1972 GS Convertible Driveline

This page will lightly touch on the driveline and component rebuild for this car, some of the problems and solutions found. Hopefully the info is of use to others.

Buick 350 4 barrel, turbo 350 transmission, GS one piece driveshaft, and 3.08 posi rear make up the basic driveline of this particular car. 1972 was the first year for "net" ratings which is the engine rated with all its accessories on and running, using a full exhaust system and simulated heat under the hood. This is why there was such a drastic drop in HP ratings from 1971 to 1972 (the drop in ratings from 1970 to 1971 was due mostly to GM lowering compression ratios from 10.0 to 1 to 8.5 to 1 for emissions).

Some additional ID of the car. Pictures of the serial number stamped on the engine block (last six digits match the last six of the car VIN so its original to the car), the code stamped on the block between the two forward plugs on the drivers side (code WB, 72 GS 350 engine) distributor number 1112109 (also correct), and the carb number 7042244 (72 GS 350 carb), sharp readers will note the date code is wrong for my car so it must have been replaced at some point.

Also, the exhaust system is still original (date coded about one month before my car was built) and the u-joints have never been changed in 29 years! First picture shows a muffler with the date code and GM part number on it. Second picture shows the original battery cables with correct p/n's (although the end was replaced on positive cable).

March 15, 2001

The wiring harness, throttle cable, kickdown cable, p/s hoses, engine mount bolts and tranny mount bolts have been removed in preparation for removal of the engine/tranny. I have still not decided on whether to rebuild original driveline or put it away for safekeeping and drop a 455/400 combo in there. One of my friends suggested today I should buy a wrecked local truck and put the EFI engine in there along with the 4 speed auto. Would be neat but I don't think it could be done without making modifications that would be destructive to the original parts....besides my Buick friends would kill me!!LOL

April 17, 2001

Found an aluminum non a/c alternator bracket that I needed at the auto recyclers.

August 30, 2001

Engine and transmission being removed in preparation for the chassis to go to the bodyshop. I delayed this as long as possible since I now have to store the engine and tranny too. Before the engine was pulled, I removed the front springs and cut two coils off each, this way when the body goes on the rotisserie and I bring the bare frame back home, I will still be able to jack up the lower control arms to get the front springs out so the frame can go for coating. Otherwise, you would be trying to jack up the lower control arms but with no body or engine on the frame, it would simply lift the whole thing and there would be no way to get the springs out without buying a spring compressor. The front springs will of course be replaced with new.

Oct 27, 2002

Here is the engine that will be going into the ragtop. Basic 455 buildup, .030 over using Sealed Power forged pistons, line bored, crank ground, decked, balanced and ready to assemble. I like the 455 because you can do a basic stock rebuild and still have useable power (400+hp) with huge torque and a quiet, smooth drivetrain.

I know you can make this kind of power with small V8's V6's and even four cylinders. That is very true, and I know some have pulled huge power out of small engines, and they are a lot of fun but it usually requires turbos, supercharging, or nitrous and I am doing a "resto" here. Even though this engine is not original for the car, it is a correct year and type of engine, and will look stock. Also, I find many of the high power high strung smaller engines are simply annoying to drive, noisy and rough...you need to hit 7000 rpm to make power but I prefer the off line brutal bottom end type of power and torque from big blocks, it works very well for these cars, especially in town. Also, with lower RPM's, you don't need any kind of exotic parts which saves money...a stock 1970 Buick 455 with a set of well done (or aluminum) heads and mild cam will run 450-500HP with no other major mods. All a matter of personal preference.

Once the car is done, I will rebuild the original engine, and will be able to change it all back with no problems should I ever want to.

Nov 28, 2003

Crank is in. Cut .010/.010, and balanced with entire rotating assembly. TA rear main seal (no trimming required), and Clevite 77 bearings throughout. Clearances are .002 on both the rods and mains. There are no four bolt main 455 blocks except for two experimental pieces. You can see why the 455 is a lightweight for its size, not much beef there. You wouldn't want to go over 600HP without bottom end reinforcement (girdles, special pans, etc are all available). No need for that with such a mild combo. You can also see the huge 3.25" diameter main bearings and the 2.25" diameter rod bearings.

March 10, 2004

Went fairly small on the cam to make the most of our high altitude and for mild engine, this is a convertible after all. Turbo 400 transmission is being rebuilt by a friend, waiting for a couple parts. Oddly enough, parts are getting a little scarce for those trannies since nobody has used them for many years. The transmission is an original "BS" code GS 455 Turbo 400, which comes with revised shift rates, extra clutch pack and a few other internal upgrades.

One sticky issue has been the waterpump. The 71 up Buick 455 used two pumps basically, a "long" a/c version and a "short" non-ac version. Cars with a/c, heavy duty cooling (all Stage 1 cars) got the a/c setup with the longer pump, dual groove waterpump pulley (5 5/8" diameter) p/n 1235778, and triple groove crank pulley (7 1/4" diameter) p/n 1235777. The pump for these cars had five vanes on the impeller, and there were two versions of those...one version the vanes extend almost to the edge of the cast impeller, and the other the vanes extend 3/4's of the way to the edge. The non a/c, non hd cooling cars used the "short" pump which has a one groove waterpump pulley (5 5/8" diameter) p/n 1238156, and the two groove crankshaft pulley (6 1/4" diameter) p/n 1235779. The pump for these cars originally had six vanes extending almost to the edge of the impeller casting. Most cars got the long pump.

So the a/c or hd cooling crank pulley is p/n 1235777 used from 71-76. The matching waterpump pulley for this combo from 71 to 73 is 1235778. In 74 there was a new p/n 1244057 (diameter unknown). In 75 and 76 the a/c or h/d cooling waterpump pulley was 1247885 and is a bit smaller than the earlier versions, being 5 1/4" in diameter instead of 5 5/8" so that is another option for a bit more flow. There is also a 1250725 pulley that does not show up in any of my parts books, it is also a 5 1/4" dual groove waterpump pulley off a 75 455, matches the 1247885 in dimensions but looks slightly different. Go figure.

Now here is where it gets weird. I wanted to run the single waterpump pulley simply because it looks better than having an unused pulley groove (even though it is correct for HD cooling cars, it looks odd). It also saves some weight, lets engine rev faster compared to hd cooling, and looks just like the 350 engine that came with car. So you order a non ac waterpump and it shows up with the five vanes, short ones at that. Now with the smaller 2 groove crank pulley, you are driving the waterpump some 16% less, so with the crappy impeller on it, there is a good chance you will have cooling problems at idle. So I am currently looking for a decent waterpump for non ac cars, will post the number if I find one. If not, I will likely just go with the HD cooling setup. Looked into swapping existing impeller, and got the one off my original pump no problem, but it needed heat to get it off the shaft (press fit) and that would likely damage the seals on the new one if I tried that....oh to have Chevy parts selection!!!

If this wasn't a stock appearing resto, I would probably go with a serpentine system, several guys are making them and you could custom order pulley diameters to fit your needs.

July 2, 2004

A stock GS 455 driveshaft will be used on this car. The biggest problem here is how to refinish it. The factory left them bare metal, and they would be rusty before they hit the dealerships but that is not a great option IMHO. Many are painted black or silver but that never looks quite right. Powdercoating has some excellent matches to bare metal but is expensive and heavy. In the end I buffed the rust off and cleaned the shaft with a rotory scothbrite pad until it was smooth then put two light coats of clear on. This worked well as the driveshaft looks new but does not looked painted. You can see the seam in the tube from when it was formed. Also, I sprayed silver paint into the weld areas before buffing so where ever the wheel couldn't touch it would still be silver. Ends were sprayed with cast iron, and new u-joints installed. The ID stripes will be painted on later once driveshaft is installed by turning over wheels and spinning driveshaft. They are freehand only, no masking was involved originally and they can be quite sloppy.

Picture of stock driveshaft before cleaning. Note how far apart the stripes are located, the assembly manual shows them side by side and people always paint them that way but these ones are a foot apart. All the other 455 driveshafts I have seen (original) are also spread out a foot or more, as is the orignal 350 driveshaft too. 1 yellow and 1 green is the code for 455 auto cars.

Driveshaft after clearcoat. Balance was fine before all this, so will go as is for now...may have to rebalance it later. Make sure whatever you do for coating is evenly and lightly put on, no need to introduce problems here. One other thing, the Skylark cars got a driveshaft that was two tubes pressed together and held by a rubber insert...if you swap up to a 455, make sure to get a solid driveshaft made up (as per the GS cars) or you could have some real problems...

July 6, 2004

More info on waterpumps. Best one I have seen so far is the NAPA P881, this is the 71 up non ac pump, and it has the correct six bladed impeller. Also, I discovered that the a/c or h/d cooling crank pulley will also work with the non a/c waterpump pully so if the basic two groove crank pulley isn't enough, you can always bolt on the other a/c or h/d onefor an extra 16%, and although it will have an extra groove, it is deep in the engine compartment and won't be in your face. So for now I am going with the NAPA pump.

Cooling is a big issue with these engines, so be sure of what you are getting. Picture below shows the ac pump on the left, the non ac on the right. Note the difference in the impeller. Also, there are different gaskets out there...the one supplied with my pump was .058 thick, the Fel Pro style is .029 thick. I usually put the pump on without a gasket and check for binding. If it spins ok, then go with the thinner gasket...since the housing is also aluminum, there should be no contact that way, plus you lose less water around the "edges"...pumping losses will show as hotter temps. Also note our lucky US neighbors can order new pumps, in Canada they aren't even available.

Apparently, the 67-70 400/430/455 waterpumps were the short style, ac or not. I have no experience with them, my cars have all been 1971/72.

July 7, 2004

Pistons are in. Sealed Power .030 forged aluminum pistons (p/n L2353F) for a total of 462 cubic inches. They are heavy but pretty tough, and relatively inexpensive. Again, for what I am doing, these are just fine, and available locally. I have heard bad stories of the hyperutectic pistons in the 455, so I stuck with forged. The block has been decked .035", which raises compression a fair bit, and also allows for another cut or two for future cleanup if necessary. Wiseco also makes lighter forged Buick 455 pistons in 10-1 and 12-1 ratios .038" oversize to take advantage of the large selection of low tension Mopar 440 ring sets available. Its a natural upgrade to redoing a block already .030 over...and others will make custom pistons for this engine but they are fairly expensive, not worth it for what I am doing.

July 9, 2004

Transmission has been rebuilt. This is a turbo 400 from a 72 GS 455 car, and I detailed it as such. A friend of mine rebuilt it with many upgrades and high quality parts. Should be bullet proof. Once mounted in the chassis, the pan and gasket will be replaced. Still need to find a dipstick tube, original was trashed.

July 15, 2004

Several holdups but finally got engine together, tranny attached and installed. Lots of detailing to do yet, but basically the chassis is done. Driveshaft markings were put on by spinning wheels which turns driveshaft and then holding a brush to it with the correct color paint. The factory was very sloppy with these markings, they were NOT masked off so I tried to duplicate that. Balance is probably all gone now :) Color codes were put back on where I found original stuff, but don't be sure all the colors are correct for your car.

Engine is 10 to 1 (calculated) with a fairly small cam (TA perf 230/240). Heads are stock, cast iron intake.Torque convertor is stock. The smallish cam and compression will compensate for our altitude here (3500 feet, some days are 6000 density altitude!). I don't want a monster, just a nice driver with some jam, it is a convertible after all.

One nice thing about a car going back together is the extra space that shows up once the parts start going onto the car. I have a dipstick tube now, and you can still buy the original dipstick itself from GM so I replaced that as well. They will go on later. Lots of details to do, manifolds, fittings, etc, but will put the body back on first as I am running out of money so will have to let the whole project sit for six months or so while I recover $$$ .

Aug 13, 2004

And you thought re-cycling was something new.....look at this picture of the original exhaust hangers from this convertible. They are bolted to the chassis and then the metal part which the pipe clamps bolt to is supported by rubber strips cut from old tires!! Currently trying to locate the proper rivets so I can replace the rubber strips. It has been sandblasted to work on, once everything is ready, the metal parts will be re-blasted and then powdercoated.

Sept 10, 2004

Your basic Rochester Quadrajet. This one is part number 7042240, which is a a 1972 Buick 455 800 CFM carb. These carbs have gotten a bum wrap over the years, yet if properly rebuilt and adjusted, they work excellent.The small primary venturies allow for decent mileage and good low end throttle response and the huge secondaries allow for all the fuel most street machines need. Rebuild kits are cheap and easy to install yourself with some basic skills. Note that the base plate has already been removed to install new throttle shaft bushings (another one of those those little items that often gets ignored yet reaps huge benefits). I won't go into rebuilding here, but I would suggest the Rochestor Carb book by Doug Roe. It has most of the info you could want. The container is used to hold all the parts. Since my engine is very mild, it will be a stock rebuild with slightly larger jets and some detailing.

Oct 27, 2004

Here is the same carb almost completed. Some of the parts will still be replaced with new once they show up (fuel inlet for one as it has some damage on the flare seal area). It has been rebushed, rebuilt and the wells sealed with epoxy. I used the Eastwood carb renew spray on the carb, and while it turned out nice I wouldn't call it correct. Perhaps I sprayed it on a bit too heavy but certainly tried to give it a light uniform coat. Regardless, even though it is a bit dark it does looks much better than it did. I went a bit rich on the primary side to ensure no lean damage to engine, once car is driveable I will tune the carb for the car.

Since I had the carb cleaner going, I went though my other spare carbs. It is interesting to note that of those carbs, all have an aluminum base, some were the "bronze" color on the air horn and the bowl section, while on others the bowl section had a slight greenish tint to it. Also note that the flash brings out some odd details and makes the carb look dirty in spots, yet it is quite clean. A proper restoration would have all the linkage parts, air valves and other bits replated or replaced with new. That makes the cost very high and while it looks fantastic, nobody is even going to see the thing.....

Jan 2, 2005 (picture updated)

While the brake system itself is in the chassis section, some items that don't fit anywhere else will be mentioned here. The brake booster (hey it's in the engine compartment so that is driveline right?!) is one of them, and I put it here as an example of what can be done. Always get the best core you can, but in my case I wanted to see what I could do with the original brake booster, which had some pretty severe rust on it, but it also had the orginal date code. Picture of the front part once the booster was taken apart:

It was quite a process to clean this thing up for plating. First, I used coarse scothbrite pads on a die grinder and solvent to remove any excess crud. The inside corners needed to be done by hand. This revealed some pretty serious pitting. That was taken off with a die grinder and grinding disc. The inside corner pitting around the master cylinder area and lower triangles was done with small grinding bits and by hand. Remember to keep moving back and forth and keep it even, no need to introduce large grooves or ridges.

After that I went over the whole thing again with scothbrite pads on the die grinder to level off the grinding marks and smooth the whole thing out. You have to be careful as you can actually change the shape somewhat if you get carried away.Try not to round off the corners too much.

Once that was done, I sandblasted out the still rough areas to clean things up and even the surface. I then beadblasted those areas to smooth the sandblasting and see how it looked. Any roughness was sandblasted and beadblasted again. Once I was happy, the whole thing was beadblasted, then buffed again with fine scothbrite pads on the grinder and by hand for the tight areas as the plating needs a smooth ands shiny surface for the best effect. Then off to the platers. Total time so far about 8 hours. I could have done more but I was sick of it by that time anyway.

It turned out pretty decent. You can see it was plated along with the hood latches, and the seatbelt bolts (once installed you can see them from underneath). Its not perfect but pretty close, and looks much better than bare or painted boosters. The zinc plating is pretty cheap too. Since the internals were good, its just a matter of re-assembling the booster and installing.

After seeing how this turned out, the carb may have to get done too!

July 20, 2005

Sharp eye'd readers have mentioned a few things such as the lower hood release bracket which should be gray phosphate, not gold zinc. Also upper control arm shafts are aftermarket, not original style, etc. I know of these things but decided to do what I did for various reasons, ie buying a new prop valve for safety vs having the original rebuilt for 10X the price, etc. As I have mentioned, the car will be correct looking and I try to keep it as correct as I can, but information is sometimes spotty, colors don't match from factory to factory, plating one part is very expensive vs batch plating, etc. There are some details not worth pursuing or which I did differently for varying reasons (save money, original parts destroyed, for contrast or just because I liked one color better, etc). Keep that in mind. Don't use my car as a template for yours, do your own research.

Aug 18, 2005

Exhaust system is in. The final alignment needs to be done and it is not clamped up, but it's mounted and that is the biggest hurdle. It should have been installed before the body was dropped on, but sometimes things just don't work out like you plan. The system is a TA Performance 2.5" mandrel bent 2007A kit, and two Dynomax super turbo 17749 mufflers, side in/side out. The TA kit was chosen as I have dealt with them before and also they are the only ones right now to have the correctly cut pipe tips. The stock manifold downpipes were an extra cost item, as the kit is made for header cars. They also make it in 3" which isn't needed until you start making real horsepower, and the extra clearance and weight penalties weren't worth it for this car. The 2.5" kit shipping weight is 60 pounds, including header adaptors, manifold downpipes with flanges, tailpipe & muffler hangers, 8 clamps, plus hardware.

The dynomax 17749 long case mufflers (bought locally) were chosen as they always flow near the top of the list and yet are also some of the quietest mufflers you can buy. I don't want a loud car. They are 20" long (body) and weigh 15 pounds each.

This kit was basically a bolt in except that the intermediate pipes needed about 6" trimmed off them to fit the long case mufflers. Also, I found the tailpipe hangers provided left the pipes kinda low so I used stock style hangers from Year One. They are slightly short but work and the tailpipes are now nicely tucked up between the aft frame rails and body. All you see from directly beside the car is the tips sticking out.

Its a good idea to completely assemble your system OUT of the vehicle to make sure all the parts fit together easily. They have a tendency to slide together and lock themselves up!! It is NOT fun trying to remove a pipe that is stuck while under the car and trying not to scratch the paint or parts. One of my mufflers the weld inside the pipe needed some massaging before the tailpipe would slide in nicely and it gave me lots of trouble. Grease on all the connections will also help you to rotate the pipes for alignment before final clamp up.

My only concern at this point is that the factory muffler hangers I want to use might be a touch too high for this system, the clearance under the tranny crossmember is pretty tight, hopefully I can sort that out before it gets clamped and then welded. I may have to use aftermarket hangers for the mufflers.

Aug 22,2005

Brake system is in and bled. That is a major relief for me, as the entire system was apart and rebuilt. Only problem I had was one line that leaked a bit, and I discovered that the powdercoating on the frame is brake fluid proof!! Lucky. Make sure to bleed the master cylinder really well, and lay out plastic or protection of some sort as you will spill a few drops and the stuff is nasty on paint. I stayed with the dot 3 fluid for this project, as I will be driving it. The master cylinder is new, rebuilt units have a high failure rate.

Its going to be interesting masking off this car for paint, but I have decided that will be easier than trying to assemble the machine with fresh paint on it. The place doing the paintwork has done several cars like this and I found 0 overspray anywhere on them so I'm happy with that. Also, it allows me to work on the details in the engine compartment while I wait for paint.

Notice the correct color plating on the fittings that go into the master cylinder.

Sept 9, 2005

Ran into an interesting snag with the engine today. Was bolting on pulleys and the waterpump pulley had a pretty good wobble. Ended up with a dial indicator and turned out the waterpump flange was on crooked (hard to believe as its 3/8" thick steel pressed onto a solid steel shaft, how can that get out of alignment?). Anyway, shaft had .001" runout and flange had .010 only 1" out from center. Add the six inches forward for the pulley, fan clutch and fan and you have a problem. Ended up taking it off and exchanging it for another rebuilt. This one is much better, but I did have to paint it, install and then paint the bolts etc as they were painted with the engine at the factory. All this takes time, and is one of the reasons I have decided not to bother trying for the world of wheels in just two weeks. I can see with all there is left to do it is not going to happen. I will not rush at this point.

Pic shows some progress on the engine. Alt and pulleys on, wiring is rough routed but not connected.

Since I am running out of webspace I will show the final details on my final assembly page. This page is concluded.

Concluded Feb 3, 2006