It run smooth just lean I have I believe size 34 jets in it and its still too lean.

 

i personally would run a 650 cfm...
but if u r too lean u need increase ur jet size...

also are u leaning out on full throttle or just driving around?
u may need to step up to the larger accelerator pump or possibly try a diff squirter...

if it a brand new carb... make sure there isnt anything in the metering block... i bought one that had a piece of gasket lodged in it

 

I think a 850 is too much for a blown 355. Also like stated is it a blow threw carb or a draw threw carb. What blower set up does this have ???

Also welcome to the site

 

its leaning out on full throttle when I have it at the track
it is still street legal so its a daily driver ( other then the 4mpg thing )
the carb on it now was at a shop and was told it was set up so it could be run on my blower (256) Iam new to this end of it all just wanted to have a toy to run on the track and iam getting over my head I think lol

 

u need to step up ur jettin in the secondaries...
does it lean out once the secondaries open?
if so it is the accel pump /squirter combo...
do u know what size jets u have in the secondaries...

 

sounds like secondarie's are the problem as stated, check the jetting and linkages. I think the 850 isnt to much of an overkill though....it leave's room for improvement
Welcome to the site!

 

Ok I took a look at the carb the one that is on it now has 84 main and 88 for secondary the 850 has the 30's in it changed the jet so much this summer I forgot what was in it . the blower is a roots . the squirter's are 4x larger then the stock size. I was thinking of selling the 850 holley and buying a 850 dominator.

 

i would call holley and tell them ur story..my dad called holley and told them everything about the motor and the car and they were dead on the head about the jetting... its a 10.0 street car...we tune a little from there but they were 1-2 sizes off...its alot better then guess...eating up plugs get costly...not to mention motors cost too..

 

Ok I talked to holley they seem to think that 2 750's !! would be what it needs
i was shocked thats way more than what I was even thinking of. I know these guys know there stuff but is it just me or does that seem a bit exsesive ?

 

That does seem a bit excessive... are you sure that its your carb? it could be your fuel pump. if its leaning out in the top end your fuel pump might be having difficulty keeping up with your engine. Thats a pretty thirsty engine set up you have there.....