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Hi folks, I'm new to posting so bear with me please. I'll try to post the problem I am having followed by my engine specs and then everything that led up to this point.


my basic problem is that 1965 mustang will crank and run so long as you give it a little throttle but it will not idle. Warming it up doesn't seem to matter although a couple times it idled just fine(I'll explain in a minute). I know very little about carbs and I've been researching here and elsewhere trying to figure out what is going on.

My engine is as follows:
1986 302 block bored 40 over( stock crank timing gear and chain and oil pump)
Comp cam(unsure of the lift, was ordered and installed by the machine shop that bored the engine, I said give me a moderate lift, she's got a good lope to her)
1985 mustang HO heads(all stock)
Edelbrock intake
Headman longtube headers
Holley 670 Street Avenger 4v duel feed Carb, automatic choke(I know, it's to big)
1" spacer between the carb and the manifold
Stock ignition coil, plug wires, vacuum advance distributer, water pump, and fuel pump
March under drive pulley kit(serpentine belt)

Tranmission:
1977 f100 3 speed column shift
hurst floor conversion
Mechanical linkage

The long story(sorry in advance because it will be long, trying to cover all my bases):

This engine was running great, everything in it was brand new but I had a problem with the transmission/linkage and I laid it up, got frustrated. I kept cranking it every so often as I was advised to do, until the brand new fuel tank rusted. Got married, money got tight, car sat.

Fast forward to now, I now have a shop that I can work in so I started back on it. I've replaced to date: fuel tank and fuel pump, changed out my in line filter and I'm getting fuel to my carb.

I pulled my holley off and rebuilt it, I bought a kit and replaced the filters, the float adjustment(I dry set them by leveling with the bottom of the bowl), I replaced the accelerator pump, cleaned out every port with carb cleaner( and made sure that it sprayed all the way through), cleaned my jets(did not use a tip cleaner or anything mechanical that would bore them. made sure that all my gaskets were aligned correctly and matched the old ones. The kit I bought was for a few different models and the only thing I had left was a small(<1") brass tube with a rubber o-ring on each end, I don't think it goes to my model carb but if anyone with a SA knows for sure I'd appreciate it.

I put the whole thing back together and it would try to fire and immediately die, so I took it to a local shop that I have used a couple times before. Turns out I had two wires running to the negative of my ignition coil(one stock and one to my tach) the mechanic said one of the must have had a short because when he pulled them the car fired right up( I have yet to set out to determine where the short is so both are currently still disconnected). He told me that I must have trash in my carb someplace because it would not idle. When I crunk it up after a couple of revs it started to idle, we thought maybe it had blown it out, he adjusted it out for me and it was running good. I trailered it home because at the time I still had to pull the clutch and modify the linkage.

I would crank it every couple of days and sometimes it would idle and sometimes it would not. I finally got the tranny back in it and took it up the street for a test drive thinking that the carb just needed to warm up but it just would not stay running if I took my foot off the gas.

I pulled the carb off yesterday and sprayed some cleaner through the ports in the miter boxes, and carb(not thoroughly), I checked the placement on my gaskets, checked my inline filters were going the right way and not clogged. I put it all back together and made sure it was all torqued down. I watched all the holley tutorial videos I could find on tuning(I know nothing about carbs). This time I set my float level using the sight window until I got a trickle out of it( have not set the rear bowl yet as I was doing this last night and I figure I am not pulling enough vacuum to worry with it at the moment). I adjusted the throttle pump screw until a .015 slid between it and the pump arm with just a little resistance. I've tried tweeking the adjustment screws on the side(currently at 2 turns each) and the idle adjustment screw. None of it has done anything to alter the problem?

The car cranks up just fine but will die right out as soon as you take your foot off the gas. This may be unrelated but I hear a slight whistle from the carb when it is running, I am not sure if this is a leak or if it is just sucking air? I've run it with the air filter and without. I had rats build nests in my exhaust pipes so I have run it open headers and with pipes and there is no difference. The timing has not been adjusted since I laid it up. Is my problem perhaps not carb related but something electrical having to do with those wires being disconnected?

I have not checked the vaccum on it, or the vacuum advance hose to the distributer. All unused ports on the carb have new caps, so nothing is dry rot or leaking.

Where do I go from here, has anyone run across this before? I have a feeling I will be wasting my time pulling the carb apart again and checking all the ports but if I have to I will.

This was mine and my dads project car and the last thing we did together before he died, I'd really like to get it going again and I am close. If anyone can help steer me in the right direction I'd really appreciate it. anyone.gif

Sorry again for the long post
 

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Sounds like you may have a vacuum leak at the manifold. Did you replace the gasket between the carb and manifold? Sometimes, (and it's happened to me) the wrong gasket will not seal the carb to the manifold, or is not covering a vacuum port allowing it to leak. Sometimes, if you run your fingers along the carb base your can feel it. The other option is to space WD40 or... near the base of the carb. If you have a leak, it will suck up the WD40 and raise the idle. You can take the carb off and gasket and match it up to the base and intake to see if your using the correct gasket.
 

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Are there any vacuum ports on the carb spacer?

Have you adjusted the idle stop screw? Even if you have to have a bit high idle to keep it going. You have a lot of stuff bolted on and it all makes the engine breathe better and a low idle just can't support it.

Are all the choke linkage, cams, and set screws adjusted.

A little confused about the wires to the coil. If you took 'both' off, what is there to run the engine?

Is the throttle linkage free and not binding?


 

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Discussion Starter #4 (Edited)
@ Imlowr2:

Thanks, I replaced one of the gaskets with one that came in the rebuilt kit( I needed two because I have that spacer block between the carb and the manifold) the other gasket looked fine but tomorrow I will try the WD40 trick and let you know. I wondered if maybe my vacuum advance on my distributer could be the culprit?

@Driveway:

No vacuum ports on the carb spacer, it's just a plain spacer block, it's not a new addition, the engine was running with it before.

I adjusted the automatic choke to where it is barely cracked open at cold start. What cams are you referring to? My set screws may be all out of whack right now, I need to readjust them. But prior to me adjusting them last night they were adjusted by the mechanic.

the linkage to the throttle is free and moves easily

Let me explain my coil situation.:
on the + side I have one factory wire(I did have my automatic choke hooked up there as well but the mechanic said that after ignition the coil would go from 12v to 9v running and so I should move it to something like my windshield wiper motor that was 12v consistantly, so I did)

- side I had three wires hooked up 1. goes to my distributor 2. was a factory wire(could it be going to my ignition set up, maybe thats causing the stall? I haven't set down and traced it) 3. my aftermarket tachometer. The two wires that are disconnected are 2. and 3.

I've been fighting with the carb but apparently a short was keeping it from cranking before, I'm starting to wonder more and more if it isn't some kind of electrical issue

Thanks guys.
 

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Hello Dark,
Not quite certain about your coil set-up - -BUT for mow let's
assume it is OK

Holley's are pretty forgiving carbs - and they will idle even if not set perfet. Sure you will need to "tweak" them - -but for now - -here is my suggestion.

Turn the idle screws in all the way to GENTLY seat the screw.
Then back off the screw 1.5 turns. That will get you idling

The BIG hint here is the sound you hear from the carb - -it HAS to BE a vacuum
leak - -just need to determine where. I like to spray a little carb cleaner around the base of the carb - - then all around the intake manifold. If the motor does not
rev higher - -then try TEST #2

Take a spray bottle (like windex) and fill it with soapy water - -spray all around the intake - -where it meats the head - -you could have an internal vacuum leak
under the intake - -I doubt this - - But if you see bubbles - - there is a leak

Most likely - -something to do with the spacer or gaskets

Here is a video - just so you know your not the only one who has had a vac leak;
This is our Mach a few years ago


Car Vids - YouTube

DOn't get discouraged - -we can help fix this

Print Dad
 

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I just looked up your carb and like mine, the choke cams are behind the electric heater. There should be a set screw or something that the step cam rests against. There should be info in the rebuild instructions on how this is adjusted.
 

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Two thing I would check. The choke cap housing has a small cork gasket inbetween the housing and the carb throttle body. This is to seal a vacuum passage between the choke housing and the throttle body, my 570 didn't have the gasket and I had a vacuum leak. The cork gasket comes in your rebuild kit.

The other thing to check while the carb is off, is check the back barrels setting with the throttle closed. The back barrels should be cracked ever so slightly as the motor idles off the front and back barrels. There is a screw on the passenger side of the carb mounting base for this adjustment, if you backed off this adjustment during your rebuild you are trying to idle off only the front barrels. Also, make sure the front barrels are adjusted correctly only exposing the recommended amount of the transition slots. Read the Holley manual on this procedure really well because it is extremely critical as these are considered emissions carbs, which are tuned lean.

These carbs also have problems with off ide stumble, getting the transitions slots correctly set on the front barrels is critical, and getting the rear barrels set up is another key. I found lots of info on this carb and the resulting problems and fixes. On mine, I set the transition slots and never touch the curb idle screw after that. Then if I had to adjust idle, I do that by tweaking the back barrel setscrew, doesn't take much. I replaced the screw with one I can actually adjust with the carb on the car. This was a fix recommended by a holley guru on another forum, and it worked for me.
 

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Discussion Starter #8
Ok, yesterday I went ahead and replaced the gasket I had reused that went between my spacer and my manifold with a new one( I figured I should have done that in the first place anyway).

I noticed when I pulled the old gasket back off that it had indentations from where it sat previously and it did have some fuel in those spaces(that's what I get for trying to save a buck). I put everything back together and torqued it down evenly(I had tried to spray carb cleaner around the spacer while I was holding the throttle open under the hood and I didn't notice any increase in rpm but it was akward to do alone).

I sprayed carb cleaner around the base of the carb and the base of the spacer, as well as along where my manifold meets my heads. I had someone giving it throttle and I didn't notice any increase in idle. There was no change in the idling situation, the motor doesn't just sputter out it is dead the minute you let off of the throttle.

@print dad: Thanks for the video, it helps to see and hear what yall are talking about. The noise I heard wasn't near that loud or high pitched as what you had going on. I only heard it the other night(it was a cool night), it was a faint sucking kind of sound when someone had the throttle cranked open so it might have just been sucking air? I adjusted the set screws like you said with no difference, I even went so far as to set it from 1.5 to 2 and still it just dies. I haven't tried the windex trick yet but that will be my next step

@driveway: I know what cams you mean now, thank you. I haven't pulled the choke apparatus off yet to check the situation with that, will let you know.

@Ranger: I read over my manual(my carb didn't come with much information, apparently Holley was confident that it would bolt on and be ready to go...). I have to do some digging today and see what I can find on it.
I use the curb idle screw to set the transition slots correct? I looked at my back barrels, and it looked like they were cracked slightly. When I rebuilt the carb I never touched the valves. I found the screw you were talking about and I read the manual on it and adjusted it clockwise some to open the rear valves a little more. It made no difference, as soon as you let off the throttle the thing dies. I even opened the rears manually just a crack more while someone was giving it gas and it still wouldn't idle.

Also I just realized that I misunderstood your last message about the gasket. I was thinking about the gasket between the choke cap and the choke housing(which I had replaced). I am not sure if I replaced the cork gasket between the choke and the carb, because I don't remember seeing one when I took it apart. I will check on that.

I'm fairly sure that my transition slots are not set correctly so I will work on finding that info. I'm stuck at work the next 24hrs then I have school all morning on friday so it will be the afternoon before I get chance to look at it again.



Thank you guys for the advice, help, and patience. It's really stumping me because it doesn't sputter, doesn't idle rough it just dies but cranks up fine.
 

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Just another thought. Since this is a later model engine, does it have an EGR valve? They don't usually just all of a sudden start leaking, but if it is, it won't idle. It will leak exhaust right into the intake manifold. You can always make a block off plate if it is.
 

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Discussion Starter #10
thanks jeepers. I'm pretty sure that I don't. When we rebuilt it I stripped the block down to nothing and put it all back together, there's no pollution control or anything like that on it. I blocked off all the old ports for things like that, though it is possible I had a gasket go bad over years of sitting up, I'll give them a look tomorrow.
 

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The only two other suggestions I have is download the manual from the Holley website, about 20 pages and work on getting the idle set according to the manual.

The other suggestion would be to bolt on a known, good donor carb just for test. This is just in case the problem is not the carb and it would keep you from wasting time, although it sounds like carb trouble.

Where do you have your air/fuel needles adjusted? I would start by turning them in all the way until they lightly seat, then back out 1.5 turns.

I'm sending you a link to a Holley guru that helped me, he's pretty knowledgeable.

http://www.corvette-restoration.com/resources/technical_papers/Holley_Carb_Tuning.pdf
 

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Is your automatic choke and fast idle cam functional?
 

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You may also want to check the timing, if it's either too far retarded or advanced, it will also cause the motor to stall at idle. When doing the spray of carb cleaner to check for vacuum leaks, it should be done at idle, not with someone holding the throttle open. You won't be able to hear the idle going up or the engine running smoother. Of course with your motor stalling at idle, it makes it tough to check. If all that doesn't help, it would sound like the problem may be something in the primary circuit (idle) of the carb. Perhaps a leak in the gasket. Check to make sure all adjustments to the linkage and accelerator pump are proper as well. Try borrowing a carb from a friend and putting it on the car to see if there is any difference? Unfortunately, without being there and actually seeing what is going on, it's hard to find the problem. Good luck
 

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holley does not have an adjustable secondary which means the plates should be closed at idle no matter what....as suggested remove vac hose to dist....put white out on 10 degree btdc mark on damper....connect timing lite and set timing to 10 deg btdc while cranking it over....leave hose off and plug it....set choke to full lean [off]....turn out idle set screw until it no longer touches throttle....turn it in until it just touches throttle then turn it in 2 more turns....turn fuel mix screws in until they stop...do not crank on them....turn them out 1 1/2 turns...disconnect all fittings to carb and intake and plug them directly on carb and intake including pcv if you have one....start car...run it for 3 minutes...set idle screw until it stays running....spray flammable brake cleaner using long nozzle GENTLY at carb base, fittings and intake at head...if you do not notice any change in rpm you may still have a leak on the bottom side of intake...check torque on intake bolts...if bolts feel loose torque to 24 ft lbs as long as they are not grade 5 hardware store bolts or stainless...see if this helps...if none of this helps the idle circuits on your carb are not working, they either are plugged or your metering block gasket is leaking...remove and spray holes on both end of the long slots with the brake cleaner nozzle, they are often plugged....set gas level to just barely below the bottom of the inspection window. kyle.gif
 

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holley does not have an adjustable secondary which means the plates should be closed at idle no matter what....as suggested remove vac hose to dist....put white out on 10 degree btdc mark on damper....connect timing lite and set timing to 10 deg btdc while cranking it over....leave hose off and plug it....set choke to full lean [off]....turn out idle set screw until it no longer touches throttle....turn it in until it just touches throttle then turn it in 2 more turns....turn fuel mix screws in until they stop...do not crank on them....turn them out 1 1/2 turns...disconnect all fittings to carb and intake and plug them directly on carb and intake including pcv if you have one....start car...run it for 3 minutes...set idle screw until it stays running....spray flammable brake cleaner using long nozzle GENTLY at carb base, fittings and intake at head...if you do not notice any change in rpm you may still have a leak on the bottom side of intake...check torque on intake bolts...if bolts feel loose torque to 24 ft lbs as long as they are not grade 5 hardware store bolts or stainless...see if this helps...if none of this helps the idle circuits on your carb are not working, they either are plugged or your metering block gasket is leaking...remove and spray holes on both end of the long slots with the brake cleaner nozzle, they are often plugged....set gas level to just barely below the bottom of the inspection window. kyle.gif
Barnett "Nailed it". This is exactly what I would do as well
 

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Discussion Starter #16
Thanks for all the suggestions guys.

I think I solved one problem, thank God. I pulled the whole dang carb apart today and made sure every port was clear and rechecked my gasket alignments, dry adjusted the floats, reset everything and looked at everything yall suggested.

What I found was when I replaced my power valve in the original rebuild, the old gasket did not come off with the old PV and I didn't notice it. I put it all back together and bolted it up, fired right up and with a couple turns of the curb idle screw she started idling just fine. Can't believe I didn't notice that gasket.

Now how do I correctly adjust the carb because when I give it throttle it acts like it is bogging down? It doesn't die but you can tell it doesn't have the power it should and it pops just a little. I did notice the sucking sound again but I'm out of carb cleaner, have to get some more tomorrow.(still nothing as loud as what Print Dad posted)
I didn't want to play with a bunch of stuff and get it out of whack.

My fuel mix screws are at two turns each. My choke is opening up fine. my fuel bowls seem to be set right, just a slight trickle when I rock the car. I think it just needs adjustment but before I did anything I wanted to consult the experts.

Thanks again
 

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Check the squirter and make sure its working, and not plugged. You may have to adjust the accelerator pump delivery. Also, those carbs are particularly bad about an off idle bog if the front barrels transition slots have to much of the slot exposed at idle. The manual covers this in detail. The link I previously sent will help with the carb setup.
 

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ok, need to know approx cam specs ie high perf or stock but in the mean time try this if you want.

float level is good by the way.

what are your carb specs, size, power valve should most likely be 6.5, if its a holley then main jet 65 secondary jet 68.

remove dist vac hose and insure it does not have vac at idle. if it dies then plug it and leave it off.

set idle timing to 10 deg.

set idle to 750.

set fuel mix screws equally to achieve highest eng rpm.

reset idle to 750.

set fuel mix screws again, they should not change much.

reset idle to 750.

reconnect dist vac hose to ported not manifold vac.


drive test

from a stop hit the gas hard to 1/2 - 2/3 throttle.

does it burble/sputter then go? this is rich.

does it simply fail to accelerate like it is out of gas then go? this is lean on jets typically.

does it have no hesitation at all? if so but it still feels slow your carb is fine and your car is just a dog, lol.

happyfeet.gif
 

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Did you check to see if the needle and seat is dripping fuel while at idle? At idle, there should not be any fuel comming out of the "squirters". Also, have you looked at your spark plugs? you mentioned that you used to start once in a while but not drive it. It's very possible that the plugs are fouled from just idling and not driving it to clear it out. This is especially true if you are using a choke and never really getting it up to temperature. This all may seem very simple, but often times we over look the simple things that are actually causing the problems, just my .02.

Mike
 

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Discussion Starter #20
Ok, so here's the update.


I read the information ranger gave me as well as everyones posts. I never could hear any difference in rpm trying to adjust it by ear so I went ahead and got a vaccum gauge.

Barnett is correct, there is no adjustment for the secondaries. I pulled the carb, made sure the transition slot was at 0.20. set everything back to a starting point

After playing with just the curb idle and meter block screws I had a consistent reading of 19 on my vaccum gauge, but if I gave it a steady increase in throttle it would get to a point that it would backfire(through the exhaust), you also couldn't romp on it without backfire. The idle sounded kinda fast but I'm no good at tuning by ear. The car would not go down the road, it idled down the driveway just fine but when you gave it gas on the street it just had no power, acted like it was starved for fuel or flooding out.

I checked timing in it. My balancer is stock and reads ATC 10, 0 10 20 30 BTC, so I set it to 10 on the BTC side of zero and marked it with white paint. When I went to loosen the distributor I noticed that the bolt was already loose, I'm guessing the mechanic advanced it some because it was way off. I retarded the distributor until the mark on the balancer lined up with the set mark. I played with the carb adjustments and could never get vaccum over 16, most times it was 15 and below. I could get the engine to idle fine but whenever I increased the throttle it would backfire after a point?

I sprayed carb cleaner around the base and noticed no increase of rpm. When I unplugged one of the ports at the base of the carb I did notice an increase in rpm. I never noticed an increase in rpm when I unhooked the vaccum line that goes to the distributor. I also did a vaccume test on that line and it checked out.

I did a compression test on all the cylinders. every one of them hit 160 in about five cranks, with the exception of number six that hit 170. All of my plugs have black soot on them which tells me they are running rich(or at some point were). Plugs were the last thing I did tonight so I will clean them up or get some more new ones and see if that improves things because it's still backfireing but since I retarded the timing when it back fires it usually kills the engine

@barnett: I have a 6.5 power valve in me carb, it is a holley 670 street avenger. What do you mean "set idle to 750", I'm carb dumb :/.


So where do I go from here guys? I know the first thing I have to do is clean up these plugs, but then what? Do I need to advance or retard the distributor?


I'm getting a lot of condensation from this engine out the tail pipes and out of my breather on the passenger side valve cover( although when I smell it there is a fuel smell?) It's cold so everything I have read says thats normal. I'm not getting water in my oil though I do have white at the top of my dipstick way up which seems consistent with condesation but it freaked me out at first, hence why I did the compression test just to put my mind at ease.
 
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