Thread: 454 problems at 3000 rpm

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I have a chevy 454 bored 100 over solid roller motor. at 3000 rpm it starts backfireing lightly. Any thoughts? it starts great, runs great but at 3000 it hits a brick wall and wont go any higher.
thanks for any tips!
jason

One cause could be that the valve springs are tired.

this motor only has about 15000 miles on it ant the valve springs were new when it was built. do you think this could still be a problem?
thanks
jason

cam is going away springs not set up right valves bad you will have to check it out. no fuel timing off

cam going away- its a solid roller would it go away?

springs not set up right- the guy who built it built race motors for a living,(I can't ask him he moved away) and had a good name but I guess I should check it out. what would be the best way to know if that is a problem?

valves are bad- stainless valves and seats would they go bad after only 15000miles?
thanks
jason
I'm not sure about the fuel timing being off. holly 750

well you need to start some where ?no the roller cam should on be going out BUT is it a iron core cam? it could .the end play may be off on the cam or are you running the right gear on the dist ? it could be going a way if it will not rpm the spring may be out for lunch. the lifter set to tight .

I guess a reasonable question would be has this started recently? And have you made any changes to the motor? Did it sit over the winter without running?

Pat

no I haven't made any changes to the motor , but yes it did sit over the winter without running and yes as far as I know it started recently. I sold this motor to a friend and he never paid me for it, so know I have it back with this problem. thanks for your help
jason

Maybe the timing advance is not working correctly in the dist.

I guess I like to think of the simple things first, if it had not been run all winter and there was no Stabil or other fuel treatment put into it, then the carb could have gotten gummed up causing it to run lean. That would cause the back firing and limited fuel would keep it from revving up to full RPM. Does it hit the wall with no load or only when driving? The next thing I would look at would be the fuel delivery system, how are the fuel pump and lines? Next step after checking those would be plugs and then wires.

Good luck and ket us know how it works out

Pat

how did it run for the first 1500 miles? look at 5 and 7 plug wires make sure they are on the right way