jb78L-82

Seriously? You are kidding? The LS7 427 all aluminum V8 is a SMALL BLOCK-OMGA living legend

The LS7 uses a unique cylinder block casting with pressed-in steel cylinder liners to accommodate the engine’s large, 4.125-inch cylinder bores – with deck-plate boring and honing for optimized bore geometry.

LS7 Tech Specs

• Part Number: 19329246
• Engine Type: LS-Series Small-Block V-8
• Displacement (cu. in.): 427 (7.0L)
• Bore x Stroke (in.): 4.125 x 4.000 (104.8 x 101.6mm)
• Block (P/N 12602689): Cast-aluminum with six-bolt steel main bearing caps
• Crankshaft (P/N 12611649): Forged steel
• Connecting Rods (P/N 12661677): Forged titanium
• Pistons: Hypereutectic aluminum
• Camshaft Type (P/N 12638426): Hydraulic roller
• Camshaft Lift (in.): .593 intake / .588 exhaust
• Camshaft Duration (@.050 in.): 211° intake / 230° exhaust
• Cylinder Heads (P/N 12578449): CNC ported LS7-style ports; 70-cc CNC combustion chambers
• Valve size (in.): 2.200 titanium intake / 1.610 sodium-filled exhaust
• Compression Ratio: 11.0:1
• Rocker Arms: Investment-cast, roller trunnion
• Rocker Arm Ratio: 1.8:1 (offset, intake only)
• Recommended Fuel: Premium pump
• Maximum rpm: 7000
• Reluctor Wheel: 58X
• Balanced: Internal

jb78L-82

I guess I will take your non response as a no.....

worship79

All right! Save for the BB vs SB discussion I first will attend to disassembly and see what's left.

"Here" is The Netherlands (Europe) and I though there are plenty of GM cars driving around here, the market is small at any rate compared to the US. Example: a mere 1500 corvettes (all generations) drive around here.

An LS conversion is tempting, but the cheapest LS I can find at the moment is a little over $5.000,-
and then I need to modify just about everything fuel related. Also there are no ECU/ECM experts here that I know of.

Big blocks are a bit easier to come by, but those are usually the cheaper low-power versions. Also parts availability is a disaster for BB's (here).

So probably another 383 is order, or perhaps a 400/406. I can get a used 400 .030 over. This is a 2 bolt though, not sure if that really is a problem or not.

In can also get another 350, 4 bolt and 1 piece rear main seal. Perhaps build a roller stroker this time with forged internals.

Choices... I will keep you posted of progress!

jb78L-82

I did not realize you were overseas.

My original comment about sticking with the 383 versus going BB or even LS was based on the sense that you wanted to conserve funds and the 383 would be the easiest for you, the OP, to get what you wanted. NOT that all BB's for everyone are bad, despite the KIA comments from some above.....Good luck with your project!

lionelhutz

No, it's not 'just like' being a COMPLETELY NEW engine design. The first small block displacement was 262ci-in so really don't see your point about the displacement of the first LS Engine either. Besides LS1 is 345.7 cu-in, not 350 and LS7 is 427.8 or LSX goes up to 511cu-in which is a big block territory.


No, its nothing like the legendary small block that was in production for 50 years with a version that came in the C3. Trying to claim a big displacement small block would be just like your LS7 makes no sense.

OldCarBum

Let it rest before you ruin some one else's thread.
This is what always happens, its childish and unnecessary.

Vette5311

383 is a solid foundation, as you know, however don't discount the 2 bolt 400. If the block is good at 030 and does not need more bore, just put studs on the mains and you will be fine. Some say the extra material removed from the bulkhead to put in the 4 bolt caps actually weakens it more than the 2 bolt but that is another argument for another day. I ran several of these to 7000 rpm in drag cars with no problems and that was using the cast GM crank. (well balanced) Just make sure all your measurements and clearances are spot on. You will have to add steam holes to your heads if you can reuse them also. Since you need new rods, if you get small journal rods and offset grind the crank throws you can pick up a few more inches there also.

jackson

? Curious what price GM vortec crate pn 12530283 sells for in Netherlands ?
Now, they're as little as $1850 in USA
see 6+ year old thread https://www.corvetteforum.com/forums...tec-crate.html​​​​​​

HMMM ... ventilated 383 anaIysis... I applied latest Finite Element Analyses software and performed deep Failure Mode Effects Analysis and employed both FoMoCo 8D and 9D problem solving techniques; ALL while I donned a triple-layer tinfoil hat: determined Root Cause at 98.6% Confidence Level.
Window in left side of 383 due primarily to Rebuilder's Geographic Location.
First, y'all made shoes from Wood; but now it seems pistons too?

derekderek

The 400 block was weakened by drilling the 6 extra bolt holes into the 3 center webs. 400 2 bolt block is superior. This is established fact, not "some say". Are you sure the one-piece 350 is a roller block? Some are not. They started one-piece rear mains in 85 and roller cams around 87. Also, few roller 350's have fuel pump mounts machined. So you are looking at electric fuel pump. And stop using wood, unless girlfriend or wife or door panel trim is involved...

derekderek

Also, external balanced one-piece flywheels are not really scarce, but not common. My preference? Get the 400. You need a 400 crank. Mains are bigger than 350. Get aftermarket tie-bar roller lifters and a modern roller cam.

jb78L-82

You need to correct GM calling their LS7 427, a Small Block V8...they are idiots !

cooper9811

I agree with Derekderek, the 400 2-bolt is more than adequate for a fun driver. I ran one for a while, so researched the 2-vs-4-bolt option myself. Building a 400/406 does require some research in other areas too - for instance, what heads to support the cubic inches? What rotating assembly? What is your budget? Not sure what heads you have (had) on your 338,but I found AFR 195 to 210 are great on a 406 (but expensive).I would lean towards the 195s just because I won't tunr massive RPMs. If you go with other brands, I would look at minimum 200cc heads.

This next comment can open up a debate in itself, but drilling steam holes are really not required IMO - but doing it (carefully) won't hurt either if you decide it's safer due to the siamesed bores. That is also worth some research - I found lots of reputable builders who run heads w/out drilling, and have no issues. You can also get internally balanced rotating assemblies for a 400 - no need to go external unless you are reconditioning an original setup.

I ran a 406 with AFR 195s, a crower retro roller with 282ish duration and .500 lift, and an Edelbrock RPM Air Gap intake - I built it for torque not HP - and it was an absolute blast to drive. That is until I broke a rocker arm or two - so don't go cheap on the finishing touches like roller rockers (hard lesson learned, all the worse because I should have known better)!.

lionelhutz

Wow, you just don't get it. The LS engines are NOTHING like a small block engine. I will repeat it again and expand on what I wrote a little bit then give up trying to get through to you if you still insist on saying they are the same thing. Saying that a big cubic inch small block based build would work just like a LS7 engine makes no sense. The LS7 top end and intake and exhaust configuration is SO much different than a typical small block build that what works for one can't be directly applied to the other.

derekderek

I think his Edelbrock heads are 64cc chambers and 185 or 190cc intake runners a bit small but not horribly so for a 400. And they are already paid for, as long as they didn't die in the explosion. Also, as far as LS Motors? Yes they are small blocks. The only thing they share in common with the regular small block is the bore spacing. But that's enough to make it a small block. technically the big block is a small block. The definition of a big block is the block casting goes below the crank centerline like a Ford FE or a Chrysler big block. So by that definition a 429 Ford and a big block Chevy, all Pontiacs all Oldsmobiles are all really large small blocks.

jim2527

No experts needed. Harnesses and ECU's are plug n play. Besides, www.LS1Tech.org is only a click away.

squared

It's more economical to buy a car with an LS than to try and buy the engine by itself and add all the stuff. And Jim's right, they're pretty much plug and play. The most difficult part is getting around VATS with the PCM, there are many folks offering VATS disable service for not a lot of money (www.LT1swap.com). I bought HPTuners and used it, not really that cheap, but something new to learn if you're into cars.

I put a 4.8 LR4 in my boat mated to a Mercruiser...not really that hard.

jb78L-82

Dude, you don't get it! I am done with you!

sstonebreaker

Actually, if you were to install an LS conversion from scratch, the aftermarket has passed the OEM computers. The Holley Dominator will not only plug directly into the engine but will tune itself as well. You still have to do some manual tweaking to get every last horsepower out of the motor, but for guys that just want to drive around and cruise, no manual tuning is required. The only downside is cost.

I know the LS engines can be pricey, but on a cost per horsepower basis, they're probably cheaper than the old school smallblocks. You might look around and see if you can find a stock engine from a junkyard - if you're not going to add forced induction, even the 5.3 liter truck engine will give you as much hp as the old school 383.

DUB

No where did I read that 'jb78L-82' stated that an LS7 engine and a cast iron small block are the same thing. But he did write is that a persona can achieve the same if not MORE HP out of the cast iron small block. Which is true.

It seems that you do not get out much and realize that many of the cast iron small block engines at a drag strip can out perform or run along side with a stock Z06 fuel injected LS7 engine when you are comparing raw power and torque and how fast a 1/4 mile time is achieved. So getting the cubic inches out of that cast iron small block and making it run great is do-able; but at a cost....depending on how much you want out of it.

And it is common sense to realize that the top end of a Z06 LS7 engine does not compare in design to a cast iron small block engine is obvious....thus nothing can be taken off of one and put on another SO why even bring that into the conversation.

Seeing how the only mention of a cast iron LS7 engine ( if that is what you are referring to) was back in 1970 and yet it is hard no prove they were made available to the consumer due to that option was cancelled.

DUB

DUB

'worship79'

Now knowing you are overseas, I hope you can find what you are looking for to repair what you have going on.

I have a source for good used running LS engines out of Corvettes if interested. I can turn you onto them and they do ship overseas. If that is something you may be interested in.

DUB