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Problems with a 1967 GT 500

1366 Views 10 Replies 8 Participants Last post by  Midlife
Hi, I recently purchased a 1967 Shelby GT 500 #1128. The car had been restored to concourse condition and only had 312 miles on a 4 year old restoration (completed 1999-2000). Prior to my purchasing the vehicle, I went to the seller's house and went over the vehilce completely and was impressed enough to put money down on it that day.
The seller was very open and provided me with complete documentation and multiple names and phone numbers concerning the vehicle. The seller had told me the longest trip he had taken was roughly 17 miles each way and at one point he had trouble with what he thought was vapor lock. He contacted a friend who was an original owner of a 1967 GT 500 and was given the following recipe for a fix:
1. 160 degree Robert Shaw performance thermostat
2. 4-core "desert special" Modine radiator
3. Stonger fan clutch (c7zx replacement)
4. Fiber spacers between carbs and intake manifold and
fiber washers between fuel log and intake manifold
5. Coolant system flush and addition of royal purple
Definitive fix with a '67 hood with louvers ws suggested. All of the above have been done except the hood and the vehilce still is experiencing stalling and failure to start after about 20 minutes of driving/idling and seems to be running rich (gas smell and smoking) I thought a plug may have been fouled and changed the plugs with no change in symptoms. The timing has not be adjusted but the car idles smoothly at 650 rpm for the first 15 to 20 minutes. I re-flushed the coolant system and added the temp reducer (royal purple) as indicated on the bottle again with no change in symptoms. The engine had been mildly modified internally and was balanced with ported and polished heads, hardened seats. A new Crower 16256 cam, lifters, springs, retainers & Sharp roller rockers with a 7 qt Cobra T-pan are also in the car. The carbs ( I have the originial BJ and BK carb boxed and in need of a rebuild) are Holley 1850's and were installed new.
PLEASE HELP!!!!!!!!!!!!!!! I have some wrenching skills but will be timid when it comes to this car. I live in Westover, WV which is one hour south of pittsburgh. Are these symptoms common? What else would you try? What else could cause these symptoms? Do you know of anyone PARTICULAR and extremely CAREFUL as well as KNOWLEDGABLE close to my area when it comes to shelby repair/maintance? Any and all info would be appreciated.
Christian (304) 685 2767 or 291 2748
PS Any idea for a fix on the gas smell in the coclkpit when crusing with the windows down? I had seen one on another web site but I am unable to find it. Is this a common occurence also?

1993 Black Mustang Cobra stock-"Thelma"
1967 Green Shelby GT 500 #1128-"Louise"
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It seems to me that vapor lock would cause the car to run out of gas or at least be lean. I would guess that the carb may be improperly adjusted or need a rebuild. The floats could be a little to high causing raw fuel to dump down the carb, I would
think it would happen sooner then 20 miles. I'm sure you'll get more posts on this...


1966 Mustang Coupe, 302 custom roller cam, holley 650dp,
I had a similar problem with my 67 GT350. Unfortunately, I could never figure out how to cure both problems. I tired several things for the car stalling/quiting on me. I thought it was vapor lock too. I changed out all the fuel system components, including a new Holley carb, but never completely solved the problem. One thing I was told by a couple of folks was that, although it may not seem to make sense, it can sometimes be a bad coil. I changed mine and it seemed to fix it for a while. Others may be able to help more. Good luck.

1966 GT convertible
As far as the fuel smell goes, I had that in my 70 Camaro. It seemed to be a leak somewhere, and as the gas fumes flowed with the natural air patterns of the car as it drove, they would find their way into the car. My guess is you have a leak in the fuel system under the car or in the engine itself. The stalling is another matter completely. I would try a hotter spark (Pertronix) and then check your fuel pressure to see what it is, is it low? I would also consider putting in a pair of electric fans in one shroud, if you have seen these they are the way to go. They can crank the air through the radiator and over the engine and are independant of the engines speed since they are electric. But it being a Concourse car, I would see maybe that would not work for you. But not driving it is worse, right? I have a problem that I can't diagnose with my 64 Corvette. It's a 327/375 horse fuel injected car, and it runs so strong it's incredible. But sometimes at an idle, it'll just die. And will NOT start. I can't figure it out. Same situation as you I guess. Mystery problems.
Good luck,
Got a picture of the car by the way? I love the 67 GT 500's.

1964 fuelie Corvette (restored)
1970 Sportsroof (project)
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When the car dies, check to see if you have fuel and spark. To check fuel, manually bump the throttle and see if you get a squirt of gas down the carb throats. To check for spark, remove one plug and put it next to a head or block and crank the engine: you should get a nice blue spark.

These two tests should tell you where to go next. me check your shorts! My multimeter is just a-waiting! Formerly known as Midlife in the old VMF.
King of the Old Farts *struts*
Should know better than to question your electrical knowledge o' master but if he's smelling gas is it a wise thing to do to introduce a spark right next to it?

Just asking?

J. Boggs
Are you still using the stock manifolds/W the heat crossover butterfly? If you are, I suggest removing the butterfly and blocking the exhaust crossover port in the manifold.

Had the exact same problem with exhaust in the cockpit of my GT500, the fumes come in thru the hacked out rear panel... My solution was windows up on the road, down in town.

Required tools for operating a Vintage Mustang:
1. Duct Tape
2. J.B. Weld
3. B.F.H. (Big Fat Hammer)
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As far as the gas fumes go...

I had the same problem. It turns out that the trunk lid seal was not installed properly and the exhaust fumes were following the air into the trunk, then into the passanger area. When I re-did the trunk seal, the smell went away.

Good luck.

Full Throttle
Sounds like it's running real rich to me. Does this problem occur after idleing for a while or after driving for a while? Remember, you're dealing with two four barrel carbs. First take the site plugs out of the carbs when the engine is cold and check to see if gas runs out. The float level should be set so that you would have to shake the car to make it come out. If this is OK, the next thing would be jet size, power valve in one of the carbs, and the list could go on especially since the engine has been modified. I currently have a '67 Gt 500 totally stock which is used daily and runs perfect. But, I did install an MSD 6AL and an MSD Blaster coil to keep the plugs clean at all times. Also have a couple of cars with 427 tunnel-ports, 2 4V single plane intakes and without the MSD's the plugs would foul out in ten minutes at anything under 2500 RPM's. If you would like, call me at 918-655-3352 and we can kick it around some more. I have a friend who may live fairly close to you, lives on the W VA/Ohio border who could probably help. He specializes in FE and multiple carb set-ups. Be very careful with leaking gas and live ignition. Keep the fire extinguisher handy! When you get rid of the rich mixture problem you will be rid of the gas smell. It seems the way the trunk lid is made with the spoiler built into it, any bad smell coming out of the exhaust comes into the car. Have had the same exhaust smell problem with my wifes car. When we first got the car it was smoking and that would get in the car and about choke you. It's hard to drive in the summer with the windows up in Okla!
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The problem is this. The car wants a new owner and I am the owner elect. When should I come by to pick it up? lol. Good luck. Seriously, I know an MD who stuck a syringe into the rubber gas line on his old Cadillac swearing that it stopped it from vapor locking. This was the same village Dr. that would do a scalp massage as a cure for a cold. I doubt if the syringe would be considered concourse.

Food for thought: Just think, If your weren't where you are you would be somewhere else.
I would presume if there is gas lying about on the manifold and leaking out the carb, then it would be unwise to test for spark as I suggested. The smell is more likely due to a rich mixture and resultant exhaust. If so, the spark test would work just fine.

Always use common sense. I don't at times, so I can now dispense this wise advice! me check your shorts! My multimeter is just a-waiting! Formerly known as Midlife in the old VMF.
King of the Old Farts *struts*
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