Distributor Cap and Rotor Fitment

[bimmerjoe]

Attempted to install a new distributor cap and rotor into my 633 today. It seems the new Bremi cap has a center part that is too long (deep) and therefore will not allow me to re attach the new cap. The new rotor went on fine and is exactly the same as the old one. I have attached a photo of the 2 different caps and as you can see, the center of the new one is about a quarter inch longer than the one that was on the car. I purchased the parts from Blunttech and they are rather perplexed because the part they sent https://www.blunttech.com/products/9969262 is what is listed as the correct part for my car (7505244 last 7 numbers of VIN) manufacture date of 10/81. Any ideas? I tried the search and was unable to find anything. Thanks for any help you may be able to offer.
Joe

[bimmerjoe]

Sorry, My photo is too big and my computer is not allowing me to compress it to a size that fits. I will keep working on it and post it as soon as I can.

[bpoliakoff]

There are two different rotors. One is a push on and the other is a bolt on. IIRC they have to be a matching pair. My guess, though I never measured, is there is a difference in the height of the rotor. I think

[olympia57]

I found the same problem on my '81 series one 635 .
This photo may help you identify the correct one for yours .
Don

IMGP1388 - Copy (Medium).JPG (237.81 KiB) Viewed 4544 times

[bimmerjoe]

Thanks so much for the help! Don, that is exactly the picture I was trying to download. The left cap in your picture is the one I have and the right one is the one that Blunttech and Real OEM says is now the correct cap for my engine. Is there a shorter rotor that you can order for the cap on the right? Or is there a way to still find the original cap like the one on the left? Thanks again! You guys are great!

[bpoliakoff]

There is a drive on the end of the cam that can be changed allowing a push on rotor to be use or a bolt on.. I switched mine from a push on to a bolt on by using the later shaft

[bimmerjoe]

Thanks. I will look into it!