m1982

Hi
I just wanted to hear how the forum feels regarding the difference between the two big block versions.
:)
Are the two equally reliable (when unmodified) and is the 454 better for crusing/ more streetable? :confused: :

Wrencher

3X2's are cool to look at and deliver good power (obviously), but all multiple carb setups are a maintenance headache at one time or another. If you want reliability, go with the single 4 barrel. They can deliver the same, and more, power and they need very little upkeep. Now me, I love multiple carbs! I have 4 (!) on the Corvair, and 2 Carter AVS's on my 409 (still looking for a recipient vehicle), besides the L-68.

Hans

garagedweller2

i agree with wrench- multiple carbs are :cool:



[Modified by garagedweller2, 11:08 PM 1/31/2002]

67HEAVEN

If we're talking about stock engines, my comments are:

L71 (427/435 gross hp; it was under-rated):
- compression was 11.0:1 (can you get enough octane?)
- lifters were mechanical/solid (do you know how to lash them every so often?)
- made when unleaded fuel didn't exist (will your valves object to no lead?)
- 3 x 2 bbl setup (if they haven't been rebuilt, they'll need to be)
- 4-bolt bottom end (stronger rods and bolts in 1968/69 than 1967)
- revs quickly and the bottom end will self-destruct if proper attention isn't taken to either the tach or correctly building the bottom end
- driveability can be difficult if you're not into maintenance and noise (running hot, somewhat lopey idle, fuel requirements, noise level).

LS-5 (454):
- 1970 horsepower - 390 (gross)
- 1970 compression - 10.25:1 (getting enough octane shouldn't be a problem)
- 1970 lead requirement - not sure (probably none)
- 1971 horsepower - 365 (gross)
- 1971 compression - 8.5:1 (octane no problem)
- 1971 lead requirement - none
- 1972 horsepower - 270 (net)
- 1972 compression - 8.5:1 (octane no problem)
- 1972 lead requirement - none
- 1970-72 lifters were hydraulic
- 2-bolt bottom ends (therefore weaker than L71)
- don't rev as well as L71
- driveability is good (like most regular passenger cars)

NOTE: Very few parts are interchangeable between the LS-5 and the L-71, even if they had both been the same cubic inch displacement in the first place. They were quite different engines (street vs. semi-race). There really is a world of difference in the feel of these two big blocks.

Hope this helps.

P.S. to garagedweller2. Nope....there is no substitute for cubic inches.
You'll know when you reach 18 and if you put your foot into a big block for the first time!


[Modified by 67HEAVEN, 8:12 PM 1/31/2002]

zwede

67Heaven:

Good comparison. Just one note: My '71 LS-5 has 4 bolt mains. I hear many (but not all) LS-5's came with 4-bolts.

Tom73

You all mind if I go a little off topic here. I love that tri-power, 435 GROSS hp, great engine, would love to have one. Just think, in its day one of the hottest cars around and one of the hottest street Vettes in history. But, fast forward 35 years to the new Z06, 350 small block, 405 NET hp, avaialble with all the comforts a drive could want including A/C. What a difference the world of electronics has made.

But back to the topic of discussion. For street driving on a regular basis, the LS5 hands down. Weekend driving, the tri power.

tom...


[Modified by Tom73, 10:00 PM 1/31/2002]

Wrencher

Sort of on the topic of practicality, I'd love a Z06 or even a regular C-5 for a daily driver. But I can tell you from the short time I've had the 'L-68, If a Z06 and a sidepipe 69BB follow each other down the street, that late model might as well be invisible to most people. Something like a Harley versus the much faster and more practical Buell, lets say...

Hans

Chuck Harmon

Tom73 and Wrencher are right on. The Z06 is a fantastic machine that has brought back more horsepower than I ever thought would be available through a factory car again. But it is the high strung Big Block that really gets the heart racing when behind the wheel.

If you just want a smooth ride with locomotive levels of torque, the LS5 is the best combination. Having a car with a high strung personality can be a high maintenance relationship. To some of is it is worth it because such cars make us feel like we are needed!

Chuck

m1982

So if the main concern is citystreet driving, going for 5-6 secs 0-60 times :cool: (L-71 and LS are fairly equal 0-60 I guss)

then the 454/390 should be the choice.........

67HEAVEN

Slight edge (0-60) here for the L-71 (depending on who's driving), but yes, in terms of driveability, choose the LS-5. If you're like me, though, it's hard to resist the L-71 lopey idle, the sound of those L-71 solid lifters, and the thump, thump of 11.0:1 compression.....but that's just me!
:blueangel:

m1982

10,25:1 :eek: (1970 LS-5) compared to the 11:1 :mad can there be that much of a difference in the sweet sound the produce :confused:

67HEAVEN

Yep.

LT1driver

I have owned both.....no comparasion, L-71 wins with a take no poopie attitude. Both are streetable, drove both dailey to college with no problems, L-71(435 car) actually got better gas mileage, 3.55 gears vs 3.08 for 454. :D :D :cool: :cool:

m1982

Aanybody got a wav file sample...................... :crazy:

67HEAVEN

Oh, you're gonna like this page.

If you remain unconvinced about the sound of a L-71 after this.....well :confused: http://www.jeffbarnettproductions.com/main.htm

And in particular...http://www.jeffbarnettproductions.com/startupgui.htm
P.S. This sound is sidepipes only.......no headers :crazy:
Still think a stock LS-5 sounds like that? :D

Or, goes like this?
http://www.jeffbarnettproductions.com/vette_gui1x.htm


Thanks to Jeff Barnett for his great site. I think he's a member here, but I also see him on the Corvette-Resto threads......you too JohnZ.



[Modified by 67HEAVEN, 11:53 AM 2/2/2002]

m1982

sweet music is in my ears :D

Any 454 wav files out there :confused:

Truck Guy

Thanks 67HEAVEN :cheers: Jeff's site is great :yesnod:

m1982

Does the high revving nature of the 427/435 engine mean that it has to be rebuilded more frequent? (High revs = more engine stress?) :confused:

427TRI

Might be. While the oval port motor is a more subdued beast, I get 17+ mpg on the highway, powershift at 7000 and show near 550 hp at the crank. Only concession to modernity is cam grind and HEI conversion on the small base.

435 HP hands down. Nolo contendre!