what do you guys think would cause my engine to hesitate when driving. While say driving down the road and I go to accelerate hard or soft it hesitates for just a second and then its fine. The timing is at 35 total and starts right up. I think its got to be the carb
engine hesitation
- Thread starter 68cuda78
- Start date
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OldmanRick
Well-Known Member
More info on the carb would help. Sounds lean.....either jetting or the accelerator pump. How does it respond off idle on acceleration?
i think it hesitates still but just for a seocnd then its a beast. was working fine
OldmanRick
Well-Known Member
Since this seams to be a new issue, have you done any mods?..... timing, jetting, etc. that may give a clue as to why it's happening now.
I tried a couple of different smaller Holleys on mine - with 273 then current 360 motor and I never could get rid of that hesitation right above idle I think your talking about. I have 3 different Edelbrocks and none of them have that. Rebuilt the Holleys, even bought the 50cc accelerator pump and put in bigger squirters in front to shoot the gas in and nothing worked with the Holleys. Hope someone can tell you what the fix is.
3406pk
Well-Known Member
If you have vacuum advance, try accelerate with the vacuum advance disconnected or hose clamped shut. See if that makes any difference. Also reference a holley tuning for Mopar article in June 2013 edition of Mopar Action.
vacumm advance not hooked up. I had to retime it and thats when I think it started doing it. It needed timed and it hesitates even if I give it gas at any speed not just off idle
you time it...and now it hesitates ...kind makes you think the timing is off?
OldmanRick
Well-Known Member
What timing numbers are you running? I wouldn't totally rule out the carb just yet, but we need to know if you close on the timing.
440Ken
Well-Known Member
Could be the power valve in the carb....Holley's were for that problem.
35 total timing
Lonewolf3165
Living the Dream!
What's your initial timing? Why isn't the vacuum advance hooked up?
Lonewolf3165
Living the Dream!
LMAO!! I know what you mean!Have at it Rick, I'm tired...
wasnt hooked up when I got it not sure it even works. initial was around 12 to 15 i foget im sorry
OldmanRick
Well-Known Member
Have at it Rick, I'm tired...
LOL....me too. I gotta have momma at the hospital at 7am for round two of chemo. The bed's looking real good about now...lol.
68cuda78, if you have some time to work thru this, i know we all can get you back on track. Bear with us.......
lol I gotta the little one to bed momma is already asleep. Thanks guys and goodnight
OldmanRick
Well-Known Member
Hello :mrgreen:.....Didn't forget about you, just getting back on. Let me get my stuff together and i'll post something soon.
lol
OldmanRick
Well-Known Member
I'm gonna try not to write a book here.....
Crackedback has a pretty tried & true method for determining what initial timing a engine likes and will tolerate. Short version and not to put words in his mouth, it involves bringing the engine to operating temperature and bumping the initial around two degrees at a time until you sense a hesitation or kickback on the starter. When that occurs, you back the initial off a few degrees and drive it normally and also with a "moderate" amount of throttle up thru the mechanical curve, somewhere up to about 3500/4000rpm's. DO NOT HAMMER ON IT. If there's no "ping" issues, you found what it likes and then you restrict the total timing back to the 34/36* range. It's time consuming, but it works.
The reason that initial timing is so important is, it determines the vacuum signal to the carb, which determines the (idle speed) throttle blade position on the idle transfer slot, which is where all the idle, low speed settings/adjustments have to originate from.
With all that said, if you want to try and rule out a timing issue quickly, i'd just bump it to 20* initial and drive it "moderately" and see if the hesitation is better or goes away. If so, it's a timing issue....If not, we can look at the carb for the possible problem.
Sorry.....I said I didn't want to write a book, but the timing really has to be confirmed first.
Crackedback has a pretty tried & true method for determining what initial timing a engine likes and will tolerate. Short version and not to put words in his mouth, it involves bringing the engine to operating temperature and bumping the initial around two degrees at a time until you sense a hesitation or kickback on the starter. When that occurs, you back the initial off a few degrees and drive it normally and also with a "moderate" amount of throttle up thru the mechanical curve, somewhere up to about 3500/4000rpm's. DO NOT HAMMER ON IT. If there's no "ping" issues, you found what it likes and then you restrict the total timing back to the 34/36* range. It's time consuming, but it works.
The reason that initial timing is so important is, it determines the vacuum signal to the carb, which determines the (idle speed) throttle blade position on the idle transfer slot, which is where all the idle, low speed settings/adjustments have to originate from.
With all that said, if you want to try and rule out a timing issue quickly, i'd just bump it to 20* initial and drive it "moderately" and see if the hesitation is better or goes away. If so, it's a timing issue....If not, we can look at the carb for the possible problem.
Sorry.....I said I didn't want to write a book, but the timing really has to be confirmed first.
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