turbo iroc

iTrader: (1)

hi everyone! im a noob to ls1 tech anyone having luck w blow thru carbs? ive been tinkering w my home modded carb and have had some luck and some questions as well. drilling the pvcrs how big is to big? im up to .136 pvcr w 74/94 jets still lean under boost. 15 psi boost. i wanna push 18-20 psi to make around 700whp. although i dont want to effect cruise afrs as they are borderline rich as of now. thanks for your help!

forcd ind

iTrader: (7)

have you changed your hi sp a/b's? .136 is getting way to big on the pvcr, most guys dont need to go much beyond .090 or even less
what is your idle vacume-are you sure the p/v is opening
did it have a p/v ck ball (blowout proof)
what size n/s's are you using, at least.120-.130, soild floats? jet ext's?
your jetting is in the ballpark if its a 750, the hi sp a/b's will help richen up the fuel curve, usually stock ones are .031-.033, you can drop them down to .023 to help-also annular boosters help out to

slow67

iTrader: (2)

X2,

What are your boosters, HSABs, Needle and Seats, etc

camarols1

iTrader: (17)

x3
smaller hsab's and annular boosters are your friend.
It will keep the fuel curve nice and rich under boost, but not overly rich at cruise.
With a .136 pvcr, you have probably maxed out the flow of the feed passage to the booster.
That HP goal will be a challenge on a home modded carb without poor low speed metering.
Give the boys at CSU carbs a call.
The will save you a bunch of headaches modding yours.
I think that a stock 750 (non-HP series) may not have big enough main well/booster passages to flow the fuel you need.

What fuel pump are you using?
I assume the f/press regulator is boost referenced right?
Is it lean at the hit of the throttle, or steady state wot?

turbo iroc

iTrader: (1)

Thanks for your help guys. i apologize if my forum ettiquette is incorrect. ok my carb is a holley 850 w a proform main body. i have size 26 hsab and 70 lsab. .130 n/s 4.5 pv pv plug in the back. i have changed the hsab the original didnt have a # on them so i dont know what size they were. pv protection has been removed. the boosters r not annular thats for sure. the main wells have been drilled to .180 so they should have adequete flow. the floats r stock plastic i need to put the nitrophyll ones in but theyve been holding up so far! float levels r fine boost referenced fuel system on the hat and im running an aeromotive a1000 -10 lines feed and return. i think thats everything lol as i said i can just jet the thing up and itll be fine but my cruise afrs w suffer. i dont wanna cruise down the highway w 10.0 afrs. its already around 11-11.5. the idle however is fine 14.3 and i can tune it flawlessly on idle. thanks so much for help guys. ill post pics when i figure that part out!
thanks again!


383sbc
afr220cc heads
8.5compression
240/246 custom turbo grind 4 7 swap solid lifters
turbonetics t72 turbo .84 a/r
font mt intercooler
procharger carb hat
best of 11.66@124 10psi

slow67

iTrader: (2)

Try blocking the HSABs first.

turbo iroc

iTrader: (1)

im going to try and block the hsabs. its going lean at wot but its also pig rich at at tip till the boost picks up. i really need to do some work here butif i can at least get it safe at wot first, then i can try to tune it for cruising. ive got it up to about 15psi boost now w afrs hitting low 13s its a little lean for my liking but hauls ***! 4th gear wheelspin at 55mph w the stickies on! oh one question. does anyone ever mod the back metering block? i figure the seconday pv should give some extra fuel right? i currently have a pv plug in the secondaries so the pvcrs dont do anything right? just a thought. thanks

slow67

iTrader: (2)

Correct. Try a PV in the secondaries, then you can probably bring your main jet down.