L98 Crate Engine
 

I've been looking for a replacement engine for my 85 L98 for awhile now and GM has disco'd the part. However, I did find a short block L98, P/N 12510737. Is it the same block? It states its a 2 bolt main, I thought C4 L98's were 4 bolt mains. Anyone have any info?

The ZZ4 crate motor is a good replacement for the L98. It has 4-bolt mains, aluminum heads, and a forged crank. It also has a one-piece rear main seal and a roller cam.

While it's advertised at 355HP and 405 ft-lbs of torque , that will drop somewhat with the stock L98 intake. You get a 4-barrel carb manifold and a long-style water pump but the L98 accessories will bolt up.

Add a set of headers like the Heedman Elites and you should have close to 300-320HP in a nice package that comes with a GM warranty.

I'd look at the Coast High Performance 383 short block.

This all depends on where you want to go with the engine, and budget. If you'd like something thats a basic replacement, with a nudge up in power, go with ZZ4. It would run best if a chip was done specifically for it, but it'll run without that done.

It wont make the advertised power, by a longshot, but its a step up.

Your '85 is a 2 bolt main.

L98
 

L98 is 2 bolt main until 88 I think,
1. The 85 is a 2 piece rear seal.
2. The 86 has 1 piece rear seal, but flat tappet cam
3. early 86 has cast iron heads, 1 piece seal, flat tappet cam
4. late 86 has 1 piece seal, flat tappet cam, but aluminum heads (cast
iron clones) straight plugs
5. 87 has modified combustion chamber heads, roller cam, and
aluminum heads, angle plugs, guided rockers 1 piece seal
6. 88 has 4 bolt mains, aluminum 58cc heads, dished pistons, roller
cam, roller lifters, 4 bolt mains, guided rockers, angled plugs
7. 89 has 4 bolt mains, 1 piece seal, roller cam, roller lifters, 58cc
combustion chambers, angled heads, guided rockers, elimination of
exhaust valve rotators, elimination of start injector, new style relays
new style electrical connectors and pins.
ok, someone who really knows jump in here............

there were no 4 bolt main L98s.All 2 bolts.

:iagree:

My '90 is 2 bolt as well... one piece yada yada...

Bascially, I'd like to keep it as stock as possible as to not affect driveability, so I'd like to reuse my stock intake, etc. I've seen the short block sell for as little as $850. It will cost roughly $2500 to rebuild the engine that's in the car now. Ideally, I'd like to start with a new, improved "bottom", install whatever else is needed from the original engine and upgrade as the mood suits me in the future. I'm not looking for astronomical HP gains. I'd like to keep it simple, inexpensive and reliable.

:iagree: You will have a well balanced street motor with the ZZ4. It may look like you are going to do it for less with a short block, but that is doubtful.

I'm actually starting to go that route. It seems all it comes complete with the exception of the intake and exhaust manifolds, etc.

My buddy uses Jasper rebuilts in his shop for his customers and he swears by them. He suggested I try them too. So, I looked up a rebuilt L98 and its roughly $2000 with the shipping. Anyone use these guys?

I rebuilt a 2 bolt 355
 

I took a core short block and had it bored 30 cleaned squared, balanced the rotating assembly , new pistons and rings , rods resized and checked, new rod bolts pistons pressed on but not installed, crank ground 10/10 and that was I think it ,, any other common rebuild stuff etc, along with gasket set and spent 1285 dollars. A cam and time chain set added another 350 approximately and plus push rods, oil pum , pump pick up, new timing cover, the list is very long,, anyway this is just the shortblock. I would say it got close to 2000 without heads. Anyway the point is ,, if I had it to do over,, I would have gone with the ZZ4 and probably been money ahead.

I still have the motor and will hopefully find a home for it someday,, I topped it off with some Edelbrock heads and some 1.6 roller rockers. It should be a stout street motor with minimal headaches. Good Luck

Our shop uses Jasper for remanufactured motor installs as well as their trannies. Good reputation and good build quality from them.

A ZZ4 is getting to be close to 4 large for a motor but this is a completely new motor; new block, crank and all new parts. If you rebuild your own motor, you really have to find a machine shop that you can can trust and will stand behind thwir work. The quality level of the parts a shop puts into a rebuild is important too.

You might check the GM Performance Parts catalog for short blocks and their other complete motors. Buying a complete motor save a lot of time by not having to wait for a machine shop and paying extra for them to assemble it or taking the time to do it yourself.

:iagree: :iagree:

Have you seen my pitch favouring of the L31 shortblock? This
together with a set of TFS 175 or AFR 180 heads and a modest cam
would result in a package that would fit in well with the rest of your
existing drivetrain, provide a healthy boost in power and not break
the bank.

Back in Jan, the L31 4-bolt short block p/n 12556121 listed for
$1,142.96 at gmpartsdirect.com. More info about the L31 appears
in 'L31: Flat or Roller Tappets from GM?'

The ZZ4 has some nice components but my vote is that the heads do
not perform as well as delivered as newer offerings and the cam is
intended for an RPM range above where the L98's TPI begins to sign off.

.