Thread: SBC Heads and Block Compatible or No?

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I had a friend tell me these heads will not mate to this block, well they will bolt together fine but will cause overheating because he says the heads are reverse flow heads and the block is not...any insight on this? Will they pair or will I have overheating issues?

Engine info: Engine Block VIN: 14016379 Small Block V8 1977-1979 350, 2 bolt or 4 bolt

Heads info: Cylinder Heads VIN: 14101083 – 1987 350, crate engines, 285hp or 300 hp, 64cc chambers, 72 degree center manifold bolt angles

I found some info on them from fellows that I trust. Here it is.....

Those heads you speak of were probably one of the better heads in the 1980s before the Vortec head was introduced. Although not aluminum they were the cast iron version of the L98 head. They are real similar to the 217 head which was used on a marine application and a crate motor as well. Xtremefi is using those heads building 355 TBI engines. They are claiming they are making about 317-320 hp with them with a roller cam with like 209 duration@.050 and .455 lift. I don't have flow data on them but I can tell you they will definitely outflow the factory TBI heads easily and really make for a way better upgrade on a TBI application.

Looks like these heads flow around 200 cfm or a little less. You wont be building any 400 plus horse power engines with these heads. If you are building a stock engine then stock heads perform as they are supposed to perform.

This is the cast iron version of the Corvette/Z28, aluminum L98 head, you need to check the angle of the center intake bolts as this casting makes 2 part numbers one with the center bolts at 90 degrees to the mating surface for 1986 and earlier intakes it is P/N 10159552; the other is PN/10125377 for 1987 and newer intakes with the 72 degree angle between the bolts and mounting face. It is a decent head it is especially useful as a performance replacement for trucks that have TBI and Swirl Port heads as it is essentially the same as the SP head without the vane where the owner/builder doesn't want to go to Vortec heads with the attentive intake manifold exchange the Votec heads need.
These are a substantial improvement over older the large chamber factory smog heads as well. Not as good as Vortecs and similar aftermarket heads , but not too trashy either.

P/n 10125377 SBC Cast Iron L98 Center Bolt Valve Cover Head.
This is a cast iron cylinder head assembly used on 285 hp 350 engine (P/N 12353641). This complete cylinder head assembly includes 1.94” intake valves, 1.50” exhaust valves, valve springs (P/N 3901068) and valve spring caps (P/N 14003978).
Technical Notes: This cylinder head has 64cc chambers. The cast number for this head is 14101083 or 14096217. This cylinder head has 1987 and later inlet manifold bolt pattern. The center two bolts are at a 72° angle.

........Nothing these fellows said points to these heads being reverse flow like the LT1 heads that were used from 1992 to 1997, so I personally would have no problem bolting them to a conventional Gen I block, although I wouldn't use them in the first place due to lack of performance. If you need a set of heads to haul a vehicle around, they will work, but don't plan on picking up any trophies at the drag strip with them. If you're looking for affordable performance, invest in a set of Profiler 195 aluminum heads, long tube 1 5/8 headers, high-rise dual-plane intake manifold like a Weiand 8150 or Edelbrock 7101, 750 carb with gears and converter. Build the motor at 9.5:1 with a 212 degree cam and 0.035" squish and hang on. OVER AND OUT......
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