I just tore my 12a bridgeport that I bought second hand. Anyways, it seems to me that the eyebrow starts lower than most I've seen. Is this ok and what would be the difference vs an eyebrow that starts higher? Also, I got a racing beat bridge template to compare as seen in the picks. Should I move the eyebrow up to match the racing beat or leave alone? Also, if I move the eyebrow up then my eyebrow would be very long- full length of the streetport. Is this ok and what would it effect? What should I do?

Thanks.

 

Yea it looks like who ever did the porting didnt take the bridge up far enough... in NA its very common for the bridge to run the full length of the port, for turbo however normally its preferred for the bridge to start 1/4 of the way from the bottom of the port and extend the entire remaining length of the main port.

The bridge not extending to the top of the main port will be hindering its performance as the bridge will close earlier than the main port decreasing flow.

Having the bridge starting 1/4 up the main port decreses over lap, as the bridge open a litle later than the main port. Thus giving a little bit more drivablilty and better fuel economy..there are other potential advantages.

Id just take the bridge up a little bit more, use the template though.. be very wary of the water jacket though....however being an old skool plate u should have heaps of meat before u hit the jacket anyway.. its those newer type plates u gotta worry bout...

 

Thanks, I just opened it up a little and beveled the closing line a little. I also did the exhaust port with the RB race port template.

 

awesome! How many engines have you built?

 

Many many piston engines but this will be my first rotary and I am looking forward to it. Most of the process is cleaning, the actual rebuild is pretty easy. I rebuild transmissions too and the rotary to me is more like rebuilding a trans. than an engine. hehe.

 

That bridgeport will make alot of brap-brap noise. You'll like it.

B

 

Just a question... have u had or seen this motor running? i only ask cos it looks as the inner edge of the main port has been ground inwards maybe a bit too much..and looks very very close to the oil control rings path.... wouldnt want u to build it up only to be a smokey motor...

Also are u gunna take the bridge up the full length of the port?

 

Yes, this motor was running when I bought it and it did not smoke at all. I snapped a carbon apex seal by running too lean as the motor needed a rebuild and I was looking for an excuse to rebuild it.

As for the B-port eyebrow, that's how it was when I tore the motor down. It ran pretty good this way. If I move it up the full length will it make that much difference? Also, I am worried if I runn full length that the bridge itself will be too weak?

 

Good to know bout the no smokey.

It will make a bit more power, maybe slightly noticble..not that much difference, but its a perfection factor for me... i know i'd be always thinking "What if" if i hadnt taken it up further... it wont weaken anything...only thinning out the bridge will make things weaker...

 

That's what I was thinking. From looking at running it higher there really isnt' much more flow factor because you have to angle down to the port runner opening so I don't see a real big power adding difference by going much higher. But every little bit does help.

 

Just watch the water jacket. just slope the bridge a tad towards the closing edge so that your on the safe side. I would just stick with the RB template for the bridge and the main port. Also, what do the runners look like. It may prove worthwhile to do a little work on them.

 

I ported all the runners too and port matched them to the intake manifold where I did a little porting there too.

 

your bridge is gay , like you jk

 

Here is mine


and the rotor Housing

 

use the front oil pressure spring(the one in the timing cover) from a 3rd gen. Rx7 and the rear oil pressure regulator also from a 3rd gen. rx7. buy them at your mazda dealer. you'll get 125psi at full throttle and the spring/regulators are cheap from Mazda.

 

What's up Manny? Hopefully you'll see my duece at some races this coming year to support the rotary community.

 

Thanks Ito, I already crushed the stock rear oil pressure regulator to compress the spring and I am going to shim up the front oil pressure spring 1/8" as well. This should bump me up around 100+. I also am running the 200 weber e-shaft jets.

 

you'll be so much happier if you install the 3rd gen. spring and regulator.
I hate the webber jet for a street car. oil pressure drops down to low... you'll be looking at 15 to 20psi at idle. scary.. remember a street car spends alot of time at idle..

 

good **** hope to see you out soon hint ,hint listen to ITO on the third gen reg , stop being a fruit oye btw Ito when is the book gonna be out , i want mines with an autograph

 

very pretty but no angles that makes it also gay

 

Alright. So you dont' recommend using the weber jet mod on the street? Just the 3d gen spring and rear pressure regulator with the stock check ball and spring on the e shaft?

 

Yes.. just inspect the check ball and spring. I have found the spring broken in half on 1 to 2 engines, very rare but it does happen. look up some of my oil pressure tips on the nopistons site..

 

Here's a 12A that I have. It apparently made really good power before roasting a few bearings.

These pictures were taken when I first pulled the motor apart..............I've since cleaned up the ports, the weren't very symmetrical.

I need to find something to put this motor in.

 

Who did those??

B

 

That's nice, Chuck. Good finish.

B