19Tyler74

Looking at what is advertised as a 71 LS6 motor.

Here is what the ad description reads:

"i have 1971 454 casting number 3999289 date h-31-71 heads are square port ls6 3994026 date f29-71 has correct intake and water pump and running engine."

Was wondering if anyone could tell me any info about what else I should ask about to find out if this is indeed an ls6...

From what I have looked up, it seems as though the heads fit the description, but the block could be from a truck.

I am thinking of putting this motor in my 74 - thoughts?

Also, what would be a fair price for the aforementioned motor in decent condition?

Thanks!

7T1vette

What good is an LS6 engine if it doesn't reside in the car having the same S/N? There were [probably] many LS6 engines sold "over the counter". There may be some market for it (if real) from someone with a pristine early 70's BB car {who wants to produce an accurate "clone"}, but it would be tough to find that person.

Good luck with it.

gofastvette

ask him what the valve lash is or what do you set the lash...as the LS-6 is a mechanical cam engine.....if he says its hydraulic and therefore no lash, then hes not selling a LS-6.....and could be lying about the engine to sell

Mike Ward

The LS6 did not use the 289 block- it used the 3963512. H3171 casting date is August 31 1971, long after LS6 engines for the 1971 model year ceased to be built.

Epic fail.

FlyLS6

Take a look here:

http://www.roadsters.com/bbc/

They show that block as being '72 - '79, two bolt. But, I'm sure some could have been built in mid/late '71. Don't know how reliable the info is, just happened to find that page one day.

But I see nothing wrong with the original idea, given the right engine. Here's my '77 LS6 crate motor in my '73. I installed it in early '78, along with ....188 open chamber heads and a ....198 L88 intake. Could care less it's a crate motor. Certainly looks more interesting than all the late model LS motors being swapped into C3s. So you pop the hood and see what? Fake "valve covers" and a bunch of tubes running across the top of the engine. Yea...that's real exciting.

Zedred

Mike Ward, I have to disagree with you about the 289' block, because I have a LS6 shortblock in my 69'(orginally L71) it is a CE engine that was cast in 1972 it has the original 840' heads, LS6 low rise intake,etc. 19Tyler74, you need to pull the pan and check
for steel crank, 4 bolt mains and forged pistons to be sure it is a real LS6.

Best wishes,

Richard

Mike Ward

A later service replacement over the counter short block that someone built- maybe even the factory, as a LS6 is a long way from the real thing.

joewill

the 289 block is a 72-75 passenger car block and was also used in trucks up to 1978. it is a 2 bolt main. definately not LS6 unless drilled out for 4 bolt mains.

the heads are from a chevelle according to my book. although according to my book, the ls6 was cancelled in 71.

i expect the engine is a pieced together intermix of parts that are at best spec'ed out to LS6 specs.. but is not a true LS6 that was put in a vette or chevelle.

it is pretty easy to build a LS6 spec motor off of ebay parts and then call it a LS6.

tracdogg2

A quick way to tell a 2 bolt from a 4 bolt without pulling the pan. Look at the oil pressure fitting above the oil filter. 2 bolt blocks use 3/8 npt. 4 bolts use 1/2 npt
Mike

Zedred

I'm not claiming its the original engine, but it is what Chevrolet used for
warranty replacements and over the counter sales, also the 289' block
was made in both a 2 bolt and 4 bolt versions, the later LS6 and LS7 crate engines both used 289' blocks.

Richard

Mike Ward

But that's strictly what the OP was trying to establish and what my post above addressed. There's no doubt that later crate engines existed and, as always, they used whatever current casting number component was in production at the time.

joewill

the point is that the seller is using the term "LS6" and trying to get extra money out of the engine because of that. what we are saying is that it is misleading to some degree depending on the degree of purist that a buyer might be. is an LS6 spec engine with pieced together parts a true LS6?

Zedred

I agree that it might not be a Factory built LS6, that is why I told the OP he should pull the pan, if it has the correct casting number on the crank and the correct casting numbers under the piston tops, that would give a good indication that it was a factory built LS6, the 1971 block casting makes me wonder if it could have been a warranty replacement or over the counter engine. The time period would be correct for this. Only God and GM know how many solid lifter Big Blocks were blown under warranty or just out of warranty.

FlyLS6

From "How to Hotrod Big Block Chevys", an image of the LS6 crate motor info.

The pic of my motor above is 1977 version, date coded E 16 77. It's a 959 casting number.

I have no idea if a 289 block was ever used. A couple of references I've seen indicate 959 blocks were built beginning in 1973.