How old is my 13-B?

bowjangles · 10-10-2013, 05:43 AM

Well, I couldn't find any casting numbers or letters btw the water pump and front cover, but I did find the letter "R" just near the oil filler tube. I think that is the casting letter. Another person that is trying to help me "date" the engine feels that "R" indicates that the engine was built sometime btw. '74 and '80. Can u confirm this? I would still like to get more specific on the date than the above range of dates.
As far as the "primary runners", I think that they are short and since there are four, I m concluding that the engine is a 4 port.
Other info that might help is : Modern MAZDA logo and twin distributors are on the engine. The mystery continues!

djmtsu · 10-10-2013, 05:49 AM

Twin dizzy engine?

Wow, the plot does thicken!

Rotary Evolution · 10-10-2013, 10:14 AM

sounds like a frankenstein motor, originally put into a pre '75 12a car that had twin dizzies for an upgrade engine swap. not even the '74 had a twin dizzy on the 13B.

ACE Rotor · 12-27-2014, 02:47 AM

Hi guys, plz help i.d where my 13b is originally from.
it has pollution gear on it.
my car is an rx7 series 2 and originally came with a 12a.
id like to know the year the 13b is from so i can look up ignition timing references
i suspect the breakerless ignition with 2 vacuum advance units on it are from a 12A?
are the dizzis interchangable between 13b and 12a?

10-10-2013, 05:43 AM	#16
bowjangles Rotary Fan in Training Join Date: Sep 2013 iTrader: (0) Posts: 62 Rep Power: 12	How old is my 13-B? Well, I couldn't find any casting numbers or letters btw the water pump and front cover, but I did find the letter "R" just near the oil filler tube. I think that is the casting letter. Another person that is trying to help me "date" the engine feels that "R" indicates that the engine was built sometime btw. '74 and '80. Can u confirm this? I would still like to get more specific on the date than the above range of dates. As far as the "primary runners", I think that they are short and since there are four, I m concluding that the engine is a 4 port. Other info that might help is : Modern MAZDA logo and twin distributors are on the engine. The mystery continues!

10-10-2013, 05:49 AM	#17
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (10) Posts: 4,043 Rep Power: 21	Twin dizzy engine? Wow, the plot does thicken! __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

10-10-2013, 10:14 AM	#18
Rotary Evolution rotaryevolution.net Join Date: Feb 2011 Location: Las Vegas, NV iTrader: (0) Posts: 248 Rep Power: 14	sounds like a frankenstein motor, originally put into a pre '75 12a car that had twin dizzies for an upgrade engine swap. not even the '74 had a twin dizzy on the 13B. __________________ http://rotaryevolution.net

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