Basque32

Hi all,

I haven’t been on here for a while as I’ve been working on restoring a family heirloom; the house that my wife’s grandfather built in the 1940s that we purchased a few years ago (another money pit! Lol).

So I just bought a Lt-1 short block that was advertised in the part section (https://www.corvetteforum.com/forums...ck-2500-a.html) and plan on replacing my current engine with it. The current engine in my 73 Vette is a CE block but it’s got the wrong casting number for the 350 (it’s a 512 block vs. 010). The Lt-1 block is supposedly, and looks to be, a CE replacement short block that’s never been fired (1974 build date).

My goal is two-fold, first is to have a more correct block which this block is to some degree (my73 is an L82 model) and second to have a better performing engine as the one I have while supposedly having the guts from the original L82 doesn’t perform all that well. My only evidence of the L82 are the 492 camel hump heads which are supposedly correct for this year and would have been swapped over when the original block was replaced (I have no paper trail on engine replacement).

The Lt-1 short block has the forged crank, dome pistons, pink rods, cam, 8” balancer, oil pump-pickup, and windage tray. I plan on using my performer intake, Rochester carb and HEI distributor and the aluminum valve covers from my existing engine. So I need heads, rocker arm assembly, push rods, etc. and I probably would replace the cam as I assume it’s one designed for solid lifters as I don’t think I want to deal with solids.

As there are no heads I would like to go with aluminum heads if that makes sense for this type of engine? Also, I don’t think I want to be adjusting valves on an ongoing basis so I would like to go with a hydraulic cam vs. the solid one that’s supposedly in the engine (btw, I don’t have the engine yet, it arrives either Thursday or Friday).

I’m also a little concerned how high the CR might be on this engine with the dome pistons. I’m not opposed to replacing those if that makes sense as I think the cylinders should be honed anyway as there looks to be some evidence of minor discoloration in one of the cylinders so most likely the other have some discoloration too.

BTW, I’m not an engine builder but I have one on tap that I plan on using to do the assembly work and post assembly testing.

I’ve learned a lot from this forum and I appreciate all of your advice.

Regards,

Marc

73racevette

Don't see a question in there...

Go with what your engine builder indicates.

derekderek

You want correct block and suspect the heads are original? Why not check the date codes for further verification and consider using them? A hyd roller with tie-bar lifters should also be considered.

Basque32

73,
Thanks for the reply,
Yeah, I get that now that I re-read it. So from my title I was looking from all you knowledgeable people how you might recommend building this engine. Maybe I should have just provided the link and asked how you (or whomever) might go about building the short block with the comments I made.

Basque32

dereck,
Thank you for your reply.
Good point on the heads, I think I've got a pic of them on my pc at home, I'll check the date code. I too was thinking hyd roller, thanks for that suggestion.

Cavu2u

Good luck and keep us posted on what you choose on the build.

Steve

Kacyc3

Im reading mixed signals here.
You say the block in your car isnt orginal and you want this LT1 becuase it is date code close and sounds like its built to original specs.
You mention the current engine has what you believe to be the stock heads for the L82.
The next thought is since there are no lt1 heads I want alum.
If you want date correct put your 492s on the lt1 with l82 cam and enjoy. If not whats the point of the lt1 with alum heads vs a 383 with alum heads?

Personally unless its some rare optioned car worth lots of money sell the lt1 short block to someone doing a correct resto and will pay good money for that engine. Rebuild the existing engine or get a crate engine to beat on and not car about originality.

jackson

OP basque
Assuming NOS shortblock is genuine LT1, I think $2000 - $2500 delivered cost justified ...
... but best used by someone wanting & needing a real LT1. Just not for your stated purpose.

AFAIK ... No L82 came with or offered OE camel hump heads ... LT1 yes, L82 no.

So ... your car is a 73 L82 ... its OE motor is lost. Your year Never offered LT1 or 64cc heads or solid lifters, right?
Seems car's current motor has cn 512 block (maybe 327 block) with cn 492 heads (maybe otc 64cc).

Seems you don't want to be bothered with solid lifters or high-compression's octane requirements.

So ... why cherry-pick a genuine NOS LT1 shortblock for a block or some rods?

FWIW ... most modern-design performance heads are Not intended for use with domed pistons ...
... they both burn & flow best (i.e. make best power) with flattops or D-dish.

FYI ... if you swap the LT1's domed pistons for something else, those ain't likely to be a weight-match ...
... and the entire rotating assembly must be professionally re-balanced by an auto machine shop.

Seems to me, your $-time better allocated buying or building a motor with no more than 10:1 compression, aluminum heads and hydraulic roller cam.
Maybe you make an earnest search for an L82 block correct for your year? Not on every corner but they're out there; takes time & work to find.

Basque32

Kacyc3,

thank you for you input, I will consider your advice.

Basque32

Jackson,

Thank you for your input. Good advice that I will take into consideration. FWIW, I did try looking for a period correct L82 block but did not have any luck in finding one. The thing that I like about this engine is that it's basically never been run so it's like a new block, has more correct parts that are similar/same to what my L82 engine should have had other than the pistons/cam, mine is already a CE engine so this too being a CE replacement engine is a wash in my mind. The casting number is correct, mine is not. So even if I just replace the pistons and cam with flat tops and a flat tappet hydraulic cam then it would be pretty much what the L82 would have. Unless I'm missing something here. As far as letting someone who might need a more correct replacement Lt-1 engine I'd be ok with that too but it didn't seem like there was any interest in it form anyone else?

Basque32

Thanks, I will.

suprspooky

I think it's a good foundation for a low cost 370-400hp build, new pistons will be in order as already mentioned. I think the LT-1 had forged internals so that's a plus, get the rods bushed for full float (can't remember if LT-1 was pressed or float), maybe upgrade rod bolts, balance with new pistons, throw on some RHS iron heads (or step up to Alum. if budget allows), a Hyd. Roller cam and you'll be happy. (yes the roller kind of negates low cost, but I think it's a worthwhile expense).

You probably will spend more this way than a crate motor, but you already have $2000ish in this so go for it.

Maybe the domes could be massaged to fit the newer heart shape, also Brodix heads usually have some meat to work with (75cc possible) to lower c/r.


As to the nobody else had interest point, I would guess most folks looking at true LT-1's need a number match vs CE

Basque32

suprspooky,

Thanks for the feedback. That's good information. Mostly what you are suggesting is along the lines of what I was thinking as well. And you're probably right about the CE where my existing is already a CE block, so...