1974 Other Ford Models Stutters/Stalls at higher RPM

Does this one have points? or Module? I would start by checking the dwell...check at idle, then raise rpm to about 1500 rpm, dwell should remain constant...if not distributor shaft is worn...also if it has trouble on deceleration, check the vacuum advance for binding and or leaking vacuum pot!

It is a point system. I will try to install the new fuel pump and reply with results. If it doesn't fix it, I'll do what you said and repair accordingly.

***EDIT*** by the way, Haven't had any trouble on decel. Just accelleration- when I was taking it home there is a upward hill. On that hill I had the throttle half floored and was at 30-35MPH (VERY slow for half floored) no knocking or noises. After the hill I pulled into the driveway fine, let it ilde (it idled like a dream) revved it - had great response and sounded fine.

Fuel pumps on these usually leak when they are no good...How confident are you about that carb rebuild? anti stall dashpot adjusted right?

I haven't checked for leaks, since its carbureted the smell of gas coming from the hood doesn't get a second look from me. Although I have had to replace a gummed up fuel filter about 10-15 times within the 1.5 years of ownership. It, for some reason, gums up easy and reduces power and throttle response after just a month or so of driving, so I figure the 34 years of use for the fuel pump (it goes gas "tank - pump - filter - carb" on my car) may have some build up.

REPLY: Not too confident really. It was cheap and came with minimal parts. To be honest if the pump didn't fix it I was going to buy a whole new carb...
I'm no auto tech, in fact Im a computer tech. I just grew up around mechanics. If I'm correct, the antistall dashpot is located on the firewall-side of the carb with a baffle over the intake of the carb? if correct, there is nothing connected to it. I think someone may have altered it. I can physically move it with my finger though which acts like a choke (during cold weather, if I move it in the close position Idle becomes smoother).

The anti stall dashpot, is located at the throttle lever, it's the part where the end of the lever rests...on the throttle side towards the front...

In that case: no adjustments or servicing has occurred. If I remember correctly, the rebuild kit came with: gaskets, accellerator pump and diaphram, fuel inlet and a measurement tool for adjusting the float (but not the float itself). Nothing else came with the kit. Maybe worth noting?: the fuel bowl had a fine, reddish sandlike substance at the bottom. not enough to cover the bottom of the bowl, but enough to get me nervous.

When you do a do it yourself rebuild, you should get the right solvent and basket for doing them, and the carb should be dismantled and soaked for a good 6-8 hours, that will remove the varnish bilt up inside! The dashpot is sold seperatly...and I think 74's had no catalytic converters, so thier natural diet was leaded gas, so to run unleaded the valve seats need to be changed to hard seats! If not done the valves and seats will end up ruined...

I think I just died a little inside... You are correct, there is not catalytic converter (it's straight pipe). So do you think it's possible to drive with unleaded gas for all these years and just now experience the effects? What should I do?

No I believe this has been done already...Check the carb for the dashpot, and have a look at the timing and dwell...

Roger that. Thanks for the help. I know what to look for now.

so I got to looking... there is no antistall dashpot on my vehicle. theres also no indication one was previously there/removed. ill take that as less troubleshooting to do and try to find a dwell meter. also I noticed there is some fluid (looks like oil maybe) that is or has leaked from the fuel pump. I don't think its gas since gas dries quickly... this stuff still looks a little wet. ill consult someone to help me with the dwelling though since I'm not familiar with it.

You might want to pull the fuel pump line and test the volume, should be a pint in 30 seconds I think, afterall we are going way back on this one! Do you have a manual or at least the impotant specs for the car? Investigate the leak at the pump! Yes I know it's a Ford!

These are some specs that may be important that I've found:

1974 Ford Maverick 250CI (4.1L) 1BBL Carbureted
Inline 6
Points distributor (Dwell Range: 35-39 Degrees)
Mechanical Fuel pump
Automatic C-4 Transmission with Ford Kickdown
No AC
With Power steering
MSD Blaster 2 Coil with Ballast Resistor
BWD Nascar Premium 7MM Plug wires
Autolite Platinum Plugs at .044 Gap
Fram Fuel filter (new as of 4 days ago)
Carter RBS carb - Single Barrel

Yeah, Investigating a leak in a 34 year old car ain't the easiest thing. Especially since it had a bad radiator about 6 months ago that destroyed nearly all the things I listed above from a huge leak. So nearly all stuff listed above is brand new. I still haven't been able to replace the Fuel Pump: I've inspected it, the difficulty for replacing it, making sure I know the ins and outs of replacing, but my job is interfering since I work during the daylight hours and have to carpool with my wife. Maybe I'll cut some hours off my shift today and get to replacing it and see what happens. :)

EDIT: BTW, someone said they think it is the fuel float since it runs fine at idle, low RPM but when gas demand is high it begins to shudder / die. I'll snap some pics of the distrib. and such today if I can and post the links.

Like I said that rebuild is questionable...did you remove the needle valve and seat? use a section of pipe cleaber to get what you can? All traces of carbon on the bottom plate...etc...etc...

Agreed- I'm not comfortable with the rebuild either. I replaced the needle and seat: there was no traces of obstruction (the passage is maybe 1/4 inches long). The problem is I never soaked the carb and I never dealt with carburetor rebuild before that: so I may have offset the float. I'm thinking I should take it into a shop for repair/rebuild. Should I consider other things too (other than replacing fuel pump)? I think you've narrowed it down pretty well. Just let me know what I should ask the mechanic to fix/look at if you would please. :)

well you can check the condition of the points...any pitting and they should be replaced, bad points usually give a bad idle, but not impossible to get your symtoms...if you apply vacuum to the advance, does it pull and release ok?

I don't have any way of testing vaccuum personally. I do however have some pictures I took today after replacing the fuel pump. I wasn't able to see if the fuel pump made things better (my upper radiator hose I bought doesn't fit...) I'm going to photoshop them and I'll post the links.

Choke thermostat is important, remove the 3 screws holding the bakelite cover on, an install the new spring. They used to make a replacemet tube for the exhaust, if you can't find one try plumbing supply, for a copper icemake line. I could not read the part about the plastic piece..

It said that the distributor rod is rounded where it meets the plastic piece (not edged) but does not appear to be worn. The plastic piece however does show signs of wear (little plastic fragments coming off). I'm just not sure what that "plastic piece" is called: Never worked with distributors- especially points systems. I've been thinking about just getting a conversion kit for electronic but I can't seem to locate one. They're all for Chevy V-8s it seems like... I'll fix that exhaust tube with some copper plumbing and maybe put some high-temp cold weld on it or something. By the way- that choke-looking-thing on the left of the carb in picture 4 looks like it has silicon all over the backside of it. There also is no spring there to move it: can the whole module be replaced? I don't know what the heck the previous owners were doing to this thing, but I don't much care for jimmy-rigging anything.


EDIT: I'm gonna go make a run to the performance parts store and try to order an electronic kit. If anyone in town can they can. I'll also see if they have the choke module.

EDIT2: Bought a new hose so I can test the car now. Bought a vacuum advance- it's on order. Figured it'd be better to spend the $20 dollars to replace it than the $70 dollars to buy a vacuum to test it. We should know how things are working by ~3:00PM PST (my timezone). The ASE cert. parts tech said if I could get it in driving order to stop back by to get the vaccuum lines checked and replaced. So I'll probably do that too.

That plastic piece is part of the points! if it's crumbling, replace them, it's all one piece...Points is one of the most important parts of your ignition system...You better know how to adjust them. Or at least have the gap spec! The carb part you need so the choke will close is the choke thermostat, it's a round cioil that fits under a black cover on the side of the carb. Also if the points are that bad get the conderser as well....

Alright. So ignition needs fixing, now the question is: convert to electronic, or just replace the points and condensor? The gap spec is 35-39 degrees. I don't think that is necessary if I convert to electronic though. The parts tech convinced me to hold off on the points systems / or electronic conversion. Obviously with the knowledge I'm now being presented with, that doesn't sound like the best plan.

So I got the new radiator hose on, repositioned the coil so it didn't arc against the fuel line and test drove it. It seems maybe a tad better? It's so freakin' weird! It drove PERFECT up until the final gear at about 60MPH then started jerking again. Pulled off to turn around and between shifting I let it idle: it idled PERFECT with no sign of wanting to die. Get back on the road and go up the hill at 50MPH- Didn't even act like it had a problem so I passed my house thinking I would max it out as much as the road let me. Once again at 60MPH it nearly died (I have custom exhaust so it's normally loud) and nearly went silent. It didn't die though, so I pulled off to turn around again. SAME THING- Idled PERFECT. Drive back doing about 45-50MPH with NO hesitation or issues.

Points arent a bad system, just not AS reliable as electronic...Youll need a set of feeler gauges to set the points, put distributor lobe, thats the worn spot you thougfht! so it is opening the points as far as it can, then set the gap. Tighten the back screw on the points, then use a flat screwdriver on the front end of the points, where the notch is to spread or close the point to match the required gap, then tighten the front screw! The dwell meter is used when it's runnung to check dwell, or how long the points are closed....if it's off, and you want to set dwell at the lower end of the spread to allow for wear, re-adjust the gap...

Well, I'm feeling a bit gutsy. I'm gonna drive it to my uncles house in hopes he has the tools. Even if not he's closer to the parts store than I am. I'll just do 50MPH on the freeway.

UPDATE: I got it there (10miles away). You know it's funny- It acted stutter-y again when I was on a county road... So I thought, to hell with it, I'll floor it if it wants to die (Yeah, I throw tantrums) and to my amazement- It accelerated like a bat out of hell! It didn't stutter anymore! It didn't fix it though- when I PARTIALLY let off the gas it started doing it again. I'm REALLY leaning toward that rebuild now! What do you think?

Okay, bought a points kit. also got some vacuum lines. Lastly, I got a timing gun- checked timing and I'm at ~4-6 Degrees BTDC. I can't find my timing specification so I don't know if that's where it should be :(


EDIT: Changed out the old points system- WOW was it pitted! Wasn't gapping at all! Installed the new points system and gapped at .018. Replaced the PCV valve (figured might as well call it a full service tuneup) and the advance vacuum hose/line. Put the distrib. cap back on and tested- EVEN BETTER RESPONSE THAN PERFECT! I didn't know it could run that good! Haven't tested at freeway speeds, but man this thing runs STRONG!!!

Didn't fix the issue: still does it at freeway speeds. So here's where we're at: Runs strong at speeds 0-50MPH (during acceleration, cruise and deceleration) BUT once the car reaches 53MPH (I don't know why this is the magical number) either from just cruising 53, or accelerating really fast to 53 it starts stuttering like someone is half pumping the brakes. By the way, there is no assisted brake system on it- I checked thinking maybe bad vacuum.

Whenit jerks, does it backfire thru the carb at all? If not, it is most likley the carb...if it does, you might have a worn cam lobe...is the new vacuum advace on the distributor yet? To get a good timing set up, do this, loosen the distributor hold sown, not so it's real loose just so you can turn it and it wont move on it's own. Then get some one in the car with it in drive, hold feet on brake and give it about 2500 rpm, now turn dst, until you hear it just start to ping, then back of just till it stops, this will be your engines best timing point...tighten distributor.

No, advance isn't in yet- should arrive tomorrow. It doesn't backfire either. I'm thinking maybe rebuild or new carb altogether. I don't think there is a timing issue- I've had the car since 2006 and it ran fine back then. I think I just have a dirty and/or tired carburetor. I'll get the advance and let you know. At least the car is running good enough to drive now. Just keep it below 53 :)

EDIT: My wife made her own assessment- I almost laughed at her but then thought about it and realized, she could be right.... What if it's just the brakes (for some WEIRD reason) causing issues? Think it's worth checking? Like I said, the stuttering can be overcome if extra throttle is used, there's no backfire or other obvious indication of mechanical issues. They're drum, not disc brakes. Ever heard of this happening to non-disc brakes before?