Hello evryone & thanks for having me here ..

I have installed a 350 flat pistons, 0.30 over w/58cc alum. vette heads in my 68 RS.

engine is topped with an edelbrock 750 carb on an airgap manifold.

It keep on getting rich fuelin idle & mid range RPM & installed a regulator set @ 5.5 with no success.

Tears R comin' down from my eyes 'coz rich exhaust .Can any one help ?

 

[X(] the carb comes to mind first as the culprit. was this a new carb or an old shelf rider?? 5.5 psi may be a little high so you may want to see what edelbrock recommends for this carb. could be several things some internal like float level. a 750 cfm IS A LITTLE BIG for a 350 unless its really pumped up (yours wouldnt appear to be in this category) assuming 100% volumetric efficiency (most engines are lucky to see 80%) a 350 can only use around 600 cfm up to around 6000 if i remember right. did some one leave something out of the used carb(metering rods etc) , idle screws missing or backed out too far, metering rods need to be adjusted check out the carb and get back to us kurt

 

The carb is new and out-of-the box ..
I know its big for this engine, yet I am planning to install a bigger cam in future .. so I went for it
Now .. since you suggest I go easy on the regulater .. is there any formula I can use to figure out how much psi I really need?? and can you post the formula for cfm limit too?

Thanks for stopping by Kurt

Ghazi

 

[&:] ghazi id go and call edelbrock and see what they recommend for thier carbs for fuel pressure, i know they have a tech line. most carbs require 3.5 to 7 psi or so and varies by manufacturer. ive probably got that formula somewhere but most likely it would be easier to find online ill take a look and see what i come up with. it would seem your getting too much fuel when this combo should be lean if anything. what kind of fuel pump are you using?? has anyone made any adjustments to the carb?? kurt

 

Hi Kurt ..

I did send an email to Edelbrock Tech & hopefully they will reply w/an answer.
I am using an AC Delco mech. pump ( I know it sounds stupid ) I am thinking about going for a Holley or Edelbrock.
&
Yes ...couple of my friends did try their luck with the floats ..[&o]

Thanks for your patience

 

[&:] it sounds like the ac delco pump is doing just fine,Getting plenty of fuel. did you have this problem with the carb before the friends attempted to adjust it and has it gotten better or worse since adjustment?? also id mentioned that this would be the wrong size carb(too big) which means things like idle mixture adjustments, metering rods and jets will all be allowing too much fuel into your motor. as i suspect your problems still lie in the carb(size selection) itself ,we can go one of two ways 1) buy a more appropriately sized carb or 2) spend some time getting familiar with and make some adjustments and changes to the carb you have... i have a feeling you would prefer the latter and id be more than happy to help walk you thru some of the necessary checks and adjustments but you will need to bone up on this carb and how it works. if your not familiar with carbs and what they do and when and how they do it, a little online research on carb operation is in order kurt

 

Hi Kurt ..

Yeah .. the carb got worse after their attempts. Thats why I had it with this carb & waiting for a 600 I orderedcouple of days ago ( that would save me some brain cells ).

I chose the 600 since the 68 will be a show piece ( it will see mild action too )
With your remarks& some internet serch, I hope things will get better.

I will let you know whatI will end up with

Thanks alot Kurt

 

[&:] i think youll be happy with your selection!! and dont go adjusting anything unless you understand that which is being done. carbs are simple if you understand whats going on, the devil is in the details or attention to detail in the minute adjustments. the carb should come with minor adj. directions but should be close right out the box. as for the 750 well sell it to your buddy for his big block project or hold onto it for that extra nasty 350 the next time around. keep us posted as we want to know when the mouse is runnin right kurt

 

Kurt ..

Thanks 4 the tips

I wanted to share what I've gotfrom Edelbrock Tech ppl ..

Quote:

It sounds like you have too much fuel pressure, have you verified it with a gauge? I have attached a picture of a commonly available regulator with which we have had numerous problems. If you are using that style I would recommend going to our #8190 regulator or equivalent. Otherwise, I would take the top off of the carburetor and take a look at the float and needle assembly. Make sure that all the parts can move freely and that there isn't any debris trapped between the needle and seat. If you are at a significant elevation above sea level you will need to recalibrate the carburetor to lean it out. Thank you for using Edelbrock products, please let me know if you have any further questions

I will keep U posted

thanks again