8 Hookers and a Holley three barrell carb on the stock aluminum pancake manifold. Lots of similarities there. Try to dig up a photo and I'll do the same on my end. Car was red on red by the way.