48IDA jetting 6port 13B NA stock port
 

Looking for some info on jetting. Racing beat lists a recommendation on jets, but they say nothing about idle jets. I found this on another site:

"13B Engine (6-Port) setup per racing beat.
Venturi - 40mm • Fuel Jet - No. 195
Air Jet - No. 205 • Emulsion tube - F-4
Needle Valve - 300

the 65F10 idle jets are just what was in there. Above 2500 rpm, she screams just fine. Is all below 2300.

pump exhaust is a .000 closed, or at least should be."

And the thread ended with out ever solving the issue. I just ordered a 48ida, racing beat 6 port intake, k&n filter assy, and related parts. I have not ordered any jets/venturies yet, but would like to. I'm just waiting for clarification before I order, some parts are cheap, but venturies are about $50 a pair and i'd like to not order the wrong ones! Also, can you just fill the exhaust jet with solder to make it .000" ?:scratch:

your air and main jets will lean out at high RPM. rule of thumb, air should be at least 50* lower than main jet. also under the hex cap near the fuel inlet, ditch the fuel filter, knock out the funnel. you also need to drill out or enlarge the fuel inlet at the carb cover. do you feel a stumble at low RPM? try using a larger idle jet. lastly, you should purchase a set of index drill bits so you can drill out the jets instead of buying a whole bunch of jets

What would you recommend as a starting jetting? I have a set of index bits I didn't even consider.. I guess now my question is, the carb comes with F7 emulsion tubes and 37mm venturies, If the other jets and stuff can be drilled out, I'll just buy the tubes and venturies, but there's mixed information on which ones to get. Should i go 40mm and F7 like RB recommends? I believe gravity fed was the guy running the setup in the original post.

you wont have any top end with 37 venturies. I had good result with f11 even on a 6port motor.

I ordered 40mm venturies, and the other parts to meet racing beat specs. Carb should be here thursday. I'm just unsure on idle jetting, the carb comes with a 70idle

70 should run, but i'd expect the low end to be pretty rich. depending on the engine and the desired AFR, you'd probably want to try a 65 and maybe a 60 too.

195 mains are a good start, although depending on the AFR you want, fuel pressure, exhaust, intake length, and porting, you might end up smaller.

40 venturi's should be about right.

205 airs seem big to me too, but that doesn't mean they won't work.

the trouble with those jetting charts is that we don't know what fuel they are on, let alone how well it ran, or what AFR's they chose (maybe it cruises at 16:1 and then has WOT at 10:1, or maybe its 14:1 all the time, we don't know).

my experience with the typical aforementioned jet charts is that they're almost always too lean for transition, and very lean at cruise.

generally wot is so pig rich it starts to miss up top...

Elevation also plays a huge role, and most of these tunes come from places like CA. If you're like me, a carb dialed in in CA will not work in the mountains in Northeast PA.

just throw whatever base jetting is recommended, and be prepared to make changes to it based on your driving style and conditions.

don't let anyone tell you that you're doing something wrong or have a engine problem because it doesn't run well on a recommended jetting.

I understand that and i'm ready to make changes, just wanted to get it close enough to run the engine. I just got my rb intake made for an 86-88 6 port engine... it doesn't even bolt up. I know it's an 88 fc 6 port engine and the packaging from RB said 86-88 6 port, the gasket lines up but the flange is so big it wont even bolt up to the engine. I have to call them when they open to find out what's going on. It would work if i ground/cut the flange down, but it's a new piece and I shouldn't have to do that. The flange hits the header studs on the motor.

Sounds like they might have forgotten one machining step.

Pictures please

they screwed up machining, i have to send mine back and they'll send me a proper one when they get them. i just put the engine together and have everything i need except the dang intake mani!

pictures