Just picked up an old skool 76 cosmo 13b
 

Like it says I picked an original 76-77 (not sure) cosmo 13b motor complete w/ carb and tranny. Its has the "MAZDA" on the housings w/ blue paint. It has 48k original miles and from the sound of the compressions after rotating and a few things here and there it does seem like a legit low mileage motor. I plan on porting it "1/2 bridge" and throwing my Edelbrock on there to put in my 83 gsl by June. Hopefully I wont run into any suprises when I crack her open. :icon_tup: Will post a few pics as soon as I can.

A member and I tried to rescue one out of the yards here in Ca. The only thing missing was the steering wheel. The white leather upholstery was still in great shape. The chrome on the bumpers was like new. The only dent it had was on the lower driverside under the door. She was just begging to be saved but the cards did not play out. :-(

I know alot of people are looking for housings that say Mazda on them. You might be able to part out that engine if you don't care what it says and make some cash on them. Probably enough for you to buy another block and some other go fast parts!

MAZDA = '74-'75 RX-4 and REPU. It's not a Cosmo engine. I would know. I have a '76 with original engine and it has the later mazDa logo.

You may be right. That may explain the huge alternator. However I'm going to try to match it up to my 83 gsl 5spd, but regardless of what year motor it is, I'm gonna open her up port it and replace anything worn out. Cant seem to find much info on the "MAZDA" housings. :wallbash:

I have to disagree. ALL pre-RX-7 housings are capitalized and italics lettering. In addition, the 76+ center plate (no matter if its RX-4 or the RX-5 Cosmo) didnt come with the rectangular smog port below center plate.


http://img.photobucket.com/albums/v3...Picture168.jpg

I could believe that a Cosmo would have the later blocky 80s Mazda script becuase that script came out in the late 70s. My Cosmo parts book has the blocky mazda logo on it and all the Cosmos I've seen have blocky script emblems not Italicized ones.

I could be wrong on the letterings but as I said, a true 76+ 13-B blocks (RX-4 and Cosmo) came with no rectangular port as you can see in the above intake manifold. If I find time, I will take pix of my extra cosmo block.

I just took off the intake and it does have the rectangular port. Hmmm, it has "automobiles" just above the "MAZDA" logo on the housings and and 13b stamped above that. I cant find my damn camera! Super strong compression and the clutch assembly looks real nice. Off to find that camera!

then its not a Cosmo but a regular 13-B.

i was waiting for u to say junk it wanko

LOL. "JUNK IT"

I have a feeling that our homeboy Latin picked up an old R5.

Nah, wacky calls everthing "junks". :)

Hey, if the rotor housings say "Automobiles" it might be a cool J-spec engine. I have a set that came from either a delivery van or the AP bus (or whatever it was called). If I had to narrow the year down, it would probably be a '75 engine. Remember their home market got stuff before we did. The exhaust port timing is that of a US-spec GSL-SE where it opens later than US-spec old 13Bs and closes at T2 spec. :)

My Cosmo was built in late '75 as a '76 model and it has the mazDa logo. It also lacks the ACV port below the intermediate intake ports. It has had a reversed runner manifold like in Wacky's picture.

....and whats the deal w/ an R5? Please tell me you junk collector.lol :icon_tup:

I'll try to get some pictures too.

Latin270, how tall were the intermediate ports? That will narrow it down a lot.

R5 has been around since the '76 Cosmo and RX-4. Only the REPU kept the earlier casting 3B plates and MAZDA logo until the end of their run in '77. It was easier for Mazda to get past emissions restrictions with the '74 spec ports of the 3B plate because it was in a truck. Only the cars got the smaller '76-'85 spec ports.

R5 ran from the '75 or '76 model year until the nitrided ones in the '80s with a high volume oil pump and other later upgrades. Then Mazda shifted their attention to the 6 port RE-EGI (GSL-SE) engines.

http://img.photobucket.com/albums/v3...r/DSC04584.jpg
http://img.photobucket.com/albums/v3...r/DSC04588.jpg


VS. pre-84

http://img.photobucket.com/albums/v3...r/DSC04585.jpg
http://img.photobucket.com/albums/v3...r/DSC04586.jpg

The J-spec rotor housings with "Automobiles". GSL-SE exhaust port timing. :)
https://www.rx7club.com/forum/attach...d=235334&stc=1

My '76 Cosmo engine.
https://www.rx7club.com/forum/attach...d=235335&stc=1

Worst case scenerio I could use these housing w/ 12a irons, right?

yes but 79-83 are preferred.

You might need to. Have you seen how small the van/bus intermediate ports are? Yeesh!

Here is a series of pictures I posted a few months ago while trying to figure out the best combination of parts to build three nice engines. Enjoy.

All the short port plates I have easy access to. Note the delivery van/bus plate in the middle.
https://www.rx7club.com/forum/attach...d=228468&stc=1

All three have the exact same port timing! (the flash messed with the R5's port)
https://www.rx7club.com/forum/attach...d=228469&stc=1

Some moron built an REPU engine with the stupid NO plate so I had to correct it. :D
https://www.rx7club.com/forum/attach...d=228470&stc=1

Comparing NO ports with standard '76-'85 12A ports. The picture speaks for itself.
https://www.rx7club.com/forum/attach...d=228471&stc=1

A couple of Y plates with the NO and R5. Notice the offset casting?
https://www.rx7club.com/forum/attach...d=228472&stc=1

Now a comparison of manifolds.
https://www.rx7club.com/forum/attach...d=228476&stc=1

I modified the back of the Cosmo manifold so it would fit my MG. I also cut channels in the top. We'll see how well they work when I get it running in a week or two.
https://www.rx7club.com/forum/attach...d=228477&stc=1

Nice collection there. :icon_tup:

Almost starting to think its a REPU 13b because it has a sensor type thing on top of the center iron.

Egr?

Heres some pics.

you suck in postwhoring I cant see shit :)

The '71-'75 engines had a water temp sensor in the top of the intermediate plate. The NO plate, as you can see from my pictures, had an EGR port blocked off by a steel plate.

Look around the base of the oil tube. It will say either 3B or NO. Let us know.

Hee hee hee, damn pics arent loading! lol. I'm going to check the base now.

try again.....

Looks like a '74-'75 engine. I think the blue background around the logo was one year only. Either '74 or '75.

You won't even need to do any porting because those '74 spec ports are practically perfect right from the factory (just smooth some of the casting flash and sharp edges but don't change port timing). I'd say keep everything the same size, even the carb jets and you won't be dissapointed.

Man you got lucky. Glad it worked out in the end.

:bigok:

Nice score. Keep us updated on breakdown, installing, etc.

Carb is going to be gone and going with my edelbrock. Do you think the original tranny will fit the stock 83 shifter hole or am I going to have to cut some metal out? Oh and thanks JeFF and Wacky! You guys rock! :icon_tup:

Anyone?

You cant use the pre-81 tranny on your 83. You should give it away to someone who has a pre-81 RX-7.

(or keep the bellhousing and sell it at e-bay).

btw, how many bottles of tylenol did that edelbrock come with.

Wacky is it because the shifter hole doesnt line up? If the rx3 guys can use 83-85 12a's in there cars why not the other way around? What exactly would be the problem??? Edelbrock came w/ a 6pack of Miller Lites. :icon_tup: Very easy on the stress level and dumb ass friendly! :rlaugh:

.....or can I just use my 83 tranny? Will it bolt up? Can I use the bell housing from my 74-75 13b and bolt that to my 12a tranny.

Shifter on a pre-81 tranny is not in the same location as the 81-85. It more like 2" forward. Yes us old school guys are using 81+ trannies but we have to notch the shifter tunnel (towards the handbrake) OR do the remote shifter mod. Now, if you use a pre-81 tranny on a 81-85 body, you have to do the opposite which will require you to fabricate a new shifter plate etc etc.

The old school bellhousing is removable so you can mount it on a TII tranny. By using doing this, there is no need to match the engine with TII flywheel including clutch assembly.

old school tranny with polished bellhousing
http://img.photobucket.com/albums/v3...cer/cosmo4.jpg

Now, feel free to find a 81+ in my collection of junks :)
Left is a SE
Right near the blue bucket is old school
http://img.photobucket.com/albums/v3...r/DSC06619.jpg

lots of excellet info in this thread!! i really think you'll get some great use out of this engine! keep us updated on the teardown.

Will do! :icon_tup:

Hey Wacky, what about the gearbox tilt issue of '74-'78 trannies? For those that don't know, Mazda tilted the gearbox to make room for the bottom mounted starter in '74. Most previous trannies were top mount starter.

The T2 trannies are not tilted. Only the '74-'78 trannies are tilted making them incompatible with other years.

Please feel free to correct me if I'm wrong, but first please look at these pictures of the trannies in my MG rotary project. It started out as a '73 12A twin dizzy (converted to single dizzy) and then a 13B.

Heh, the whole car is tilted here. :) '73 top mount starter tranny
https://www.rx7club.com/forum/attach...d=161463&stc=1

'74 bottom mount starter tranny
https://www.rx7club.com/forum/attach...d=161464&stc=1

Nice closeup.
https://www.rx7club.com/forum/attach...d=161465&stc=1

the old school trannies are tilted but its only on the gear section and not on the tailshaft. I got to take a better pix but heres an oldie (SP and Cosmo trannies)

http://img.photobucket.com/albums/v3...r/DSC06544.jpg

The SP has an extra oil fill/level fitting on the 5th gear housing and no breather tube (the breather fitting is on top). Yes, I know the difference. :)

As for the tilt, they made up for it by tilting the receiving end of the tail housing. If you compare it to a top mount starter tranny, the tailhousing on those is not tilted.

Hmm Wacky, you may be right about the tailhousing on Cosmo and SP trannies though. Perhaps the tilt is absorbed in the 5th gear housing and the tail housing is straight. I have a Cosmo tranny, REPU 4 speed, and an RX-2 top starter 4 speed sitting in my garage. Maybe I can take a look.

Okay I gathered some info from my Philly and NJ rotorheads. According to them my 83 gsl tranny will bolt right up to this "MAZDA" motor. I hope there info is correct. Hey there is only one way to find out fore sure!

here are some pics of a fist year 13b, car is 4/74, 50k all original.
center iron says something like 3B by the oil fill neck.

latin you want to sell me that tranny so i can ditch this auto??

There ya go! Thats the same motor :icon_tup: The carb is already spoken for. As far as the tranny goes PM me and lets work something out...I dread shipping.

Im not a fan of a hitachi carb. I usually replace it with a RX-2/3 carb and if you need 13-B headers, I have several to trade for your 12-A. My son is ready for headers in his FB and I dont feel like mocking with my other 13-B's. (told him to take it one step and a time before he can go fast). LMK


http://img.photobucket.com/albums/v3...Picture167.jpg


http://img.photobucket.com/albums/v3...r/DSC08134.jpg

will an rx7 13b header fit the wagon?

The bottom one was originally a RB 13-B roadrace header that I modified to fit a 12-A (cut the engine and rear flanges). Then Rene (61620B) modified it for my 75 RX-3 while Im waiting for all turbo related parts. It has a 3" outlet/exhaust as this RX-3 is turbo ready.