hi. please help. i hav a rx7 s1 with a new rebuilt 12a secondary bridgeport and extand port primarys. all parts are new with carbon apex seals. its using ported tall port plates and manifold. 4barrell nikki carb. with unknow jet mods ment to suit engine tho. points dizzy and std fuel pump that flows 1.5liters a min. it runs ok at idle 1800rpm and on primarys soon as ya hit secondarys it misses real bad and wont rev past it. bot 5000rpm on like having fouled sparkplugs (tryed 3 sets) i have tryed 3 dizzys and redune timing, weights locked and set to 20deg btdc even put battery voltage to coils not through ballast restors. exhaust is 2" headers that join under drivers seat and then 21/2" stright through to open flow rear muff (im in nz there no noise or emmision laws really) my queston is, is my exhaust at fault? run headers to diff then join in2 1. or is std pump not pumping enough? carb jetting wrong? was sent to a rotary workshop to be jetted. or do i have spark probs. any ideas would b great

 

oh and engine has 110psi hot or cold

 

Standard fuel pump - that is to say FACTORY Series 1 fuel pump?

If that's the case, you are running out of fuel!

I am assuming you are measuring the flow at the proper pressure, not zero-pressure flow.

It's been a while since I did the calculations, but the fuel pump in my car should be enough to support 400hp at operating pressure and it will flow 1.5l in about 12 seconds. So 1.5l/minute being only enough for 100 or so HP makes sense.

In practice, even with a completely stock car, you can tell in a Series 1 when the fuel filter is dirty, the engine would start to cut out at sustained speeds over about 120km/h. That's with a stock fuel pump in good condition. In fewer words, the stock fuel pump is insufficient even for stock power levels unless everything is perfect.

 

^ Not only that but the Nikki carb will not flow enough to support a bridgeport. It's going to fall on its face.

 

thankyou. std s1 pump mesured free flow. i have a holley red pump and 4psi resulator to try 2nite ill see how that goes. the nikki carb is off a 1985 6port 12a cosmo. venturies bored out to 20.5mm and jets been drilled out on primarys and secondarys etc. anyone got jet spec for a nikki carbruning on a secondary bridge. i know that its not ideal set up but cash is tight 2kids and morage etc. will my headers joining at fire wall matter or should i run twin pipes to diff then join? headers are 2" now and join into 1 21/4 pipe.. i hav just locked weights in dizzy and set timing to 18deg btdc. we have lots or rotas over here runniing nikki carb set up as ida is very costly. eg $1300 for s/h ida and manifold. cand buy std nikki and rejet for $400. my float height is at factory.. doesnt fall flat just realy fast misses like fouled plugs.