Hey there guys I’ve done my fair share of reading and I can’t find much info on people doing a more budget friendly bridge port job to there 12a. I have an 83’ rx7 and wanted a little more power and something to do over the winter. I know that building the 12a’s are more expensive but I don’t have “buy a new motor” money at the moment. Just wondering what kind of shopping list I need to make. I don’t need the car to make crazy power just some occasional 8k bursts and just a fun, kinda powerful car to drive around. Kinda just looking for the bare minimum here as I’m a college student with limited funds. I’m planning 48mm ida Weber, I already have a full 2.25” exhaust with the pacesetter header I think? I planned on buying the 3mm steel apex seals from Atkins as well as factory spec corner and side seals, but that’s about as far as my list has gotten, would love some tips thanks!

 

How drivable to you want it? A bridgeport idles much higher and is less friendly as a daily driver or street car. They are also loud.

 

Don’t mind if drivability isn’t great I don’t do hardly any highway driving mostly just around town and the high idle is actually one of the things I’m looking forward to. In terms of drivability I know what I’m getting myself into I just don’t know what kind of supporting mods I may need other than carb and exhaust

 

Carb and supporting fuel delivery, exhaust, and good spark, good oil cooling, think about the flywheel/clutch, and possible AFR for tuning.

The drivability is worse at low speed.

 

Put an IDA on it and enjoy the extra power. After that save for a build that isn't cheap.

 

I already have the afr gauge and suitable exhaust and an aftermarket fuel pump, and as mentioned before I plan on ripping the Weber just kinda wondering in terms of the oil pump/ regulator do you recommend I change either of those? I’ve read about people tossing the fd pump and regulator in their motors however everyone I’ve seen doing that also plan on revving way past 8k. And I’m aware that low speed drivability will suck.

 

And yeah I thought about just tossing on the Weber and playing with that but I think I want to do a 13b build anyway so I think I’m just going to have fun with this while I have the motor out the thing is prolly due for a rebuild anyway

 

the Bridgeport is like putting a big cam in a piston engine. you're going to notice, its going to do stuff.

for the oil system, the stock setup is fine for a stock engine, but for a modified engine, like the BP you want more pressure. the bang for the buck is the FD regulator, N3A1-14-230
to come from an 83 12A, you'd also want a bigger oil cooler. one of those baffle plates that RB sells would be a good idea too.

fuel system: Mazda wants 1.5 Liters in 30 seconds, which is about double stock. the Weber runs around 4.3psi. the last one i did used a Mallory pump, which had a regulator in it, and that worked really nicely. the stupid holley regulator hurts the flow, and pressure was all over the place, so i'm not a fan of those.

if it is going to be a street car, the heavy stock flywheel helps. it dampens the pulses from the misfiring a lot, you loose throttle response.
also on the street you're going to need to spend a LOT of time tuning the carb. a BP is much more picky about what it likes and doesn't like, and if you give it the mixture it wants, it will drive really well. if its not what it wants is when it'll get angry.

 

Thanks that’s more what I was looking for can I get a little more specification on the baffle plate you mentioned tho? Never heard that term used before

 

any chance you have a name or part number for the fuel pump you were talking about? Also you guys have any recommendations on clutch options? I won’t ever be running more than a 205 tire so it’s not like I need a super strong one but I’d assume the stock on won’t do.

 

https://www.racingbeat.com/RX7-1975-...tem/11823.html

I also suggest replacing the oil pan bolts with studs.

 

Thats the whole point of owning a rotary🤣