AVS tuning help

[gtxno1]

Hello everyone I am about to overhaul my carb and get it ready for use I am determined to build a sleeper. This what I am doing 67 Gtx 440 flat tops 30over Lunati mechanical cam 264/272 526/546 Indy dual plane intake 915 heads larger valves pocket ported The carb is a 69 avs 4640 I will be using a wideband for setting it up here is the question there are no strip kits for this carb I was thinking about changing over from the 3 step metering rod set up and going with the 2 step because of the availability now the tricky part do I just match up what was in there and install the closest combo or do I pick a combo from an eddy carb like the thunder or the 1407 or 1412 and use that as my base line and make my adjustments as needed. I know at the very least I may have to replace the springs vacuum may be a little lower at idle.

 

[BB14404SPD]

Hello everyone I am about to overhaul my carb and get it ready for use I am determined to build a sleeper. This what I am doing 67 Gtx 440 flat tops 30over Lunati mechanical cam 264/272 526/546 Indy dual plane intake 915 heads larger valves pocket ported The carb is a 69 avs 4640 I will be using a wideband for setting it up here is the question there are no strip kits for this carb I was thinking about changing over from the 3 step metering rod set up and going with the 2 step because of the availability now the tricky part do I just match up what was in there and install the closest combo or do I pick a combo from an eddy carb like the thunder or the 1407 or 1412 and use that as my base line and make my adjustments as needed. I know at the very least I may have to replace the springs vacuum may be a little lower at idle.

Check out http://thecarburetorshop.com/Perfparts.htm

 

[lewtot184]

i prefer the 3 step to the 2 step, but 2 step rods are available and 3's aren't. i'd start with .104 primary jets with a 65x47 rod. i'd open the idle feed tubes to .037" and use edelbrock fuel-mix idle screws. i'd also use the edelbrock accelerator pump and an edelbrock .028" squirter modified to fit the factory carb. i'd start with .098 jetsinnthe back. don't use edelbrock jetting specs from any of the edelbrock carbs; they're too screwed up OOTB.

 

[gtxno1]

Thanks for the help I actually have a donor carb a carter 4740 can I harvest any items from there also have a afb strip kit as well

 

[gtxno1]

I can not find a squirter that size they list .024 .033 .043 as far as the feed tube make that mod at the top of the housing?

 

[lewtot184]

I can not find a squirter that size they list .024 .033 .043 as far as the feed tube make that mod at the top of the housing?

they make .028's. if nothing else just drill a .024. the idle feed tube is the small diameter brass tube sticking out the bottom of the primary cluster. the stock size is .031 and the engine will never idle good at that. .035 should be considered a minimum with .040 a max. i use .037 in a 4618s and it seems to work very well.

 

[gtxno1]

Thanks a million before I posted here I called the carb shop he told me to throw it away and take my manifold off and use a cast iron 73 with a thermoquad I knew there was a solution

 

[gtxno1]

I do actually have a .031 and a .035 but I will not stray from your recommendations

 

[gtxno1]

I forgot to ask about the step up springs should i use the originals

 

[lewtot184]

I forgot to ask about the step up springs should i use the originals

you will have to take a vacuum reading to know which springs to use. orange edelbrock springs would be a good starting point. that cam will definitely reduce vacuum and cast iron exhaust manifolds with cams with tight lobe separations don't always mix well.

 

[lewtot184]

Thanks a million before I posted here I called the carb shop he told me to throw it away and take my manifold off and use a cast iron 73 with a thermoquad I knew there was a solution

there's nothing wrong with the avs's. people don't understand them so they think they're bad. thermoquads can be made to run good also but it will be easier to chase and substitute parts with the avs. the indy dual plane wouldn't be my first choice but will work. iron heads not properly ported when big valves are added may not give the best results.