Don't be that guy.

A 3970010 block is probably about the most common 70's 350 block in history. If you want to know if it's a 4-bolt block, pull the pan and look. No one cares if it was originally in a Corvette or a truck, or an El Camino or anything else. The vast majority were gutless smog laden wonders. Trying to say it's from a "vette" or any other nonsense is just blowing smoke. Don't worry about the stamping, the chances that it hasn't been apart and/or rebuilt in 40+ years are pretty slim. The only way to know for sure is to take it apart.

 

That block is obviously not original to the car. Which means it's been torn down, all of whatever made it into whatever motor it used to was has been scattered to the 4 winds, and it's been "rebuilt" into something COMPLETELY else.

Those numbers stamped on the BLOCK tell you only about the original installation of the BLOCK. The tell you NOTHING WHATSOEVER about whatever the MOTOR that you have now is. I can assure you, from long years (decades... significant portions of CENTURIES...) that your cast iron retains NO MEMORY WHATSOEVER of whatever glamorous (or not) start to its life it may have been gifted. It has LONG SINCE forgotten what shape of sheet metal, or even fiberglass, it was wrapped in the first time it operated.

Once you have a "rebuilt" motor, all of that "codes" crap becomes LESS THAN MEANINGLESS. It becomes a DISTRACTION from things that DO have meaning. The SUREST sign of a n00b that I can think of, is somebody that thinks that those numbers, on a small block Chevy BLOCK, will tell ANYTHING at all that has use or value.

What makes a MOTOR includes the crank, the rods, the pistons, the heads, the cam, the machine work, the attention to detail that went into building it.

You can take the mightiest "LT-1" BLOCK out of a 70½ "Z/28" and turn it into a pitiful pathetic oil-burning 17-second 7-mpg SLUG. Similarly, you can take the BLOCK out of the lowliest humblest dowdiest 145 HP 76 Impala 350 2-bbl and turn it into a 750 HP Outlaw (ish) MOTOR.

EFFFF the "codes" on the BLOCK. Look at the PARTS and PERFECTION that went into building your MOTOR.

If you want to know how many bolts are holding the main caps on, count em. Look at the PARTS.

 

 

CLA
1973 350 190 HP 4BBL TH400
1974 350 195 HP 4BBL TH400
1977 350 180 HP 4BBl A/T

The bottom 8 digits are last last part of the VIN that the engine came out of. It's a pre 1981 VIN number.
1 - Chevrolet
7 - Date code and based on the above numbers, that would put it as a 1977
S - Engine plant Saginaw Service
42092 - Production sequence number. Starts at 10001 so that would be the 32091 vehicle made that year.

At least that's what the engine was back in 1977. Considering the stamped numbers are still on the block, you'll know the engine hasn't had a proper rebuild where the deck gets milled to make it flat again.

There is no way to tell if it's a 4 bolt or not without pulling the pan. Truck engines are generally 4 bolt. Not sure about vette engines. The Vette classification really means nothing. It's a generic 010 block with a very small 180 HP rating based on what heads, cam and pistons were installed in 1977. Low HP smog engine from the factory.

 

 

The 4 bolt main is WAY over rated. A 2 bolt main Vortec block casting is likely stronger (spheriodal graphite ductile iron) than those 70's 4 bolt blocks.

And generally you want a 2 bolt block that can be modified for billet splayed caps.

You can get a Vortec complete engine for about $200 these days that are factory roller equipped. Those 70's blocks have so many factory machining problems and then it's not a hydraulic roller block so..... garbage is what I classify that junk as.

GD

 

 

Unless you open up the ring gaps (and probably even still....) it's going to break the pistons with NOS. It won't go far enough to drive over the crank before that happens.

GD

 

@LsxMatt you can get a bore scope off amazon that blue tooth's to your phone for cheap and run it in through the drain plug (assuming you don't run into a baffle or other issues) look and see if its a 4 bolt. The other thing you really want to know if its a two piece or one piece rear main seal if you are trying to buy all the parts for a budget refresh.

4/2 bolt main will not make much of a difference below 300hp assuming it got at least a cam in the swap if you keep the NOS shot under a 100 shot the main caps would not be the week point. The factory pistons ring groves would be the most likely to go, as pointed out above you can buy some time by gaping the rings, but by the time you do that work, unless you are just trying to fill some air time I would do mild rebuild and have it over 300hp without the NOS.

Not recommending NOS on an unknown engine though unless you don't mind blowing it-- A you tube title of NOS+rod through the side of my engine might get you a few more views though LOL.

Never realized asking what car did this engine come out of so I can try to order the right parts ahead of time was a touchy subject-- mine came out of a 2000 firebird, and its 100% factory 2000 firebird from the Throttle body to the pan, but when I tell people its a 5.7 LS1 and a T56, 9/10 the response is "that's a Vett motor right"? Its not worth explaining so I just go with yes the vett had the LS1.... Although the guy at Autozone tried to argue with me that LS1 was either a 5.3 or a 6.0 but couldn't be a 5.7 LOL...

 

 

I watched your episode on the bird, that car has a lot of things not stock on it. The wheels are formula wheels I beleive.

You could do a video of decoding the RPO's (sticker in the center console or there is typically a build sheet under the carpet over the gas tank hump) and identifying all the things that has been changed over the years.

Also check where your spare tire should be and in other side a lot of times water will work back there and collect if the little drain hole is plugged on T-top cars.

With it being a t-top put sub frame connectors on it before you go drag-racing it, you will be shocked at the body flex, especially after you LS swap it.

 

Oh yea subframe connectors are on the list before I Ls swap it. I'm really trying to keep the look and ride stock, really make it a sleeper. Whenever I get one of these cars, I never have any luck with the stock engines. My first 305 Sport Coupe developed a rod knock before I could even get it registered. That turned into a parts car for my current Camaro. Then the 2.8 that was in my Camaro now when I got it developed a rod knock about a month into owning it. I never had a "stock" smogged down v8 to play around with. Looking forward to messing around with it before I go LS. I know the car is going to get "just another ls swap", but a 200 buck JY small block that can reliably hold 600rwhp, as much as a lot of my viewers like it, it just doesn't make sense to keep a gen 1 in it.

I took a quick look at the RPO's but haven't had time to look through them all. I know the power seat was optioned, but from what I understand the cluster is supposed to be a 120, not a 140. The diff is an open 2.73, but I haven't checked anything else. I'll look for the build sheet when I get around to replacing the carpet. That's a great idea with the RPO video. I was planning on doing something similar with the Camaro, but by running a CarFax. I'm not sure if I swapped the center console out of the Camaro or not. I really wanna take a look at the Sport Coupe RPO's!

 

IIRC, only the L82 engines were 4-bolt; your L48 is 2-bolt. Additionally, L82 had forged crank and pistons while the L48 components were cast.