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Discussion Starter · #1 ·
Hello everyone, first question for the BB. After a lot of work done to my new to me Alfa, I was finally able to take her out for a cruise today.

At 100kmh I’m sitting at right about 4000rpm. From what I’ve gleaned so far from the search function is that I believe this is not standard.

When I purchased the car, it was described as a very original example. Upon inspection, it does seem the transmission has been replaced at some point as it was less patina’d as the rest underneath (also had a tag attached up top).

The rear diff has a blueish green paint mark on the flange. I believe there is a color code for rear end ratios?

Ill include photos of trans numbers and owners manual ratios.

Trying to figure out what is original and what isn’t, any help would be appreciated.
1693366
1693367
 

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Welcome. Nice looking Giulia, garage, cat, and back house. Is your car color white or gray?

Regarding your question, I'm not sure hope helpful this is, but here's what I know: My 1971 Giulia 1300 Super does right around 71mph (114kph) at 4000rpm. I believe the car has the standard 0.79 5th gear and 4.78 (43/9) rear axle, and has slightly undersized tires. The two most plausible options for lower gear ratios would be a 0.86 5th and a 5.12 rear axle, both of which, I believe, were used on some non-Super models. Doing the math, swapping in both of those would put my car at 98kph at 4000rpm. So that could be a possibility. Other things to consider are tire size and speedometer accuracy, Alfas speedos are notoriously inaccurate, though usually on the high side; best to check with GPS. Sorry, I have no specific knowledge of axle color codes, but do see a yellow paint mark on the front of the housing on mine. I've also read, but not verified, that the number of teeth of the axle crown wheel is stamped on its circumference and can be read through the oil filler hole. It's also possible, with patience, to raise one rear wheel, rotate the drive shaft by hand, and count how many times it turns for one turn of the wheel. Advanced Search function might be able to help with axle color codes.

Good luck.
 

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Discussion Starter · #3 ·
Welcome. Nice looking Giulia, garage, cat, and back house. Is your car color white or gray?

Regarding your question, I'm not sure hope helpful this is, but here's what I know: My 1971 Giulia 1300 Super does right around 71mph (114kph) at 4000rpm. I believe the car has the standard 0.79 5th gear and 4.78 (43/9) rear axle, and has slightly undersized tires. The two most plausible options for lower gear ratios would be a 0.86 5th and a 5.12 rear axle, both of which, I believe, were used on some non-Super models. Doing the math, swapping in both of those would put my car at 98kph at 4000rpm. So that could be a possibility. Other things to consider are tire size and speedometer accuracy, Alfas speedos are notoriously inaccurate, though usually on the high side; best to check with GPS. Sorry, I have no specific knowledge of axle color codes, but do see a yellow paint mark on the front of the housing on mine. I've also read, but not verified, that the number of teeth of the axle crown wheel is stamped on its circumference and can be read through the oil filler hole. It's also possible, with patience, to raise one rear wheel, rotate the drive shaft by hand, and count how many times it turns for one turn of the wheel. Advanced Search function might be able to help with axle color codes.

Good luck.
Thanks, she is grey!

Just checked the rear axle and counted teeth, stamped 9/4 and counted 43 on the ring. So 9:43 then. That is a very good point about the speedo reading incorrectly. I’ll download an app for that. Will report back.
 

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Discussion Starter · #5 ·
Ah, look like Grigio Indaco, same as mine.
I really dig it, it’s a respray though.

Just got back from a stint using the gps speedometer, 4K at 100kmh. I’m really perplexed now, must be some really funky gearing in the trans.

185/70 14 tires, 9/43 diff, accurate speedo. Could my tachometer be that far off? It doesn’t seem like it though.
 

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Edit -- never mind last post. My speed/RPM doesn't exactly agree with calculations based on tire size and gearing, so my tach may be off a bit. Good idea to check the tach, though.
 

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Discussion Starter · #7 ·
It looks like I gave you somewhat inaccurate info earlier -- my car actually goes about 75MPH (120 kph) at 4000 RPM. So something is definitely off with yours; good idea to check the tachometer next.
Thank you for the info and suggestions!
 

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Speedos are pretty much certain to be inaccurate and tachs are a gamble too. You were getting an electric tach to compare? I'd be interested to hear the results.
Andrew
 

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Actually it’s more like130 kph at 4000, 120 kph is around 3500, I paid attention on my drive to work today and felt compelled to correct my previous post.
 
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