i tryed posting this in the tech/general engine forum and no one seems to wana take a crack at it. since changeing my spark plugs to ac delco rapid fires and setting my base timeing from 4 to 8 degrees ive been haveing a slight hesitation problem when i start to accelerate (or just rev it in park sometimes). i have a feeling this is carb related. ive tryed ajusting the idle mixture screws and it doesnt seem to help out much. is it possible i need to change rods/jets? its a totaly out of the box 600cfm carb. everything is hooked up correctly(choke, all vacume ports) there is no leaks anywhere either. every hose and gasket has been replaced and there is no emissions system.

 

Since the symptoms started when you made ignition changes, sounds much more like it's ignition-related to me.

 

Check your timing again.

 

What are the plugs gapped to? The rapid fires(a waste of money IMO) might have too much gap and require additional power from the coil--that it can't provide.

 

the ignition system is brand new, the coil "says" Hi-output on it so im guessing it can supply the extra power. the timeing is deffinately set to 8 degrees (base). the guy at the "parts counter" said they come pre-gapped, i have a feeling that was a load of bull though because it says right on the box to make sure they are gapped properly..... but this is only an idle-to-slight acceleration problem, at WOT its great and charges forward without any problems. honestly ive never gapped a spark plug in my life, as far as i knew all spark plugs came pre-gapped and that "gapping" your own spark plugs was a thing of the past. the spark plugs are in there now, and it would take alot more than a slight hesitation to make me wana pull them out again what would happen if i set the timeing to something higher like.... 10 or 12 degrees? what "should" my timeing be set to anyway? i have a higher than normal compression due to the TPI heads i have on my block, exactly what does a higher compression effect?

also, whats so bad about ac delco rapid fires? they were the most recomended brand/type of spark plug on this site

 

id deffinetly check the plug gaps. some claim to be pre gapped but most of the time there not gapped right.

 

not to mention the countless times they have been dropped changing the gap , I'd try taking it up to 10 or so see how it sounds some times it helps to just listen and feel the motor rather than rely solely on a timing light completely as lon as you don't go nuts it should be allright

 

when i gun it now i get more haul than i ever had before and the engine sounds NICE. i just re-adjusted the idle mixture again this time going alot richer. surpriseingly after a few rev's it sounded better and was idleing sort of smooth would a lean a/f mixture cause this kind of hesitation? it was only at idle-to-acceleration from a stop or VERY slowly rolling when it happens, never while i was accelerateing or slowing down while moveing fairly fast. i havent tryed driveing it yet, but i will tomorow morning when i wake up. is it safe to take it up to 10 degrees? whats the worst that could happen? 8 seems pretty safe to me, i havent given my car the "huge hill test" yet to see if it detonates at 8 degrees WITH the new plugs, i dont wana be driveing down the road detonateing

 

Yes, lean would do that. But, since you didn't do anything to the carb to make it appear, it doesn't follow that the carb is to blame. Weak spark will bring out problems with a lean condition, however. So, enrichening it will just crutch the problem.

One of the reasons the car companies came out with electronic ignitions back in the early smog days of the 70's was so they could live with leaner mixtures.

I don't know enough about Performer carbs to tell you how to tune out an off-idle lean spot. Holley or q-jet - yes. But, that's what you need to do.

10 degrees probably won't hurt anything, nor would 12. Pinging is the worse thing that could happen, and basically you adjust to get the most advance possible w/o pinging. Shoot for about 34-36 degrees total mechanical advance (I worry more about that than initial advance, anyway).

 

It probably leaned out because you advanced the timing. Jet it up.

 

unknown_host, thats exactly what im thinking i need to do. idleing alone its "ok" but its the whole transition from idle TO acceleration is when it hesitates. i was driveing around with 4 people in my car yesterday and it was doing it alot more. another thing i was considering is my adjustable vacume advance canister. since putting in the new plugs i re-adjusted it to its initial setting, this would make the timeing jump up really fast at the lower rpm's right? it is hooked up to my "timed" vacume port wich only gets vacume after a certain rpm. hmm... mabey i should try driveing around with it unhooked? also, under a friends recomendation i didnt put in the limiter plate in the distributor

 

Hey speakin bout timming, can anyone tell me how to reall adjust the cars timing?




I mean what part of the car do I touch? is it a carb, a hose, a nut, bolt? what what what?

 

Distributor.

 

if your still reading this juan, you need a timeing light first of all, and get yourself a distributor wrench/tool. ask some guy at your local autoparts store for one, they are pretty cheap. as for the timeing light u are gona be screwed if you dont have some money to burn. you MAY be able to rent one, or get some really cheap *** one (if they still make cheap *** ones). clean off your indicator near your vibration dampener and use some white out or white paint on the little notch(line) on the vibration dampener so you can see it easyer. i set mine to 8 degrees but you can either go by the book or set it to whatever you want. dont go below "0" though or you could screw something up. just dont go too far away from the indicator and you should be alright. basicaly hook up the timeing light to your no.1 spark plug terminal/wire (and to the battery if its an expensive one) WHILE THE ENGINE IS OFF!!!! losen the nut on the distributor a little so you can just barely rotate it by hand. turn the car on check where the little white line is by flashing the timeing gun at the indicator on the vibration dampaner, use your free hand to rotate the distributor to change the timeing to where you want it, tighten the distributor nut and check the timeing again to see if its where you want it. sometimes the tightening of the nut can throw it off a bit so you have to play around with it a bit.