It is currently Tue Sep 07, 2010 9:54 pm

All times are UTC + 10 hours [ DST ]




Post new topic Reply to topic  [ 22 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 10:02 am 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
hi i have a tall port 12a want to bridge port pretty big can any one tell me the best way to go about it and if any one has a template of it that i could buy or where to get one from and is it a good block to start with


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 10:30 am 
Offline
Spitting Seals

Joined: Tue Feb 06, 2007 2:48 pm
Posts: 830
Location: rolling one up
try pineapple racing they have porting templates


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 10:55 am 
Offline
Moderator
User avatar

Joined: Wed Oct 30, 2002 11:52 pm
Posts: 4640
Location: Central Coast
So you want a big BP?

For what use, what carby, injection? Exhaust, gearbox, diff ratio???????

One size does not fit all.

_________________
Ego, is not a dirty word


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 11:49 am 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
webber locked dizzy s2 box not shore about diff yet


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 6:03 pm 
Offline
Moderator
User avatar

Joined: Wed Oct 30, 2002 11:52 pm
Posts: 4640
Location: Central Coast
Just remember before you go nuts with the porting tool, with a road exhaust, no close ratio gearbox and a Weber you want to aim for an engine with good mid range torque, a good spread of power, and not a porting style designed to work with a very loud exhaust that peaks at 8,500rpm plus.

_________________
Ego, is not a dirty word


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 7:53 pm 
Offline
Dr Wankel Himself
User avatar

Joined: Tue Jun 06, 2006 12:43 am
Posts: 6413
Location: uranus
Dazz wrote:
Just remember before you go nuts with the porting tool, with a road exhaust, no close ratio gearbox and a Weber you want to aim for an engine with good mid range torque, a good spread of power, and not a porting style designed to work with a very loud exhaust that peaks at 8,500rpm plus.

read : use a template and big doesn't mean best

_________________
Image
20 years of DIY rotary experience
my posted advice is free- time, effort and parts are not
post it, dont PM me your problems
when the going is hard, don't retard, remember your lubrication


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 8:11 pm 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
so where do i get a template from


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 8:13 pm 
Offline
Dr Wankel Himself
User avatar

Joined: Tue Jun 06, 2006 12:43 am
Posts: 6413
Location: uranus
pulled apart someones 12a today and have some great pics on how not to bridge it nicely :lol:
the -- lets port one side so big it lets the corner seal fall into the port method
( you can see where the corner seal has grooved the top of the port whilst rubbing itself flat )
Image

the lets cut it so badly its not even straight by eye method ( same centre plate , other side )
Image



Image

this one was a jetty port ( half bridged ) , built from the centre plate outwards to turn the apex small chip towards the unbridged ports
[ and done without the angle cut housings ,, and with a tiny stock exhaust port , all show, no go ]


oh,, and ,, s3 rotors,, yet s1 rear flywheel :roll: ( imbalanced )
and to take the cake front rotor in the rear,, rear rotor in the front ,, effectively changing the factory LDR ( leading deep recess ) rotors to TDR ( trailing deep recess ) :lol:




these are just some of the ways to build a motor badly,, seems to have got the full monty in this one

--- use a bloody template or dont bother !! ------------




PS

templates from pineapple,, or from racing beat ,, personally RB has a very nice small bridge template
( and also 12a and 13b custom exhaust profile template )

_________________
Image
20 years of DIY rotary experience
my posted advice is free- time, effort and parts are not
post it, dont PM me your problems
when the going is hard, don't retard, remember your lubrication


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 8:46 pm 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
and all so are the tall port 12a better to start with then a standard 12a


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 9:20 pm 
Offline
Moderator
User avatar

Joined: Wed Oct 30, 2002 11:52 pm
Posts: 4640
Location: Central Coast
Yes

_________________
Ego, is not a dirty word


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 9:37 pm 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
what makes them better is it just because the have bigger ports and can you take them out more or are they just the same as a normal 12a with bigger ports from factory


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sat Jul 31, 2010 11:24 pm 
Offline
Boost Me Up

Joined: Sun Sep 21, 2008 9:22 am
Posts: 705
Here's a few pics of Mr Rota doing my mates (13B) Bridgy if your interested :thrust: =D>
Originally a Pineapple Racing EXTEND, with his own EYEBROW...

viewtopic.php?f=21&t=190090&start=140


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sun Aug 01, 2010 10:38 am 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
thanks mate they were a big help do you no if you have to take a grove out of the houseing whem you bridge them or dose the bridge miss it if its not to big


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sun Aug 01, 2010 11:35 am 
Offline
Boost Me Up

Joined: Sun Sep 21, 2008 9:22 am
Posts: 705
12a1000ute wrote:
thanks mate they were a big help do you no if you have to take a grove out of the houseing whem you bridge them or dose the bridge miss it if its not to big


Yeah for that particular Bridge, the housing had to be modified to accomodate the eyebrow properly.
I have little to no experience with porting, just what I have picked up from Mr Rota, and a few other mechanics.
But I would say that not all Bridgies would require the housing to be modified.
It would all depend on the size of the eyebrow, you'd have to measure and have a look and see if the housing needs it for the port to work properly.


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sun Aug 01, 2010 11:43 am 
Offline
Moderator

Joined: Fri Aug 02, 2002 9:40 am
Posts: 6271
Location: Alice Springs
12a1000ute wrote:
thanks mate they were a big help do you no if you have to take a grove out of the houseing whem you bridge them or dose the bridge miss it if its not to big


I believe if you make the eyebrow small enough, you wouldnt need to chamfer the housings, but then it would be a very small bridge.

_________________
1973 RX-4 resto
1973 RX-4 rally car
1970 1300 12A project

and thats just the Mazdas.


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sun Aug 01, 2010 11:51 am 
Offline
Rotary?... What The?

Joined: Sat Jun 26, 2010 9:55 am
Posts: 41
so if i bought a template from pineapple racing would i have to cut the grove out of the houseing


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Sun Aug 01, 2010 12:42 pm 
Offline
Boost Me Up

Joined: Sun Sep 21, 2008 9:22 am
Posts: 705
E-mail them and ask.
I'd just buy it anyway and measure it out.
Have a look at see if the eyebrow extends outwards past where the housing sits against the faceplate.
If it does, then chamfer the housing to suit...


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Thu Aug 05, 2010 3:06 am 
Offline
Rotary?... What The?
User avatar

Joined: Thu Jun 03, 2010 10:35 pm
Posts: 25
thats a termn8er special that porting thats the engine out of laynlows car can you beleive my mate payed 1600$ for that porting and seals kit !! the guy said the motor was a1 lies!


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Thu Aug 05, 2010 9:42 am 
Offline
Moderator
User avatar

Joined: Wed Oct 30, 2002 11:52 pm
Posts: 4640
Location: Central Coast
Some porting fails so hard it's just not funny.

The trouble is the poor suckers with these motors then think that how their car goes is a good indication of how they should go. Very sad indeed, as most of these shit motors would go no better than a good stocker!

The biggest problem is people don't understand "how" a Bridge Port even works, so it's no wonder that their porting fails so hard.

_________________
Ego, is not a dirty word


Top
 Profile  
 
 Post subject: Re: how to bridge port a tall port 12a
PostPosted: Thu Aug 05, 2010 10:54 am 
Offline
Rebuild Time
User avatar

Joined: Wed Aug 03, 2005 9:27 pm
Posts: 1051
Location: Coolah, NSW (AKA, the middle of nowhere)
Is there a good porting thread?

As much as i understand how port timing works, and the need for a bridge when talking about bridgeporting - i would still like to read something about what makes a good port, and what makes a bad port.

Handing over a wad of cash for porting is okay - i just would like to be able to know what im looking at!

_________________
Fast, Cheap, Reliable - Pick and two, and the third is laughable


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 22 posts ]  Go to page 1, 2  Next

All times are UTC + 10 hours [ DST ]


Who is online

Users browsing this forum: Died Rich, djsa86, Greg E, Old Grey, sa22c13bbp and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group