I know the '68 Wildcat has a longer nose by 3" as I own one since '77. You can easily tell by the added length of the front fenders behind the front wheel. Standardization started at GM in '64 with the A-bodies. It wasn't until the mid/late 70's that the larger cars started to be standardized. Tom T.
I'm a bit late to the party on this one, but I did this swap last year so I thought I would say what I did and add some pictures for anyone interested in doing this. Pre Swap Information Fist off I'm not a Buick expert and I'm not a engineer, no don't take any of this as the right thing to do, as it's not a exact science my any means! What I started with was a 73 455 out of a Electra and I used the frame mounts out of that car was well. (I'll go more into this later but we did not bolt them in, and had to cut and weld them in) My LeSabre was a 400 Model, so it already had the TH400 in it. We never took out the transmission and used it to help line everything up and insure the pinion angle wasn't going to be jacked. 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM A welder is needed and a forklift / skid loader would save you a lot of time with a engine hoist. Also some way of cutting out the old frame mounts would help. The wiring between the two motors did not change for my setup, the 350 wiring was a direct fit for the 455, as far is I know it was all stock wiring. The Swap The first and easy step is to remove the engine . After removing all the wiring, linkage, and hoses, and tranny bolts, it should just be the two mounts welded to the backside of the crossmember. 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM After the motor is all out of the way it time to decide how committed you are as there is no good way of going back once you cut out the old mounts!!!! Now that you have decided that that more Cu = more funnier, it's time to cut the old frame mounts out so the 455 can fit. Our process of fitting the new mounts consisted of bolting the frame mounts to the motor and lowering it into the car to see where it would sit, modifying when needed. For our application with the 73 Electra frame mounts (which are a bolt in style originally), we ended up cutting about 1'' of the bottom of the mount so that the motor would sit lower and more level in the car. The more you take off the mounts, the lower that it will sit in the engine bay. This may vary depending on the mount used and setup, but it should be a good ballpark (no science here like I said). We got this number by putting the motor in and out and bolting it up to the tranny to try and get the best fit. (Why it's nice to have a forklift / skid loader). We kept shaving down the mount until we seemed to get the best fit where everything seem to bolt right up and sit right in the car. We then traced were the mounts where with a marker, took the motor out again, and welded them into place. And just like that, 90% done! Easy as pie (not ) 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM The new mounts should like something similar to this^^ They should be a bit staggered, the motor will sit strait. If you look at images of 69-70 wildcats with the 455, the mounts are staggered as well. (From my research) All that's left it to do is dress the motor back up and plug everything back in as if it were the 350! You will probably need a bigger carb, but I believe that was the only change we made (Maybe a bigger radiator as well). Also a clutch fan did fit just fine, had room for a bigger radiator if I wanted as well, no clearance big clearance issues. Only thing that didn't work was my shroud, because I broke it when I took it out , might sit a little higher as well, that's the only uncertainty I have. Worse case, electric fans I suppose! 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM 455 Engine Swap by Sean Hawkins posted Dec 15, 2023 at 2:00 PM After thoughts I see talks and read about how the LeSabre is a 123" frame and the Wildcat is a 126" frame in 69, but I'm not too sure that it's a actually thing, the 69 and 70 are basically the same car with different bumpers and updated engine options, but I suppose the only way to find out would be to line them up next to each other. Either way, shorter or not, plenty of room for a big block! While this is a lot of words, it could just be summed up to "Drop it in and make it fit" as that's basically what we did. The car ran and drove, didn't seem to have any problems going down the road or with the driveshaft having strange angles! (Besides the used motor having rod knock ) Would recommend getting stiffer springs to account for the larger weight up front, I'm going for a coil over setup from QA1, so I'm not much help there. Unless you like the raked up look, plan for different springs! This project took two weekends to complete from driving in to driving out, we had it on a lift, but didn't really need to use it for much, and this could easily be done on the ground! We never dropped or moved the tranny, just used it as a point of reference to help place the new motor correctly. This is defiantly not the 100% correct way to do this, but I hope this helps people who are interested in putting some more power into their 69/70 LeSabre with a big block Buick! (Now good luck with the rear end)
Thank you. Mine is too, and now I have spare leaking on my garage floor. Yeah, when I pulled the wiring on 430, I wasn't noticing any big changes from what I see on the 350. Between the 430's spun bearing, and me not welding I'm not that committed, so I'm still running my 350.
