Some of the parts I'm looking at for my 71 BB specify Early or Late (specifically spark plug wires). What are the differences between early and late 71s and how do I determine which mine is?

Thanks!

 

The build date of your car or approximate build date determines if it is early or late. Early 71 has headlight washer nozzles and the fiber optics. There are other differences and I am sure Alan will chime in. He has 71 and is extremely knowledgeable.

 

Hi,
The only difference that I'm aware of for BB spark plug wires is a change in the configuration of the 'boot' at the spark plugs. I thought that changed from 71-72… if it changed DURING 71 production (and it may have) I'm not aware of it.

When determining early/late for CARS early/late is easy because the sequence number determines that.
But when when determining what PART would be on a particular car it depends on when the actual time or period was that the change occurred on the production line.
For example…. if a part changed during the second week of production only the cars built during the first week of production would be considered early, all the rest would be late.
The reverse is true near the end of production… a part that changed during the next to the last week of production would make all cars before that change early and only cars after the change would be late.
It gets worse… often the 'new' part was mixed with the 'old' part so the change didn't occur at a specific time but rather over a period of time.
An example of this is the 71 front grills. The 70 grill had studs, the 71 grill had holes for screws. Early production 71 cars are seen with two 70 style grills, they're also seen with two 71 style grills, AND they've been seen with one of each.
Another example is the change in the distributor shielding and open/closed air cleaner base. The change is thought of as being a 71 change but late 70 base motor cars have been seen with the 71 style air cleaner and distributor shield.
So…. way more than you wanted to know.
Regards,
Alan

 

Makonut, Thanks for the info.

Alan, wow, that is a messy system. I appreciate the explanation.

Here is what I'm finding on willcox.

https://willcoxcorvette.com/corvette...adio-71e-71-71
https://willcoxcorvette.com/corvette...adio-71l-71-71
https://willcoxcorvette.com/corvette...k-w-radio-2024

The first link is for "early" cars, the second link is for "late" cars, and I have no idea about the third link.

I'm not going to go crazy over finding all 100% correct parts and try to reproduce an original show car, but I would like to replace parts with the correct parts when possible. To that end, is there a good resource for finding GM part numbers for my specific car (71 LS5 coupe)?

Thanks!
- Voss

 

Are you considering going with the braided spark plug wires?

 

Hi V,
The 71 Assembly Instruction Manual (AIM) is your best source of parts numbers for parts that were used to build the car in St.Louis.
It's not perfect though because some parts came to the production line as 'assemblies' which are made up of several parts, but only has one number.
A GM Parts Book helps in figuring out what the part number translates as.
Parts are an entire WORLD to some folks.
Regards,
Alan

Some but not all the answers.

 

My car has a radio and it was my understanding that cars with a radio should use the braided wires. Assuming this is correct, I will be getting braided wires.

 

What do you currently have? I'll bet your shopping list is growing.

 

The car currently has the correct braided wires, I just can't tell if they are "early" or "late". The car is misfiring and is in bad need of a tune up, so I'm going to start with new plugs and wires then go from there.

My shopping list is indeed growing ,as you can tell from my previous threads, and I'm sure I will start many more threads in the near future asking for advice.

Thanks!

 

What they are referring to on the braided plug wires, when they ask about early or late, is the production date printed on the wires!

What Wilcox doesn't tell you on their website is that the the "early" wires have a date of the 3rd quarter of 1970, and are correct for a 71 Corvette built between August and December of 1970.

The "late" wires are dated the 1st quarter 1971, and are correct for any 71 Corvette built from January and July 1971.

The third set on their website, is an undated set of replacement wires.

If you have a set of the repro wires now, that may be why you have the misfire, because there have been issues with the quality of the repro braided wires.

 

Gb, thank you so much! This is exactly the information I needed. Now to figure out when my vette was built.

 

Ok, If I'm reading this correctly then the build date for my vette is: May 29th 1971. Correct?

 

Alan, is this the Assembly Instruction Manual you were referring to?

https://willcoxcorvette.com/corvette...y-manual-59-82

I went ahead and ordered this too: http://www.ebay.com/itm/like/361615659694?lpid=82&chn=ps&ul_noapp=true

 

Also, how would I determine the correct spark plugs to purchase?

Thanks, all!!

 

The E29 is the date the body of your car was built. The actual assembly date of your car, may be a day or two later.

E29 is not May 29, 1971 though, it's actually December 29, 1971. The body build dates don't run on a calendar year, but instead are based on the production year. 71 production started in August 1970, making "E" December, not May.

If you go to the link below, and plug in your VIN, it will give you an approximate build date for your car.

http://www.c3registry.com/?job=BirthdayCalculator

Yep, that's the Assembly Manual, or AIM as it's often referred too.

The original plug installed in the 71 454 was an AC Delco R43TS.

The R43TS is still available from Delco, though it's outward appearance is somewhat different than the 1971 version. Delco offers the 41-817 as the platinum replacement for the R43TS, and Accel, Champion, etc all have equivalent replacement plugs, for the R43TS also.

 

FWIW: keep in mind early 71 production was affected by a strike at St. Louis. The shut down began about September 15, 1970 and ended just before Thanksgiving in November. No October cars were produced. Some of the early December built cars could have original parts dating back to September.

 

Hi ckv,
gbv gave you the answer on the spark plug that was originally used in your car.
That sort of information is contained in the Owner's Manual.
The Manual is also a good thing to have (relatively inexpensive) since it lists lots of info about other 'service' items like the various light bulb #s used on the car and also how various things are supposed to function like the heater/ac controls and switches for the wipers and headlights.
Good Luck!
Regards,
Alan

 

No, December 29, 1970.

http://corvettec3.ca/sitemap.htm

 

Alan, GB, Easy Mike, and 71 Green Thanks so much for all the info, it has been very very helpful. The C3 community is great!

 

For those interested, here are the parts I just ordered:

https://willcoxcorvette.com/corvette...adio-71e-71-71
https://willcoxcorvette.com/corvette...r-4-slot-67-74
https://www.amazon.com/ACDelco-R43TS.../dp/B000C9S696
https://willcoxcorvette.com/corvette...ve-cover-67-74
https://willcoxcorvette.com/corvette...adra-jet-64-81
https://willcoxcorvette.com/corvette...y-manual-59-82
https://willcoxcorvette.com/corvette...-blue-code-979