highcking

Thanks, both good suggestions and both on hand in my shop. It would be interesting to know how the factory did this assembly.

I'm trying to replace the seals in the front vent windows of my '58 Roadmaster. I have the seals from Steele and I have the window frame and glass out of the car. The problem is installing the window into the seal. The seal is a very tight fit in the channel but I got it in. The window "arm" goes down through the lower part of the seal, no problem. Here things get tough. The upper part of the window frame has a short (1/4") chromed shaft that is supposed to go into a hole in the seal. This part of the seal is thick and solid to hold the window shaft in place. The problem is getting that little shaft into the seal! Despite pushing down on the window as hard as I dare to gain clearance, that shaft will not go into the seal at the top. Anyone else done this task and have a suggestion? Bill Shields Virginia

The '58 brake booster (and probably the '57 as well) is mounted to a housing that is attached to the firewall. What was this housing called by Buick? Anyone know the part number? Bill Shields, Virginia '58 Roadmaster

Great piece of information! That will save my weatherstrip if I can find the right material.

Trying to finish my 1958 Roadmaster in time for the July show. I installed the roof rail weatherstrip the other day and it looked fine ... until I closed the rear doors and found that both doors are not set properly on the hinges. This causes the full windows to dig into the weatherstrip at the front edge and the vent window assemblies to squeeze the weatherstrip out of position. Solution seems to be re-setting these doors. The Body Manual warns about the weatherstripping so Buick knew about the problem. But I recall this adjustment procedure as a nightmare from a 1959 Fleetwood I owned years back. My memory was correct. There are two sets of three bolts at the top hinge and two at the bottom hinge, and in the Roadmaster one lower bolt on each door is covered by the door skin! The Buick shop manual helpfully suggests using a 90 degree screwdriver. These Phillips-head bolts take a ton of torque to turn without stripping. In short, the suggestion is ridiculous. The Buick mechanics must have had a bitter laugh over that one. In any event, after many hours of struggle I've managed to improve the situation somewhat on the left rear, and not at all on the right. Loosening that 12th bolt on each side seems all but impossible without taking the whole door off. (Reluctant to do this as I work alone and only have so many hands.) Anyone else faced this problem? I wouldn't care much about a slight misalignment of the rear doors ... but I can't buy into wrecking fresh weatherstrip.

Fixed at last. The issue was a connection to the ammeter. Some bungling on my part - plus I lost the set of pictures I took of the instrument panel wiring before I disconnected things. (Traded in an iPhone with the pictures on it!) One note: the long post on the ammeter is the ground (black), at least on my car. Putting the red wire on the long post resulted in a "discharge" when the car was running. Thanks to all for the help. Every suggestion helped to eliminate possible problems.

Tto - when I return from the Middle East, I plan to run a bypass only for testing purposes to locate the specific issue. I agree about not adding wiring. I've had to "unwire" many a car in my collection. This Buick has its original harness, but someone thought it would be a good idea to spray everything with black undercoat. I'll do a new harness next year. I'm just trying to get the car to the Allentown show this year.

Jim - you obviously know this harness very well! Today I did a few more things. I ran a continuity check between the bulkhead connector for the red wire (I cleaned those three connectors) and the fuse box red connector. It shows a completed circuit. When the battery is connected, a circuit tester shows that the bulkhead connector has voltage, as do the voltage reg, relays, etc. So it seems counterintuitive that with battery voltage at the bulkhead and a continuous connection to the fuse box connector from that point, the fuse box connector is still showing zero voltage! I'm missing something. The two changes from last fall are jostling the wires replacing things, as you noted, and the fact that the power seat and power windows are all disconnected -- the interior is being redone. By the way, which ammeter terminal is which? They're not labeled, but one post is longer than the other. I've come around to the splicing idea. Connect a fat red wire at the fuse box and touch the other end to various "live" spots under the hood. There has to be some important difference between my connecting up a 12v power supply (see earlier in the thread) that made everything work, and the connection to the battery which is brand new. I also plan to unwrap the wire bundle you mentioned if nothing else works. You can reply to my personal email if you like: highc.king@verizon.net. Thanks for your help.

Thanks for the excellent photo. My engine compartment is not quite so dazzling! I did check that connector, and the left hand big red wire did not show hot. But I need to recheck and also see where that feed is coming from. I'm pretty sure it's off the BAT terminal of the voltage regulator.

After hours more of checking, I ended up with the conclusion that the red power feed to the fuse box is dead. To test, I connected a separate 12volt power supply to the power pin on the back of the box. Immediately, my dome lights came on, clock started, as when I turned the ignition switch I saw a distinct extra drain. Everything under the hood seems OK. The ammeter posts are both showing battery voltage when the battery is connected. The battery terminal of the voltage reg is also live. The problem now is why is this feed dead. The wiring diagram shows the fuse box power lead going into a big red bundle but that's about it. Anyone have an issue like these?

Robin - you may be onto something there. I'll check tomorrow, but I'm pretty sure that when the battery is connected, one ammeter post reads battery voltage and the other reads zero. It so happens I have a spare ammeter in a box. But I'll try the two-leads-on-one post idea first. I'll reply again tomorrow. I'm attaching the '58 Buick wiring diagram for others who might want to see it. 1958 Buick Wiring.pdf

Still stumped, but did some more testing. To check for a weak battery, I put jumper cables from a good battery on the Buick's battery cables. No change. I have voltage at the junction block on the wheel well (where the plus cable attaches), voltage at the back of the ammeter, but here's the strangest thing: no voltage at the "battery" lead of the voltage regulator. That lead should be hot when the battery is connected. I also checked the battery ground cable and it shows a good block connection. I'm running out of things to check. When I shut the car down last fall to pull the upholstery and the speedo, radio, etc., everything worked fine.

When I get home later, I plan to check the battery ground cable connection. it's one of the few connections that could cripple the whole system, because current could not flow through the battery.

Jim - Excellent suggestions. At some point in the car's past, the ammeter wires were swapped out, leaving one black and one black with white stripe. Which of the two ammeter posts is positive and which is ground? They're different lengths but I don't see labels.

Certainly a possibility. But the horn doesn't blow and the ignition doesn't come on. I've considered the voltage regulator too,

Over the winter while my interior was being redone, I removed some dash components for rebuilding. I had the radio, temp gauge, and speedo done by well-known folks. With the onset of beautiful weather this week (in Virginia), I installed the rebuilt items plus a new light switch and reconnected everything as needed. (Not that easy ...) Battery was dead so I charged it. When I reconnected the battery - nothing! I have 13+ volts at he battery and at the ammeter. Otherwise no power. I cleaned various connections like junction blocks. Cleaned the battery posts and cables. Not so much as a courtesy light comes on. Ignition key does nothing. There aren't many components that can fail everything at once. ideas? Anyone else encounter this on their Buick?

Yes. I finally pulled the distributor and discovered that the oil pump shaft was not properly engaged with the distributor shaft - which is the one being driven by the camshaft. I got the engagement right (not that easy, given the location...) and the oil pressure spun up to normal as soon as I cranked the engine. Not sure that arrangement is the best, but I doubt I'll have to mess with mine again.

I need to order new trunk cardboard pieces for my '58 Roadmaster. (None came with the car.) There is a reputable dealer on eBay who sells '57 sets. They told me these sets were copied from an original '57 set, but so far no one has sent them a '58 set to copy. I'd like to order the '57 set. Anyone know for sure if the trunk compartments were changed from 1957 to 1958? Bill Shields Luray, VA

Wow, great information! I would never have guessed that explanation. I need to go back and look at my service bulletin set - not sure it's complete. I have noted the the vast majority of service problems discussed in the bulletins dealt with the ill- fated air suspension system (which my Roadmaster had when first sold) and the AC system. I owned an air conditioned 1959 Cadillac and had a hard time keeping the system working right. Since the timing change was not carried into 1959, they must have solved the fan issue another way.

Centrifugal advance was changed and given a different number--that's how you can tell the difference. My references show the vacuum unit was left the same. Probably too expensive to order a different vacuum advance. What puzzles me is the 12 degrees BTDC -- that's a lot of initial advance. Yet there had to be some reason to make the change. I'd like to find a 12-degree centrifugal advance set and see what happens when I retune the car. The ID number is on the underside of the centrifugal unit.

John - it does in a sense. In 1959 Buick went to electric wipers and dropped the vacuum/oil pump. But no 58's were made that way, yet this distributor change was made during 58 production. The actual change was a different centrifugal advance - the vac advance unit was left alone. Twelve degrees BTDC would probably increase idle vacuum, though, and lead to greater advance throughout the rpm range at the risk of serious pinging. I wonder if octane numbers jumped that year? I need to see if any other GM makes also made a mid-year shift. Bill

Anyone know why Buick changed distributor specs during 1958 production? The earlier builds used a distributor adjusted for initial timing of 5 degrees BTDC. The later ones called for an initial adjustment of 12 degrees BTDC, but used a different centrifugal advance mechanism. I believe the 1959 engines continued the 12-degree setup. My '58 Roadmaster has the earlier distributor and draws about 14 inches vacuum at idle, correct by the shop manual. Was this found to be too low and the more advanced setting used to draw a higher vacuum? It's certainly an unusual change and 12 degrees BTDC was very high for the time. Bill Shields Virginia

Very helpful, thanks! The carb has four idle jets but only the two primaries are adjustable with screws. I've done more research and decided that I was slightly mislead by the vacuum port that feeds vacuum to the vacuum advance - it looks like the idle jet but isn't. The idle jet is much smaller on the primaries. I also see why later versions went to a slit to add fuel flow as the throttle moves away from idle. The 4GC has a bunch of TINY holes and I'm pretty sure they are what is wrong with this carb.

I pulled the 4GC from my recently-acquired 1958 Buick, which runs poorly at part throttle but idles OK and runs fine at wide-open throttle. Looking carefully at the throttle bores, I found that only one of the two primary barrels has an idle jet showing. The secondary barrels both have idle jets. This certainly could explain why the car runs lean at part throttle. Anyone ever seen this? Surely there should be an idle jet on each barrel? Bill Shields Luray, Va

My Roadmaster part-throttle stumbling has not yet been solved -- but now I may have an answer. Several folks on this forum suggested pulling the "rebuilt" Rochester 4GC and taking a close look at the primary throttles. I did this and found something I can't explain. One of the primary barrels seems to have no idle orifice. The other primary barrel does and there are idle orifices in each of the the secondaries. I looked very closely to see if the orifice was simply obscured or blocked up, but I don't think so. It's not there. Anyone ever see this? Every 4-barrel I have has an idle orifice in each primary barrel. Otherwise why have two idle mixture screws? Could this be a factory defect? It certainly explains why the mixture is too lean until the throttle is open pretty wide.<!-- google_ad_section_end --> Only one idle feed is active. I can't find any reason to believe this is the way the carb was designed.