Technical Differences In SBC's

I know manifolds have been mentioned...there is a plethora of varied factory Carb setups matched to their factory Hotrod setups per year with numerous valve covers from chrome to aluminum and of course the fuelie...and didn't some have pcv earlier and plumbed from the filler tube on the fwd manifold...oil filler caps varied as well...

 

The filler tube PCV started in 65/66 on the 350hp/365hp motors. Then the 302 in 67 had it. Those same high hp small blocks then had the water bybass from the water pump to the intake manifold.

 

If a later block was tapped, it means that it had optional accessories usually. My 68 327 was drilled and tapped on the driver side only for the power steering as the stock bracket used those holes. If the block was left undrilled then the car it was originally stuck in was didnt have accessories that had to be mounted.

 

My 66 C10 had a 327 4 barrell, high torque 327, painted Detroit diesel green. It had the small valve heads, and a different thermostat housing/ bypass arrangement. Sadly, dad swapped it out before I could get my hands on it

 

Probably been mentioned more than once, but the only sure way to tell what an engine WAS when it was fitted to a car/truck for the first time is by the SUFFIX CODE which followes a bunch of other numbers stamped on the flat area in front of the passenger side head. It's a three letter/number code that can be decoded here - http://www.1968ss.com/sbcsuffix.asp - online and reveals much about the motor and the car into which it was first installed. If the suffix code is missing, it may be a replacement block or the block may have been decked during a previous rebuild. Good luck!

 

But from what I've seen, the changes are all external, and other than the bolts for the spider that holds down the roller lifters, internally they're the same. So by swapping on a pre '87 pair of heads, and intake, plus distributor, these engines can be made into pre '87 SBC engines. Of course it requires the use of an electric fuel pump, even if you use a carb, just because they're not machined for a mechanical pump.
I did all this to the 350 in my '39, and it looks like any other earlier SBC engine after finishing the changes.

 

Yes, and no on the machining for the fuel pump. For several years after 1987, the blocks were still machined for the pump, and had the pushrod hole drilled.

The pushrod hole disappeared first, but could be drilled by a competent machinist, and later the boss went away, too.

 

Do not confuse the LT1 with the truck engines. The LT1 main difference is reverse cooling. Note the difference in water pump inlets, timing cover, and water pump drive, as well as crank hub. This has the optispark delete plate covering a big, about 3 inch hole in the center of the stock timing cover. Heads and manifold will bolt up, cooling ports Do not match. Note intake manifold does not have a thermostat. At first glance this looks like a standard small block. It is not . An enterprising hot rodder can adapt manifolds, distributors, and valve covers. Internals crank, rods can swap, strokers can be built. You can not get away from the water pump assembly, and accessory set ups without effort, but the reverse flow was a game changer.

 

I think going to an old junk yard popping hoods, and going over iron at a swap meets is like a good test after reading piles of hot rod how too books. You can learn something every time..

 

That caused a hell for big uproar among the tri 5 Chevy guys and other engine swappers in that time period. Chevy decided that they could save a little bit of money by not drilling and tapping those holes. They caught hell from all over the place from guys who wanted to use those engines in a car or truck that used those holes.

 

Mine is a 1990 block and it came with the fuel pump blockoff plate, but was machined for a mechanical fuel pump, so I converted it back to mechanical as I prefer them.

 

Yup. Mechanical pumps are where it's at, if you have a carburetor.