Ok I'm rebuilding my carb and the after burner valve is going along with all the other bs emissions and such. Question is I see the side of the intake with out the valve is machined out some. I've see friends do this to there v8 dual plane intakes so that all 4 barrels still kinda mix instead of have a barrel per intake port. So I'm think I the valves gone I should throw it on the bridge port and match it or maybe even machine it so all 4 port touch. What do you guys think?

Here's a pic so you can see what I'm talking about. You can see the right side is pocketed out.

 

match it primary to secondary to be similar to many middle run manifolds
( early ones keep all ports separate with only a minor bridge primary to primary under the carb base )

do not go open plenum.. or secondary to secondary

 

as the carb is not setup for an open plenum, and won't like it.

 

for those with the individual runner manifold.. or without a mill or a die grinder .. and have space above the engine ( ie,, rx2,3,4 ,5 )
another trick is to fit longer studs and then double or treble up on the bakelite phenolic spacer
,, and cut the primary to secondary crossovers through that
this will also give a little boost in plenum volume and seems to help the mid range a little

 

Ok thanks for the info guys. I was thinking about that spacer also. I know there's one in the junk yard I could get. So it would kinda act like a carb spacer. Do those really help on a rotary like they are supose to on a piston engine?

 

Will Machining the other side to match give it any power gain? I doubt it would be noticeable.

 

if i recall, i think Rx7Carl discussed this a while back. if you search using his name, you mind some pertinent info.

that said, if you are planning on using this on a bridge, you may want to look up a thread that Jeff20B made more recently (but still some time ago). if i recall correctly, he did some fairly extensive work with inter-port signals in the manifold.

 

cutting out the valve.. matching them the same with the crossover and spacing it up a little , and deleting the coasting richer solenoid connection has always been good for a small but noticable gain with the only a trade off being in the decel bucking and burbling qualities

( there isnt any huge gains with a stock carb except maybe when you first add the light flywheel and extractors )

PS.. i think the bridgeport he is referring too is a type of mill ,, not the engine port
( of which if bridgeporting he is advised to go straight to an aftermarket carb and manifold like a weber 48 ida )

 

Thanks diabo. And yea I was refuting to a bridge port milling machine lol. Sorry I really didn't even think of that. And I am doing the nikki strip down so the coasting valve will be gone.
Yeah I assumed there's no big power to be gained from a stock carb but it's off so I figured might as well do what I can. I can't swing 1100 dollars right now for the race beat set up.

 

With the coasting valve out on deccel bucking won't be to terrible unless your running under 2500 or so in too high of a gear. You will probably be downshifting a lot.

 

diabolical1 =

i'll go stand in the corner and let the grown folks talk now.

 

The 'Nikki and Mani' thread in the archives is a good one. There are others . Maybe 'dimpled manifold'.

 

You could try to mimic the SA manifold, or just source out and use one

20131008_211904_zpse78289d4.jpg Photo by 1stgenrx | Photobucket

 

I made it the same as other side. Whats the sa manifold?

 

SA refering to the 78-80 Rx-7. The early Rx7's didnt have that little throttle in the runner

 

sgt..... thats what i did. machined it to match other side.
full nikki strip and rebuild
all emissions removed rom carb and intake
cat deletes
msd direct fire ignition- 2 accel super coils for leading and a msd mega blaster 2 for the trailers.
all new 8.8mm wires.




dont like the red wire loom but i had it laying around