Have decided to rebuild my matching numbers engine rather than go the crate engine route. What can I do to increase the performance while still having the
engine appear totally stock. Should I keep compression @ 10.25 to 1? Guys
over in the C3 forum said yes. Head porting? More aggressive cam?
This car is only driven on weekends so if I have to add octane boost I can.
I do want too keep original intake, Quadrajet carb and exhaust manifolds.
:confused:

 

If you want it to SOUND stock as well as appear stock you need to exercise some restraint on that camshaft and other hi po parts.

 

Would boring the engine to increase displacement decrease the value of the numbers matching block?

 

No boring has no value on the price of the car. No one could tell if it is bored and if the motor is rebuilt they expect it to be bored. You will not gain a whole lot of displacement by boring. I would go with a slightly more aggresive cam, mild port on the heads and you should pick up another 50 or so HP. Stock intake and exhaust manifolds are going to be the restrictions on that motor.

 

Ditto re Gordonm's comments above.

Boring .030 will increase displacement seven inches, a negligible increase.

Mild head work, and changing the cam, springs, and lifters would be the most cost effective improvement. Keep in mind that a cam swap may change the dynamic compression ratio, even though the static CR remains the same. Consequently, CR could become a problem, even if it isn't now.,

Other options to consider:

- Aluminum heads (better air flow due to modern design and bigger valves, less weight, increased tolerance of CR by .5 or so, can paint to resemble stock iron heads)

- Hydraulic roller cam and rockers (less friction, more air flow due to quicker opening and closing of valves)

- Stroker crankshaft to increase displacement (496 ci should be attainable)

- Extrude hone the cast iron exhaust manifolds to improve airflow

- Use an aftermarket aluminum intake painted to resemble the stock iron unit, along with an aftermarket Quadrajet carb having a higher CFM rating

- Build the motor to outwardly resemble a '69 L68 or L71, which would address the restrictions of the existing carb and manifold

Before you do anything, buy a desktop dyno program and plug in the changes you are considering.

Outside of the motor, you could lower the rear end ratio to 3.55 or 3.70 to significantly improve acceleration.

 

Thanks Guys,
Beautiful car Mike! :cool:

 

IMHO, one of the advantages of owning a 65-67 or 69 (my favorite C3) is the availability of factory side exhaust (I like the as-built, factory appearance of older Corvettes). There may be a small improvement in performance, but the attraction to me is how great the cars sound, particularly the big blocks.

Once you've heard the rumble of a 396/427/454 through those pipes, you'll never be satisfied with a stock undercar system.