nasty stumble

[Madmaxx]

took the cuda for its first spin today (finally)..ok has a nasty stumble..340 unsure of cam but must be small..600 edelbrock carb...really stumbles bad timing at 10deg. no vac advance.does have a msd box..anytime you give it throttle it hesitates then goes..steady speed..then give it a little throttle, hesitates..i tried changing the pump shot no change..not sure if i should be chasing a timing issue or carb..just got this car trying to sort it out..trying to take off in traffic was not fun (stick)..as it would stumble then come to life as you give more throttle to get over the stumble and lay rubber (not so cool when the cop is right across the intersection from you)..lol..ideas/comments/suggestions?

[UKcuda]

Some carb. things to check (in order of what's easiest):

1)  Pump shot linkage - is there any slack in it?  Look to see if fuel squirts as soon as lever is moved.

2)  Air leaks around gasket/base.  Spray a bit of carb. cleaner around it on tickover and the revs will change if you hit a leak.  But note that you may identify a small leak around the throttle shaft/s which does not usually cause a problem.

3)  Float/s level - low fuel level can mess up everything else.

4)  Primary rods/jets.  I think stock setting is 98 jets with 75/47 rods.

5)  If everything else looks good try going to the next stiffer step-up springs.  Sometimes the stock springs don't lift the rods early enough as it comes off idle.

[cudabob496]

msd have cutoff for high rpm? high rpm setting may be off/incorrect?
had mine at 2600, instead of 6200 rpm once!

spark plug wires not hooked up right?

[dutch]

makes me think of a leaking accelerator pump diaphragm

[MEK-Dangerfield]

makes me think of a leaking accelerator pump diaphragm

Or he is just not getting enough shot...But unfortunately, I'm a Holley guy, so I have no advice to give on Edelbrock's.

[Madmaxx]

thx for the reply's..pulled the plugs..super lean....i have an old rod/jet/spring kit..i'm going to try to fatten it up some see what happens..this thing has 3" exhaust and i also think that is playing into the lean condition..i will keep you posted!

[Chryco Psycho]

Check float level first , usually low .
larger squirter , only three psotions to choose from for pump volume but it will not help if the squirter is too small so do that first .
 Change to a better carb

[Madmaxx]

yea not a fan of these carbs..but its on i will try to work with it for now..probaly a new carb in my future..lol..thx!

[CUDA8U]

yea not a fan of these carbs..but its on i will try to work with it for now..probaly a new carb in my future..lol..thx!

get a holley with 4 corner idle mix and you can also play with jets,floats,squirters,cams...............once you tune your holley they are awesome

i had a 600 eddy on my 440??? wen i got it,i bot a holley street hp 850(no horn),once i set the timing to 36 total i checked pump arm clearance at WOT,set floats to slow trickle,hook up vac guage and set 4 idle mix screws for best reading(in gear dist line plugged)

mine stumbled off the line so i upped the front squirter til it was gone(main jets 82 front 84 rear),next i jumped the rear squirter up 2 sizes,have someone follow you to see if there's a puff of smoke when you put er down on the highway,if there is drop a size

this thing is super responsive now although my pipes look a little black.It could be from cold  starts without a choke or puttin around town because it runs awesome......going to get it warmed up,change plugs and take it for a burn and look at plugs



 

[Madmaxx]

ok changed jets and rods and springs...WOW!..what a diff.  it had what looks like 98s on the jet size i went to 107's  and 2 sizes up on the rods and springs...no hesitation now!..man it really runs good..i'm going to drive it 50 miles to a cruise/car show and pull the plugs tomm..thanks for the help!...dam it sounds nasty with that 3" flowmasters..(even tho i normally dont like the flows)

[Chryco Psycho]

Tuning is everything with carbs