F-Body Lover

will this work? I have 850 double pump holley on my 383ci and the car smokes real bad from the exhaust I didnt have this issue with the old cam now Im running 220/230 112lsa cam it used to be 243/257 107lsa I only changed the cam shaft and it starts to smoke I had this problem but I found out that the old cam need too much initial timing and I have to retard the distributor and I leaned the air mixture screws and the problem solved I did the same thing with this cam and no result so I figured why I dont use 750dp metering block the current 850 with 71/80 jets and 6.5 power valves on both sides so will this work? another thing I was thinking about what causing the problem that Im running HEI Mallory I think there is not enough high voltage sparks to burn the fuel !

ZONES89RS

iTrader: (25)

So, will it die if you tighten the idle mixture screws all the way in?

F-Body Lover

no it wont but it will smoke much more if I screw them all the way in with the old cam I turned them all to 2 and half turns with little retard and the smoke stopped

F-Body Lover

with the new cam if I tighten the screws the idle rise and if I open the screws it starts to act like a rough cam the carb is brand new but I think its to big for my engine

F-Body Lover

Zones I tried the 750 metering block on 850s the car starts fine but it has rough idle anyhow when I removed the vacuum advance hose the smoke cleared a little bit and when I connected it again the smoke came back I will send you a PM that has a video of the smoke

ZONES89RS

iTrader: (25)

Damn, that video sounds like that cam is bigger than that, but you need to get it so that the metering blocks will kill the idle when the screws are all the way in. Also, you dont have a 750 carb?

fleetmgr

If it does this, then you're getting close to having it adjusted properly. But you have another problem somewhere that's dumping fuel in, I'm thinkin'. Could be a bad power valve.

F-Body Lover

ZONES I have 750 but there is something wrong with it sometimes it works perfect and sometimes it dont I was gonna use the throttle plate from 850 on 750 main body and 750 metering block but I only changed the metering blocks on the 850

fleetmgr well it used to have blocked power valve and the same issue was there,I think there is something wrong with the timing or something related to ignition because when I pull the vacuum hose off the smoke comes out little but when I put the vacuum hose back again it starts to smoke I will change the distributor to full MSD from distributor to box I think there is no enough sparks to burn the fuel

quick77

I think you`re way big on carb I`ve seen motors like this on my motor builders dyno, you may see a few h/p way at the top end, but you loose so much mid-range , and lower rpm throttle response. A 650 dp should work fine, one modified with dog-leg boosters would work even better. You can`t put an 850 baseplate on a 750 main body, although it bolts on the 850s 1 3/4 throttle plate size is too wide to clear the 750s throttle bores, they are 1 11/16 plates, a few aftermarket carb shops back bore the 750 body to clear the throttle plates , but its still too much cfm........if you can , invest in an MSD ready to run dist. use the black advance bushing, take out the blus one first, this gives you 16 degrees dist advance , use a dial-back timing light, set it for 34-36 total , this gives you more initial adv, creates a stronger signal to the carbs boosters, idles better, and cleaner. It should be a 4 corner idle carb, each idle screw should be out a little less than a full turn , also check this , see what condition the cork gaskets that are located in the metering blocks, for the idle mixture screws, they get hard and you won`t be able to set idle mixture very well

F-Body Lover

big thank to you,isnt 650 small for 383ci and Brodix track 1 heads? I will get the MSD package as soon as the shop gets it

ZONES89RS

iTrader: (25)

The 650 will work, but a 750 is about optimal. A 700 carb would be the best.

I have a 750 on a 305 and it does ok, but i run 750s on all my 350s and 383s.

quick77

Thats why i mentioned a modified 650, and i think we`re both giving advice off of our own experience, i thought this to be more street than strip, what i`v seen the smaller carb gives it a nice advantage thru the midrange,without giving away much topend,its more a decision of useage.also, wasnt aware of the track 1 s !!