Well i have a tool sickness so on the snapon truck yesterday i picked up a porting kit im not ready to tear down my whole engine yet as im new to rotary but is there any gains to be had by gasket matching the intake and smoothing it up some ? ty in advance o btw its a 12a all stock except for cat removal and custom 2 1/2 exaust (stock manifold tho)

 

Be very careful doing this. Definately do NOT match the primary ports. Also dont widen them. You can enlarge them slightly top and bottom, but just a little. On the Secondaries, you can match to the gasket but no further.

 

ok leme check and make sure im straight on this the primaris are the center ports right like i said im a roto newb by verry little how much are we talking like 1 1/16 inch and also what kind of power gains am i looking at or how far up the rpm scale is it gona move ty for ypur patince

 

Yes the primaries are the 2 center ports. What year manifold are you using? You'll get a little mid-top end power, and if your conservative with the primaries, you wont lose your low end. Actually if your new to this I would suggest just leaving the primaries alone for now and work on the Secondary ports. Also try and clean up the top end of the manifold (smoothe the bumps) but be careful as the metal is thin in spots and you dont wanna breakthrough anywhere.

 

My intake manifold porting greatly boosted the low end. Note that porting also includes *adding* material where necessary.

To reiterate: DO NOT ENLARGE THE PRIMARY EXITS. They are too tall as it is for best flow, but there's only so much that can be done with ports that narrow. Making them taller will hurt, not help.

 

It's a 79 manifold leme see if i got all this info straight primary ports are to big stock so leave them alone except for a lil smoothing of the entrance secondairys ok to be smoothed and pnly mached to the gasket sound about right? im not new to porting ive done many ford and chevy heads and a few hondas im just new to the rotary for being a simple engine i find it to be quiet complex lol its very finiky ty for all your guys help and advice im going to listen to a lot more befor i actualy start this port job!!!

 

How are you coming on your 12a ported intake carl?

 

79, that sounds about right.

Its comming along. Got 3 different plenum configurations to test and hopefully we'll be there.

 

any update on this? any pics?

 

not sure what you were searching for, but in addition to the thread being 6 years old, Carl hasn't seemed to be on here for about 2, so i wouldn't hold my breath for an answer.

maybe you should just start a thread an ask whatever it was you were searching.

 

I took an SA intake and just cleaned up the curb rash. I also ground out a bolt hole mold and welded in from the back side. Now all the ports are smooth. Didn't touch the primaries really. With the RB header and this intake my 30,000mile Pineapple 12a made 110RWHP. Better than stock but was hoping for more with all the work.

 

https://www.rx7club.com/1st-generation-specific-1979-1985-18/carb-rebuild-sa-intake-swap-881627/

https://www.rx7club.com/1st-generation-specific-1979-1985-18/dyno-after-rb-header-sa-intake-mod-carb-tuning-891720/