Olds 403 Buildup

Discussion in 'General Discussion' started by foxtrot, Dec 30, 2008.

  1. foxtrot

    foxtrot G-Body Guru

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    My olds buildup wasn’t a “scientific” build -- It basically started with a stock olds engine.

    The engine has a nice Edelbrock 3711 intake and cam. The cam is the basic idle -- 5500 RPM performer... The heads are nicely rebuilt with stainless valves, new springs, and are ported/polished. The rest of the engine has a typical rebuild with new rods, bearings and flat pistons.

    I know that more could have been done with this rebuild but I didn't want to spend big $$$... This car isn't a daily driver and probably will only be driven a few miles a week when the weather is nice...
     
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  2. olds307 and 403

    olds307 and 403 Royal Smart Person

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    I recently rebuilt mine after heating issues. I put the 403 in my cutlass and set the secondaries and burnt the one wheel but good. It was a pretty weak otherwise without a better exhaust swap. Add a set of headers and duals or at least a cat back setup. The cat back setup made a huge difference, my motor is very similar to yours without the porting. The headers, 2.5' duals with x pipe, 1" carb 4 hole carb spacer, recurving the distributor and adding richer hanger and rods to the Qjet made big differences. I am now using a CE rod and B hanger, would bog and ran worse with just the cat back setup. Opening the secondary air door to approx 1.3" opening helped also.
     
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  3. foxtrot

    foxtrot G-Body Guru

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    Did you maintain the CCC stuff?
     
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  4. foxtrot

    foxtrot G-Body Guru

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    since you mentioned that you don't have any porting work, I'm assuming that your using the stock 403 heads. What plugs are you using and what is the gap? Is 10W40 oil okay for the 403?
     
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  5. olds307 and 403

    olds307 and 403 Royal Smart Person

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    I ran it with that cam and the 4A 403 heads but switched the #8 350 heads for a slight compression increase. The CCC stuff was all removed when I got it. Most cars up here didn't get it till 86 and all cars except the Hurst/Olds, 442, Delta 88,98 and the 88 model Cutlass Supreme Classic all got the 3.8 v6 or 305 sbcops: :( v8
     
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  6. olds307 and 403

    olds307 and 403 Royal Smart Person

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    I used the rapid fire #7 plugs with .045 gap. Use a quality diesel oil or a specific break in oil. I personally like something like a 15w40 diesel oil, you can throw in the CI-4 Super tech brand from Walmart. Cheap, you can run it long enough to break in the cam and dump it. I would run WIX oil filters too. That oil will have the higher zinc and phourous levels, which will help protect your cam. Make sure your rad is heavy duty, good hoses and water pump. Do not use under drive pulleys on your 403, they do not cool properly on 403 no matter what. Definitly prime the oil pump before start up too.
     
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  7. foxtrot

    foxtrot G-Body Guru

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    Do you run 15W40 all of the time or just for the break-in?

    Thanks
     
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  8. jrm81bu

    jrm81bu Comic Book Super Hero

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  9. olds307 and 403

    olds307 and 403 Royal Smart Person

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    I run a few different grade diesel oils. I suggested the Walmart brand for down there because it is still CI-4 rating. The new Rotella and other CJ-4 rated oils are not as good. I am currently running 0w40 full Synthetic oil from CO-OP up here. I like 15w40 in not too hot or cold weather, 30w in hot, 10w30 or 40 in cool and 0-5W 40 in the cold. I actually burnt rotella 5w40 full synthetic oil. I use the CO-OP oil up here because it costs less and still has a CF,G-4 rating on all except there new gold stuff. I know synthetics have mixed reviews for break in and cost more. I would run regular for at least the first 1000 miles and do multiple oil changes.
     
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  10. 85 Cutlass Brougham

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    I would have raised the compression seeing as it is a major weak point with late 70's engines. The actual compression ratio may have been as low as 7.5:1! (you could run 75 octane on that!) Raising compression allows for a more aggressive cam too. However, seeing as you did not raise the compression, the best cam choice would have had a long LSA of around 114 degrees to raise low RPM cylinder pressure and offset the low static compression ratio with a little more dynamic compression. I did this in my 355 with 9.5:1 ( or thereabouts) compression and was quite happy with the results.

    As for the 403's weaknesses, it's not a race motor, but it's not ultra fragile either. I think anything below 400hp would be perfectly reliable. It's just not a race engine, or a heavy duty truck engine. I have never played with one, but enough people have built them that I would think it's not that bad.
     
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