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High Mileage Oldsmobiles

Old January 12th, 2019, 07:21 AM
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Location: Pittsburgh, PA
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Prior to fuel injection, cars typically ran richer,due to less precise fuel control. This did have an effect on engine life. Looking back, you had flat tappet cams, non-stainless valves, valve seats & valve guides which were the same cast iron that the heads were made of & less precise tuning/engine control. I used to see a lot of engines needing rebuilds in the 80-100K mi. range. Not all were bad, but this seemed to be a reasonable range.

Back in the mid 80's I used to work in a garage/machine shop that did a lot of engine rebuilds. Replacing Olds diesels with 350's was a common thing for us, so we rebuilt a lot of them. 1 thing we regularly noticed is that most Olds 350 junkyard engines had good cylinder bores into the 80-90K mile range where you could still see the crosshatch. The Crankshafts also showed similar results where a lot of Olds engines still had excellent cranks.
The Olds engines showed less wear than the Chevy engines also. I'm not just bragging up Oldsmobile as I have been a big Chevy guy my whole life.

Chevy engines showed a little more wear, probably lasting about 10K mi. less. We saw more bore wear, but most cranks were usually in good shape.

The worst engines were the 351M Fords that showed significant wear in the 40-50K mile range. Basically if we took it apart, it needed bored & the crank cut. The 302's seemed to have a slightly better survival rate, but I cannot quantify it after so many years.

I'm not necessarily blaming the engine design for wear, but mostly the metals used in the products.
We could detect the cast iron was harder on the Olds engines when boring/honing them & the shop cutting cranks also commented on the material differences between Chevy, Ford, Olds etc.

Seemed Chevy suffered mostly from the stupid nylon coated cam timing gear they used, they either jumped time, or plugged up the oil pump pickup with plastic, causing low oil pressure. The Fords had poor oil drain back & tons of sludge buildup in the heads & valleys. On the Olds we saw more head gasket/cooling issues than anything else.

Obviously camshafts went out periodically in all vehicles & valve seat wear became more noticeable as the lead was removed from the fuel. As we hit the '90's hardened valve seats & guides, along with better valve materials solved a lot of issues as did roller camshafts.

Just some trivia I thought I would share.

Last edited by Lonnies Performance; January 12th, 2019 at 07:24 AM.
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Old January 12th, 2019, 08:03 AM
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The mid 70's sbc almost all the cams went flat. GM finally fixed this in the early 80's, the sbc also lasted about the same miles as the Olds V8 did as far as wear at that point as well. Yeah, we replaced a lot 351M/400M motors. The 302 was better. I think a big part of it was carburation, Ford carbs were terrible. I remember a few carbed Ford being towed in because they flooded going down the road. Usually the needle and seat but almost all were big slobbering 2 barrels. A long time Ford tech mentioned how much longer Ford motors lasted once they switched to EFI. I did see some heating issues on Olds, mostly in an oddball situation. I never saw any issues with the 307 or 260, thicker cylinder walls help a lot. The Olds 350 is considerably easier to cool vs the 403 or 455. I have seen 20 to 30 degrees difference between an Olds 350 and 403, both 8 to 1 compression and same 204/214 cam. Same going from an Olds 350 to an Olds 260. Most complaints are on 403's and 455's, more ci and thinner cylinder walls.
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Old January 12th, 2019, 05:07 PM
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Location: Sherwood Park, Alberta, in the Great White North
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I can agree with most of the comments above regarding longevity of some types. The Fords were the worst, and yes, they didn't seem to understand carburation very well. I've owned a number of mid-seventies Ford trucks and that was the biggest problem, keeping a carb working. Switch it to a Rochester or a Carter, and life got better. Motocraft, forget it, absolute trash. And the Holley derivatives were by for the worst.
As for block longevity, yes, the more "senior" the car line, the more nickel they had in the block. Chevy was mass transport and cheap; - they had low or no nickel content and wore out rather quickly, - same thing with Fords. Buick and Olds used high nickel content in their blocks and heads, - also the reason why hardened seats aren't necessary whereas they might be recommended in a Chevy. As the 80s wore on, they all cut down the nickel content; they wanted people in the showrooms buying cars, they didn't care how long they lasted as long as they did the warranty period. It was the Japanese that forced the domestics to smarten up, the Japanese had always been hindered by metallurgy and when they got it together and improved, the domestics were caught short.

Good to read that Olds primarily had issues with head gaskets and such; not like Chevy with bad timing gears or Buicks with terrible oiling. The compression test I did on my 53 Super 88 shows what looks like classic head gasket failure; - I'm hoping it isn't a cracked head.
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