High Octane gas/timing?
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
In overly simplified terms, an engine is just a glorified air pump. An air charge and fuel mixture are introduced, compressed, ignited and then expelled as exhaust, --repeat process.
Advancing/retarding the cam or advancing/retarding the distributor doesn't change the compression ratio of the engine. It only alters the timing event of when the air/fuel mixture is ignited.
The only way to increase the compression ratio of the engine is to change/mill the heads, install thinner head gaskets, install flat top or pop up pistons or, any combination of these.
If my '03 Mach 1 didn't have a high compression ratio, I wouldn't pay to put high octane fuel in it. The 240 in my '69 F-100 definitely doesn't get high octane, since it's a low compression engine and high octane fuel would just be an extra expense for no advantage in it.
But, if someone feels like high octane fuel in their low compression engine is doing wonders for it, put that more expensive magic motion lotion over in it.
Advancing/retarding the cam or advancing/retarding the distributor doesn't change the compression ratio of the engine. It only alters the timing event of when the air/fuel mixture is ignited.
The only way to increase the compression ratio of the engine is to change/mill the heads, install thinner head gaskets, install flat top or pop up pistons or, any combination of these.
If my '03 Mach 1 didn't have a high compression ratio, I wouldn't pay to put high octane fuel in it. The 240 in my '69 F-100 definitely doesn't get high octane, since it's a low compression engine and high octane fuel would just be an extra expense for no advantage in it.
But, if someone feels like high octane fuel in their low compression engine is doing wonders for it, put that more expensive magic motion lotion over in it.
orich
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Somewhere on the web was reading a neat scan of some old auto repair article, think it was originally from the 1930s and they were complaining that "Gasoline quality has declined greatly since the 1920s" hm.
Fleet Mechanic
Joined: May 2001
Posts: 1,396
Likes: 4
From: Cupertino
Ted, "Gasoline is not oil as such but has some lubricity..."
Funny, my son and I tore down his 351W a month ago. Four cracked pistons on the bottom side of one bank. Gasoline leaked out of the carb, washed the gasoline off the rings, cracked pistons and rings.
Not much lubrication there.
Funny, my son and I tore down his 351W a month ago. Four cracked pistons on the bottom side of one bank. Gasoline leaked out of the carb, washed the gasoline off the rings, cracked pistons and rings.
Not much lubrication there.
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Ranch57
1948 - 1956 F1, F100 & Larger F-Series Trucks
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Feb 10, 2006 10:12 PM
