Engine wanted (400) for 1968 Buick GS 400 convertible

Discussion in 'Parts wanted' started by hafuch, Mar 27, 2013.

  1. hafuch

    hafuch Active Member

    I've got a 1968 Buick Skylark GS 400 in need of an engine and transmission.

    I've got a 430 and 455, but no 400. Trades welcome.

    I'm in Southern California.

    Any ideas or leads?

  2. flynbuick

    flynbuick Guest

    Unless you just want a 400 the 455 is the better choice. More parts are available, the al heads are a better fit for flow purposes, more torque and horsepower etc.
  3. gscalifornia

    gscalifornia Small blocks rule!!

    Just put '68 valve covers with 400 stickers on the 455, no one will know the difference!
  4. hafuch

    hafuch Active Member

    My mechanic said that the 455 was too big for this car. Is the 455 block the same size as the 400 block?

    I understand that the 430 block is the same size as the 400 block, just a different bore and stroke, but is that also true of the 455?

    I also understand that the oil pan on the 430 interfered with the crossbars under the engine bay (an issue only on the convertible), which is why we never got the 430 in there.

    Where would I get 400 heads to throw on this thing to make it look like a 400? Or even 400 stickers?

    How would you proceed with this project? I'm wide open to suggestions. I'm pretty new to this whole thing.

  5. David G

    David G de-modded....

    You need a new mechanic...
  6. 65specialconver

    65specialconver kennedy-bell MIA

    Find a new mechanic,seriously! All 3 will bolt right in,just use the 400 manifolds & valve covers & nobody can tell the difference at a glance.
    The oilpan problem is because the 430 is from a big car,not an A-body.Just find the correct pan & pickup & your good.
  7. hafuch

    hafuch Active Member

    Guys, thanks for your input. I REALLY appreciate it.

    Out of curiosity, will this 455 engine require modifications to the car itself (meaning, will we have to cut into the wheel wells, etc.) to get it to fit?

    65specialconver said it (or even the 430) should bolt right in. Are the motor mounts the same for the 400, 430 and 455?

    Will I also have the oil pan issue with the 455, or is that only with the 430 (because it came from a 1968 Electra, which is a large-body car).

    What about the transmission for the 455 (it is currently bolted to the engine). Should that also fit right into the 1968 GS400 convertible engine bay?

    Sorry if these questions seem stupid or basic, but I really am new to this whole thing and your input is really helping me figure out how to move forward with this.

    No answer is too basic for my level of knowledge about these things.

    Many thanks for your input!
  8. GS44667

    GS44667 Worlds First Stage1 Conv

    I have a 68 400 Engine if you would like to stay correct. Pm if interested.
    Located in Oregon.
  9. 69GS400s

    69GS400s ...my own amusement ride!

    400 / 430 / 455 have the EXACT external dimensions and may interchange with no issues. A rear sump oil pan and pickup tube is needed for A-body cars

    BIG car motor mounts are different - I think there is a locating tab that interfers when used with A-body frame pads

    TH400's can have a long or short tailshaft. While the transmissions themselves can interchange, the increased length of using a long shaft where a short shaft used to live will show up if using the drive shaft used with the short shaft tranny.
  10. hafuch

    hafuch Active Member

    Thanks again for your input, 69GS400s.

    Is it difficult or expensive to alter or change the motor mounts on the 455 to fit this car? Is that something that can be swapped out or just moved to fit the 1968 GS400 convertible?

    Did 455 engines go only in the large-body Buicks or did they also put them in A-body ones?

    How about the oil pan on the 455. Am I going to have to find an oil pan from a 400 engine to put on this 455 before I can get it into the car?

    Regarding the transmission that came bolted together with the 455, is that going to be a long- or short-tailed tranny? I don't know what car this engine and transmission came out of, so any input is appreciated.

    I'm not at all sure what the situation is with the drive shaft on this car, but are they difficult to come by (whether long or short drive shafts)? I suspect this car will have the short drive shaft, since it is an A-body with the shorter wheelbase. Does that mean that the transmission I use for this car should have a short tail?

    If the blocks for the 400, 430 and 455 are the same, why would my mechanic think it would be too big for the car? It should fit, right? Is a big ordeal to get it to fit, though?

    Again, many thanks to you all in advance!
  11. gscalifornia

    gscalifornia Small blocks rule!!

    The fact that your mechanic thought the 455 was different than the 400 is why people are telling you to look for a different mechanic, he obviously doesn't have knowledge of Buick engines.

    Motor mounts are bolt on parts, no modifications needed. Oil pan as stated should be a rear sump from an A-body, they did install 455s from the factory in A-bodies so you could post a wanted ad if you need the pan and sump.

    If you measure the transmission from where the driveshaft connects to where the tail section bolts to the main case and post your findings the nice people here can tell you if it will work.
  12. 69GS400s

    69GS400s ...my own amusement ride!

    unbolt old ones / bolt on new ones.

    A-body's in 70-74

    No, any 400/455 A-body REAR SUMP oil pan will work

    No idea - take pics and show / measure what you have

    No idea what you have - you will have to take pics / measure and show us what you have.
    The only reason I could think of your mechanic saying "its too big" maybe because of the increased power from a 455 over a 400 ? but stock thats no problem. Or, as others have hinted, he's not the brightest crayon in the crayola box

    OK, I'll break this down real simple for you:

    Your wife bakes 3 cupcakes for you for your birthday in a cupcake baking tin where all three are the same exact size.

    After she bakes the cupcakes (and they all are deliciously the same exact size) she then looks for candles ... unfortunately all she has is leftover candles that are all slightly different sizes but :Do No:

    So she pokes candle #1, the smallest, into the first cupcake ... candle #2 which is slightly larger into cupcake 2 and the biggest candle into cupcake #3

    The wife, kids, grandparents, neighbors, Facebook friends, and even the dog sing you happy birthday ... you blow out the candles and remove all three of them.

    in cupcake #1, there is a little hole - in cupcake #2 there is a bigger whole, and in cupcake #3 is an even bigger hole than all the rest - BUT THE CUPCAKES ARE ALL THE SAME SIZE ON THE OUTSIDE.
  13. hafuch

    hafuch Active Member

    I'll try to get that information and post it as soon as possible.

    Thanks again!
  14. David G

    David G de-modded....

    The 455 was available in the same Buick body for the 70-72 GS cars, and there is NO issue whatsoever with it being "too big" for your 68. You have the wrong mechanic to work on your Buick, seriously.

    For the motor mounts and/or frame pads, TA Performance sells new parts. Or post a Parts Wanted ad here. The rear sump A-body oil pan can be had thru Parts Wanted also, or TA also sells repros, I believe.

    Your mechanic has you worried needlessly about this deal. My 68 is in process of getting a 455 in place of the 350 in my garage. Tons of 68/69 owners have done this swap.
  15. hafuch

    hafuch Active Member

    On the subject of using a mechanic who is familiar with these engines, can anyone recommend one in North Orange County, CA?

    Any leads are welcome.

    Thanks again!
  16. hafuch

    hafuch Active Member

    And thanks 69GS400s! The cupcake analogy is perfect! NOW I get it! (and it got me laughing, too!) :grin:

    Thanks again, and I'll come back with photos and measurements!
  17. 69GS400s

    69GS400s ...my own amusement ride!

    Always glad to help .. who doesn't like cupcakes anyways ? :beers2:
  18. 65specialconver

    65specialconver kennedy-bell MIA

    Great,now I want cupcakes!!!:rant:
  19. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    Just to reiterate, the big block Buicks (BBB's) are referred to as the 400/430/455 for a reason. They all interchange except for the pistons. Rods are the same, crank's the same, the 400 and 430 blocks are the same, with the 455 being slightly different, but all have same exterior dimensions.

    Every single part interchanges, except the pistons. The 400 has thicker cylinder walls than the 430, and the 430's are thicker than the 455. This means the 455 is the lightest of the three, and of course the 400 the heaviest. The valve train was a little different over the years, but they're all interchangable with some slight mods, and the heads were a little different over the years--all will bolt up to each other, but some had different head chamber designs, valve size, etc.

    There's a better piston selection for the 455 simply because it's the drug of choice for all the torque addicts.

    There's low and high compression stock pistons for the 455, where the 400/430 only have high, though custom pistons can be made for anything if your desire is to spend money.

    Depends on what you want. Ask yourself a few questions:

    1) What kind of gas do you want to use?
    2) What kind of gas mileage do you want?
    3) What sort of drivability do you want?
    4) How much power do you want/need?
    5) Are you interested in keeping the car as close to original as possible?

    There's more details to all this, if you're interested I'm sure you'll find a wealth of knowledge here on this website.


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