i just got a mustang today that was setup to run a 300 shot of nitrous and it loads up really bad w/o it... i was told the jets in the carb are too big for trying to make this motor run all motor witch makes since

its a 347ci
750 cfm holley carb
not sure of the specs on the cam but its deff a high lift
3" dual exhaust w/ 40 series flowmasters
edelbrock intake mani (i have a 1" carb spacer that i took off)
steel heads off of a thunderbird

can someone give me an idea of what size jets i need to run this on the streets so it doesint load up so bad, i still wanna run a small shot of nitrous maybe a 130 shot

 

if its loading up also check the power valve. Doesnt make sense to jet a carb for nitrous and different for just motor. You need to check to see what size jets you have first and go from there.

 

i don't think there is a power valve in there im pretty sure its in the glove box i don't even know what it is or does (forgive my knowledge on the subject ive never messed with a car like this... long time Honda owner first time mustang owner lol)

 

I hope something is done to the heads

 

It really hard to give you a jet recommendation over the internet not knowing what size the heads are and how big the cam is and everything else in between. But I would start buy putting a power valve back in it. The power valve is also hard to judge over the net but start with a 5.5 in the front cause i'm guessing its got a pretty big cam in it and keep the rear P/V blocked. As for jets 72's in the front and 77's in the back. It would really be nice to know what jets are in the carb now.

This is only my 0.02 and should be a pretty good starting point for you. If you need anything just pm me or call me my numbers in my sig.



P.S. If i knew more about your setup i may be able help you out more.

 

i would be more curious about where the timing is set.

 

i was just thinking about the timing today im gona throw a timing light on it tomorrow, after i throw a timing light on it im gona take the jets out and see what size they are and also check for that power valve, i have been talking to a few people who have been helping me out alot, the car idles great but dies as soon as you open the carb all the way up it runs like crap when you try to drive it also

the heads are not stock im not sure of the quench area but they are just ported and polished with a 5 angle valve job