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  • Buick 401 question

    I've been driving a 63 Buick Riviera (401) that sat in a relative's garage from 1976 to 2018.Everything was stock. This thing has lots of oddities. The trans is a Dynaflow 2 speed automatic with a switch pitch torque converter (stall increases with a lever connected to the throttle), which seems all about smooth shifts (and not performance). I was shocked to see it leaves 2 patches!

    My question is are these engines not meant to rev? It seems real strong up to near 5000rpm but falls off after. The engine has 90,000 miles on it and sat for so long, so I'm guessing the valve springs may be toast. I've been reluctant to tear into it since it seems to be running great.

    Here's a pic of how it looked coming out of the garage after 42 years and after a hose down. It looks way better in pictures than in person!
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    Weird manifold (with small looking ports).

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    Added EFI and came up with a way to use the stock air cleaner (which I restored but not looks way crappier). I tried to rebuild the old carter (twice), but there are a bunch of oddball parts that I may have screwed up, so I never could get the carb running right.
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    Might end up one of theirs!?
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    Tampa, FL

  • #2
    5000 rpm would be about it, would be my guess. Did you look at the way the ports work on those things? not really the best design in the world.

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    My fabulous web page

    "If it don't go, chrome it!" --Stroker McGurk


    • #3
      What are you trying to do with it? A little more power.... A lot more power? No, stock they don't survive long at above 5500 rpm. The best thing you can do is exhaust. Look at the picture Squirrel posted. The exhaust port does a weird j hook. Anything you can do to open it up or get some more flow is a good thing but then you are tearing into a good running engine. I would put a good quality header/exhaust on it and cruse quite happily.
      Well I have stopped buying stuff for cars I don't own. Is that a step in the right or wrong direction?


      • #4
        It's just a cruiser, but who wouldn't mind a little more power? I was aware it wasn't a high-perf engine. I agree the ports have odd shapes. The pushrods/rockers look like they have a weird geometry too. I think I might look into headers and keep rpms under 5500.
        Tampa, FL


        • #5
          They are torquey motors. The 445 on the air cleaner is the torque rating for it.


          • #6
            I worked for a Buick dealer when these were current. First, I hate you for having this car when I don't!! (J/K - but I've long lusted after a first-gen Riv). If it gets in your way I'll come and get it!

            Second - the Dynoflow is NOT a 2 speed. It's a continuously variable one speed. I'm remembering that there is a low gear gearset but it's not used in drive at all - just to help you drive out of a snowbank. A word of caution: park is a sort of weak link in this trans. I don't know if it's still available but at one time there was a thing called a "quick link" available that braced the parking pawl against the case and that made park work w/o removing the trans and replacing the broken internal bits. DON'T use this repair!! The next time park fails it'll take out the case! We advised our customers to use the parking brake if you're on any kind of grade - problem solved. BTW - I've heard this trans described as a "Powerglide" when, in fact, it has nothing to do with a Powerglide. Again, IIRC, I think this was the last year for the Dynoflow and a lot of our customers missed them. '64 is when corporate standardization started to kick in.

            The 401 is a great engine and they'll run forever. 5K RPM is about it (as pointed out, the engine is port limited). These engines CAN be built successfully (TV Tommy Ivo did OK with them!) but if you did that you're getting way far from the intent of the car. It was designed to be a personal sporty car for doctors and lawyers and such - take the clubs to the Country Club sort of car. The stump pullin' torque worked nicely with the the Dynoflow, hence the ability to lay rubber. If I were mine I'd keep it that way. I think the EFI (and a points replacement if you haven't don that yet) is a great addition just to make it even smoother and more reliable.

            You probably know this, but underneath it's pretty much a LeSabre with different bodywork. It's been a long time so my ol' memory is foggy but I think there's some difference in sway bars, shocks, etc. but pretty much LeSabre. The engine is, of course, like what was installed in the Wildcats and Electras. Seems like the LeSabre had a 401 2bbl, just pulling that out of my memory bank.

            Have fun with it!

            Deaf Bob likes this.


            • #7
              Dan - Thanks for the background. That's wild you were at Buick back then! I guess I misunderstood the trans (which I had an old timer rebuild). I originally thought something was wrong with the trans since it didn't shift (but also wondered how it got to 80mph w/o feeling a gear shift). Should I not be taking off in L and shifting to D (which I've been doing a lot)?
              Tampa, FL


              • #8
                Not much to be gained. It's designed to start in a lower simulated gear (I guess you would call it) and basically drive the stator more aggressively as you gain speed. The trans is a lot like a modern CVCC trans (did I get the acronym right?) where it continously changes the gear ratio though the Dynaflow does it thru the pitch in the converter. If you're curious I have a '56 Dynaflow that you could have if you come and get it (we're a day from Tampa - I made the drive from here to Clearwater many times when my Mom was sick) so you could tear it apart and see what makes it tick. The '63 is at the highest stage of development on this trans and we were bummed that they quit production just as they were getting it to work well.

                I'm trying to remember if manual shifting from L to D has an impact on durability but it'm guessing it might. It would likely hold up longer if you don't do the manual upshift with your right foot on the floor but I really don't "know" that.

                Love to weld up those lower fender corners and paint 'em. Otherwise the body look pretty good. Lots of Buicks in those days were painted that gold.



                • #9
                  I have a '64 and Dan is mostly right about it being a full sized (more Wildcat/Electra than LeSabre though) shrunk to more large A-body proportions so the same parts made it feel much spryer. The car is a great driver with the stock stuff and though I upgraded to discs on mine the stock aluminum drums really are plenty powerful The top end of the handling range for that platform would be the H2 suspension package with slightly shorter and stiffer springs and a slightly bigger front sway bar.
                  I actually have a set of H2 front springs I pulled off of my '64 when I swapped in a Buick Turbo6 (a much modified Grand National engine) and the front end sat too high.

                  As for the 401, it's been covered that the valves are just tiny, the exhaust port restrictive, and the rotating assembly just too heavy to really wind it out. Parts are strong and should give you plenty of good service. Dan know far more about the Dynoflow since I picked up a '64 specifically to avoid it. The crank pilot is different so you can't just bolt a ST400 (first few years of TH400 with a different valve body and pan) off of a 64-66 in there despite the same bellhousing.

                  Check out the under floor bracing for the seat mounts for rust as the factory assembly jig holes like to let dirt in there and it collects at the flange where they meet the rockers and rusts them out. Also check the body mounts in the trunk as they like to do the same thing.
                  Central TEXAS Sleeper
                  USAF Physicist

                  ROA# 9790


                  • #10
                    Great info from CTX-SLPR. He's doing wonderful but unnatural things to his early Riv and has a lot of good info especially concerning the body. See, there's lots of input on here!

                    How about a build thread??!!



                    • #11
                      Thanks guys - Great info!

                      A build thread would likely be boring since all I've done is convert it to EFI, have the trans rebuilt, and added seat belts.

                      The seat belt thing was interesting. I saw in the manual that there were reinforced areas under the back seat for the dealer to add back seat belts. I found the dimples under the seats where the holes go.

                      I did something a little weird for the front seat belts. I have kids that will be in this car and really didn't like the front lap belt with seats that just flop forward. I bought a cheap roll bar and cut it up to make something for front shoulder belts.

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                      The crazy thing is after sitting in a garage for 40+ years, all the electric stuff works. I think my only complaint is there seems to be more room in the trunk than interior!
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                      (Goalie hockey equipment fit check - awesome being able to get this super smelly stuff in the trunk!)
                      Tampa, FL


                      • #12
                        That's a reasonable solution on the belts. Probably safer than a factory arrangement. And yes, those trunks WERE mighty!

                        Last edited by DanStokes; November 10, 2019, 08:20 AM.


                        • #13
                          Originally posted by MadmanMark View Post
                          Weird manifold (with small looking ports).

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                          Ok, what is the point of that groove and 2 small holes?
                          (smile and 2 dimples) on the carb pad?

                          Is that connected to a heat crossover, for heating the carb in cold weather?
                          Last edited by Eric; November 13, 2019, 12:00 AM.


                          • #14
                            Eric - That's exhaust heat to keep the carb from icing in cold weather. Those passages sometimes got carboned up and we'd have to pull the carb and clean them or the engine would run like crap in the winter. A common performance mod was to plug those to keep the intake heat down and to resist fuel boiling in the summer but the trade-off was poorer cold weather operation. So ya pays yer money ya takes yer chances......

                            Buick also had a heat riser valve in the (IIRC) driver's side exhaust manifold to restrict exhaust flow also to encourage engine heating. The heat riser had a bi-metallic spring to open the heat riser once the engine warmed up. There was also a tube from one of the exhaust manifolds to the air cleaner to deliver warm air into the carb as soon as possible. Smooth cold weather operation was a big deal back then and GM (and the others, too) did all sorts of things to try to make them work better. It was a common customer complaint and that has pretty much gone away in the world of EFI and now direct injection.

                            Last edited by DanStokes; November 13, 2019, 02:33 PM.


                            • #15
                              We used to clean the holes and add JBWeld.