Three neat projects
03-23-2007, 05:10 PM
#12
Senior Member
Thread Starter
Join Date: Nov 2001
Posts: 2,284
Yeah, they gotta be good for something. 
I've never actually driven a Cosmo manifold on a stickshift that flowed correctly (it's always been with the REPU engine and the stupid NO plate). I can't remember how it drove on my Cosmo with the automatic since I removed it several years ago before it ran right. All I know is the primary power didn't change much and since I upgraded the ignition, the secondaries now add a lot. It really gets up and moves at higher RPM but takes all day to get there. Converting it to a manual 5 speed is my summer project.
I just went through some old posts about manifold ports and Carl thinks the short port 3B intermediate plate will have great low end. It will work better than a tall port plate. This is encouraging since I want to use all three 3B plates in the REPU and junk the NO plate. He and heretic say that a small mismatch of .040-.060" from manifold to side plate is fine. I'm going to check the mismatch of a '74 manifold with the 3B intermediate right now...
I've never actually driven a Cosmo manifold on a stickshift that flowed correctly (it's always been with the REPU engine and the stupid NO plate). I can't remember how it drove on my Cosmo with the automatic since I removed it several years ago before it ran right. All I know is the primary power didn't change much and since I upgraded the ignition, the secondaries now add a lot. It really gets up and moves at higher RPM but takes all day to get there.
I just went through some old posts about manifold ports and Carl thinks the short port 3B intermediate plate will have great low end. It will work better than a tall port plate. This is encouraging since I want to use all three 3B plates in the REPU and junk the NO plate.
03-23-2007, 06:26 PM
#14
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Jeff20B' post='865024' date='Mar 23 2007, 03:53 PM
I broke out the digital caliper and it came out to .07"
Next I'd like to post some pictures.
it depends on which way the mismatch is. the 81-85 12a, with the tall port center, has a big mismatch, intake is small, tall ports are well, tall... so like if the manifold is smaller, eetz steel good
03-24-2007, 11:53 AM
#16
Senior Member
Thread Starter
Join Date: Nov 2001
Posts: 2,284
Ok I took some pictures. I posted them on the other forum because I wanted to save room to show off the build of my projects here. These pictures are just general curiosities anyway. You might get a kick out of them.
http://www.rx7club.com/forum/showthread.php?t=635642
http://www.rx7club.com/forum/showthread.php?t=635642
03-27-2007, 03:50 PM
#19
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Jeff20B' post='865570' date='Mar 27 2007, 10:07 AM
Are talking about the 13B or the 20B? Do they have the same size ports on the inside?
Yes you totally should take some pictures. Especially the X casting!
13b cosmo and 20b are the same port wise.