Stumbling after hitting bumps - Team Camaro Tech
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post #1 of 7 (permalink) Old Mar 19th, 03, 05:15 PM Thread Starter
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I have a problem with the Goodwrench 350 that is in my 68 ragtop. I recently rebuilt the carb, carefully and using a book, so all new seals, needles, seats, etc. I also replaced the fuel pump, an Autozone no name with a Carter mechanical about the same time. I now have a problem where whenever the car is warmed up and cruising (partial throttle), if I hit a medium sized bump, the engine will bog down right after hitting the bump. Depressing the accelerator further does nothing, it acts as if I cut the ignition. If I let off the throttle completely, it will usually backfire through the exhaust and then I can resume driving as normal. My best guess now is that when I hit a bump, the floats in the carb are dropping, and the (possibly) too high pressure of the Carter pump is causing gas to rush into the carb faster than it should, and overflow into the engine. Thus I'm thinking I should install a fuel pressure regulator, but I'm not having any problems at other times - it seems most people with too high fuel pressure have problems with the engine running too rich all the time. I was hoping maybe someone could suggest something else to check. I had some problems with it behaving similarly occasionally when cruising down the highway (even without hitting bumps), but that seems to have been fixed by changing from R44TS plugs to R45TS. What plugs should I be running in this engine? It's stock from the crate.

Thanks for any help.
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post #2 of 7 (permalink) Old Mar 19th, 03, 05:22 PM
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Sounds to me your ignition is cutting off instead of carb. trouble.Check all wires going to dist. & coil.

67 Plum Mist Met. 408 TH350 3.08 posi
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post #3 of 7 (permalink) Old Mar 19th, 03, 05:30 PM Thread Starter
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It's a Mallory HEI distributor, so no coil. I have checked the wire going to it, and it's fine, no short or anything. The plug wires are also relatively new spiral core, so they're not shorting anywhere.

Another point: The engine ran fine with R44TS plugs before I put headers on it. Is it normal to have to increase the heat range after installing headers, and if so, by how much?

Thanks again.
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post #4 of 7 (permalink) Old Mar 20th, 03, 05:16 PM
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Pull the cap and look at the wires inside the dist. see if any are shorted inside or bare. If they are they could be grounding out. I had a problem one time with a Chevelle I put an HEI in. When I got on the gas it would stall, when the RPM's went back down it would come back to life, rev then stall again. What I found was a chafed wire under the vacume advance mechanisim in the dist. When the vacume advance mechanism went over the bare spot it went to ground and shut of the ignition (basicly grounding the coil). A trip to the bone yard had me fixed and running for free. It the asprin I had to buy while looking for the problem that cost me the money.

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post #5 of 7 (permalink) Old Mar 20th, 03, 07:40 PM
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Just making sure, but you did set the floats correctly right? Not just a dry test but wet, when the car was running?



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post #6 of 7 (permalink) Old Mar 21st, 03, 05:21 AM
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I had a jeep with bad distributor bushings, the shaft would rattle around on good jolts and kill the engine, double check the float level like previous posters say


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post #7 of 7 (permalink) Old Mar 21st, 03, 05:35 AM
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I had a similar problem with a 68 using and HEI cap. The cap would rub aginst the firewall and when I hit a bump the cap would sometimes move so that it was no longer seated correctly. Problem was amplified by really worn body bushings.

You may also want to check the module in the distributer to make sure its ok. I had one that would act up when it got hot sometimes. Very inconsistant problem but changed the module and it was fine.
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