Extended port, or bridge port. I can't decide??
 

I need help weighing out the pros, and cons to port a 12a I'm currently rebuilding.
I've decided to just do a street port to the exhaust. But I'd like to have that lope to the idle. It just sounds cool.
I've heard it on both types of ports.
I'm gonna run the RB intake, and an Edelbrock AVS 500cfm carb.
That being said. Will a simple street port with the template from RB actually make a difference? Will the bridge port kill streetablity, and make the car hard to drive in traffic?
It seems like most people bridge port, and rip up the streets with no issues. But I just need to know if it makes a huge difference over a mild extended street port??

Just need info..

hope it helps

That's stuff I actually knew but I appreciate it.
I've never seen that video.. But I'm still not really sure?
Call me indecisive, but I just can't weigh out the differences.
Though that black FB with the extended port did sound great, and the streetablity of the of a extended port is my drawing point. But there aren't any templates for an extended port.
The added power, and revs from a Bridgeport still peeks my curiosity. Those templates are easy to get.
I know I could add the brow to the port down the road if I didn't like the extended port as an added option....
I dunno??

stop and ask yourself what are you planning to do?
Daily Driver, AutoCross, drag, Drift?
and how long do you want to go between rebuilds? (mostly the way you drive, high long Revs 8k+)
is it just for sound?
turbo?
NA?
My car is stock and I love it that way, not the fastest but fun to drive.

Well I just found the pinepple racing templates. They have 3 different street ports, from mild to large. Then they have a racing port. I'm thinking the medium, or large would fit my wants.
The motor I'm building is going into a 78' Datsun 510 wagon. I actually scavenged a GSL-SE rear end from a local junkyard. So I'll have rear disc brakes, and 4.11 gears. While keeping the 4x114.3 bolt pattern. I have 280z front struts, and I'm gonna build a custom strut tower brace.
But it's basically just gonna be a fun street car. It might see the odd track day.. Going both straight, and twisty.
Mostly it'll just be a weekend driver.

well IMO i would vote a mild bridgeport not stock but not over the top

So something like the racing beat template, and just do a street port on the exhaust?
That would probably be around 200hp at the flywheel.
I'd like to keep it fairly tame, so I don't have to tear it apart every winter.. lol
I appreciate your input bud.
thanx.

the advice wasn't free, I demand build pictures one day :)

I've also found that a full bridge isn't really streetable. Large streetport seems to be the way to go if you want to drive it on public roads.

Port the exhaust and port the secondaries, leave the primaries alone and then tune the carb to feed the secondaries. Nice streetable driver that wakes up when the secondaries open. I think this would work best with a hogged out Nikki, not sure about the carb you are planning to use. Look up threads and posts by Jeff20B for details that explain my recommendation.

The above suggestion is what I’ve been thinking about for my 12a. Cruise around on stock primaries but big open secondaries. Only issue is that I’d like to switch to EFI at some point and not sure how I’d keep the 2-stage throttle.

Ha ha.. Right on.
I was thinking about starting a thread on the build. But I don't think there are a lot of Datsun fans on here?
I'm still a ways off from really getting going on everything. All I have right now is a rusty 510 wagon, and empty housings laying on a bench in my shop.

But after hours of researching, reading, and a lengthy chat with Rob at pineapple racing. I have kinda come to a decision.
Only I'm kinda messed up from what he told me?
He told me to go with the racing street port they offer, and the EP2A exhaust port. On the pineapple website that's an exhaust port for a 6 port 13b. Can you even use that template on a 12a, or did I miss something??.. lol
Anyway he tried to talk me out of the AVS carb to. But I'm still gonna do it. I have a plan, if I fumble that idea I'll eat crow. I bet it works though.

to my knowledge the 12 and 13 housing are too different to use a template for a 13 and use on a 12 and vice versa. they may have a template you can buy off of them or you might have to let them do it. don't ever leave a shop without knowing what they will be doing and always give a price you can't/won't go over and specify with or without fees (tax and what not) I always go over what I will be doing and how much it cost and why it is priced that way (i charge flat rate) so if they can't give you a straight answer as to "how much" always ask why. you should never have questions if the shop/Technician explained it well enough.

I'm guessing that part number carties over to the 12a exhaust templates as well. But online it reads different?
I emailed him about it anyway..
I'm gonna really take my time putting this bitch back together.
I jumped in with both feet, and decided to use all Mazda parts in my rebuild instead of aftermarket. So I hope it goes together a bit easier.
If I do everything right according to Rob. That same setup made 215hp with a Weber 48IDA. I should be able to copy that, plus some with the bigger carb.

I'm seeing different selections for exhaust port templates on Pineapple Racing's site.
Their templates fold and sit on the housing so you can accurately trace the port.
A 13B exhaust port would be wider than a 12A's and you do not want to make the port wider. I'm guessing he was referring to the upper and lower dimensions which control the timing.

Yeah I know the template won't fit the 12a rotor housing. I was wondering if he had a trick I missed or something.. lol
He really knew his shit though. Glad I got to chat with him.
kinda cleared a few things up for me.
My guess is that the medium 12a street exhaust would be a EP2A?

i would always stay with a street port and a nice turbocharger ^^

As much as I love to turbo stuff. This is going to stay simple...
I'm going to do the Pineapple racing Race ports. Intake, and exhaust.
It'll be cool in it's own way..
I have the idea to make it a mad max looking rig.. lol

I like 74 spec ports.

Ok, I'll bite.
What's the deal on a 74 spec port?

Stock 12A intake ports close at 40 degrees
74 spec ports were stock for the early 13B and were continued for the T2 and FD in the secondary ports only. They close at 50 degrees.
The RB "streetable" template closes at 60 degrees and opens slightly earlier than stock. Almost everyone calls these streetports but they are more of a race port that is still streetable. Pineapple ports are very similar in size from what I understand.

74 spec ports are the perfect "street" port.

I've got an old-logo 13B in my REPU but I don't know what year. Is there a way to tell the port size?

From what I gathered for info, the RB street port is pretty tame.
About the same as the Pineapple racing medium port. Just from hearsay of course. But I also heard that the racing port from Pineapple racing is a huge extended port, and even makes the idle brap from the overlap.
That was the port I was feeling, cause I wanna race my car a bit. But I still want it to be reasonably streetable..