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I have a crate 460 in my truck. When idling it seems to vibrate a lot, and when I step on the gas its smooth running again. My dad and I were talking about this, he has a suburban with a 454 in it and it doesn't do this. I'm pretty sure it's the cam that is causing the vibration at idle. Why is this happening? Is this how the old engines run and it's nothing to worry about?
Its kinda hard to tell without looking at it and hearing it, but a vacuum leak can cause problems like youre describing. Check around for them if you have a vacuum guage. If you dont, spray some starting fluid around vacuum hoses and see if the idle picks up briefly.
No , they don't run that way just because they are old. The first thing i would check would be for a vac leak like "justins " said. Does it have dist. points ? may not be set right. How's the carb. new,rebuilt or just a used carb ?
It has a new edelbeock 1405 on it. I just installed new metering rods and tuned it for altitude. I don't have a vacuum gauge, but did find some vacuum ports that were left unplugged and plugged them. Been trying to get this truck running right for awhile. Had a falling out with the guy that installed the motor and been trying to fix it since. Like I said, runs smooth when giving it gas, a little rough at idle. I'll buy a vacuum gauge and try to figure it out.
My 79 has the counter weight behind the balancer. A vacuum guage can help set the idle , but you need to do as "justins Green Truck " said about spraying around the intake , carb., ect where a gasket may not be sealing. Check for loose vacuum hose connections, doesn't take but a small leak to foul it up.
Also wanted to say that it is a constant vibration at idle. Feels like the engine is a little out of balance or something. Feels perfect when accelerating though. The RPM's appear to be constant
Yeah I would think if it were a balance issue you would notice it worse the higher the RPMs got. Never experienced that though, so I can't say for sure.
What I would do is research exaclty what year 460 you have and determine weather it should be internally or externally balanced. Then check to see if the counterweight is behind the harmonic balancer as previously mentioned.
Then I would get all the specs on the engine and carb as to what they should be set at and then just start going through with a fine tooth comb so to speak. Usually i've found that all these old trucks want is just a little bit of your time... haha.
Dont overlook the easy stuff like a fuel filter. Do some researching to make sure that each component is exaclty what is supposed to be on that particular engine. For instance, make sure if you havnt already done so, that the edelbrock 1405 is the correct carburetor for that particular 460 with that particular intake, ..... such and such, right on down the line.
Good luck to you
I thought 79 was the balance change year,but i never did research it. Yeah ,these old trucks are allways after your time and money,greedy old things.L.O.L.
if i recall corectly , the changeover was mid year 79 earlier ones had no wieght behind balancer , and the later ones did. most of the crate motors ive seen use them