What is the difference between a pre-87 350 versus a post-87 350. I'm planning on using a post-87 350 in my 54 Ford sedan and will be using it as a boulevard cruiser. No smog laws involved. I've gotten rid of all the smog stuff and the "electronic carb". What else should I be aware of or do to make this a simple and plain install? I will also be using a 700r trans. I've kept the TV cable at it's current adjustment as I removed it from the donor car. I've heard the importance and results if not adjusted properly. Any help or input would be greatly appreciated.  

Starting in '86 I think, small block Chevrolets went to a one-piece rear main seal instead of the old two-piece.  

Starting with the 1986 model and continuing into 1987 several changes were incorporated into the SBC.

A. The heads received 4 changes, first the valve cover mounting was changed from four perimeter bolts to four down the center. The second change goes with this, which was the rails under the covers were raised and machined to provide an oil proof leak tight gasket seal. Third the center 4 bolts (2 per side) of the intake manifold were changed to an angle of 72 degrees to the manifold mounting surface. Older designs are 90 degrees to that surface. The fourth change was all engines went to self aligning rockers guided on the valve stem, like FoMoCo, instead of from the pushrod. 

B. The front end of the engine goes to serpentine belts which relocate most accessories into aluminum castings bolted onto the front of the block and heads. The water pump and if so equipped pump driven fan rotate the opposite direction to non-serpentine engines making them incompatible even though they will bolt up one to the other, lots of folks have fun with this one when not carefully ordering parts.

C. The rear of the block on all engines and the crankshaft is modified to take a one piece rear seal. Cranks and blocks across the 1986 boundary cannot interchange. The flywheel or flex-plate to crankshaft attachment bolt pattern is also unique to each type crank. However, the good news is that the bolt pattern for the clutch or torque converter did not change so all you need to exchange older and newer installations is the fly wheel/flex plate that bolts to which ever crankshaft you're using.

D. Some but not all blocks got changes for roller cams; this is true till 1996 with the Vortec which finally brought all SBCs into roller cams. However, between 86 and 95 you've got to watch the casting numbers and even then????? Here's as much as I know! For 350 flat tappet blocks look for casting number 10045727, 14079287, 14088548, and 14101148. Roller blocks are more complicated because even though the casting number indicates the block is provisioned for a roller cam, it doesn't for sure mean the block has a roller cam. But if so provisioned, a factory roller cam can be installed to one of these even if it currently has a flat tappet cam. The roller cam modifications to the block are several. In the center of the valley on the main oil galley are three bosses that mount the spider which keeps the lifter alignment bars in place. The lifter bore bosses are raised about .4 inch for the taller lifters. The front is modified to accept a thrust plate that retains the cam from having front and rear movement. This requires a special step on the cam and a unique cam gear that is thinner thru the mounting boss to provide space for the thrust plate and longer cam snout. A standard flat tappet or pre 1986 aftermarket roller can be put in here if you don't use the factory thrust plate and use the pre 86 gears and chain to make up the dimensional difference of the thrust plate. For 350 roller tappet blocks look for casting numbers 10243880, 14011148, 14088526, and 14093638. However, the 880 block is the Vortec block it appears in late 1995 production without Vortec heads and with TBI. While it's provisioned for a roller cam, like the other roller blocks, prior to the 1996 model year it might be fitted with a flat tappet cam it can be found with 2 or 4 bolt mains. There are two blocks that have casting numbers ending in 148, this is a GM test to see if you're on your toes; 14101148 will be a 4 bolt main flat tappet block, 14011148 is a roller block.

Reverse coolant LT-1s and LT-4s are different again.

Bogie

Jeez! I knew they were different, but not THAT different.

I guess I'll head out to the garage and be checking some casting numbers. I have my fingers crossed this is going to have been a decent purchase. I bought the entire 86 Monte for $1400. The 350 crate motor was a recent install with 1200mi. put on it and the 700r4 rebuilt at the same time. Too bad the guys teen kid couldn't wait for the brake cylinders to be rebuilt before driving it. Needless to say, the car was purchased for it's running gear and not it's body........

Okay, maybe I'm better off than I'd originally hoped. After fetching the casting numbers, and with the newfound knowledge in my noodle, I've discovered the motor has v-belts, and perimeter bolts on the valve covers, indicating it's a pre-86 if I understood correctly. The only casting numbers I found were on drivers side/rear of the block. They were 10066036. Was I looking in the correct area, and if so, what does this new information indicate?

I'm hoping this ends up being a nice purchase and is able to be hopped and dressed up at a later date.

It's a Mexican built Mr. Goodwrench 350 block. These are pretty stout, as they're intended as a truck replacement item often they have 4 bolt mains but not always, they use the two piece rear seal.

Bogie

So I'm assuming that this will be a safe basis for my future plans of going with the 383 build recipe that had been printed in the current issue of the magazine. I was impressed with the numbers pulled for a realatively inexpensive build. Anything you'd have changed from the printed recipe? I'm hoping to achieve the old and attainable goal of 500hp or better. With these plans will I still be safe using a stock 700r4? I'm not planning on racing it or anything, just like the idea of knowing I've got it on tap should a friendly challenge arise. Thanks again Bogie!  

This block is plenty good for what you want to do. The old 700R4 isn't up to the task. There's several reliable places on the web who will take it in trade for a beefed up version that will handle the motor of your dreams.

Don't waste time tring to run the old automatic with the super engine, everybody I know, including your's truely, who tried to do that just ended up taking everything apart in a couple weeks to a month because the transmission is now toasted. Actually your lucky if it's just toast on the darker side is busted cases, spit out driveshaft, broken crank end, and holes in the engine cooling jackets from flying pieces inside the bell housing. So just spare yourself some grief while you still have a core to trade.

Bogie

Thanks for the heads up on my ill fated transmission idea.

What is my next step to get the engine I have now to the base of the Dec. 06 build-up? It stated that it started with a 388ci small block before bolting these top end parts to it. What parts and part numbers would you recommend I go with to bring my current 350ci up to the short block used on the tech. build in this particular article? I read the specs on page 23, but with my limited knowledge and hestitation because of it, I don't want to start a build going down the wrong path with incorrect or inferior parts. Thanks again.

I am replacing my 92 Chevy 350 with a 81 GM Goodwrench.  I am building it up and will be running TBI on it.  Other than a different Flywheel, what else should I need to make this motor work.  I am doing heads and intake.  Your remark about the Water Pump has me nervous as I am going to retain the serpentine drive so I can use my A/C and everything else.  A Clutch for a 92 should work with a pre 87 Crank and Flywheel right because I plan on using my NV4500 5 Speed still