possible carb problems, please help

[luke_hopper]

I took apart my edelbrock 1406 to install the off road needles and seats. In addition to doing this mod, I also installed a block between the bowls on the back side of the carb (as described on the pirate 4X4 site). I put it all back together and I have a few probelms. Idle sounds like it surges a little. The tach on the timing light shows a surge of approx 40 RPM or so. When I drive it, at low constant power settings, it seems to surge and sputter. I can hammer the gas and get good response and strong acceleration its just at barley open throttle when I get the probelm. In addition, at idle with the vacuume guage hooked up, I get a flucuation between about 13HG and 15HG vacuume (at idle). Is this normal or should it be stuck on a number and stay there. I have since taken the carb apart to put back in the stock needles and seats, readjust the floats and remove the block that I installed. To no avail though as its still doing the same thing.

This is very frusturating as I had zero problems before!. Please help.

 

[fordtrucksrule]

i beleve it should pretty much be steady at a # it sounds maby you got a intake leak or something else

 

[broncnaz]

Did you reset your idle mixture screws after reinstalling it? If so and they dont make any differance. You might have gotten some dirt/debris in one of the passages when you swapped out parts. I'd pull the carb off and blow it out. I'd also look at a vaccum leak somewhere. Did you use a new base gasket?

 

[72Quarterhorse]

It does sound like you may have picked up a small vacuum leak. Check all vacuum lines and rubber plug caps. Run engine until normal running temp and check to make sure the chock is all the way open then Using your vacuum gage to adjust your idle bleeds go for your highest but most steady vacuum and that should be good but then open it about 1/8 turn more Making it just a tad on the rich side. If that doesn't clear it up then Some thing inside may have got plugged. Was your base gasket in good shape? How does it run at 800 RPM. or just above idle?

 

[luke_hopper]

I did not use a new base gasket as mine was in pretty good shape. I am going to put on a a new one today though and see if that will make a difference. While the carb is out, I will take it apart again and blow everything out. I did not adjust the idle mixture screws as I did not think I needed to do this being that nothing had changed with them. If this does not fix it, is there a sure fire way to find a vacuum leak? I sprayed carb cleaner at the back of the manifold last night and did get it to go about about an inch and a half on the vacuum but am not positive that it was not being sucked into the carb.

 

[luke_hopper]

How does it run at 800 RPM. or just above idle?

at idle, approx 800 rpm, the vacuum bounces around a little. between about 12 and 14.

 

[broncnaz]

You pretty much always need to readjust carbs once they've been removed especailly if the idle is not quite right. You never know if something got bumped or some dirt got in or cleaned out of the system. But it does sound like you may have a small leak. OLD gaskets no matter how good they appear are almost always a sure way to get a leak.

 

[Explorer]

I agree with the vacuum leaks. Hose and gaskets are cheap, replace them. Readings are a bit low. Check this website out.
http://www.users.bigpond.com/ergoff/vac1.htm
Two pages with visual indications of readings and possible problems.