SBC Question

1. I was told that a 307 SBC is a 283 with a 327 crank, is this true?

2. Why is there such a bad rap on the 307?

3. Where do 301, 305 fall into the SBC story?

CRUISER

 

1- essentially, yes. 283 bore with 327 stroke.
2- mostly because there was never a "high performance 307" from the factory. They were the base v8 only. Also, there was a period of soft camshafts at hat time- a lot of 307s had cams that were worn prematurely and weren't diagnosed, only the "weak 307" was to blame.
3- 301 is what they called the homemade version of the 302- a 327 block with 283 crank. 305 was a smog era engine that also earned a bad rap, possibly rightfully so. Also not usually high performance from the factory and have an odd small bore, long stroke that isn't ideal for rpm.

 

1. YES
2. Because they had soft cam lobes and poor flowing early smog era heads
3. the 301 was built useing a 283 block bored out 4.000/ and the 305 had a small 3.736" bore and 3.48 stroke (same as a 350) so it couldn't really breath very well.
Also i think the 307 came from the factory with a whopping 140 H.P. the lowest of and sbc.

 

1. YES

2. They are the essence of Planned Obsolescence, made to melt down as you drive in order that you revisit the dealership and fill GM's pockets with more profits all to the delight of the GM stock holders.

3. See Above, just another cam lobe eating poorly cast engine in a line of common melt downs since the 1924 Copper Cooled 4 cylinder fiasco.


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brb........ with info

 

The 307 and 305 were less oversquare engines in an era when high-performance engines were generally going more oversquare in order to allow bigger valves and higher rpm for any given mean piston speed.

Restricted to five litres, GM chose to go racing with the 327's big bore and the 283's short stroke, resulting in the 302 (4942cc). The 307 is the other way around (besides being over the five-litre limit); the 305 is even more so.

The 302 is actually 301.59 cubic inches, which may account for the 301/302 thing.

Note, however, that even the 305 is quite emphatically oversquare. Engine designers today would not hesitate to design a high-performance engine around those dimensions. The potentially more compact combustion chambers resulting from that combination could have less surface area for their volume, which would allow higher compression ratios.