apehead

Hello all,

I've been circling this 1977 Caprice for a couple weeks now, and I think I'm going to take the plunge. As I began to contemplate building a 350 for it from scratch, the proposition became more and more intimidating. Then took a look at Dart's website, and noticed the MSRP for their SHP short block vs the bare block. They are built almost exactly how I was planning myself, and they cost about as much as a do it yourself job. So I am now pretty set on just buying the whole short block. So I head over to Summit to see what else is out there. I stumble across a GM Performance ZZ350 short block, and it's even cheaper! So now I'm torn. Both have some pros and cons. This will be a 4000lb daily driver with a 200-4R, EQ 64cc vortec heads, an HSR EFI, 3.73 posi, and target output of 400HP / 430 Ft.Lbs. with a 5500 redline. Also considering a 75-100 shot NO2 system.

DART SHP 372CI SHORT BLOCK

4.125 BORE 3.48 STROKE
CAST STEEL CRANK
HYPER FLAT TOPS, FLOATING PIN
4340 FORGED I-BEAM RODS
MOLY RINGS
CLEVITE BEARINGS
PRICE: $2975

GM PERFORMANCE ZZ350 SHORT BLOCK
4.00 BORE 3.48 STROKE
FORGED 1053 STEEL CRANK
HYPER FLAT TOPS, PRESSED PIN
POWDERED METAL RODS
? rings
? bearings
PRICE: $2379

SHP - PROS

More displacement (more power!)
Beefy SHP block
Higher compression

SHP - CONS

More Displacement (more gas!)
Cast crank instead of forged
More expensive

ZZ350 - PROS
Smaller displacement (less gas!)
Forged crank
Cheaper

ZZ350 - CONS
Smaller displacement (less power!)
Description less specific
Weaker late-model OEM block
Less compression

So, as you can see it's a toss-up. Which would you take? Are there some other options I should consider?

Camarslow

If it was me, I'd go for the 372, you'll seriously appreciate the extra cubes to get that boat moving.

gregsz-28

iTrader: (1)

+1 for more cubes. With 400hp/430ft.lbs., and a 5,500 redline, a cast crank (especially an aftermarket one) would be sufficient.

apehead

Another concern I have with the 372 is the inability to rebore the block. If I'm spending the money, I'd at least like to get a rebuild or two out of the deal. I'm assuming you can't rebore those blocks. Is that true? Also, since the increase in displacement is all in the bore, would it really help low-end torque all that much, or just high rpm HP? Damn these compromises. I wish I could get the Dart block with the GM displacement, crank and rods, and the Dart pistons!

gregsz-28

iTrader: (1)

why do you think you couldn't overbore it?

apehead

I just took a look at the Dart website, and the maximum recommended bore is 4.165, so I guess it's got at least one rebuild in it, maybe two, hell that could be 300,000 miles worth of block, so I guess it ain't much of an issue. Do companies usually "season" blocks before they are assembled into short blocks?

Camarslow

I don't think so unless it's stated in the product description.

apehead

Hmm... maybe I should try to find a machine shop that builds short blocks from remanufactured blocks. I might be able to get some goodies that aren't options in the Dart or GMPP short blocks (total seal rings, partial block fill, blueprinting, etc.) any recommendations in the Connecticut area (or guys that ship for cheap)?

1brd2brd3brd4

Check out YEAR ONE. They have thier "Power crate 350". 400+hp,400+lbs/ft torque,9.5:1 comp,Ported vortech heads,dyno-tested w/ dyno sheet, 12 month 12,000 mile WARRANTY(Key words!) for 2,990.00 +tax and shipping. thats a HARD deal to beat!

gregsz-28

iTrader: (1)

I agree, a warranty is important, but a 12,000 mile warranty sucks. IIRC the GMPP crates come with a better warranty than that. You could probably find a local shop that would give at least a 50,000 mile warranty. And, I'm sure wherever you buy an engine from will be able to ship it to you for only a couple hundred dollars.

apehead

That YearOne crate is a great buy, but I have two concerns: the cast iron crank and the stock vortecs. I've heard that the OEM vortecs were prone to cracking due to thin castings, and I'm not sure if the iron crank is up to the job of handling that amount of horsepower/stress for 100,000+ miles. Any thoughts? Would it be worth it to look for a somewhat more pricey crate with EQ, RHS, or GMPP bowtie vortec heads, and a steel crank? Or is this being overly paranoid about component failure for my HP/Tq window?

iroc a 86 berli

id go with the dart short block.

apehead

Ha ha, found this thread while searching for comparisons between the ZZ4 short block and the Dart SHP short block! How little things change...

The '77 Caprice coupe is gone, had some kids, left the GM world for the tame dependability of Toyota for several years... recently sold my Tacoma because a two seater just can't cut it with a minimum three passengers, and it was far too nice and valuable for the dump-run mobile it had become since I stopped daily driving it.

So yesterday I bought a '94 Suburban, and am already searching for new engines. I will keep barraging you fine fellows with questions until told to shut up, since this forum seems to be the premier source for all things GM fuel injection and 80's 90's GM drivetrain info in general.

Definitely leaning towards the SHP 400 short block in this beast, but the ZZ4 is literally HALF the price! That does make it a bit of a struggle to decide... judging by the comments regarding the Caprice, I already know where you all stand on that subject in an even HEAVIER Suburban.

So my paper engine at this point consists of:

SHP 400 short block
Promaxx 185cc runner iron vortec heads
Edelbrock Victor Jr. 2bbl vortec intake
Hydraulic roller cam (haven't picked one out just yet. Suggestions?)
454 TBI throttle body with 9C1 police package (65 lb/hr) injectors.

Next would be the tranny. This truck has over 200,000 miles on it, so it needs a rebuild soon at least. I've heard the 4L60E transmission is somewhat weak, so is it more economical to buy an HD 4L60E, or upgrade to a 4L80E, or maybe a 4L65E/4L70E?

Can I find out the rear end gears from the VIN code?

Thanks

apehead

RPO code "GT4", 3.73 gears

five7kid

iTrader: (14)

If it's 2WD, 4L80E.

The 4L60E is only "somewhat weak" in comparison to a 4L80E.

Kingtal0n

Lots of completely stock 5.3L LSx engines are $500 - $800 from junkyards and go 50,000+ miles with 500-600bhp reliably.

I would never spend more than 1k on an engine to support 550rwhp for 5-10 years. The place to put the money is in the transmission, get a really well built automatic, like from Dana at Probuilt. That is where the fun is at on the street, once you have the power.

apehead

Overhead cam LS engine would be sweet, but the complexity and cost of such a swap is way out of my depth.

Sort of the same story with a 4L80E swap.

A Gen I block and 4L60E just need to be built and re-attached.

I'm not trying to run 10's in a 4wd Suburban! It would be pretty nice to have a roaring 450 hp that will last for years with a tranny that can handle the juice for years.

That is why I am so enamored with the SHP block and the Promaxx heads. Very thick castings for increased rigidity and proper ring and gasket sealing. I wish there was a performance cast iron intake manifold I could use!

The original drivetrain made it past 200k miles with no failures. I hope I can replicate that success with over twice the power for under $10K. That's the "win condition".

Orr89RocZ

iTrader: (20)

For an all motor car you can go alot further and still have good wall thickness. 4.185 is doable

I would just go 400-406 if goin dart block. I also rather see a forged crank

aliceempire

iTrader: (14)

Not trying to tell you what to do, just trying to lay out some facts.....LS engines aren't overhead cam, they really aren't that overly complex to install (including the 4L80E swap), and you won't hit $10K for twice the power output of the original powertrain using LSx powertrain. I don't think it would be any harder than the swap you're already planning. But it's totally up to you. I like to do things my own way aswell. I'm not sure why you want to put thousands of dollars into a 200K mi truck though.

apehead

Chevy still makes pushrod engines? Wow, I can't believe it!

No offense, but I am somewhat skeptical of your claim. New engine, new ECM, new crossmember, new tranny, new wiring loom, new engine mounts...

That sounds way more complex and expensive than new trans and a new engine, maybe a new chip... maybe I'm wrong?

You're probably right in that investing that much into an old beater isn't very prudent. I've been considering putting the promaxx heads and the Victor Jr on the L05 and just tooling around until something in the bottom end or the tranny fails. At that point I'll probably broach replacement, since the frame is pretty nice, panels are in decent shape, etc.

aliceempire

iTrader: (14)

You probably wouldn't make the budget with a NEW LSx, but a JY donor 6.0L for sure. I guess it depends on how much you're detailed orientated and how thrifty you are. New crossmember isn't needed though new mounts are, and the wiring could be reworked. Exhaust would probably need to be fabbed, but thats needed with both engines and relativley easy on a truck. The rest comes with the donor. Mostly just odds and ends and details, but that's with any swap that isn't straight on bolt out, bolt in. Not trying to talk you into it. Just laying out what's possible.

A real set of heads will probably wake up even the most tired of 350's that had 093's on it. Either way, have fun with your project.

apehead

This truck has the swirl port heads on it, so the vortec style heads should net me something like 50hp, assuming the compression is still up to snuff. My fear is that this will kill the worn out 4L60E. Only one way to find out !