Anybody want to diagnoss the problem???

[Cags70PolaraConvert]

So after being a bad owner and not starting my car over the winter I got her started back in April and took the car to my mechanic. The car started but I could not hit the gas pedal without her stalling. I wanted a few upgrades and had him install a weiland 4bbl intake manifold and edelbrock 600cfm 4bbl carb. He also ended up doing a tune up as well. I replaced the points with an accel conversion kits a few years back for some background info.

Well I first get the car back a few weeks ago and it starts right up and idles nice. It rode nice at average speed and very little throttle but when I hit the gas it just wasn't very responsive and didn't feel quite right. It is a 383 by the way. The following week I drive it out on the highway while out getting estimates on interior work. That morning it didn't fire right up. As I drove she started to hiccup and backfire, like a rollercoaster going up its first hill and slipping back a little. I ended up driving a good 25 miles with the car like this, sometimes running nice a smooth and then out of the blue having the hiccups. When I finally get her back to the mechanic we notice an oil leak from the timing chain cover. He changes the gasket and while in there I tell him to check the timing chain which he changes. The car has 140K miles so I figure its as good as time as any to change.

Well I get the car back Saturday and she fires right up, sounds really nice. He says that the slack in the timing chain was causing the hiccups and all is good to go now. After driving her to get some gas she feels much more responsive then the first time and I think all is good so I take her for running my errands for the day. She drives nicely as I go to pick up food for the dogs about 20 miles away. When I come out of the store after about 10 minutes she wouldn't start. She's just turning over and over without any hint of starting. Not really knowing about how to check on items on my own I figure I will walk down to the store and get some carb spray, maybe she just needs a little kick. When I come back after another 10 minutes I try to start her first before using the spray. Well she starts, but not really fired up. It was more like I released the key and she started, but she started. I figure I will just take her back to the mechanic. I thought I would make one more stop at the bank first. Backing up into a parking lot she stalls and won't start again. I figure she just needs to cool down, so I get some lunch. I come back out and she starts, but in the same manner as before. I get her on the parkway and she is driving nicely but I am not pushing her at the same time either.
After about 25 minutes on the parkway, just as I am getting to my exit I feel her starting to lose power and acceleration and starting to hiccup. As i get off at my exit she stalls. thinking that all she needs to do is cool down again before she starts I wait. I try starting her after 20 minutes and she almost kicks, but then there is a gunshot of a backfire from I think the carb. another 20 minute wait and no sign of firing up. Fortunately a well doing mechanic stops by and tries to get her started with me. We check spark, gas flow, ect and all the components seem in place that she should start, but all she does is turnover. So a tow truck ride to the mechanic and now I am waiting on his findings. I told him this morning about what I have read on the website here regarding the sputtering and the intake manifold issue that was in a recent thread but he kind of blew me off on that thinking it wouldn't have idled or ran nicely in the first place if that was the problem. So, who wants to try and diagnose the issue? I will bring up any suggestions with him in conversation. Remember there are no points in the distributor if that makes any difference.

 

[celticwarlock]

Pull the plugs and have a look at them. At first guess (and knowing nothing beyond your illustration, it is a guess for sure), it sounds like a fuel system issue. It could be that something washed into the carb and is causing mayhem. I had this happen on my first car ('72 NY). The car ran progressively worse as the problem intensified until it all got sorted out. Pull the fuel filter and blow it out OPPOSITE the direction of the fuel flow onto a clean, white rag, and see what comes out. If you see a lot of particulate matter or brownish residue, you may have to dig deeper. Again, this is pure speculation, and I'm mentioning it only because I have witnessed a car I owned do much the same thing.

 

[Cags70PolaraConvert]

Fuel pump was pumping gas as we pulled the fuel line at the carb and had good flow

 

[twostick]

Coil.

Kevin

 

[azblackhemi]

I would start small and work my way up. Start with the ballast resistor. It's cheap and easy to change and everyone should have a spare in the glove box anyway.

 

[Cags70PolaraConvert]

I haven't picked her up yet but mechanic replaced coil and said all is well.....until I get it back and it breaks down again or sputters around. we will see.

 

[70_NPORT]

I keep ECU, VR, BR, and a couple of fusible links in the glovebox....just incase.
Im betting you have ignition gremlins...its been my experience a crack will deep 6 a ballast but otherwise it is inert. Also a coil it seems is a work/doest work item too...I went thru a couple due to heat related failures. The ECU...the last one I had began doing crazy **** while Im out on the highway...all of the sudden no spark and backfire thru exhaust...then everything was fine, it would happen quick. It began to get more and more frequent until one day the thing just died....out on the highway of course.(it didnt last long after it started to malfunction). I put in a fresh one and those problems went away. This was a few years ago. Im starting to see this happen again coincidently. Ive long heard of the MP ECUs being made in China...dont know if that might have something to do with the failure rate...lol.

 

[cantflip]

All good guesses and the mechanic was probably right... I would still clean up all the wiring connections I could and especially the grounds. A little corrosion goes a long way to causing trouble and failures in electronics. To some extent, this kind of thing wasn't unheard of during the years these were just used cars. With age and mileage, don't let it give you any bad impressions that the car is unreliable. To give it a real shake down run, get her nice and hot running around close to home or someplace you feel safer if issues reemerge, then do the same on the highway. After all of that, if it fails again, it would be very difficult to predict or have done anything different.

 

[The Horvaths]

Battery, battery, battery, battery, battery. (If your problem is not solved). I had this exact issue with my '67. It was bad wiring causing the battery to not always charge / charge all the way.

 

[Gerald Morris]

Clean up your bulkhead connector connections. Check for cracked, nicked wires, esp in the ignition wires from the ballast resistor to the bulkhead con, and to the coil. After ~50 yrs in a 180 F environment, the vinyl insulation on the old wiring will be brittle, cracked, discolored and full of potential short circuits. I'm rebuilding much of my wiring harness after an alternator cracked at the battery stud, destroying much of the old harness around the charging conductor and ignition wires. Also, go a size larger than the stock wires. The cost is minimal and the effect is worth it. Replace your fusible links. Again, after ~ 5 decades, while they MAY still carry some current for you, they also might be compromised, even though the hypalon insulation yet appears intact. Fools will sometimes discard these, without realizing that they're overcurrent protection for primary circuits. Also, check that the battery stud on your alternator is insulated. Use rubber tape if you lack the little rubber cup that hangs on the lead to cover the stud and 7/16" nut securing the lug.

These measures should buy you peace of mind and eliminate many possible sources of your problem. they might even SOLVE it, though I caution against such wild optimism. I've reduced my own ignition stutter drastically by taking these steps over the past month, though it hasn't disappeared 100% of the time yet.

 

[fatwagn72]

if the 383 was a 2 bbl before, than the 4bbl intake and carb could be the problem. i believe that the 2 bbl 383s were detuned from the factory. and you could be drowning the engine, but only if the motor was previously a 2bbl.

 

[Cags70PolaraConvert]

the motor was a 2bbl, but I only put an edelbrock performer 600cfm carb on. which I would think a 383 could handle. I will have her back this week with the new coil, distributor, ecu, br and let everyone know how she's running.

Battery is new so should not be an issue. I will check all connections when I get her back.

Thanks for all of the feedback

 

[Gerald Morris]

BTW, I've seeming got rid of the LAST of my own stall when stomping the gas pedal AFTER REPLACING THE VOLTAGE REGULATOR! So, I had to 1.) replace the alternator. 2.) clean my bulkhead connector contacts. 3.) replace all wires with brittle, cracked insulation which were in any way connected to the ignition circuit 4. brand new ballast resistor and finally, the new voltage regulator Since you had your mechanic do much of this already, drop another $9 and get a voltage regulator from Rock Auto and see.

Again, a 600 cfm carb is MORE than you will need unless you've also upgraded your exhaust, heads and cam. 383 2-bbls had a different cam than 4-bbl motors, so just pouring more petrol into the cylinders might be counter-productive. I won't do this until every preparation is made for it.

 

[Cags70PolaraConvert]

Thanks everyone for the feedback. I got it back a couple of weeks ago and it ran great, haven't really had the chance to drive it a lot yet thought. going to look into doing all of the suggestions as I can. I did have the mechanic install a new distributor with an ECU ignition system to go along with the new coil so ignition should not be the issue for awhile.

 

[Zwap]

Again, a 600 cfm carb is MORE than you will need unless you've also upgraded your exhaust, heads and cam. 383 2-bbls had a different cam than 4-bbl motors, so just pouring more petrol into the cylinders might be counter-productive. I won't do this until every preparation is made for it.

IMO a right tuned 600 cfm works just fine on the 2-bbls 383. Adding a 600cfm 4-bbl it's not the same as "just pouring more petrol into the cylinders". If you tune it right there's no more petrol than with the 2-bbl.
The secondaries only open if the engine ask for it, and it does if you floor the carb.
But of course it would be even better if you upgrade the cam and exhaust.

 

[Knebel]

If you are running points, put in a new condenser.

 

[Gerald Morris]

IMO a right tuned 600 cfm works just fine on the 2-bbls 383. Adding a 600cfm 4-bbl it's not the same as "just pouring more petrol into the cylinders". If you tune it right there's no more petrol than with the 2-bbl.
The secondaries only open if the engine ask for it, and it does if you floor the carb.
But of course it would be even better if you upgrade the cam and exhaust.

Well sure, IFF you tune it right! Meaning, change out the jets, likely the linkage too. Then you'll have plenty air available so be sure you DON'T make it TOO LEAN, and burn holes in the pistons. Its a bit more work than merely bolting one on. I'd say get a 500 CFM Holley 2bbl until you've got that motor good and ready for those 4 barrels. Better yet, go w the 350 CFM version of the same, if you don't want to stick w Stromberg or Carter. If you are or know of a good carb wizard and are just itchin for them extra two barrels and all the fun with them, then go ahead. But if you bolt on a 600 CFM carb meant for a 4 bbl cam, and you don't modify that carb to get it "right" then you'll be huffing some unburned gas in that undersized exhaust.

Here's a nice little chart from Holley cross referencing displacement vs desired rpms with their suggested carbs. It might help.

 

[Rooster34]

I know this is an old thread but as far as the hard starting after getting up to temp and letting it sit for 10 min or so that piece sounds like a heat soak issue from the weiand intake. my 66 charger 318 poly that has a weiand intake with a edelbrock 650 4bbl with electronic ignition and new coil and has a hard time starting after sitting for 15 20 min. Pretty much what we do to start it when we run into that problem we just hold the gas pedal down while cranking the key and she'll fire up. As far as loosing power while driving 20 plus miles I would listen to these guys on here. I'm dealing with 2 plugs getting fouled on my 65 fury with 318 poly and I'm running a 500 cfm 2bbl holley on top of OE 2bbl inake, it's a lot more peppy and faster than the 66 charger with the weiand intake and edel 4bbl. I'm getting the OE dizzy rebuilt and hopefully that will solve the plug fouling, possible bent dizzy shaft or worn shaft bearings. Just my 2 cents