The FCR Thread...

[PazzaEP82]

Guys with FCRs assemble! Long time no post on Club4AG!

Im in the process of ironing out some teething issues with my FCR 20v 4AG, so i figured i would throw a thread up to see if anyone else has any experience etc. and to talk about setup. I have 41mm Keihin FCR's, Toda 304 deg 10mm lift cams, Toda Gears, Toda Valve springs, a Cometic 0.6mm MLS Headgasket and AE111 pistons/Forged Rods. Currently im using a Haltech E6K for Ignition Control, with 35 Degrees of total advance.

All i know about the carbs is they have OCEMP Needles second clip from the top (this seems to be the needle that most run in Japan), 180 mains, the idle air screw is 2 turns out. Im not sure what size the Pilot Air Jet is. Ive read that 45 Pilot Air Jet is the usual setup also. I set the float height to 9mm this morning as per Keihin spec. The car idles damn near perfectly, starts off the key pretty much and revs up very nicely under no load.

Ive been having a missfire at a certain RPM (Circa 6000) and i think its down to running too rich, very black plugs etc so i started to lean the setup out where i could. Moving the Clip up on the needle would allow the car to rev cleanly at 1/2 to 3/4 throttle or so, past the usual missfire spot, after which WOT was ok. Going to WOT earlier causes the missfire. So im going to downsize the main to 170 and see how i get on.

Sadly i dont have access to an AFR setup at the moment, but ill try to get some tuning time once ive cleared the missfire up. Anyone else have FCR's? What mods and jet sizes do you have?!

[Nomnom83]

Hope to help you with your problems soon, I'm rebuilding my small port with fcr at the moment. Does your set of fcr have the leak jet for accel pump tuning? Mine did not and I bought a boyesen quickshot 3 so I could get a screw adjustment it was well worth it. What fuel pump and pressure are you running? I was using a carter 4070 that I used on my webers, but I had issues with fuel pissing out the overflows probably due to improper psi. Every Japanese mag says 0.15k for pressure but that number doesn't make sense.

Setup will be
Ae92 small port
FA size valves
Trd valve springs
Toda 288/288 8.5 cams
Wiseco 82mm pistons (12:1 compression)
Ae101 rods
Electromotive hpx crank fire ignition

[yoshimitsuspeed]

I think you would find a wideband well worth the investment. As soon as you buy one you will wish you had one from the beginning.

[jondee86]

Some chitchat on fuel supply here...
http://forums.club4ag.com/zerothread?id=76945

Cheers... jondee86

[ogdougynutty]

Im running 40mm mikunis on my car
Its a Large port w/ 83mm bore, 11.5:1 compression, HKS 272 cams, and with E85 I'm running a 162.5 Main and 91 a 135 main

Mikuni and Keihin jet sizes are not the same so, vvv theres a conversion chart.
http://www.jetsrus.com/FAQs/FAQ_mikuni_ ... _sizes.htm

Also i wouldn't go with "what they run in Japan" settings on your car. It might get you close (or not), but you have no idea what DA they are set-up for and it could be completely different to yours, and gas responds a lot to DA.

*edit* Also where are you located, because like i said DA comes into play a lot with carbs and even my settings could be completely different to yours.

[saiGone]

Did you disable VVT? if not how are you triggering it?

[gotzoom?]

He's got a fixed intake cam gear.

[PazzaEP82]

That Mikuni Conversion chart could come in useful, thanks! What is "DA"?

As said, you cant run VVTi with 10mm lift cams, so you use the Toda Cam gear to elimiate it.

I dont have an accel pump either, its blocked off on my FCR. But it doesnt seem to suffer for it? (i used to run these FCR's on my 16v and they were OK). Im using the OEM fuel pump with a return plumbed in before the fuel filter and the fuel pressure is set to about 2.7psi. However, the gauge that comes with the SS Works FCR Kit that i have reads in Kg/cm Squared (I think, i will double check when im with the car next), and 2.7psi is about .19 kg/cm squared. So from that we can maybe work out what the .15 pressure reading is in psi.. 2.1 psi maybe.

I will drop my pressure a bit and see how it goes.

[Nomnom83]

I mean this little cover, if you indeed blocked it off your car would not run as well when you floor the gas really quickly.



On some but not all fcr they have this leak jet in the cover that controls the amount of the accell pump jet. (Mine did not)

I would also suggest wideband if you still don't have it.

[PazzaEP82]

I will look into an accel pump jet, cheers!

So far ive had some success. I had my max ignition timing set at 35 deg BTDC, and even after fitting the 170 mains the missfire was still present. For whatever reason we decided to play with the ignition timing, dropped it to 30 deg BTDC max and the missfire is gone. So perhaps the base timing on the Haltec im using to control ignition is off (though when i lock the ignition at 0, the timing light says zero) or.. well.. i dont know really, i know 35 BTDC is a good amount of ignition timing on a 4AG but i dont know enough about timing to know why it would cause a missfire. Obviously its firing too early in the cycle which causes the missfire but i dont get why, when ive ran 4ag's at higher total advance in the past..

But im just glad to have it running better! Not perfect, but not far off. Must get a wideband or some dyno time now.