First question. About when during production did they go from clear overflow lids to black? Second, curious if anybody has ever heard of them not installing the hose support hook for the upper rad hose at the factory? I swear, there were never screws ran into my original fan shroud. No sign that a hook was ever bolted to it, and the car has never been wrecked or even apart.
1) About January 1970. 2) Sure. They weren't making show cars ya know. Lots of stuff happened back then.
My X has a clear lid. It’s a 3rd week of February build. It’s also covered in rustproofing, just like the rest of the under hood. It doesn’t look like it’s ever been apart. In fact, it doesn’t look like anything has ever been replaced other than rad hoses and a couple of clamps. Like you said though, anything is possible.
Anything is possible. One board member has a late January car w/a plastic rad. cover. If I'm correct that the invoice date is the closest thing we have to the day it rolled off the line, then about Jan 4, 1970 was the day at Flint the switch happened. My old Stage 1 4-sp (@Brett Slater's current car) was invoiced that day and had clear overflow orig. I looked at another '70 Stage 1 4-sp invoiced the same day (not that it matters whether a GS or Skylark) and it had an orig. black top. Both had the same lenses & rad. cover (tbh, I can't remember if flat/convex or plastic/ metal). Brett's car has the nicest orig. fan shroud I've ever seen (could pass for NOS) & it didn't look like it'd ever had a hook installed. Could it have been replaced in the '70's when NOS was still avail? It's possible I guess. PS belts are known to take them out if the belt breaks & grabs the hook.
The reason the lid was changed to black was they were having problems with the clear lids failing due to Ultraviolet light. If you look at a clear lid jug that has been on a car for years, you will see that where the lid touches the inner fender, it looks sunburnt. That is from the light going down the gap between the fender and the hood. When they were changed, both top and bottom pieces used a different type of plastic. The clear lids used the same material for top & bottom. The black lids use a more milky plastic for the bottoms. As far as the change-over from the early to late parts, Lasseter wanted me to write up an article to be put in the GSCA Newsletter. I will post it below so everyone can read it. Duane 1970 SKYLARK/GS PARTS CHANGES If you work with 1970 Skylark/Gran Sports for any length of time you will notice that quite a few parts changed during the production year. The most obvious changes include the radiator cover plate, radiator overflow jug, rear courtesy light lenses, instrument panel lenses, and the height of the numbers/letters on the instruments themselves. Now that more and more people are interested in restoring these cars correctly, I am often asked when these changes took place, and if these parts changed gradually or happened all at once. To answer this I compiled data from talking to hundreds of original owners and looking at many unmolested original cars. I also took both the body build date (Located on the ID plate on the firewall.) and the various production plants into consideration. By doing this I discovered a few things; (1.) the production plants introduced the new style parts at different times, (2.) even weeks after the new style parts were introduced some cars were still being built with early style parts, and (3.) as time progressed the ratio of early/late parts decreased, until at the end of the transition period, only 1 early style piece could be found on any particular car. Below is the time sequence for these parts. Cars built on or before week 11D would have been built with only early style parts. Early Style Parts, Up through 11D (4th week of November 1969) Plastic Radiator cover, with metal end caps, and associated emission decals. Clear Top and Bottom Radiator Overflow jug Tri-shield Courtesy Light Lenses (4-tab) Pointy Instrument Panel Lenses Tall Numbers/Lettering on Gauges Transition Period (Week 11E thru 01A) Starting week 11E some later style parts were introduced. At first the cars had only 1 or 2 new style parts, but by the end of the transition period, the reverse was true. Later Style Parts, after 01B (2nd week of January 1970) Metal Radiator cover, with associated emission decals. Black Top with White Bottom Radiator Overflow jug Concentric Circle Courtesy Light Lenses (4-tab) Flat Instrument Panel Lenses Short Numbers/Lettering on Gauges By week 01B the changeover was basically complete, so cars built after this would have been produced with only the later style parts. The above info is offered as a guide only, there are probably exceptions. Duane Heckman
I almost asked the question the other day about trishield courtesy lenses vs the concentric circles. Thanks for answering that!
Now I need to know about the size of the numbering on the gauges, was it because they went to the flat lens and it looked better?
Yeah maybe it should be a sticky. To answer this I looked in my computer for the article I wrote. I have a bunch of different articles about many subjects on these cars. I posted one up about fire extinguishers, but did not see any folder here that fit that subject so I put it in the bench. Is there a folder here (on the V-8 board) where some of these articles could be put as reference material? Duane
I don’t know why the numbers changed but do believe it coincided with the change of the face plate lenses. The early 70 cars have the tall numbers/letters and the later 70 thru 72 cars have the shorter style. The differences are sometimes hard to see but if you put the two types next to each other it is noticeable. Duane
Great info as always, Duane. I think at this point, I’m probably gonna leave the car alone. As much as I want to drown the engine bay in mineral spirits to remove 50 year old rustproofing, I think it’s kinda cool left as is. Would love to hear some insight on the overflow jug, as I originally thought that this car was built too late to have a clear lid, like you and Brad mentioned.
Yeah, it might have been replaced very early in the car’s life. If so they may have only had the earlier style “clear” available in the parts division. We may never know. However this brings up a good point here. The replacement parts used (NOS) to repair the cars depended on when the car needed fixed. Case in point, if you wrecked your 70 car during the 70 model year, then it would have received a 70 style core support. However if it was wrecked in 71 then it got the 71-72 style core support as that was what they were making at the time. At one time I had a good handle on what parts were available as NOS pieces, good used pieces, or repro pieces, and could tell within a few years when a particular car was wrecked/rebuilt by the parts that were used to fix it. I used to floor guys with this, but sadly those days are over. Duane
I don't know that I have ever seen a lot of them rustproofed like that.. you would think if it was common at the dealerships, you would see more, especially up north.. in this case, I am wondering if this was not done as an add on, after a collision repair very early in it's life. It would explain the early parts on a later car, as well as the "OE" rustproofing on everything. It also could be as simple as an inventory control issue at the factory.. "hey Fred, put this box of overflow tanks on the line, it was sitting behind the door here.." And Bang, 10, 20, 30, 50 or however many were in a "case" all the sudden show up on cars that were built "too late" to have those parts.. As we all know, lots of stuff happened at factories that should not have. Original owner cars are usually the best examples to use to answer these questions.. Because the OO knows the history. I am sure that is what Duane relied heavily on. Thanks for posting the letter, will make this a sticky.. JW
Also moved it to the "Resto Shop" under Chassis restoration, so it won't get so lost in the stickies on the bench.. JW
I’m still in contact with the original owner’s son. Pretty sure he told me that the rustproofing/undercoating was done before they took delivery when it was new, but I will confirm and report back. He also told me that they drive their cars year around on snow tires, as that area is usually hit hard with snow. That would explain the spare.
Tim, Here is a white '70 GSX Stage 1 that was in the September 1970 issue of Road Test Magazine. Notice the overflow tank lid color. This white GSX also has the early style plastic radiator top plate
The full article. If you want full size scans of it, send me a PM with your email address. This same white GSX was used in the road test that appeared in the July 1970 issue of Car Craft Magazine.
Tim, although your car has the metal radiator cover, it appears that it had the smaller decal like the early cars with the plastic cover instead of the long thin decal that we normally see on the metal cover. You have a very unique, early GSX.
wow, I learned something new today.. They actually made a Polyglass GT snow tire.. Or was it a recap? JW
