idles good...runs bad
 

i have a 1974 dodge tioga motorhome with 318 holley 2bbl.it idles well got the timing set.replaced some rubber fuel hoses and both fuel filters.replaced vaccum lines that looked suspect,new wires,new plugs.wires are separted well plugs are gapped correctly.carb has been rebuilt.new electronic dizzy.good gas in it.BUT when i start easing the gas on it hesitates like its gettin too much gas or not enough.no backfires or nuttin......im bout ready to shoot the 318 or myself.....i know what my wife would like!!!!!!!.....LOL!!!!!.....help me out guys thanks

Need More Accelerator pump shot, rite from the get go... Or you have the timing still to slow... Reset at 12*At Idle and see if that helps.

Do the easy stuff first. There has been mention of miss marked timing sets ???

Previous to this it was not idling and was surging with timing fluctuating, suggestions of new distributor drive, timing chain and other suggestions. Can you tell us what you have done to stop these problems allowing it to idle smoothly now?

Without knowing the progression of this repair and how each problem has been rectified, we all would be starting the guessing game again. Can you please elaborate?

idles good...runs bad
 

thanks for the reply guys.found a bad vaccum line that got it to idle good so was able to get the timing dialed in.its getting good shots of fuel into carb.the guy who rebuilt the carb is a good ole boy been in business around here for 30 yrs.im sure he did a good job on it.how do i check the fuel pump pressure? or should i just go get a new one.

What is your timing with vacuum advanced hooked up, at idle and off idle (breakaway, part throttle)?

Should 40-50 degrees. If it is, needs more squirt.

idles good...runs bad
 

timing is set about 12 degrees with vaccum line disconnected and plugged.what about fuel pump pressure? how to check?

Tee into fuel line at carb inlet is best.

Timing with vacuum attached will tell if canister is bad, and could be your problem.

You could in fact yank the vacuum hose off and burn it in ceremony and it would run just fine. The only difference would be mileage, not performance. Anytime you are "into" the throttle asking for power, the vacuum "goes away."

So pulling off that vacuum hose off will correct the problem and make it "run just fine"?

Any modern engine made after about 66 or so uses ported vacuum. This is for fuel mileage, IE light throttle, higher RPM produces "most" vacuum. As you get "into" the throttle, the vacuum falls off

idle......no vacuum, no effect

"fair amount" of throttle" OR MORE at acceleration = no vacuum.

So yes. You can LITERALLY throw the vacuum advance hose away, and it will run "just fine."

I'm 66 years old. I've been working on these since I was 16. I can assure you that this is how this works.

Only the older cars, in the 50's and early 60's "before smog" commonly used "manifold" vacuum for vacuum advance.

That was sarcasm. Here's the answer which differs from your's, it comes from the Chrysler Corporation.

http://www.dippy.org/upgrade/ignition.pdf

See page 6 item #2. (advance with vacuum at 2600 rpm set to 50')

Now how about we get back to solving the O.P.'s original question, not use this to prove "how right your are".

You know absolutely nothing

"Proving who is right" is EXACTLY related to helping the OP. Wrong information is the last thing he needs

So far as your little Googled document, interestingly enough came from some joint named "dippy.org" actually proves MY point

If you ACTUALLY READ that document, what it ELUDES TO is that there IS NO vacuum under heavy throttle........just exactly the situation you DO HAVE when trying to accellerate.

These cars have been this way since the advent of smog controls, some before that. If you cannot comprehend that, stop insisting that vacuum is the problem.

IN FACT if the OP has somehow WRONGLY connected the vacuum advance to FULL MANIFOLD vacuum as was NOT designed originally, it might just be that "throwing away" the vacuum hose WILL IN FACT make it "run just fine" --- at least for the purposes of testing.

Yes your right, I know absolutely nothing, I could only dream of being a know it all like you 440.

So if your last response was to be helping the O.P. what was your suggestion to help correct his problem? I think I missed it in there while you were correcting me.

Oh, and thanks for judging me and putting me in my place, that was very helpful and needed in this thread. Keep up the good work.

I was jusy reading along here ....catching up .
ig you use the correct vacuum port on the carb you vacuum will increase as volocity in creases , taking its signal from the thoat of one of the primary barells .
So at wide open throttle there may be 0 vacume but there is high volume/velocity.
So with vacuum , mechanicle , and initial timing...used as a whole is key too power .