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What Truck to Buy?

Stanley Doble

Call Me a Cab
Messages
2,808
Location
Cobourg
Old wive's tale.

Plain old standard valves and seats are just fine in any car with a compression ration of around 8.5:1 or less, which would include just about anything that you are considering. The tetraethyl lead additive didn't lubricate nor did it seal all that well. Note that most cheap pre-war gas did not have a substantial lead additive. Before the mid-1930's, leaded fuel was by far the exception, rather than the rule. I've personally put a couple hundred thousand miles on various T Ford engines, most of which were fitted with original valves (cast iron heads) and plain original valve seats. These engines probably had NEVER had leaded fuel run through them.

Leaded fuel, and the additives necessary for soluability of the Tetraethyl Lead, did, however break down when burned into hydrochloric acid, which explained the short life of exhaust systems back in the "bad old days". The acid blow-by which landed in the engine oil also dissolved the main and connecting rod bearing babbit, greatly shortening engine life unless the oil was changed very frequently indeed.

You have a good point. Before 1955 or so, gas was low lead or no lead, low octane, and cars had low compression. Many came with hardened exhaust valve seats and valves, at least I know all Chrysler products did.

The cars that suffer from today's unleaded gas, are the high compression models from 1955 to 1970. After 1970 they were made to use unleaded.

A quick rule of thumb is, the octane should look like the compression ratio. So, if your compression is 8.7:1 or less, you will be fine with today's 87 octane regular. If your compression is 9.2:1 use 92 octane Super.

This is not an exact rule, just a guide. But if your compression ratio is 9.5 or higher you may need water injection or octane boost additive.

Some old car owners add kerosene or diesel fuel to the gas to LOWER the octane. They find their cars start easier, run smoother and cooler, and develop more power on a heavier fuel. This only applies to really low compression cars from the twenties and thirties, with 4:1 to 6:1 compression.

In any case, you can always add some Redex, Bardahl or your favorite upper cylinder oil to the gas. Even a shot of 2 stroke oil to lubricate the valves. It can't hurt .
 
Last edited:
Messages
10,181
Location
Pasadena, CA
Reminds me of my granddad...always wanted one.

1955-1956-chevrolet-series-3100-pickup-2.jpg


1955-1956-chevrolet-series-3100-pickup-1.jpg
 

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