timing problems
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New User
Joined: Apr 2008
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timing problems
here is the issue, my truck is running real skiddish. I drive a 77 1/2 ton with a 460 and msd ignition. at idle she sounds like shes hopppin and a skippin, I'll turn the distributor untill she smooths out a bit and then when you hit the throttle it will back fire through the carb. That is only half of the problem, the other part is when I try to start it really struggles to turn over, I think the batteries are the weak point being they are only putting out 620 cca. but someone had said that this is also indiciative of a timing problem. anyone have any ideas?
Posting Guru
Joined: Nov 2008
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From: Halifx Pa
I can't tell you guys enough of how important it is for you to get a vacuum guage, timing light, and tach. You will spend about $60 for all of this and when you got them all hooked up and fine tune your engines, you will be amazed how easy it is and how good your engine will run for you. It eliminates all the frustrating guess work, and is a piece of mind knowing it is done right.
These tools will pay for themselves time and time again for years to come!! If you can't swing it right now, remember Santa is coming soon, put these items on your wish list.
I agree with the others, it sounds like you got the timing to far advanced.
These tools will pay for themselves time and time again for years to come!! If you can't swing it right now, remember Santa is coming soon, put these items on your wish list.
I agree with the others, it sounds like you got the timing to far advanced.
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New User
Joined: Apr 2008
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mechanical timing
I have a vacuum gauge, tach and timing light. however, my experience with dialing in an engine is very little. I have had people say any where from 10 to 14 BTDC is what I should time it to. it depends on how the engine is set up. right now it seems to run better at around 14 but not exact. I have a msd pro street distributer running mechanical advance. Would the problem be with my weights or with where the distributor is pointing. I know that the timing marks on the gears are exact so it has to be something with the distributor. I got it to run a little better flirting with it today, using guess work. It will idle smooth, but when you hit the throttle she'll rev nicely but when she comes back down it dies. If the carb isn't tuned correctly meaning its running to lean or to rich, would that have an effect on the timing? Thanks for the replies.
77 Hi Boy 4wd 460 C6
77 Hi Boy 4wd 460 C6
Senior User
Joined: Nov 2009
Posts: 226
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Set your base timing so the truck runs without shutting off.
Then set your idle fuel mixture correctly and your idle speed correctly
Then you can play with your timing to get more power out of it.
Verify there are no vacuum leaks with carb cleaner sprayed lightly on the hoses if the rpm goes up you have a leak, if it does nothing you are ok.
Verify that all your plugs are firing,
Verify that your choke is set correctly,
Do plug chops to ensure that your plugs are the correct color throughout your rpm range to verify that the mixture is correct, otherwise you could be good at idle but your jets may be too small or too large in the mid to high rpms and you won't know this until you see what color the plugs are at those rpm's.
Be methodical and eliminate each potential problem one at a time using your vac guage and plug chops and your engine will be running smooth in no time.
Then set your idle fuel mixture correctly and your idle speed correctly
Then you can play with your timing to get more power out of it.
Verify there are no vacuum leaks with carb cleaner sprayed lightly on the hoses if the rpm goes up you have a leak, if it does nothing you are ok.
Verify that all your plugs are firing,
Verify that your choke is set correctly,
Do plug chops to ensure that your plugs are the correct color throughout your rpm range to verify that the mixture is correct, otherwise you could be good at idle but your jets may be too small or too large in the mid to high rpms and you won't know this until you see what color the plugs are at those rpm's.
Be methodical and eliminate each potential problem one at a time using your vac guage and plug chops and your engine will be running smooth in no time.
