Should I Build A 301?
Good day and great magazine! I have a '69 Bird and a '71 Formula 350, both of which need TLC. I want to pick your brain about a couple of topics-some of them most people wouldn't recommend due to cost or horsepower, but I have my reasons.
First off, I'm tossing around the idea of using the dreaded 301 since I have access to both a turbo and a naturally aspirated version. I know '80-'81 blocks are stronger, but are the crankshafts really as weak as rumored? And why do they only rev to 4,400 rpm? I'd think that a good balance of the rotating assembly would get me in the 6,000 to 6,500-rpm range.
Also, the intake might be part of the problem, and I'm prepared to build my own if necessary. I also have a spare crank from a '77 400, and I believe you had an article about a Third- or Fourth-Gen with a stroked 301 that measured 359 ci and had traditional Pontiac heads.
Do you know a geardrive timing set for the 301 and/or 400, and are the camshafts interchangeable?
I also want to run a five-speed from an '85 Z28. (I know it has a different bellhousing pattern, so I'm going to make an adapter plate.) I've heard they're not that strong, but behind a 301 it might live for a while. What would the correct flywheel be: 168-, 166-, or 158-tooth? What diameter? Would the pressure plate for the Z28 from Centerforce bolt up?
Thanks, and keep it Indian!Trevor LawAlberta, Canada
Rocky Rotella responds:?
Pontiac introduced its 301 in 1977 as a response to Chevy's 305. Available with only a two-barrel carburetor that year, a four-barrel version debuted in 1978 boasting increased output. The 301 wasn't, however, designed with performance in mind. Its developmental focus was low-rpm operation and weight reduction to maximize economy. As a result, the engine weighed about 150 pounds less than a similar vintage 350.
Containing a 4-inch-diameter bore, the 301 utilizes a low-deck block, which brings the cylinder-head flange closer to the crankshaft centerline. A substantial amount of material was removed from such areas as the block's lifter galley, main saddles, and cylinder walls to reduce weight. The connecting rods were shortened by more than 1/2-inch, and the casting was trimmed of excess material.
Like most other Pontiac engines (besides 421 to 455), the 301's 3.00-inch-stroke crankshaft uses a 3.00-inch-diameter main journal, but its rod journals measure just 2.00 inches as opposed to 2.25. It's central counterweights were removed in a direct attempt at shedding weight, leaving one large counterweight at each end of the crank.
The 301's reciprocating assembly was externally balanced. Otherwise identical to a typical 166-tooth Pontiac unit of similar vintage, a 301-specific flywheel or flexplate had material added around its circumference, which serves to balance the engine. On the opposite end of the crankshaft is a 301-specific harmonic-balancer that shares this characteristic to serve the same purpose.
No. 01 cylinder heads feature 1.72/1.50-inch intake and exhaust valves, and produce a compression ratio of 8.0:1 on the 301. With relatively small intake port volume, peak intake airflow is about 170 cfm at 28 inches of pressure. For reference, a traditional Pontiac intake port with a 2.11-inch valve flows some 40 cfm more. In addition to its limited port volume and valve size, the 301 intake port arrangement is also very unique.
Paired intake ports of a typical Pontiac cylinder head are isolated from one another by a central dividing wall, and it extends into the intake manifold runners toward the plenum. The 301 cylinder head and intake manifold lack a common dividing wall. Instead, the intake features four equal-sized runners, and each feeds a pair of Siamesed intake ports. This was another direct attempt at weight loss with little regard to its effect on performance.