Olds 350, 409 questions. New Olds owner!!

[sadisticsavage]

I was just wondering, what cars to look for as far as looking for a 350 or 403 Oldsmobile. I have an 86' Cutlass with the 307 that needs to be replaced. Not really interested in rebuilding a 307 when I want something with a bit more power than a light "chirp". I heard the Olds 350 is a very reliable motor for power and easy to build as far as power output. And if anyone built one, let me know what your build-up is and what your power output was like. I'd like to go with a 403 but with overheating problems that could be a problem. Would it just need a cooler thermostat and a bigger radiator? And what kind of rpms make it overheat? And last but not least would I need to go with a bigger transmission. I think I have the smaller trans in my car. On the bellhousing it says 409. Does that mean anything? Thank you all very much for your input and help. First Oldsmobile I have ever owned and I am pretty excited to have it. I am mainly a truck guy but have owned only 2 cars in my life. A 76' Camaro which is like putting a tricycle together. Easy. And a 65' Buick Wildcat with the 425 Nailhead. Which is like owning a 2 headed dog. Nobody has one quite like yours haha. So hopefully this car is somewhere in the middle as far as difficulty in build. Thanks again so much and I am glad to be part of the G-body community.

 

[silvertbo]

403 makes a good street motor if properly assembled.i suggest you do your homework get the olds performance book by bill travato and read.i have a 1980 cutlass with a 403 it makes 498@5800 hp and485@4100tq makes for a fun street car never raced it but i am sure it is an 11 second car.runs no hotter tha 180 degrees.like i said know what you doing before you make mistakes.and find a good engine builder to work with bill travato is one of the best but there are several others that are good to deal with as well.these engines need to be assembled correctly or they will fail.also look on realoldspower.com or highperformanceolds.com lots of info on both.

 

[STL84Calais]

Both an Olds 350 or 403 would be a great drop-in replacement! Not with your stock trans though. It won't take it. Both can be built to make some good power, but with the 403 you have to watch your bottom end (windowed main webs), but a girdle is cheap insurance. A good cooling system will solve any cooling issues with the 403. 350's are plentyful, and up until 1976 had full main webs. Check out the Olds based sites for some more detailed info, good luck with your swap!

 

[ronbz455]

I'm doing the same thing right now. I will pick up my 403 tomorrow. Just trying to find some 67-72 350 heads for more compression. It seems the 403 has 8.1 compression. That won't produce any power. If you can get to 10 to 1 or bigger you can start driving easy or you will be wearing out tires! I was also thinking about Flat top pistons from Mondello but don't really want to spend that kind of money knowing I will put a 455 Buick engine in it later. It is a Regal.