I need help! 454

[Tonys1963]

Hello all and thanks in advance to those who respond. I have a 350 hp 454 in my 63 c10. It has been running great for the last year. I had it out last week and it started running rough kind of like it was loading up, missing etc. I found two spark plugs loose and a couple of plug wires were melted. I put in fresh plugs and put on some old wires i had that were good to replace the burnt ones unitl my new ones get here. now it is running alot better and will cruise smooth, if i accelerate hard it sputters and pops thru the carb. I went from enough power to break the tires loose at 15 mph to not enough power to break the tires loose at all. I really dont know where to start

[Captainfab]

Have you checked your timing lately? Are your rockers making noise? If so, your cam may be going flat.

[Tonys1963]

John - no top end noise and the timing is at 18 degrees at idle

[geezer#99]

That would be 18 with the vac advance plugged off and checked at 700 rpm, correct!

[Tonys1963]

That is with the idle set at 700 rpm and the vacuum hooked to the carb. This is where the engine has been set and has ran very well. I’m not getting any valve train noise and the idle is smooth.

[geezer#99]

So with that set up depending on how much advance the vac pot gives you then you likely have only a few degrees initial timing.
You might even be atdc.
You need to plug off the vac pot and set your initial correctly.
Try 12 degrees.
No initial is the reason you have no power and sputtering thru the carb.

[crazy longhorn]

yes, as the other geezer said...12 initial....to 14 initial not to total more than 36 degrees, with the vac can unhooked/ plugged....shorthorn

[Tonys1963]

Geezer - I owe you a hand shake and a cold beverage of your choosing. I adjusted it and it’s running great. What worries me is why it ran ok than suddenly changed, my distributor was tight.

[geezer#99]

Check the weights and springs in the distributor. They could have been stuck and loosened up or are stuck.
Also check the vac advance moves the plate easily.
Wierd things happen!

[74CustomK20]

My old man had this problem on his 92 350. Screwed with the dizzy timing all that never made a difference. Come to find out another plug wire had shorted out and he had zero passing power.

[mattfranklin]

Sometimes advancing the timing a little helps to make up for power lost due to other issues. Like a carb being not quite right. Advancing the timing on my old '84 S-10 made up for the flaky emissions carb that badly needed a rebuild, but I didn't have time or garage space or talent to do that. ;-)