In 35 years of working on Buicks, I have never done a 455 swap into a 64-67 A Body. I have been stuck in a rut with 68-72 cars, lol. Well, I bought a 65 and am doing a 455 swap, which I thought would be pretty straight forward. I ran into several issues and after a lot of internet searching, I found very little definitive information. So, I am making this thread outlining the things I know for sure about this swap. Two major issues I have ran into, the aftermarket frame pads and motor mounts and an aftermarket oil pan.
I found some information stating that the aftermarket frame pads and motor mounts raise the engine about 1 inch higher than the factory pads and mounts used in a 67 GS400, but nothing affirmative. I do know that the aftermarket parts allow you to move the engine back 1 inch for header clearance. I can affirm that the aftermarket pads and mounts definitely raise the engine at least 1 inch maybe a bit more. This makes the valve cover come in contact with the brake booster. Some people simply run a smaller diameter booster, but I did not want that option. I happen to have a set of factory 67 GS400 pads and mounts, which dropped the engine allowing everything to clear properly. You can see the difference's in booster clearance in the pics.
Fix one problem and create another. With the engine lowered to clear the booster I then discovered that my oil pan was hitting the crossmember, damn. I am using a TA aftermarket 6 quart pan and discovered a production difference in it versus the factory pan. There is a step just before the sump in both pans, however in the TA pan this step goes straight across the pan. In the factory pan this step is curved, or rounded. See the pics. This curve allows the pan to clear the crossmember when using the factory 67 GS400 pads and mounts. As a note, I have never had a problem with the TA pan hitting in a 68-72. So, to sum up, if you are going to use the aftermarket frame pads and motor mounts it definitely raises the engine and will not clear the factory brake booster. I would imagine that this would also contribute to air filter clearance issues. Secondly, if you are going to use the factory 67 GS400 frame pads and motor mounts you can not use the TA 6 quart oil pan, without modification anyway. You will have to use a factory oil pan. I hope this information is useful to other people.
i have the old Poston mounts in my 64 and have had driveline angle issues. my trans, drive shaft, differential, alignment is in a \_/ angle (trans points up in relation to the driveshaft) instead of the preferred /_/ angle, if that makes any sense. I always thought my engine was too high. Are the 67 frame pads different? engine mounts different? or both? Question?- Are your second and third motor mount pictures of the aftermarket mounts? or the 67 mounts?
The pics are the aftermarket ones. Yes the frame pads and the motor mounts for a 67 GS400 are different than the aftermarket ones. The original pads and mounts are a one year only special deal, and the after market frame pads have been modified to use the 68-72 motor mount, which is actually a better design and is still available. The og 67 motor mount is hard to find and does not have a safety catch built in if the mount breaks. The later ones have this feature. Thanks Brent
I put a 455 into a 65 skylark, with the TA frame pads I had none of the issues you are having. Something is wrong. I would use a factory oil pan to get a reference to get the motor in. The only changes I had to do was use a short shaft water pump and move the tranny cross member back 1 inch to use the turbo 400. I also am using the small brake booster.
Reading your post picked my interest and prompted me to drag a couple of pans out of the garage rafters. I never knew there was that much difference between them, but the later pans are quite a bit different from an original '67 GS pan as these photos show..............
An original 67 GS 400 oil pan will not work with an original 5/8 pickup tube. I found out the hard way.
That's good info!... I would have found that out myself if I had tried to use my original, it's a good thing I changed pans.
67 GS400 oil pan is different because it wasn't designed to accommodate the exhaust crossover pipe that all the other cars had with single exhaust.
I used Poston mounts that I believe are higher like the TA ones. I had interference with the factory brake booster. I swapped it out with a 1980 Pontiac Turbo Trans Am double diaphragm unit. It bolted on and I just had to thread the rod and screw the original clevis on the end to go to my brake pedal. It works great. One other thing to share for guys doing this is the radiator shroud. I had originally had a fibreglass reproduction of the 67' shroud to use. It fit like **** and I was not happy with it. I ended up using the small block one from my car and just turned it upside down and trimmed 1" off it's depth. The fan on the big block is offset opposite the small block. Turning it upside down moved the offset the other way. I changed the top piece of the rad support that holds the radiator in with one I had from a second generation Nova and attached the rad shroud to it. It fits good and still looks pretty much factory. My car is a 66' Greg
Good to know regarding the reproduction shroud. I have a new 4 row radiator and will try using just the factory finger guard first.
I bought my 67 skylark with a BBB in it with the Kenne Bell VC on it & P A E mounts... The brake booster clearance was not there so Im using manual brake boosterhttps://www.napaonline.com/en/p/NMAM1922.. I believe with stock Valve Covers I would have had clearance. The PO cut the bottom out of the fiberglass Fan shroud from 4:30 t0 7:30 o'clock position. Fan is a 18'' 7 blade. Plenty of blade clearance from the 9 to 3 o'clock position... Does get tight at the 4:30&7:30 I imagine it would be touching if no out of the circle at 6:00.... That tells me the motor sits low....I did Tweek in a piece of Aluminum to fill in cut out portion at the bottom of the shroud.... Don't look very good but till I come up with a better fix it will do... I am using the TA http://www.taperformance.com/proddetail.asp?prod=TA_1511D. It fits with no issues... Although I did have to hammer out a spot on the pan for crankshaft clearance no bid deal..... I do have a 300-340 fan shroud I would have to cut way more than 1'' off its depth like photo in a above picture.... My fan would be totally inside the shroud so dont understand... I think I would need to remove the whole front strait edge (ruler in pic) of the shroud.. Only them the shrouds would be the same length and not swallow the fan... Sorry the pictures suck... Car is on ground... FWIW the PAE mounts on my car look different
