wnc71vette

I have a 71 conv and it came with 270hp. it now has MSD distributer, Torker II intake and a 488 cam, ceramic coated headers(sounds great!, but, still does not have the power I want. It has a 3.08 rear, which I am going to swap out for a 3.70 and see how that feels.
How much Horsepower can I get this 350 up too with out getting to much? is 375-425HP about right? Can I use the stock heads(of course rebuild them) or should I go aluminum?

SpyderD

Dude you will get so many different answers to this question...or none at all because people will be tired of answering them.

Anyways you need to change the heads, that's the key to power. Seems like you have everything else in place. Lower gears is a wise choice. You don't say how many miles are on your short block. If you've lived a good life your bottom end should take 400 HP range and that's about all you can get a N/A 350 to and stay streetable anyways (without high tech options added).

isosceles

you are going to feel a HUGE difference going from a 3.08 to 3.70 rear. Depending on your tranny (man or auto with ? stall converter), the base 270 HP and those mods you should be in the 13's for 1/4 mile ETs.

isosceles

you're on the right track. I learned the hard way. Set the car up right (gears, converter, wieght reduction and suspension) THEN throw HP at it.

Check out my signature: my 383 in Olivier's car was 1.5 seconds faster for the reasons I stated above.

Boofers

Switching from 3.08 to 3.70 will be a big difference. Your engine RPMs will be a lot higher though so be prepared to stop more frequently at the gas station, especially if you are highway driving. The ultimate would be to get an overdrive tranny.

Hopefully your headers are going to a true dual exhaust, at least 2" diameter pipes with new or no cats & decent flowing mufflers...

Set your distributor up like this: How to set your timing for peak performance by Lars

Unless its been done already there is a good chance you could find some power by tuning your carb, probably richer.

Switching to an electric fan instead of the belt driven clutch fan will free up a few horses.

Fuzzy dice from the rear view mirror are good for about 10 horses.

Otherwise here is a quote from an old race engine builder I know...
"Speed costs money, how fast do you want to go?"

Matt Gruber

yes, i can't even begin to answer without a budget.
is it $4500
$8500
$25,000?

holley505

Are you looking for BRAKE HP 400? Or RWHP 400

That will make a huge difference... assuming brake HP.
That would be about 330-340 rwhp. And that will still require HEAVY mods.

A 300 brake HP car should make about 250-260 rwhp
***depending on tranny and gearing...

which would be a low 14 to a mid to low 13 second car with a good setup.

YOU WILL NEED HEADS and good intake... can be iron (HEADS) but something with a small chamber 58cc-64cc 2.02 valves (maybe 1.94) //vortec heads a good and cheap?//

Head flow numbers depends on cam selection which depends on gear and tranny and exhaust....


QUICK! SOMEBODY GET OUT THE DEAD HORSE!!!

**KEY**
Gotta have a budget and a goal... and decide who is doing the work.

I am shooting for mid 12's in my 77 vette... I am almost 6k in it. Not including the car...

JUST parts and labor and things that POP up.

good luck

wnc71vette

my 71 has a 4sp, 2" pipes with cross over pipe. 105 miles on motor. I tried the electric fan, but went back to regular shroud and a better fan.
I of course will see what the 3:70 rear does, and then make a plan for the motor for this winter.
sounds like i will probably pull motor and go through with new heads, possibly alumium for good flow and shoot for @400hp.

holley505

400 Brake HP.... will be a NICE set of heads... AFR or Victor Jr with a cam matched to your rearend ratio vehicle weight. A compression ratio 10.0 or up

Longtube headers and at least 2.5 in pipes. Should be close to 400hp.