an updated 496 bbc combo

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
heres a rather interesting post , a guy on a different web site made about upgrading a street driven 496 BBC

ShouldntBeHere posted this interesting bit of info


I recently had Mark refreshen my tried and true 496 that he built for me over 9 years ago. It had 25k miles, almost 100 passes, and countless street races and highway pulls, not to mention 2 cross country road trips. I was restoring the car so it was a good time to go through the motor. Mark has wanted to update it for a few years now, both with changes in port design and windage control. Originally, 9 years ago, it made 661.8 hp @ 5900 / 674 tq @ 4400..


After a refreshen, updated heads, new cam and valve train, here is what he have now:

1Jd4b40l.jpg


DG9DATDl.jpg



We spent the better part of a day testing different things I always wanted to know about...different carbs, distributors, air cleaners etc... We made 14 pulls, as the day went on, we started loosing a little baro pressure so we decided to call it a day.

Here is a vid that Mark made of the engine the day before it was final tuned..
GM Iron Oval Port Headed 496" Big Block Chevy Dyno Test - YouTube


The new combo is:
496" (reused the same pistons)
9.8-1 compression
GM 049 oval port heads with 2.19"/1.88" Ferrea valves and a lot of work in the ports/bowls/chambers. Flowed in the 320s @ .600"
Isky 248/258* @ .050", .608" / .617" lift, 109 lsa HYD roller cam, Morel SOLID roller lifters, tight lashed.
RPM Air gap intake (stock)
#4781 Holley 850 DP (also tested an AED1000). Peak numbers were with the 850.
Windage tray and oil pan mods
A lot of attention to every detail in the engine, especially valve train weight.


Roughly a 37hp gain, 5# avg tq gain, better oil pressure through out...And extended my usable rev range by 400-500 rpms...

I'd call this one a win.


I can't wait to get it in the car, dial it in and see how it does..... I'm hoping to bust 130 mph traps with the rest of my car combo identical as before. We'll see.
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The 496 BBC is the best value Chevy Big Block Combo I agree Grumpy.

Pontiac guys are fighting similar.
$20k for a DCI RAV top end with custom headers to match.
Still can not get 1000 Hp N/A pump gas easy at justifiable cost.
Decent idle street manners also.

Make due with less.
Change gears. Highway gear.
Dragstrip gear.
Middle of the road 3 series gear for street action.

The aftermarket block for Chevy BBC and Pontiac just costs.
Has to be fully BHJ Blueprinted too.
Adds $650-900 more money.

Many reports by BBC guys pushing it to 1000 + on stock production blocks.
Fully prepped of course.
A few Pontiac guys have done the same.

Turbo charging the answer.
Need a fat wallet.
 
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