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403 olds

Discussion in 'The Garage' started by REDCRO_REDNECK, Sep 14, 2005.

  1. REDCRO_REDNECK

    REDCRO_REDNECK 1/2 ton status

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    does anyone know anything about a 403 olds?

    There is a guy who is selling a complete carb to pan engine with a 350 tranny all suppost to be in good condition for 300
    "no smoke or nocks/noises when pulled came from 68000k mile car" 1978 something.

    any and all help appreciated.

    how hard is it to put in a 1976 k20 frame motormount wise?
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    it will fit...

    If you can find a 5.7 diesel in a 78-81 GM truck,it used the Olds 350 block ,and the motor mount pads will allow any olds 350-455 motor to bolt up--or you can make plates to make the chevy mounts reach the olds block motor mount location..another guy here said firebird ones that had the olds motor would work too..

    Dont know too much about the 403 Olds,or the other motors,they seem to be decent engines..I hardly ever sold rings or bearings for any olds motors at the parts store--either they never needed rebuilding,or people junked them instead I guess--same goes for pontiac,buick,and caddy motors too..My friend put 455's in 2 81 GM trucks that had junk olds diesels in them he bought cheap from the phone company--they went like a raped ape!.. :D
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    403 is kind of the bastard engine of the "modern"(? lol) Olds family.

    '77-79 only, huge bore, (siamesed cylinders too) windowed mains, two bolt only, low compression. Not a high RPM motor by any means, but low end is fairly impressive. Earlier heads will get some compression back and flow better. Essentially replaced the 455. Max recommended overbore is 40 IIRC, although mines at 60. Pretty much impossible to keep cool in traffic with that overbore. Didn't know that when I rebuilt it, and the machine shop apparently didn't either.

    If you ask me, it's a decent swap in a car/truck that originally came with a smaller/crummy Olds motor, but not worth the effort to swap into something that didn't have an Olds motor in the first place. Possible, but you might as well find a Chev 400SB, get the same displacement, and save the hassle.
     
  4. REDCRO_REDNECK

    REDCRO_REDNECK 1/2 ton status

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    my thoughts are 403+th350+ divorced 205= decent drive train for a mud trail rig.

    Background:

    have a 1979 GMC sierra grande with title but no motor/trans/case k20.
    also have a 1974 k20 frame to build trail rig from scratch.

    do not think I can go wrong with that combo, but I know nothing about the ease of swaping and olds or basic olds info.

    keep it coming please.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    You say mud, I say not Olds. As-made, Olds motors, and especially smog era ones, are not buiilt with high strength parts and will come apart fairly easily with higher RPM use. I knew a guy that ran those things at the track and destroyed them fairly regularly at about 5200RPM.

    I have a picture of the main journal of a 403 that broke out of the block due to the windowed mains. They allow alot of flex in the crank area, just one more thing that these motors have against them for high RPM use.

    Alternator/starter is on the wrong side for a Chev, unless it was non-AC, but the starter is still on the wrong side.

    Also, exhaust system on Olds engines SUCKED, (almost universally this was the setup) the exhaust crosses over from drivers to passengers side, routing the pipe directly over the starter and the oil pan, and goes into the drivers side manifold, then dumps into a single pipe. You either make a cap for duals, or find headers, which may or may not be easy to do for a truck with an Olds motor. Not much selection for 403 headers last I checked, but that was for a car. Starter problems are pretty common on these vehicles.

    If it's all about low RPM torque then the engine should be fine. You mention mud though, and to me that means engine RPM.
     
  6. gambit420s

    gambit420s 1/2 ton status

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    try here Olds FAQ or here Mondello Performance

    with the faq you have to read all the different sections to get all the info as they dont restate every thing in every section

    Joe Mondello was somehow affiliated with olds at some point and knows his stuff, but some of it seems like crap for the money>brains people


    403's are ok but the siamesed bores dont like rpm when cold...
    somewhere i read about a guy cracking the wall when revving the engine cold

    Olds350 diesel mounts would work perfectly, but take the block too!! its the best olds sb block!! you can use it to build a gas motor but you get solid webs and all kinds of cool chit

    you will need a BOPC 2WD trans case built with 4WD parts(the best way. or adapter which kind of suck, or just not bolt the top two holes, but this way you'll prob end up cracking the block or trans case

    you can use a chevy TBI system or aftermarket by using a later 80's comp controlled distributor

    you really want early heads(1,2,3) as porting the AIR bumps on the exhaust port is a PIA, i got 3 ports done on a "Ga" head and said fark it!! just bought another car just for some "C" heads, still cheaper than 1 Edelbrock head.... even with new hard seats, guides, etc.

    You want a block that has the higher nickel content(faq has a chart) it makes the block less prone to wear, and better machining surfaces

    you want a forged or nodular iron crank, forged should be easy enough to see, but nodular cranks have a giant "N" cast on the #1 weight

    the locations for important info are :

    engine id is stamped into the oil fill tube about 3" from the top, and usually facing to the front

    block ID is on the front of the block to the left of the oil fill tube, you care about the first number it should be 1.25" tall, but take brake cleaner and a rag as this area is a grime catcher. the earlier the number the better

    head numbers are on the #1 cyl to the left of the spark plug, if it has a/c on it and blocks you, you can check the #8 cyl, there are casting numbers directly above the #3 & #5 and #2 & #4 exhaust ports but the v/c lip might cover them



    if you tear into it before you use it, use acdelco 350 diesel gaskets as they come with steel core rubber oil pan and v/c gaskets, the cheaper ones i've seen are just gas motor cork ones...

    dont use gear drives, you have to drill a hole in the main web to mount an idler

    either port the oil drain back holes in the rear of the head, or drill and tap the side of the head with NPT fittings and run a line back to the oil pan, if you plan on running at rpm's continuously, as the drain holes suck, it'll hold 1/2 a quart in the head alone...

    right now i'm working on a 455 for a caddy, but it might all get stuffed in a burb at some point(with the title-able caddy CDV body, same wheelbase you know....)
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Forget the Olds diesel block, unless you want to run NASCAR or something, the cost and effort are NOT worth it.

    I figured it approaching $10,000 to build an Olds diesel/gas conversion engine.
     
  8. K5Steve

    K5Steve 1/2 ton status

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    403's tend to crack between the water jackets.I have had a few like that.
     

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