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I have recently discovered that the 1940 oldsmobile I am restoring has a 248.9 ci pontiac straight 8 made november 19th 1938 that I know absolutely nothing about. I have researched it online and found very little my local library district has nothing even close to informative. I'm asking anyone out there that has seen these engines before to fill my brain. I would love to be overloaded with information. If you have tips tricks, pictures, diagrams, measurements, stories anything that can help me not destroy this engine with my hamhanded efforts to restore it, I would greatly appreciate anything you can teach me.

Thanks :D

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No doubt in my mind (although I have owned 8 Pontiacs and my daily driver for 50 years has been one) that as good as the Pontiac eight was the Olds eight was/is superior (hence the higher price). However it is probably ten times easier to get parts for the Pontiac. Everything is available for the Olds if you contact the right people. For a complete engine rebuild (by a competent auto machine shop) you would be looking at about $6,000.00 here in Canada.

Buy yourself a parts book and a shop manual for your car and for a Pontiac if you do not plan on going back to original. These are available on ebay most of the time.

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Thanks guys!

Dave it's nice to know something about the people behind the car. Someone in another forum had even suggested that Harley Earl may have had a hand in the design of the series 90. not sure if it's true but it would be amazing to think it was. I wondered if someone had replaced the old 257 with an older engine. now my only question is why did they go so much smaller.

TinIndian, I think your right, the info I've seen about the olds 257 makes it look a lot better than the 248 I've got. I'll just be happy if I can make it drivable at the moment though. Kanter has a rebuild kit with everything but the block for about $1300 U.S. and I found a mechanic that said he will rebuild it for $500 if I supply the parts and pull the engine myself. Problem is I know nothing about this engine so he could tell me it needed new pontoons to help it float better and all I could do is nod and smile. Your idea about the manuals was great I just found both of them reproduced on cd's for $36 apiece and there's a fisher body manual online for the 39/40 model year that was free! Is that your car in the picture? it's gorgeous!

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  • 2 weeks later...

Oil filtration! There is no filter. The engine has a sedimentor in it though. Mu engine has 56,000 original miles on it when I cleaned the oil pan, and there was a full quart of sediment. But, everything else was clean. Just use non detergent oil, so everything can fall out of the oil, and you will be fine.

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Thanks Mr Lang, I was a little perplexed by that, When I first started looking over the car I couldn't find the oil filter. I just assumed it was missing or placed somewhere I had never seen before. Then again until I bought this car I had never seen a sediment bowl on a fuel line before. I'm embarassed to admit I looked for what you typically think of as a dip stick with the finger ring on it for two days. I'm still trying to find out where the fill neck is for transmission fluid. Information on prewar cars seems to be kind of thin online.

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Ravensmiles,

It would be worth the money for you to get a pontiac shop manual. It will describe in detail the operation, maintenance, and care of the engine. I see that maybe you have one now?

I would be leery of any mechanic that says that the engine could be rebuilt for $500, I could see the number closer to $5000. I don't have my shop manual in front of me, but it seems to me that at least the camshaft bearings have to be line bored after being put in the block.

If your engine has compression, it will more than likely run. They are sort of bomb proof. If you can get it running, I would not rebuild it. Use it and drive the care, while you find a factory engine, rebuild that, and place it in the car.

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Thanks guys, as you can tell I'm starting all over from scratch when it comes to these cars.

Mr Lang , yeah I ordered one online and i'm waiting for it to come in now. I also found a website called the oldcarmanualproject and another called the second chance garage that have a lot of info.

Thanks Streamliner 49 I'm going to see if I can find the plug your talking about. The transmission has a clutch pedal so I know its a manual and not a hydramatic, next step is to try to identify what kind it is.

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Hey guys, I got the service manual for my oldsmobile, it shows the manual trans mission having four positions configured like an h laying on it's side (their description not mine)

My transmission appears to have three positions like a modern automatic transmission all arranged vertically. There doesn't appear to be any horizontal movement in the shift lever at all. Does this sounds familiar to anyone?

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  • 4 weeks later...

Ravensmiles

My guess is that the original engine in your Olds went belly up during WW II and the availability of replacement parts was restricted and maybe not at at all available where you car was located. Easiest fix, swap a readily available used Pontiac into the Olds as it was pretty much a bolt in with little or no modifications needed.

A local mechanic here that builds engines for cars in the Great American Race each year, says to budget $1,000 per cylinder for a proper rebuild of an antique (over 30 years old) engine. As suggested above, drive it until the Pontiac is dead and them put in a correct Olds. That way you can get a good block and crankshaft and build on a pay as you build basis and not have to come up with several grand at one time.

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Another comment related only about the oil. An aftermarket oil filter can be fitted to your engine but is not necessary. Pull the oil pan and clean out the sediment/sludge. Then use a single grade (weight) oil appropriate for the weather and change it every 3,000 miles or 90 days, whichever comes first. DO use modern "detergent" oil. It does NOT contain a detergent and will NOT loosen existing carbon buildup or sludge. It has an additive that keeps the contaminants (carbons and acids) in suspension so they do not settle out into the bottom of the oil pan. If the "detergent" additive is working properly the oil will be black with carbon at change time. The contaminants are drained with the oil when the oil is changed. The term detergent is a marketing thing to explain to the consumer how brand x oil keeps your engine clean. Engine lubricating oils do not wear out. They just become contaminated with carbon and acids. Properly processsed and filtered "re-refined" oils are just as good as newly refined oils.

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Ok, I don't see where anyone asked this. Does your car have an automatic transmission? The H shift pattern in your shop manual is for a 3 speed manual transmission. The straight line pattern you describe is for the Hydra-matic transmission which from left to right is reverse, neutral, drive and low. Hydras had no park position. It locked between reverse and neutral when the engine was off. Hydra-matic was offered as an option in Oldsmobile beginning in 1940. It was offered in Cadillac in 1941 and in Pontiac after WW II. It was coupled to Cadillac and GMC engines for military vehicles during WW II.

Possibly your Olds had the Hydra-matic option and it was retained when the engine swap was made.

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buick started the hydra-matic project in 1936, shortly thereafter, it was handed to oldsmobile, and was introduced in 1938 as a safety transmission, cadillac offered the hydra-matic in 1940, pontiac in 1948, gmc and chevy trucks in the early 50's, it was also used by nash, lincoln, rolls royce, and perhaps more. charles coker, 1953 pontiac tech advisor,poci.

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Bob, I just replaced the shift lever and in the process of installing it I found out that the shift lever passes through two different shafts and the inner shaft had twisted when I lined up the holes in the two shafts and installed the lever there is forward and back movement in the lever. I do have the syncromesh transmission. now I just need to find a replacement flange so the lever will stay put.

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