I'm sure this has been asked before, but when I did a search for it it pulled up some odd 1000 results, and I only found inconclusive information in the threads I did read. Would it be more worth my while to find an L98 block, and put the money into restoring it to spec, and then building it up, or would I be better off buying a ZZ4 block? And some of the threads talked about the differences between the ZZ4 and the L98 being in the bottom end. Well, I'm talking just about blocks, and barring the 2 bolt/4 bolt main issue (I believe I can get the L98 machined to a four-bolt splayed cap, which would eliminate that advantage of the ZZ4) is the ZZ4 block really any better than the L98, or any other Gen 1 SBC? If so, which is the best Gen 1 Bowtie Block (not aftermarket. I know better can be had there, at aftermarket $$ though).

 

The condition of the block is more important than what casting it is.

 

That was fast. But otherwise if the block is in good working condition, I shouldn't really have a problem other than having it machined to spec?

 

For a streetable engine, any block in good condition will do.

 

Other than flat tappet or roller cam and 2 pieces rms and 1 pieces rms, and main cam number, a gen 1 small block is pretty much just that.

 

Okay, at the risk of sounding dumb, what is a main cam number? Is that the size of the bearings at either end of the cam, or am I overthinking this, and it's like DOHC, or SOHC?

 

I believe he was trying to say the difference in the number of main cap bolts.

The ZZ4 and L98 blocks are the same casting. The ZZ4 is machined for 4-bolt main caps (center 3 only). It also had a steel crank, but you were specifically not including the crank in the discussion.

It could be argued that a 2-bolt main cap block is stronger. It becomes even stronger when 4-bolt splayed caps (aftermarket - machining required) are installed.

I would say any one-piece rearmain seal, roller lifter cam block is the best choice. That would include L98, ZZ4, LO5, and L31 engines. However, some LO5 blocks (installed in trucks) didn't have the roller cam provisions machined, so watch out for that if you want to go with a factory-style roller cam.

 

That was exactly the information I was looking for. All of those engines are basically the same, with the L98 and the ZZ4 being the exact same casting. I hear some of the early L98 blocks had flat tappet cams, you wouldn't happen to know what year they all went roller, would you?

And a one piece rear mains is better because it has less chance for leaks, but I was reading that there are more cranks for a two piece rear mains?

 

OR TRY TO FIND OLDER BLOCKS WITH HIGHER NICKLE CONTENT....PRE 76 BLOCKS.?

 

It's spelled NICKEL.

When you spell it the other way it's my last name.

Sorry, couldn't help myself. But it's a good suggestion nonetheless.

 

It's too hard to tell if a block actually is a high-nickel block (the much touted 010 casting mark behind the timing cover is unreliable at best), and nickel content won't make a substantial difference in strength for street use.

 

Yea, there tends to be more selection as far as cheap bottom end parts (crank) for a 2 piece RMS, probably due to the fact that there's more of them out there.
I'd still go for a 1pc RMS, due to the cheapness of using a roller cam in it. Roller cams are the cats *** right there.

What's the L31 block? I mean, what's it found in?

As far as "easy to find cheaply", L98 is probably the most rare (well, along with ZZ4, not gonna find that in a JY), whereas truck 350 roller blocks should be pretty common. Not sure what fraction of truck 350's had roller cams (or provisions for it), and what year it started though. L05 is the TBI 350 used in caprices and trucks IIRC.

 

Sometimes it's cost-effective to use a common and relatively inexpensive 2 piece RMS crank in a 1 piece RMS block.

 

So the plus side of the 1 piece RMS is that most of them have roller cams, but the 2 piece RMS generally have flat tappet cams? How would you use a 2 piece RMS crank in a 1 piece block?

 

The 1 piece RMS blocks are the "factory roller" blocks, except for some of the LO5 truck engines. You can usually reuse most of the factory roller valvetrain, saving quite a bit of money.

All 2 piece RMS blocks had flat tappets from the factory. To put a roller cam into a 2 piece RMS block requires the use of more expensive retro-roller lifters.

There are adapters available to put 2 piece RMS cranks into the 1 piece block. The adapter itself can be a bit pricey, but sometimes there can be enough of a difference in price between 1 piece and 2 piece cranks to make it worth it.

 

L31 = truck Vortec.

Roller lifters came out from the factory in the 1987 model year. The only L98's that would have flat tappet cams/lifters were in Vettes. 1-piece RMS came out in the 1986 model year. Makes those blocks very odd-ball.

I've heard people try to argue that the 1-piece RMS cranks are heavier and therefore not as good for performance. I don't buy it. The aftermarket has responded very well to the 1-piece RMS application, so I can't see how you could use that as a factor in the decision. If you're going stroker, the 1-piece RMS are easier to find internally balanced - personally, I find that very attractive.

I would say the casting and machining quality of the '87-up blocks is far superior to what they were doing when the nickel content was higher. The bore wear on my 180k LG4 block was near nil - I never saw that in 60's-70's blocks (although admittedly, engine oil has also improved since then).

 

So 86 and earlier blocks are Gen 1 and 87 and newer (minus LSx) are Gen 2's?

 

No. LT1's (reverse cooling, Optispark ignition, etc.) were Gen II.

 

And the LS's are Gen III/IV depending on the LS.