hesitation..Carb or HEI?

I have finally got my 225 to idle..about 650 rpm. Starts right up when you hit the key. HEI is timed at 10 btdc. Problem I have know is.. it hesitates upon giving it gas while driving (under a load) It rev's fine sitting still. it's just under load. It does seem to have a little miss on the passenger side but all the pipes on the headers are hot so it's not a dead cylinder. I pulled #6 plug wire of and it didn't really seem all that different and pulled #5 also..same thing. I did notice that when the plug wire was off (from spark plug) that the fenders had a small amount of electrical charge. What caused that? No idea here?

 

I'd play with the timing some. Book calls for either 5*btdc or 0, depending on whether California emissions or not.

 

sounds like you have been fighting 2 issues. How did you solve the idling issue? Maybe this is related. Did you remember to hook up the vacuum advance? Is the accelerator pump working in the carb? You should see 2 straight streams when you pump it.

Also, are the plug wires new? Old plug wires will leak. Replace them all and move on. I don't know much about HEI distributors- I assume the caps suffer from cracks like regular distributors. Can you change the cap?

 

What carb are you running?

I had a similar problem with HEI and a Holley 4160. Just a very brief hesitation or stumble, like half a second when opening the throttle under load. Went away with some minor adjustment of the accelerator pump linkage. Basically had too much play.

 

Be careful with the HEI and pulling plug wires. They put out a LOT of voltage. Enough to stop your heart if you are grounded well enough. I'd be suspicious of having an electrical charge on oyur fender. Sounds like a short somewhere. Also, your initial timing is not as important as your total timing advance. I needed an adjustable vac advance on my HEI as I was well over 40 deg total advance at the higher rpms. Here's a great writeup on HEI on a 225 oddfire.
http://www.americanjeepsterclub.org/sw/hei-2.html

 

I solved the idleing problem by removing the base plate of the Carb. (Roch. 2G) and removing the idle mixture screws and cleaning everything real good (again) The mixture screws went in further after cleaning and that did the trick. The plug wires are new...universal fit..you know..make them yourself. They are 8mm for the HEI. I have replaced the cap rotor and coil once already. When you get on the gas it will stumble but it never really clears up...it acts like it wants to have power but it don't quite get there. I moved the timing all around..with vacuum advance..without..never made a difference.

 

I had suggested that on your other thread. Now you really need to pull the venturi cluster and spray carb cleaner down through the ports. You are not fully clean yet.

 

Sounds more of carb problem than electrical if all your doing is cleaning various parts of the carb you would do better to have it rebuilt

 

Loss of power under sustained load - could be vacuum leak. Brief hesitation under sudden load, maybe accelerator pump.

 

Can also be caused by excessive timing advance. My engine reved up fine in the driveway, and was good "out of the hole" but wouldn't rev up above 2600 rpms because of to much total timing advance. If you don't know how much total advance you have, you need to check it.

 

Sea Foam through the carb.

I used to set my engines using just the vacuum gauge. Unhook the vacuum advance, and plug that off temporarily. Actually, I still do!

Hook your vacuum gauge to manifold vacuum, not ported. Loosen your distributor hold-down bolt just enough so there is a slight resistance when you turn the distributor.

Start the engine and turn the distributor, watching the gauge. When you reach maximum reading on the gauge at idle, back the distributor off just a hair and lock it down.

Adjust your idle speed back down to what-ever it is supposed to be. (I prefer 1,000 rpm. I like it best there). Hook up the vacuum advance and take it for a drive.

If you get a stumble at the high end of your normal operating engine speed, stop and back the distributor of another little bit.

With the engine good and warmed up, shut it off and re-start. If the starter whirrs the engine right over, then you are good to go. If the starter is now sluggish you need to back the timing off a little more until the starter acts normal. Should run, idle and start better here (with the idle speed set where it is supposed to be.) And get better gas mileage too. Even if it is only a tad better mileage.

 

I had this a few years ago on my 225 OF with HEI. That hesitation can really take the fun out of driving. During my research everything and everybody who comments all suggested that I had a vacuum leak. I spent a lot of time measuring vacuum and looking for a vacuum leak. Then one day the problem just stopped so I never did figure out what it was.

What granny said above about the venturi cluster would be worth checking out. Also, put a vacuum gauge on it so you can see what it's doing while you drive.

Regarding the vacuum timing control. I wouldn't think that would affect tip in unless the timing is pulled way in (lots of timing advance while just cruising) then doesn't go back down when you hit the gas. You could eyeball the vacuum gauge while doing this. You could also disconnect the vacuum timing advance while troubleshooting.

Good luck and let us know.

 

All great advise....thanks. I have been out of town so I have not been able to post in a few days (no lap top..spent money on jeep instead) Just to update.. I have cleaned the Carb. very well ( I thought) every time I have taken it apart (4) I did find last night that I had the 2 check balls in the wrong place....so I swapped them but still the same problem. I am curious though.. where do any of yall have the number 1 plug on your cap (HEI)?? I have the cap with two missing spark plug towers. I was on CRT Performance web site and their directions for putting in an odd fire HEI tells you to make the tower just to the right of where the hot (bat) lead goes into dist. the number 1 post. I have read other info and it says it should be just to the left. If you google "HEI Exposed" it will say that number 1 should be to the right using the long tang inside the cap..but pic shows different on the same site.. Mine is currently to the left of bat. lead. It fires great every time. If I move it to the right it won't run hardly at all. Also, are any of yall runing that small filter in the inlet of the Carb??(roch. 2G) I was going to take mine out..my thinking...maybe it isn't getting enough fuel and the filter could be stopping it. IDK!! just trying to think of every and anything. Any idea about fuel pressure and what it should be? Could the weights/springs in the dist. be causing the hesitation? What cap and rotor are any of you running ? Maybe its the dist. It is a Cardone 30-1693 ( i think)

 

Thanks for the pic. That is where I have my number 1 at also. I took the small filter out of the fuel inlet on the Carb. but it didn't make a difference. I turned the idle mixture screws out evenly until idle was at max and then turned them back in a 1/4. That is what i was told was correct. (trying to get my hands on a vacuum gauge) It will rev up sitting in garage and seem fine but every now and then it will spit back thru the carb and it also just don't seem very crisp in regards to responsiveness. The same when driving.... it will hesitate upon until acceleration..sometimes sptiting back thru carb and it just not crisp and responsive. If I wind it up in first gear it will feel like it is getting better but then i shift to second and it is sluggish aand the same with third.

 

"trying to get my hands on a vacuum gauge"

A vacuum gauge is one of the least expensive tools you can buy. Well worth owning.

 

Backfiring through carb and no power is typically a timing issue. I'd try to get the timing down to 5-10 btdc and see what you have there.

 

That is where it is at....8 degrees btdc.