To build up the 300 hp engine similar to the one used on the senior '57 Buick series, swapping in stock parts should do the job:
Carb, 4-bbl, Rochester 4GC or Carter AFB
Manifold, intake, 4-bbl, no 1175328
Pistons, 10.0 compression ratio, oversized as needed
Miscellaneous fittings-- air cleaner, throttle rod, fuel line, choke feed, etc.
Engine valves are the same for synchromesh vs Dynaflow cars. The camshaft variation goes according to synchromesh vs Dynaflow. These are not interchangeable per shop manual. Keep .015" head gaskets to avoid lowering compression ratio. Your car will already have pieces unique to the synchromesh setup such as crankshaft, camshaft, flywheel, intake manifold gaskets, 3.58 axle ratio.
Someone had an original '57 4 bbl carb for sale on this site a few months back. The intake manifold can be found on '57-'58 Century/Super/Roadmaster cars. Also on '59-'61 LeSabre cars having the power pack option.
Different pistons were used in '57 to get the three different compression ratios. All used the .015" head gaskets except for unusual applications. Going to the 10.0 ratio will now require premium fuel.
Although it was an earlier design, the synchromesh transmission was used previously with 4-bbl carburetion on 322 nailheads in '54 and '55. Factory even issued a service letter giving customers the OK to install 4-bbl '56 engines in '56 Specials having synchromesh transmissions. Granted hp levels were lower in earlier years, but a synchromesh transmission paired to the 300 hp 364 should hold up under reasonable operating conditions.
Buick was elusive in the late '50s about publishing hp figures for the synchromesh cars. The compression ratio was always the lowest of all. For '57, Specials with synchromesh had an 8.0 cr. and a hp rating about 210. Dynaflow Specials with 9.5 cr. were rated 250 hp. Senior models (Century/Super/Roadmaster) all with Dynaflow and 4-bbl had 10.0 cr. and the 300 hp figure. That number for the synchromesh setup is taken from the '60 model which had an 8.5 cr. and published hp rating of 210.
The Standard Catalog of Buick 1903-2004 indicates 98.5% of all 1958 Buicks came equipped with Dynaflow. Assuming similar numbers held in '57, then 1.5% of the 405,000 total production gives about 6076 cars with synchromesh. Since only Specials (220,746 that year) could be ordered with stick shift, that works out to 1 in 36 Specials with standard shift. The manual transmission was even discontinued in full size Buicks later in '61-'62.
Last edited by TODD; 11-04-2017 at 05:25 AM.
Reason: Correct typos
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