How old is my 13-B?

[bowjangles]

Greetings:

I have a unknown year 13-B engine in my '80 Tr-7 roadster. It has a Hitachi 4bbl. carb on it. The engine number is B63798. How can I tell what year the engine was made? Really hard to get parts w/o this information.

Second question is: Do the holes on the black plastic throttle body spacer (under the carb) face up or down? My guess is up because the little tubes from the oil metering pump enter it from the back, but would like confirmation.
Thanks for your help in this matter.

[My5ABaby]

http://www.banzai-racing.com/faq_housings_ID.htm

Any of those fit? If not, http://en.wikipedia.org/wiki/Mazda_Wankel_engine#13B , there's a couple other options but someone else would have to chime in as to how to tell them apart.

[bowjangles]

thanks I'll check that out

[djmtsu]

Pictures are worth a thousand words.

Also, the script on the housings can tell quite a bit.

[Rotary Evolution]

if it has a hitachi it is likely a 74-78, i don't see why anyone would bother trying to make it work on a late series 13B.

74-75 had the old slanted MAZDA logo(all capitals), the 76-78 engines have the traditional logo used up until current.

[bowjangles]

Originally Posted by Rotary Evolution

if it has a hitachi it is likely a 74-78, i don't see why anyone would bother trying to make it work on a late series 13B.

74-75 had the old slanted MAZDA logo(all capitals), the 76-78 engines have the traditional logo used up until current.

If, by logo you mean the word MAZDA on the engine block, then it must be a 76-78 engine cuz the word is in upright (not slanted) letters- is this correct?

[ACE Rotor]

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?

[djmtsu]

Or, it could be an old script engine that was rebuilt with newer housings like mine.

But, like Rev said, Hitachi means its old school, 4 port NA 13B (in theory)

[Rotary Evolution]

yes, it could have any mix of parts up to 1985, maybe even beyond but the ports are bigger on the late engines and the hitachi wouldn't even be close to ideal and would require adapters for the intake/carb to work.

[wackyricer]

yup

[rxtasy3]

74-75 large framed "mazda" script.

[Rotary Evolution]

and all beyond that have this style script with some minor variations:



sorry, not many hits with the logo came up at the top..

[bowjangles]

Here is a pic of the Mazda logo from my 13-B.Using the info and pics that you sent me the engine can't be a '74-76 because the word MAZDA is not in slanted script, right?
So, we are getting closer to finding out the age of this engine.Are we now sure that it was made from'76-78?

I just found a complicating factor. When I ordered a new manifold intake gasket from Racing Beat Inc. I matched up fotos of available gaskets with my old gasket and it matched perfectly with #of a gasket that fit a '74-75 13B. Now I'm, really confused.......What year can the engine be?

[Rotary Evolution]

it is probably a 3B REPU casting block with the short primary runners, the housings look like 76-78 year castings. i believe even the 76-78 model year REPUs still retained that early 3B small port design.

there should be a cast number/letter on the front iron under the water pump with either a 3B or a Y, Y is the tall primary runner casting for the cars.

[bowjangles]

I found a number under the water pump as u said I would. It is a "4". Does that help us determine which year it was built/ What it came out of? Don't know what a "primary runner" is. Thanks for taking the time to help me with this