67 GTX 440 - Poor Driveability Issues, Need Help

[SlinktRR]

I had an interesting new development this week. I have been thinking about taking the car to a local shop that works on all types of muscle cars to see if they could help narrow down the problem. I had not personally used them so I went there to meet the owner and check it out. We talked at length and he mentioned a number of possibilities so I added my name to his list. One of the things he talked about was the ballast resistor creating too much resistance when combined with an internally resisted coil. I checked and the coil on my car is a Pertronix Flamethrower with a 1.50 ohm internal resistor. I searched this forum plus read the Pertronix instruction sheets and it looked like the coil resistance is all I need, so I made a jumper wire and bypassed the OEM ballast. I took it for a ride today and noticed improvement! It starts better and runs a little smoother at slow speeds but there was a big difference at higher speed, where it used to hesitate and fall on its face now it takes off and feels more like it should. Apparently the over-resistance was killing the spark as the rpm increased. I've still got issues and will have this shop take a look but I am now much more encouraged than I was before.

Check it out with a voltmeter. Typically look for 9-10v at the coil positive with ballast. Would be interesting to see how many volts you had without the jumper wire in place.

 

[TxDon]

This morning I took my car in to the shop I mentioned before. The owner pulled out the coil and eliminated most of the way too many wires that were attached to it, some were from a shift light that I don't need and he deleted. He checked the timing, turned out it was too far advanced. He set it at 36-37 total with 13 initial, we were then able to reconnect the vacuum advance. Combined with the previous ballast bypass the car now runs quite a bit better, no pinging, smooth secondary tip-in and easier starting. I still have the hot soak starting issue and gas smell, he blames it on the Edelbrock carb and says they are crap. I'll need to drive a few more times for final judgement but so far so good.

The shop is Collin County Customs in McKinney Texas and the owners name is Rob Wechsler, I'm happy with the friendly service and will most likely go back for future needs.

 

[AR67GTX]

The timing specs sound pretty good. I'm running about 16 initial and 36 total but I recurved my distributor to get there. I would try an insulator gasket under the carb - you should have enough room for at least a 1/4 inch one. If you have to dig into the Edelbrock sometime you could try lowering the float levels slightly to help with the hot starts and fuel smell. However, Chryslers are a funny car to start hot. Most old cars you can just turn the key and they will fire and run. Chryslers seem to respond better to holding the throttle down about 3/4 of the way while cranking the motor. I don't much like doing it because you have to get off the throttle fast to avoid reving the motor into oblivion - but that's what it takes to start them when hot.

 

[TxDon]

I actually had about 18 degrees initial in which put the total over 40, way too high. His timing light had a digital readout that allowed him to check total or initial plus rpm, first time I saw that, gotta get me one of those. I may still need to get the distributor recurved down the road. I agree about the hot start process now but I don't remember ever having that problem with the old AFB's.

 

[AR67GTX]

To be honest I don't remember having to hold a lot of throttle while hot starting my 64 Plymouth Sport Fury I had in the late 60s. But - I may have forgotten. Or it's modern gas or crappy Edelbrock carbs. Or something.

Dial back timing lights are definitely the way to go. Makes it really easy to map your timing and centrifugal advance curve. Only issue is trying to remember to "zero" it again before setting initial timing. There's that memory thing again.

 

[TxDon]

To be honest I don't remember having to hold a lot of throttle while hot starting my 64 Plymouth Sport Fury I had in the late 60s. But - I may have forgotten. Or it's modern gas or crappy Edelbrock carbs. Or something.

I'm sure the gas is part of it. I looked at Holley carbs, the shop recommended a 750 double pumper, but they sure are expensive! Of course I haven't priced a new Holley in maybe 40 years...

 

[miller]

Not worth much, but man, all the good words on eddys has me wondering now. Picked my poison, have to live with it...x2.

Just finding rebuilt AFBs is a chore, tossed in the parts suppliers $400, plus a core. Another $100 if no core!
Other choice could be finding AFB, and rebuild it, or even a AVS. Just talking to myself, lol!

 

[dave dodge]

Not worth much, but man, all the good words on eddys has me wondering now. Picked my poison, have to live with it...x2.

Just finding rebuilt AFBs is a chore, tossed in the parts suppliers $400, plus a core. Another $100 if no core!
Other choice could be finding AFB, and rebuild it, or even a AVS. Just talking to myself, lol!

Hi Don, had the same problem in the past with the carter carbs which drained down after sitting. My present build 67 r/t has a mild 440 with comp cams xe 268 cam, edelbrock chb intake, 750 Holley vacuum carb and pertronix 3 ignition conversion, pump it once and it fires right up.

 

[TxDon]

Hi Don, had the same problem in the past with the carter carbs which drained down after sitting. My present build 67 r/t has a mild 440 with comp cams xe 268 cam, edelbrock chb intake, 750 Holley vacuum carb and pertronix 3 ignition conversion, pump it once and it fires right up.

Dave, that engine looks great! How do you like the vacuum secondaries, do you have stick or automatic, the shop guy said the double pumper would be better with my 4 speed. Also looks like you have a manual choke, does that do the job?

 

[barbee6043]

I've bought more than a few new Edelbrocks, that ran perfect right out of the box. who knows what has been done to a used carb. dist. etc....... Holleys are great for racers and guys that love to fiddle with a carb!?

 

[dave dodge]

67 gtx..

Don, my car is a 4 speed which was a race car most of its life. I converted it when I purchased it and returned it to the street last year, first time since 1969. It still has 4.56 gears in it which keeps the revs up avoiding any stumbling but isn't expressway friendly. No choke necessary in the warm weather only car is driven! Car shows 8900 miles. Plan on replacing gears this year.

 

[TxDon]

Ok, its been a month, the car drives a little better but still not what I want. I have ordered an Edelbrock calibration kit, gaskets and a 1/2" heat resistant spacer, figure I should at least check the carb out before thinking about a Holley. When I get into it I will be looking for some help with jet and metering rod application...

 

[Mebsuta]

If I was in your situation, I would consider pulling out big lumpy and use factory pattern cam (something like Speed Pro CS-661), factory intake, and similar carburetor to factory original.

 

[TxDon]

If I was in your situation, I would consider pulling out big lumpy and use factory pattern cam (something like Speed Pro CS-661), factory intake, and similar carburetor to factory original.

I have already considered that, the original intake and carb came with the car. Before I get into something that big I want to be sure it is not just a simple tuning problem.

 

[Garys1969RR]

I think you can get the specs of the original factory calibration for those carbs. Look it up online, or some one here may know what you will need. Prob need the carb number from the tag. It also should be stamped on front of the carb base plate near the mounting holes.

 

[Garys1969RR]

I also wonder if your cam pulls enough vacuum to drop the metering rods down while idling. Also check the cam timing. I had one in a car I bought that was 20 degrees off! It would run, and idle OK, but no power! Set the cam timing right, and it ran great.

 

[TxDon]

I think you can get the specs of the original factory calibration for those carbs. Look it up online, or some one here may know what you will need. Prob need the carb number from the tag. It also should be stamped on front of the carb base plate near the mounting holes.

I'll do that if I go that way. I did look at the carb recently and saw it is an AVS so it is not the original carb for this car...

 

[TxDon]

(Warning - long post.) I've made some more progress. I pulled the Edelbrock off and opened it up, it was very clean inside with no debris or signs of wear so it appears to be as new as it looks on the outside. I checked the float level and float drop, one float was a bit off so I adjusted. It had 410 primary jets and 7047 metering rods which were correct for the 1411 carb.

In researching Edelbrock issues on this forum and other sources I saw that a common issue with the carbs tuned for "economy" like the 1411 was that they were way too lean for cars with non-stock cams and lower vacuum. (I think it's pretty funny that they make a 750 cfm "economy" carb at all!) So using the Edelbrock owners manual and the Calibration Kit I converted the carb to the specs of the 1407 model which is the "Performance" version. I bumped the primary jets up to 413's and went to 7042 rods which are actually 1 step richer than the 1407 carb. I left the orange popup springs and the stock secondary jets alone.

I also added an Edelbrock 1/2" wood composite heat spacer under the carb. When everything was back together yesterday I started it and let it warm up. After the idle mixture was adjusted and the idle speed set at 850 rpm it was definitely running better without the pig rich smell it had before. I took it for a fairly long ride and it ran MUCH better at both low and higher speeds, pulled harder on acceleration without pinging. After it was totally heated up I put the A/C on (low 80's outside temps) and drove a while longer. Where before the A/C made it heat up and run worse now it had almost no effect and continued to run smooth.

I'm going to take it out again today and make some stops to see if it restarts better, before the fuel percolation made that real interesting. But so far I'm very encouraged and surprised that richening the carb tuning actually seems to have fixed what I thought was an over-rich problem!

 

[miller]

That's great to hear, Don! Good to make sense out of this stuff, dealing with the crummy gas these days. That rich/lean mixture can throw you for a loop sometimes.

Looks like you've got an iron intake. Guess on one of those, might take one of the spacers on it.

Trying two of the Edelbrock insulated gaskets on mine, though on an aluminum intake.
Still have to open both of my Eddys, to swap sides on fuel intake ports. Gonna be sure to check floats.

Now all you gotta do is try enjoying that thing a bit more!!!

 

[bigmanjbmopar]

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