Holley 80457-2 stumble

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sireland67

sireland67

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I have an off idle hesitation on a holley 600 I just installed.

Vehicle: 78 Dodge Power Wagon 318 4-speed 3.55 gears completly stock bought off the original owner 79K miles.

I bought the truck last summer, rebuild the stock BBD Carter and run it all winter. Started right up idled fine even afters sitting for weeks at a time but it was lazy in the mid range.

Just put on a LD4B intake and a used 600 carb that I also rebuilt, but was so clean inside that it did not need it.

It has an off idle hesitation, enough to where I know my wife will not drive it, it also hesitates at part time throttle.
 
Set up for the inital run down the road I had 15 degrees inital timing, 34 total with vacuum at 21 inches.
Throttle response at a stop light was very poor for about 2 seconds, then responsive.
Running down a straight flat road between 40 and 60 mph the carb was surging very mild, I don't think a passenger would notice.

Now keep in mind this is not a hot rod but a stock truck that just is used for about a 1000 miles a year but my wife and 70 year old dad drives it once in a while.
 
Check the float level,adjust as necessary. Pull the sight plug,engine running. Fuel should be right at the bottom,of the hole. Step 2: do the a/f mixture screws respond to adjustment? If not,turn the screws in.Count and mark,side to side.Seat the screws,remove them all the way.Take a rubber tipped blow gun.Shove it in the mixture screw hole,blast it with air.Do both sides.Seat the screws back in,back them out to the marked settings from before.If it still doing it. Time to tune the accelerator pump circuit. This is assuming the timing is close to where it was before,good luck
 
Thanks
I will check tomorrow.
Sounds like my problem not enough fuel shot.
But...... will it cause the surge at cruise speed, no load?
The truck pulls hard if it is moving and you push the throttle any more than light pressure.
 
Abodybomber said:
Check the float level,adjust as necessary. Pull the sight plug,engine running. Fuel should be right at the bottom,of the hole. Step 2: do the a/f mixture screws respond to adjustment? If not,turn the screws in.Count and mark,side to side.Seat the screws,remove them all the way.Take a rubber tipped blow gun.Shove it in the mixture screw hole,blast it with air.Do both sides.Seat the screws back in,back them out to the marked settings from before.If it still doing it. Time to tune the accelerator pump circuit. This is assuming the timing is close to where it was before,good luck
Click to expand...

#1 Float set running.
#2 Mixture screws respond instantly to anyting over 1/8 of a twist.
#3 This is what I am going to do tomorrow.

$4 I checked the timing before I tore it apart and it was at TDC 0 deg.
Maybe the reason the BBD was a dog in mid range, started easy and got 14.3 mpg. Down low idle to 2500 rpms it was great, ran smooth, my wife and dad had no trouble driving it.
 
Sireland,is 0 stock? You probably bump initial, to 4 or 6 B.T.D.C. You added a lot of airflow,some intake velocity. Usually,bump initial a bit,or curve the distributor. This alone,could solve the bog,and proceed to lay rubber. Get that timing sorted. Bump the initial timing,if it improves.More timing needed.
 
73AbodEE said:
I posted that info for you because all I run is holley 600's. if you want to ignore it , fine . you don't want my help then F-bomb it...
Click to expand...


I do appreciate everybodys help, I was planning on watching the entire video this morning when everything would be fresh.
In later posts I was just stating what I have done or know to be true.
 
just a couple of ideas ; the vacuum sec. spring in that carb is black ,may need to be changed . the power valve in the kit was a 6.5 might want to run a 2 stage , I had to make these changes on my 80457-2
 
Make darn sure the accelerator pump is shooting as soon as throttle is pulled. Any delay there will cause a lean spike.

This is another reason I'm a BIG fan of A/F meters so you can see what's happening in actual driving situations. Saves time in the end. No guessing and throwing parts at it. Make it portable and all you need is a bung in the exhaust headpipe/collector. You can do a lot with an A/F meter and vacuum gauge.
 
sireland67 said:
I do appreciate everybodys help, I was planning on watching the entire video this morning when everything would be fresh.
In later posts I was just stating what I have done or know to be true.
Click to expand...
sorry man I was having a bad night

crackedback said:
Make darn sure the accelerator pump is shooting as soon as throttle is pulled. Any delay there will cause a lean spike.

This is another reason I'm a BIG fan of A/F meters so you can see what's happening in actual driving situations. Saves time in the end. No guessing and throwing parts at it. Make it portable and all you need is a bung in the exhaust headpipe/collector. You can do a lot with an A/F meter and vacuum gauge.
Click to expand...

this is exactly what the info was I posted. of course timing first , but if the pump shot is screwed up nothing else is going to help until that is rectified
 
hotstuff1 said:
just a couple of ideas ; the vacuum sec. spring in that carb is black ,may need to be changed . the power valve in the kit was a 6.5 might want to run a 2 stage , I had to make these changes on my 80457-2
Click to expand...

I don't think the vac spring and power valve affects the issue I am having.
But I will keep it in mind.
 
crackedback said:
Make darn sure the accelerator pump is shooting as soon as throttle is pulled. Any delay there will cause a lean spike.

This is another reason I'm a BIG fan of A/F meters so you can see what's happening in actual driving situations. Saves time in the end. No guessing and throwing parts at it. Make it portable and all you need is a bung in the exhaust headpipe/collector. You can do a lot with an A/F meter and vacuum gauge.
Click to expand...

I messed with the truck today, and found an issue.
For some reason, the gasket on top of the pump discharge nozzle was leaking slightly at idle????
I replaced the gasket and it helped the throttle response slightly.
To me the pump shot is weak, It does not shoot hard as soon as the throttle is moved.
Everything in the acceralotor pump seems in spec, it just seems to be a weak shot of fuel.
I am out of ideas to check unless for some reason pump diaphragm in the rebuild kit I used is defective.
I bought this carb used cheap, maybe it had issues from day one?
 
73AbodEE said:
sorry man I was having a bad night



this is exactly what the info was I posted. of course timing first , but if the pump shot is screwed up nothing else is going to help until that is rectified
Click to expand...

I think the pump shot is the issue, but cannot figure out why, the arm touches the adjustment spring and has the clearance at wot.

I did play with the timing and it seems to like about 6 degrees BTDC, Idles at 750 rpm with 19 in of vac.
The truck starts easy, idles smooth but for the 1-2 seconds when the throttle is first pushed it stumbles.
Even if you do not touch the gas and just let the clutch out in 1st gear is still has the hesitation.
The truck has the bull dog 4-speed with top speed in 1st at about 6mph.
 
Hi Shawn. This has all the markings of being lean in the primary jet, with a tip-in and cruise surge issue. I can't count how many late 70's manual trans vehicles I had to tune with this exact issue.

In Holley's infinite wisdom, on this carb, they put a big nozzle in to cover for a lean primary jet. As long as the accel pump is working correctly, which I think it is...the #31 nozzle should not be the issue.

I know it's timing first, but this has all the same character issues that i've seen before. Assuming the carb has stock specs, i'd jet up from the #64 to at least a #66 primary jet.

I also have my own way of adjusting the A/F mixture screws on Holley's.......Turn one in slowly clockwise until it stumbles and then back it off until it just smoothes. Go to the other side and do the same. Now go back and do both again and when you have them at that point, open them 1/8th a turn and your done.

The beauty of getting it rich enough is, you can probably feed it some more timing and it will run even better.

Just my thoughts.....
 
OldmanRick said:
Hi Shawn. This has all the markings of being lean in the primary jet, with a tip-in and cruise surge issue. I can't count how many late 70's manual trans vehicles I had to tune with this exact issue.

In Holley's infinite wisdom, on this carb, they put a big nozzle in to cover for a lean primary jet. As long as the accel pump is working correctly, which I think it is...the #31 nozzle should not be the issue.

I know it's timing first, but this has all the same character issues that i've seen before. Assuming the carb has stock specs, i'd jet up from the #64 to at least a #66 primary jet.

I also have my own way of adjusting the A/F mixture screws on Holley's.......Turn one in slowly clockwise until it stumbles and then back it off until it just smoothes. Go to the other side and do the same. Now go back and do both again and when you have them at that point, open them 1/8th a turn and your done.

The beauty of getting it rich enough is, you can probably feed it some more timing and it will run even better.

Just my thoughts.....
Click to expand...

Rick,
Thanks, I will try jetting up, yes the squirter is #31, and the jets are stock.
The pump shot just seems a little weaker than I am used to seeing on Holley carbs.
I will need to order some jets so it will most likely be the first of the week before I can get them.
This carb runs really smooth except for this slight hesitation.:banghead:
 
sireland67 said:
Rick,
Thanks, I will try jetting up, yes the squirter is #31, and the jets are stock.
The pump shot just seems a little weaker than I am used to seeing on Holley carbs.
I will need to order some jets so it will most likely be the first of the week before I can get them.
This carb runs really smooth except for this slight hesitation.:banghead:
Click to expand...

Like I said, this looks all too familiar to me. Maybe some others have different thoughts. I just wanted you to know what I would personally do in this situation. Good luck and let us know any results you get. Just trying to be helpful.
 
I gave away almost all my tuning stuff years ago. I did find a box of jets recently, but there's only one set of 65's and the rest are in the 70's and 80's from what I can tell. I do have a unopened 600 that's supposed to have #66 jets. I can open it on Friday and check. If the're in it, i'll send them to you. I'll let you know what I find.
 
OldmanRick said:
Like I said, this looks all too familiar to me. Maybe some others have different thoughts. I just wanted you to know what I would personally do in this situation. Good luck and let us know any results you get. Just trying to be helpful.
Click to expand...

Ordered the jets 64-99 from summit, might be here by Saturday??
I also ordered the 50 cc kit and extra pump shot cams, but I should not need these on this stock engine, but I can use them on other engines I have.
I will let everybody know of the results.
Thanks everybody.
Shawn
 
OldmanRick said:
I gave away almost all my tuning stuff years ago. I did find a box of jets recently, but there's only one set of 65's and the rest are in the 70's and 80's from what I can tell. I do have a unopened 600 that's supposed to have #66 jets. I can open it on Friday and check. If the're in it, i'll send them to you. I'll let you know what I find.
Click to expand...
what do you need for the whole carb Rick, if sireland doesn't need anything from it
 
OldmanRick said:
I gave away almost all my tuning stuff years ago. I did find a box of jets recently, but there's only one set of 65's and the rest are in the 70's and 80's from what I can tell. I do have a unopened 600 that's supposed to have #66 jets. I can open it on Friday and check. If the're in it, i'll send them to you. I'll let you know what I find.
Click to expand...

I hear you, I gave all my holley jets, carb tools etc years ago to my cousin which was just starting out playing with his mopars.

I ordered the jets and when they arrive we can see if that is the problem.
Thanks for the offer on the jets.
 
Hi Lance, i'm planning to hold on to it.....don't ask me why at this point...:banghead:. Just hoping someday i'll be able to use it, and I do like to jet them up a hair. If I ever decide to let it go, i'll get intouch and if you want it, it's yours.

Please bare with me, got so many personal issues right now, I just pop in and want to look at some tech stuff to clear my mind. I just hope May brings good news....and some income...lol, to help me get my mind right.
 
sireland67 said:
I hear you, I gave all my holley jets, carb tools etc years ago to my cousin which was just starting out playing with his mopars.

I ordered the jets and when they arrive we can see if that is the problem.
Thanks for the offer on the jets.
Click to expand...

Yes sir....I hope this cures it.
 
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