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455 longevity

Posted: Wed Aug 01, 2018 5:35 pm
by Val
What is the expected life span for a 455? I'm seeing many early Toronados for sale with mileage under 100k but with rebuilt or non original motors? Recently found my car also has had a motor change, at around 70k miles, which is when it was restored to this present condition.
Thanks
Val. T

Re: 455 longevity

Posted: Thu Aug 02, 2018 4:58 am
by Otto Skorzeny
I think the biggest problem with the engine is that GM used nylon coated timing gears. The nylon disintegrates over time regardless of mileage. The pieces flake off and clog the oil pump, etc.

Hopefully yours was replaced with a regular, nylon free gear set.

Re: 455 longevity

Posted: Sat Aug 18, 2018 6:03 pm
by Mikel
A well maintained and tuned 455 will last a very long time.

These old engines didn't have the benefit of a self-adjusting EFI system, positive crankcase ventilation or modern oils.

Re: 455 longevity

Posted: Tue Aug 21, 2018 6:03 am
by bcroe
My own experience is that the emissions engines starting about 1976 need
a whole lot less attention than the high performance 60s engines. I credit
this to the hardened valve seats, valve rotators, HEI ignition, and likely better
rings. My 60s engines seemed to soon need valve jobs and other levels of
overhaul, but the emissions engine properly maintained (new timing chain)
just keep running. Peak power is down some, but the 87 unleaded fuel is
a lot cheaper.

Olds 403 is the choice here, 350s run well also. Bruce Roe

Re: 455 longevity

Posted: Thu Dec 13, 2018 2:40 pm
by gearhead141
I just wanted to say that if you look back at the time that these cars were made, they weren't expected to make 100k miles without a rebuild. I can remember that my Dad wouldn't keep a car more than 60k miles because things were starting to need repair. Ring technology was not what it is today. Valve stem seals and valve guides would wear out sooner than today's engines. And as Otto mentioned, GM tried to quiet down the timing chain with the nylon cam gear, which again will most likely not last 100k miles. Folks lived closer to their jobs and didn't commute as far. The average yearly miles put on a car was on the average of 10k miles or less. For the time that the 425 was made, it was a great engine, but at the very least, seals need to be replaced. If properly taken care of, the engine will last a very long time; longer than the body will depending on where you live.