...can you quote exactly what it says about the octane requirement for all four '62 engine configurations?
Duke
Duke
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Re: If you have a '62 owners' manual...
Duke,
See the 2 attached pictures from my original 62 manual.
Note page 75 upper right corner for octane requirements.
Hope this helps,
Tony -
Re: If you have a '62 owners' manual...
Excellent, and thanks for the quick response. As you may know, during '62 production Flint began double gasketing SHP/FI engines (the production steel shim gasket was .018" thick) due to customer detonation complaints; 1962 was the year that Chevrolet pushed the CR beyond the practical limit, and if one didn't have "super premium" (100+ RON) fuel available, detonation could be an issue on the two mechanical lifter engines.
All '63 SHP/FI engines were double gasketed from Flint, which reduced the as-built CR by about 0.5, but the fuel octane requirement listed in the '63 owner's manual remained the same.
For '64 the advertised CR on SHP/FI engines was reduced from 11.25 to 11:1 due to the relief cut for the 2.02" inlet valve that increased head chamber volume by 1-2 cc. Plus the 30-30 cam had a later closing inlet valve, which reduced the octane requirement, so single gaskets worked out okay.
Actual as-built CRs were typically lower than advertised due to broached deck height being up to .015" greater than the nominal 9.025". An extra .010" deck height (9.035") reduced the actual CR by about 0.3 relative to the nominal 9.025".
DukeComment
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Re: If you have a '62 owners' manual...
Duke. are the octane numbers usee back in 62/63 the same basis as the ones on the pumps today. there are 2 numbers right? octane and research octane?Bruce
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Re: If you have a '62 owners' manual...
Although the method is not specified, back then automotive octane number requirements were almost always specified as Research Octane Number or RON. Another measuring method using a higher jacket and inlet air temperature yields the Motor Octane Number (MON). Then there's the Aviation Method, which yields about the same results as the Motor Method.
The difference between the MON and RON is called Sensitivity, and it is usually in the range of 8-10.
Nowadays what's posted on the pump is PON, which stands for Pump Octane Number or Posted Octane number. It is the arithmetic average of RON and MON.
To convert today's PON to RON specified in the old days you have to add 4 to 5, so today's 87 PON is about 91-92 RON.
Europe still uses RON, so their "98 octane" is about the same as our 93-94, and 100LL avgas is about 104-105 PON.
DukeComment
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