Car blubbering in high gear....

[jasonsensational80]

Ok im needing some help. Just put a brand new 602 crate in my b-mod. Fresh carb on it. When we took it to the field to test high gear it started blubbering under initial throttle in high gear... it will clear after a couple seconds.. but every time you slow back down to simulate a slow rolling start it does it on take off...Changed 4 carbs from 750 to 650 to 390 all with the same result. Changed fuel pumps, changed regulators, put new battery in, put new solenoid in, put new module in the HEI... re-wired the car where it litterally only has power to the switch and then to the distrubutor. None of which fixing it. The car will not blubber if the RPMs stay up, but if you try a slow start and gas it, it does it. It's also turning the spark plugs black like its not getting enough fuel.

Any thoughts or suggestions? I feel like we've changed everything but the number the last 2 days!

[smirk]

Ok im needing some help. Just put a brand new 602 crate in my b-mod. Fresh carb on it. When we took it to the field to test high gear it started blubbering under initial throttle in high gear... it will clear after a couple seconds.. but every time you slow back down to simulate a slow rolling start it does it on take off...Changed 4 carbs from 750 to 650 to 390 all with the same result. Changed fuel pumps, changed regulators, put new battery in, put new solenoid in, put new module in the HEI... re-wired the car where it litterally only has power to the switch and then to the distrubutor. None of which fixing it. The car will not blubber if the RPMs stay up, but if you try a slow start and gas it, it does it. It's also turning the spark plugs black like its not getting enough fuel.

Any thoughts or suggestions? I feel like we've changed everything but the number the last 2 days!

How are u setting your idle mixture screws? Try backing them iut 1/2 turn each.

[Confused?]

If the plugs are black, then it is WAY too rich and/or oiling the cylinders down. They would be white if it was too lean.

[JustAddDirt]

Ok im needing some help. Just put a brand new 602 crate in my b-mod. Fresh carb on it. When we took it to the field to test high gear it started blubbering under initial throttle in high gear... it will clear after a couple seconds.. but every time you slow back down to simulate a slow rolling start it does it on take off...Changed 4 carbs from 750 to 650 to 390 all with the same result. Changed fuel pumps, changed regulators, put new battery in, put new solenoid in, put new module in the HEI... re-wired the car where it litterally only has power to the switch and then to the distrubutor. None of which fixing it. The car will not blubber if the RPMs stay up, but if you try a slow start and gas it, it does it. It's also turning the spark plugs black like its not getting enough fuel.

Any thoughts or suggestions? I feel like we've changed everything but the number the last 2 days!

black plugs are a sign of too much fuel, hince the stumble and blubber.
what is engine timing set at?
does car smell rich at idle? if so turn idle air mixture screws all the way in, and back them out 1.5 turns. turn them in 1/8 turn at a time to lean motor down a bit on idol.
How many CC squirter pumps do you have 50cc or 30cc? Motor may be getting too much fuel on initial hit
have you replaced the sparkplugs? If you changed all those things, did you change the plugs as well, or just use the same ones.
Typically once a plug has fouled, it is fouled, and needs to be replaced, or you will still continue to have the same symptoms.
What power valve number do you have? 3.5 4.5 5.5 or 6.5?
what is your plugs gapped at?
Are you using racing plugs?

[jasonsensational80]

black plugs are a sign of too much fuel, hince the stumble and blubber.
what is engine timing set at?
does car smell rich at idle? if so turn idle air mixture screws all the way in, and back them out 1.5 turns. turn them in 1/8 turn at a time to lean motor down a bit on idol.
How many CC squirter pumps do you have 50cc or 30cc? Motor may be getting too much fuel on initial hit
have you replaced the sparkplugs? If you changed all those things, did you change the plugs as well, or just use the same ones.
Typically once a plug has fouled, it is fouled, and needs to be replaced, or you will still continue to have the same symptoms.
What power valve number do you have? 3.5 4.5 5.5 or 6.5?
what is your plugs gapped at?
Are you using racing plugs?

We've been replacing the plugs with new ones after every time it's ran and blubbers.
Timing is set at 34 or 36 I believe.
It doesn't smell rich. 4 different carbs... All do the same thing so I don't think it's the carb.
Plugs are gapped at 40 I believe.

This motor with our carb was on the dyno before it was put in the car. Ran perfectly. Which makes me think its another factor?

[jasonsensational80]

The plugs are black and dry after a warm up and 2 times around my yard in high gear.

[mudeater18]

We've been replacing the plugs with new ones after every time it's ran and blubbers.
Timing is set at 34 or 36 I believe.

Plugs are gapped at 40 I believe.
?

Recommended timing for a 602 is 32 degrees. I also seem to remember the plug gap to be .035 also, but it's been awhile. Worth a try !

[DANNY]

All things aside how about the float levels sounds like it could be shooting fuel out and that causes the stumble. At an idle see if it drips fuel from the venturi... Or is there a sign of fuel shooting out the tubes it can run off into the carb and make a mess of the running too...

[racin6mod]

we had the same trouble with my brothers mod. the problem ended up being in the ground on the msd box once we grounded it to the engine block the blubbering was gone. may not be your issue just don't over look the ing. system.

[jasonsensational80]

We've definitely been going though ignition as well. We have to run the Softtouch Rev Control box which we have unplugged. Basically have a power wire coming to the power switch and from there to the starter button and the distributor and thats it at this point that is hooked up.

Considering grounding the engine itself.. heard some oddball instances of that..
Also considering grounding the on/off switch... supposedly they ground theirselves.. but at this point I'm trying anything.

[cuda9009]

replace the on/off switch we had the same problem once did everthing you have done and it was a bad switch

[JustAddDirt]

fat

What is fuel pressure?
Do you have a bypass on it?
It could be ground to MSD.
Make sure to grind a bare spot on your front motor mounts on chassis and on mounts to motor for a good ground. But you could run a chassis ground to an intake bolt, or a mid-plate.

If motor runs good after it cleans up, I would think it would be fuel related.
Did the dyno run use the mechanical pump, or electric pump attached to dyno?
You may need to lengthen the squirter bolt to give it less fuel on the accelerator pump or pumps .
It is hard for a dyno to simulate that initial heavy hit on the throttle cause the motor is useually loaded on a dyno at a higher RPM.

What spark plugs are you using? I hope to god not an AC Delco plug.

[jtrent64]

I am having this exact problem with my 602 crate, just lowered the float levels even further, I was having some fuel wash down the venturi's. I also will be changing the squirters and cam to try and help.

Jason, did you get this fixed????

[racin6mod]

the problem is electrical even the ground at the battery could be the issue. a couple years ago a local racer had the same type of problem turned out to be the battery. also run the main ground for the msd box to the back of the engine block and the main hot straight from the battery. your getting a weak spark due to a bad connection or ground also if you haven't yet unhook your tach they do go bad and could be the issue.

[hipower17]

how big is your yard?