bstbrgr

For Sale a G.M. 454 LS-7 crate motor dated 1974
$5,900 Thanks Strat 630-772-0554

mousecatcher

huh, did they re-use the LS7 designation? I thought LS7 was the modern 7.0L.

fcarga

Interesting, I didn't think that the 454 LS7 crate motor was still being made in 1974.

SDF

Check the LS-7 designation? The only option of the 454 in '74' was the 270 HP LS-4. There were two versions in '71'. That being the LS-5 and the LS-6. Hope this helps...........

TheSkunkWorks

FYI, many "modern" RPOs have been recycled once or more, including Z06, LS7, LT1, ZR1 (C3, C4 & C6)... Corvette's hi-perf heritage isn't exactly a recent development.

Note that the OP didn't say this engine was available in the '74 Corvette (in fact, tho it was listed as an option for a while, the factory never actually installed a 454 LS7 in a Vette), but one shouldn't confuse an old-school LS7 with anything less than the beast it is.

QbnSuperman

LS7 was originally a boat engine but installed in just one vette. it was recently sold at Barrett Jackson

Zip Corvettes

The LS7 was a 1970 454 option that never materialized, it was basically an L88 but a 454 instead of a 427. You could however buy them over the counter and that is probably why his is dated 1974. The new LS7 borrowed its designation from this engine, just like the LS6 borrowed it from the 70/71 LS6's and the ZO6 and ZR1 borrowed from previous models also.

Slalom4me

I am taken aback to discover people do not know about the LS7.
Funny how time wears away at legends.

The LS7 was used in boats but it was not a 'boat' engine.

The LS7 is a 454 ci (4.25 x 4.00) big block Chev rated conservatively
by GM at 465 HP. Third-party tests repeatedly reported considerably
higher figures. The crate version was a long block that came complete
with a dual-plane, hi-rise aluminum intake (and water pump, IIRC)

While the 450 HP LS6 was the highest performance engine installed
at the factory, the LS7 was swapped into cars like Novas, Chevelles
and Corvettes at the dealership level. This occured as late as 1974
and possibly beyond.

Somewhere I have an issue of Hot Rod (or possibly Car Craft) that
featured a new 1974 Nova (big bumpers) that had received an LS7
at Nickey. The article is particulalry memorable because the car was
FLOWN! out to the west coast on a shipping pallet in 747 in order to
beat a publication deadline.

Specifications:

• Iron block w/ 4 bolt mains & HP/HV oil pump & windage tray
• Iron heads w/ open chambers & rectangular intake ports.
  CR - 12.5:1. 2.19" Int / 1.88" Exh valve dia.
• Forged domed pistons with floating pins
• Forged rods w/ 7/16" bolts
• Forged crank w/ 8" harmonic damper and A/T flexplate
• Dual roller cam chain (similar to but not a Cloyes Tru-roller)
• Flat tappet camshaft & mechanical lifters
• Splash shield in the lifter valley
• 7/16" push rods, 7/16" rocker studs, stamped 1.7:1 rocker arms

As for the use of the LS7 in boats, one person here used them in
several jet boats for river racing locally, on the Rio Balsas in Mexico
and in New Zealand. Aside from blue-printing and durability mods,
the engines were used as delivered with great success.

My recollection is that the engines came from inventory that had
been built in the earlier part of the 70's. I do not recall LS7 dollar
figures but the impression was that prices were a value. I DO
remember that turn-key Olds 455 engines were going for $800
- these were popular for recreational boats and they were very
plentiful.

.

redvetracr

sold by GM under the part number 3965774....I still have the Chevrolet "hotline" paperwork (service list/tune up specs) dated 7-25-73 that came with mine....sadly I don`t have either the motor or the 67 silver 427/400 hp roadster it went into....but I do remember all the fun I had with it.

SDF

Good Stuff Guys! Learn something every day.........

bstbrgr

Your right on the money with your description of the LS-7, but you missed it has a nite tyrited crankshaft also(which is temp treated crank, the L-88's did not have). Real ratings of 560 HP and yes floating wrist pins not pressed like the other high horse motors had. Basically its a 427 L-88 in a 454 version plus the nite tyrited. This motor was never installed in any production car( it was for the 1970 vet but never installed factory) it's a over the counter race engine that was dealer installed or purchased over the counter back in the 70's. One bad (As_) motor!!!

Slalom4me

Brevity is the soul of wit. Neither characteristic being strong points for me.

Tuftrided, not nitrided.
Also, the rods were specially selected, then prepared by being peened,
magnafluxed and having the casting flash polished from the beam. The
rod bolts are undercut with a 'waist' left at the parting line.

How did this one come to be in your possession?

.

bstbrgr

Your right on the money! Tuftrided that's what I meant but I couldn't remember the word. I remember what it was but couldn't explain it exactly. It's so nice to hear true and accurate knowledge, the older info gets passed on and on and the info changes with time. But your right and accurate.
I bought this 19K mile 1969 L-88 427 Nova last year from the 2nd owner and in his garage he had this LS-7 motor also that he bought new from the dealership back in the day. He had some other neat tuff that I picked up also from the garage too. You can read the story a little on the drag forum under "67 drag vet" midway through you'll see the Nova. I was thinking to put this motor in my 1979 road race vet this spring if it doesn't sell.

Slalom4me

Sonofagun - you're the guy that bought John Bougher's '67 roadster !

I only came to know about him and the car through the thread you
started before going to look at the car, but wasn't THAT an eventful
and touching journey of discovery !


.

jakesindy

LS-7's Had aluminum heads just like L-88's

Slalom4me

Categorically wrong.

.

jakesindy

How do you figure l88 and ls7 had the same heads My father retired from tonawanda mark IV line after 30 years built just a few

Slalom4me

No disrespect to your father, but they didn't.

Perhaps you are thinking about the ZL-1, a 427 ci with both aluminum
heads AND aluminum block.

There were two versions of the L88 head: the first was an aluminum
closed chamber design, the second was an open chamber design.

The 2nd gen head was installed on L88s as well as the ZL-1. Pictures
also show that the 2nd gen had round exhaust ports that are larger
than the square ports on the 1st gen head and the iron heads.

The LS7 head was cast iron, with open chambers and square exhaust
ports.

Number 1 at Tonawanda !

.

jakesindy

I will scan in the plant assembly manual witch was used into the 80's to built LS-6 and LS7 create motors, tonight at home and post it tomorrow . Have you ever seen one. At the entrance to Tonawanda Mark IV building there is a zl1 l88 and a ls7 on display. Been there for ever And I think you need to Google it?? Sorry. In the 1970 corvette brochure it list LS-7 12.25 to 1 aluminum head. I used to run one in my S/G nova back in the 80's . Right from the dealer in 1984. Then I sent it to John Lingenfelter in Decture IN. John used to sell LS-6 and LS-7 crate engines Balance and blue printed

Slalom4me

Over-the-counter LS7s delivered here in the mid-70s were equipped
with the #6260482 cast iron heads.

2.19 Int / 1.88 Exh valves. Intake ports were rectangular, the
exhausts were square.

.