I recently purchased a 1972 Skylark Custom Convertible. There are several things that I know for sure I want to do to her including: --Swap the 350 for a 455 mated to a TH400 tranny. --Change the hood to a GSX style hood --Change the rearend gears and add posi --Upgrade the brakes and suspension I have the ability, and the room, to do a body off restoration/revamping. I am a firm believer of using NOS items when possible (I try to build 'Green" and a contractor and I would like to do the same with this vehicle.) The first thing I would like advice on is upgarding the suspension and drive train. What part vehicle(s) should I look for when looking for parts? Can I use the stock rearend, and install new gears, or should I look for a 12-bolt GM rearend? How much of the exisiting front suspension can I use and what should I upgrade for putting in the 455? If I wanted to convert to disc brakes do I need to buy an aftermarket kit or can I salvage front and rear discs brakes from another vehicle? This car will be a fairly regular driver so I don't want to get to radical with the rearend gears and engine setup. Since this is my first Buick all suggestions are greatly appreciated.
Not all GM rearends are the same, even among same "types". For instance, 10-bolt from Chevy would be different from 10-bolt for, say, an Oldsmobile. Most differences are internal. Some makes made several changes over the years to certain sized rear ends, yet continue to identify it by the same moniker, such as "10-bolt". One suggestion I would make would be to change your tranny option from TH400 to 4L80, which is the same tranny, just with an added overdrive 4th gear. It's a little longer and heavier than the 400, but otherwise the same tranny. This would allow you to use a slightly deeper gear and still realize some comfortable freeway cruising. Amount of OD for that tranny is 25%, so (for example) a 3.73 gear ratio would become an effective 2.80 gear ratio in 4th. As for suspension mods, I think any A-body will fit. Depending on how much of a canyon carver you wanna make the car, you might even want to look into aftermarket suspension modes, such as tubular A-arms for the front, which would have a better built-in steering geometry than the stockers. Polygraphite bushings would be a step in the right direction, as well as sway bars, larger shocks and maybe even progressive rate springs. Suitable wheel and better gripping tires should, of course, be considered as part of the suspension upgrade. One mention about your brake comments. In case you're not aware (and not everyone is), if you switch the front brakes from drum to disc, you MUST also change out the master cylinder. Disc brake style uses two chambers and a proportioning valve (separate piece from master cyl.) because of the different volume of fluid the disc system uses, compared to the drum system. If you wanna upgrade to POWER front disc, I suggest sticking with something donated from a mid/late 70's cars or newer. The braking is much smoother and safer. Older power front disc systems had all the power come on at once. When I was a kid, my parents had a '72 Nova w/power front discs and I almost broke my nose the first time I drove it, because I had gotten used to my Dad's truck and his '67 Beetle, both of which had non-power brake systems. Otherwise, yes, any GM donor will work in your Buick. ...however, your comments beg the question...what's wrong with the 350? Its quite light in weight (same as SBF and 100lbs. lighter than SBC), yet an incredibly strong powerplant. If there's nothing wrong with the car's current drivetrain, you might want to consider workng with that equipment instead. ...just a suggestion. Bob
GS and GSX hoods are the same from 70-72 except the 71-72 hoods have a front spring and mount. Rust free examples are rare. Most have rust in the seams where the two halves meet. Once it is there is almost impossible to stop. The inserts in the inlets are essentially the same for 70 and 72 but different for 71.
FlyinBuick, Thanks for reminding me about the hood, as I wanted to comment on that as well, but spaced it in my original post. -------------------------------------- PNWRon11, When changing out the hood, look into the newer style hood springs, as well. When your car was built, GM used a system of 4 articulated arms (per side) that used a coil spring in the middle as a hinge. The problem with this system is over time the joints for the arms wore out and would bind. As the hood got more flat, the pressure exerted on them (usually just ahead of the flange that connected hinge to hood) would cause a crease in the hood, with the ultimate result being the hood folding in half, yet the hinge would remain open (takes on this shape - /\). Anyone who's owned or worked on any 70's era Chevy trucks, know what I'm referring to. One cure is to simply push in (towards the windshield) as you close the hood. However, most people tend to either ignore or simply forget that step and end up folding the hood. GM's remedy came about around the '82 model year and that was to simplify the hinge, by redesigning it as a two arm unit with a flat wound spring (looks like a watch spring). While the flat spring is rated at the same force as the old coil spring, its design allows you to use much less force to overcome its tension. The result is less stress on the hood and thus, no more folding hoods. Check the bolt patterns to be sure, but as far as I know, the newer design of hood hinge is straight bolt-in swap of the older system. Bob
Ron, The rearend in a 72 should be the 8.5" rear. Unless you're looking to build a 455 for the strip and put out well over 500 hp, you should just get the one you have rebuilt. Plus, being a Buick rearend, it has bolt-in axles. Since you want a driver, a 3.08 rear would work well for you. You could also go with 3.42's and run a bit taller than stock tire to fill the wheel wells. The taller tire will bring the 3.42's down to more like a 3.08. If you go with a TH400, understand that you'll want a "short-shaft" TH400, and that you'll want a "BOP" bolt pattern. Chev bolt patterns are different. The big Buicks that came with a TH400 have a "long-shaft" TH400. They could be made to work with a custom driveline, but you'd be better off with a short shaft version. If you wanted to go with an overdrive trans, then you may want a little more rear gear, since the overdrive will cut it down. You could look for 30 year old factory stuff, or you may want to check into www.scarebird.com for upgrading your brakes. They make kits that use off the shelf stuff that is common and inexpensive to replace your factory (drum?) setup. And, they're local to you - Lynnwood. You will likely want to replace front springs too, as the 455 is heavier than the 350 and it will bring the nose down. Plus, the original springs are 35 years old and probably due to be replaced if you're planning on cruising comfortably anyhow. As far as a 455 goes, if you're planning on a rebuild, the later 70's blocks are usually preferred. They have lower compression from the factory, but if you put in new pistons and swap to an aftermarket (aluminum) head, it won't matter. The GS/GSX style hoods can be pretty spendy as they only came on GS's. There are fiberglass hoods you can use, but that may not be what you're looking for. The only one I see currently on ebay is a 1970 hood that has a starting bid of $800, and it looks like it doesn't include the grilles, etc... Lots of Buick people in your area - I'm sure you'll find them quickly!
71GS455, Where did you get the picture of that license plate? I haven't seen one of those in YEARS! ...and shouldn't there be a "Y" before the "L"? Bob
There's a place online that you can "make" your own images of custom personalized plates. I don't have the URL off hand, but you can probably find it with a search. They included the older plate images. Actually there should be an E on the end, but we're limited the number of characters we can put on it. I figured the Y would just confuse people...:idea2: If only I could put the line over the "i" to signify it's hard not soft. But anyone who reads it and gets "quarter mill" out of it deserves to be confused. :Brow:
how about leave the 350 engine in it with a supercharger or turbo and a 4speed automatic and 3.73 gears for the hood they are not cheap ,but fiberglass repros are available thepartsplace may repro them in the future you could call
You mean its supposed to say "Quarter Mile?! :eek2: pp ) Thanks for the info. I'll check that out. Bob
I am in the same situation, I am "dressing up" my 72 Skylark and would really like a GS hood for it. Can anyone tell me the disadvantages of using a fiberglass hood?
Groovy! Thanks a ton. MALTA, I think one disadvantage is Fiberglass is more fragile. The first time you slam it, it may crack. That might be an old problem that has already been remedied, though. Bob
Does anyone else know if the fiberglass hoods that are available now are any tougher thatn the older ones?
dont forget to change the hood hinge springs to a lighter set ford ranger hood springs im told work well
