Stumped and Frustrated with a Holley 670 Hesitation

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Would you think the very first shot was as strong and immediate as the following strokes? Try and imagine your foot motions on the gas pedal when it hesitates,, and try to reproduce that motion at the carb,.. You can try this with the car running,, but keep your face to the side,, and not over the carb,, where a backfire may singe your eyebrows, pls br real careful here,, safety glasses a must,., a mirror is helpful here..(if the car never backfires, you're relatively safe..) I have 2 thoughts,, As mentioned previously ,, there's a small needle underneath the squirter,, if it's not seating,, the fuel will drain back outta the squirter creating a void/hesitation, that the pump has to fill before it can squirt.. To try and remedy that,, take the squirter out, and you shoud see the needle sitting in the squirter hole,, if you have a small punch, you need to give the needle a light tap a coupla times to re-seat the needle.. Also if the squirter gskt leaks, same deal,, drains squirter.. 2nd, and drove me nuts half a day,, is in the accelerator pump cavity, (take the diaphram off) and there's a small shiny ball captured by a metal strap,, make sure that there no crap stuck in there,, and more importantly, is that the strap holds the ball almost snug,, if the ball appears to have quite a bit of motion off the seat,, tighten it up by adjusting/tapping the strap.. That ball,, if left really loose,, will cause a healthy hesitation,,, Readjust the linkages to no slack,, and cross your fingers,, .lol as always... hope it helps

I would say that each shot afterwords was about the same as the first. I was trying to mimic what my foot would do and how I drove the car, trying to get that same shot.

I didnt try tapping on that needle when I made sure it was under the squirter but that is simple as well as checking the stuff you mentioned in the pump also. Its nice because I still have the carb off the car, from checking that check.

Thank you everyone for the help once again, I'll let you know what I find next.
 
Ok, just did both things tapped the needle with a small punch and it seemed to be seated and didnt move at all.

As for the pump itself. I didnt have what you described. I took the cover off and I had a diaphragm with a metal disc on both sides of it and a spring, then a small red flapper, in the float bowl housing. To me nothing could move around or come loose and everything was in good shape.
 
Ok, lets talk about the dribble.
-If you have a dribble at initial tip-in from idle, and nowhere else, its not the end of the world.But if it dribbles every time at tip-in, say from 1/4 throttle or from 3/8 throttle, then thats a problem.
-The idle tip-in dribble, may just be too much clearance between the pump cam and the pump arm.
-The anywhere tip-in dribble is something else.This is usually a problem in the supply or discharge side.
-The supply side is the pump check-valve ( the red flapper). It fails in one of 2 ways: no1;foreign material stuck underneath it preventing it from sealing, or no2;loss of elasticity usually due to fuel contamination or old age.
-The discharge side is the passage to the squirter.That passage has 2 gaskets in it.The first is between the bowl and the mainbody. The second is between the mainbody and the squirter. That passage absolutely has to remain full of fuel.That is the job of the 2 gaskets and the 2 check- valves.
-There is another gasket between the squirter and the squirter retaining screw. The squirter can store a tiny amount of fuel in it between the check-needle and the very top of the passage before it turns down to the nozzles. If the gasket is missing then airflow past the nozzle could evacuate that fuel.I say could because its not likely, only, possible.
-Should maybe add; that as the squirter nozzle size gets bigger, and idle vacuum is still quite high, idle tip-in will sometimes suffer.I imagine it could be due to airflow evacuating the nozzles.I usually just put a faster pump-cam on it or downsize the squirter.
 
Ok, just did both things tapped the needle with a small punch and it seemed to be seated and didnt move at all. As for the pump itself. I didnt have what you described. I took the cover off and I had a diaphragm with a metal disc on both sides of it and a spring, then a small red flapper, in the float bowl housing. To me nothing could move around or come loose and everything was in good shape.

Well,, that's all I got,, and as AJ said,, the red flapper style can get hard or debris caught under it,, keep us posted,, I'd like to know how it's resolved,, hopefully with-out a new carb..
 
Oh yeah, one more thing. That spring in there is very important.If it looses its springyness, then the pump cavity might not be completely refilled, or fail to refill rapidly enough.And if the arm was not adjusted for an improperly parked diaphram, then you might have an intermitant idle tip-in problem.I guess it would manifest as a stumble on take off, or hesitation, due to a time delay between tip-in and pumpshot.
 
Ok, lets talk about the dribble. -If you have a dribble at initial tip-in from idle, and nowhere else, its not the end of the world.But if it dribbles every time at tip-in, say from 1/4 throttle or from 3/8 throttle, then thats a problem. -The idle tip-in dribble, may just be too much clearance between the pump cam and the pump arm. -The anywhere tip-in dribble is something else.This is usually a problem in the supply or discharge side. -The supply side is the pump check-valve ( the red flapper). It fails in one of 2 ways: no1;foreign material stuck underneath it preventing it from sealing, or no2;loss of elasticity usually due to fuel contamination or old age. -The discharge side is the passage to the squirter.That passage has 2 gaskets in it.The first is between the bowl and the mainbody. The second is between the mainbody and the squirter. That passage absolutely has to remain full of fuel.That is the job of the 2 gaskets and the 2 check- valves. -There is another gasket between the squirter and the squirter retaining screw. The squirter can store a tiny amount of fuel in it between the check-needle and the very top of the passage before it turns down to the nozzles. If the gasket is missing then airflow past the nozzle could evacuate that fuel.I say could because its not likely, only, possible. -Should maybe add; that as the squirter nozzle size gets bigger, and idle vacuum is still quite high, idle tip-in will sometimes suffer.I imagine it could be due to airflow evacuating the nozzles.I usually just put a faster pump-cam on it or downsize the squirter.

Ok the dribble is only at the intitial movement of the arm. After that at partial throttle where ever it may be at it will squirt. It only acts as a dribble if I slowly open the throttle, and I mean slow. Like easing into the gas very economically. LOL

I also checked all those gaskets, I have all of them in place. The more I play with this the more I think it is a immediate shot and not delayed at all. I try to mimic actual driving, when I would hit the gas and sure **** as soon as I would hit the gas I get a nice strong shot of gas out of the squirters. Oh and I went back to the stock 31 nozzle.

That red diaphragm in the pump is nice and pliable and there was nothing under it.

Well,, that's all I got,, and as AJ said,, the red flapper style can get hard or debris caught under it,, keep us posted,, I'd like to know how it's resolved,, hopefully with-out a new carb..

I do really appreciate your help!

Oh yeah, one more thing. That spring in there is very important.If it looses its springyness, then the pump cavity might not be completely refilled, or fail to refill rapidly enough.And if the arm was not adjusted for an improperly parked diaphram, then you might have an intermitant idle tip-in problem.I guess it would manifest as a stumble on take off, or hesitation, due to a time delay between tip-in and pumpshot.

The spring was nice and strong feeling as well. With no gas in the carb after checking everything. I could hear it rush air back into that pump like it was pulling a good vacuum to get gas in it.. If it had gas in it.
 
So, I also picked up the other carb today, a QFT Slayer 750, to try out. Man is that carb light compared to that other one. So I got that one installed today as well. I did some minor adjustments on it, fuel level, idle, and a rough A/F setting for the moment.

I watched the squirters on the QFT, they look to be squirting the exact same as the 670. After playing with the squirters for a bit I started the car up. I started reving it just to listen and when I start to give it gas of course the rpms come up and then I cracked the throttle. Holy responsive!!! The 670 carb just didnt seem that quick to respond. So from a idle I decided to crack the carb and it bogged out right away. I did that a couple times and then got a back fire thru the carb.

It didnt like that at all. But if I eased into the throttle so that I was just off idle it didnt seem to do that at all. Only at idle did it bog right away. I remember watching a video that inertia posted or it was one after I watched those 2 that talked about this so Im going to do some quick research and see what would be causing that bog and then back fire.

It was also raining on and off so I didnt actually get to take the car for a drive and see how it did with the QFT.
 
So all those tests in post #82 were done in Neutral or Park?
Yes

I also forgot to adjust the pump arm. So I just went out to verify where its at. When I went WOT, the pump arm would push down then the bolt and spring would raise. I tried to feeler gauge it and it was so tight I couldnt even get the feeler gauge in. So I readjusted the pump arm so that its just barely touching. Now when I go WOT, the pump arm pushes down thru the entire range of the throttle shooting gas thru the squirters the whole time.

That is the one big difference that the 670 didnt do. Like I mentioned in other posts that stopped at about 3/4 throttle.

I didnt start the car because of the time of night it is. Curious if this removed the bog from idle.

I also watched those videos about the backfiring and it could be many things. Being that a couple of my plugs were black and sooty they may be miss firing so Im going to pick up some new plugs and try again. Im also going to check my timing again. I have the car timed at 20* with 36* total timing. Just have to make sure that hasnt moved.
 
Ok, new update. I decided to pull my plugs and change them due to when I pulled a couple just a while ago they where black. Well I pulled them all, holy hell Im suprised this car even ran. In the pic the top is the front of the car and #1 being the top left and so on.

View attachment IMG_20140925_154001_759.jpg

I also changed my heat range and went to a different plug. I was running NGK ZRF6F-11, I swapped to ZRF5F-11.

I started the car verified everything was good and took it for a drive. I still have the QFT carb on the car. I got it out on the road and gave it a quick bump of the throttle. Not bad, it responded nicely. I finally got it out on the open road and went WOT. It took right off with out any hesitation. I got on and off the throttle many times and each time it was as good as the first. I turned the car around and was at a dead stop. I stomped on it to WOT, it broke the butt loose and started to get sideways on me so I let off :burnout:. Once straightened out it stomped on it again. No hesitation at all. Thru the entire throttle range. This is something that the 670 never did.

Now yes I installed new plugs, but when I put the 670 on the car it also had brand new plugs. That 670 hesitated from day one. Something with that carb ended up making my plugs look like they did above. What was causing them to turn black and carboned up I have no idea.

When I got home I pulled the #1 and #2 plugs just to take a look. These are those pics.

View attachment plug1.jpg
View attachment Plug2.jpg

Up inside the insulator is black with carbon, but I have to think that may just be whats burning off the cylinders still. I only took the car out for about a 5 mile drive. Only time will tell with some miles on this carb what these plugs will look like.

I hate so say it, but I truely do think something was wrong with that Holley and that is why someone returned it to them to start with. I really do appreciate everyones input on the Holley 670 situation. I have learned a lot about how Holleys work and how to adjust them thanks to everyone here. Sadly the 670 carb is now no longer in my possession I didnt want anything else to do with it. So I worked out a deal on this QFT with the carb shop guy. Im finally going to consider this case closed.
 
Looking forward to the update after you get a chance to dial it in after letting it warm up and get a chance to romp on it. Would love to stop by or cruise somewhere this weekend! There's a deal on Saturday in Lilydale/West St. Paul that I wanna check out if you and the little woman are up for it.
 
Looking forward to the update after you get a chance to dial it in after letting it warm up and get a chance to romp on it. Would love to stop by or cruise somewhere this weekend! There's a deal on Saturday in Lilydale/West St. Paul that I wanna check out if you and the little woman are up for it.

Our weekend is mostly open. Call me or shoot me a text with the details. I have not heard about anything like that. Besides we need to have a couple beers and talk about my daughter situation
 
What about the Whoosh/turbo noises? Really curious about that.

Oh damn forgot about that.. LOL

Yep still have that! Only at WOT, and is either a long or short whoosh/whistle depending on how I let off the gas. I think it may have something to do with the edelbrock insulated heat gasket that I installed. I thought about removing it and driving the car with out the gasket or installing the 1" spacer again to see if it goes away.. That is the only thing that changed. Im going to play with that this weekend to see if I can figure out what it is.. I can keep you all posted on that.
 
Our weekend is mostly open. Call me or shoot me a text with the details. I have not heard about anything like that. Besides we need to have a couple beers and talk about my daughter situation

There's a benefit For that Officer that was gunned downed a couple months ago, Scott Patrick. Live bands outdoors and great weather! Wanna go there around 2 or 3 pm for a bit. I will shoot you a message, man!
 
Glad you got the issue resolved,, and you sure know a lot about tuning a Holley..

That 750 will give you way more of a grin at WOT anyway,, cheers
 
No, Im still trying to find the source of that! I doubt this weekend I will get a chance to do it, since it is so fricking cold here.. They had snow in parts of the state last night... Brrrr to early for that yet!

That is for sure the last thing I want to find before the snow is here for good so the next nice warm day we have I will be working on it..
 
mine did the same thing accelerator pump was bad and my pump cam needed moved up 1 space pull it apart and clean it out 1 spec off dust can make a holley run like crap. I like holleys but they are touchy
 
How did that make it whoosh?
-I disagree about Holleys being touchy.I think thats a blanket statement. Of all the carbs I ever worked on, I think that Holleys are the least touchy. I bet I havent had mine off or apart in 8 years. Thats like 80,000 miles. Probably more. And it was born in the 70s. And it sits all winter, sometimes 5 or 6 months. Sometimes with a foot of snow on the hood.
-Now;new Weed whackers have touchy carbs. The new ones are set so lean sometimes they wont run right, even when new. And every time you bring it out,hey,bring the screwdriver too.
-But circuits in the 3310s are so fat;as long as the filter is doing its job, fugitabowdit.
-If yours is touchy.....
-end of rant
 
Figure I would just give a update on this Whooshing sound.. Didnt get to play with the car a lot before I put it away for the year. But when I did get some time I pulled the carb spacer out and mounted the carb right to the manifold. Took it out drove it and still had the whoosh sound. Again, its only happening when I go WOT, let off and the secondaries begin to close. The faster or slower I let off the gas determines the length of the whoosh sound.

I put the car away for the year, but I'm going to probably pull the intake and reseal it, just to eliminate that as a issue. Sorry guys, wish I had more news for you about this..
 
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