400 conundrum....
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Lead Driver
Joined: Apr 2008
Posts: 6,945
Likes: 13
400 conundrum....
Okay... i have a 400 in my truck. Runs really good, edel intake. 600cfm carb.
Problem... it knocks. Dunno if its a rod or a main, but my bet is its a rod.
So, i dont want to put money into this thing, i will be replacing it. But until then i will be doing alot of driving, and quite a bit of towing. I need to wake this thing up a little. I heard that 400's have retarted factory valve timing. So for $40 bucks i can get an adjustable timing chain and gear set. Is it worth $40 bucks? What else can i do to it? I bumped ign. timing up a couple degrees, and that seemed to help. Was thinking about having the heads/intake milled say 30 or 40 thou.. but that gets into costing money again, and i dont think the bad bearing would like any more compression. Just looking for some ideas and help, thanks guys.
Problem... it knocks. Dunno if its a rod or a main, but my bet is its a rod.
So, i dont want to put money into this thing, i will be replacing it. But until then i will be doing alot of driving, and quite a bit of towing. I need to wake this thing up a little. I heard that 400's have retarted factory valve timing. So for $40 bucks i can get an adjustable timing chain and gear set. Is it worth $40 bucks? What else can i do to it? I bumped ign. timing up a couple degrees, and that seemed to help. Was thinking about having the heads/intake milled say 30 or 40 thou.. but that gets into costing money again, and i dont think the bad bearing would like any more compression. Just looking for some ideas and help, thanks guys.
Cargo Master
Joined: Dec 2004
Posts: 2,232
Likes: 3
From: NE Texas
Been there, done that with the timing chain and it didn't work out good at all. My experience was on a 78 engine. I think the ones that respond to this are the early ones like the 73.
If it were my engine, I would feel the same as Mark regarding modifying a knocking engine.
Again if it were me, I would pull the pan and do a little exploratory surgery. Determine the problem, then formulate a plan from there. It very well might be that turning the crankshaft and replacing the bearings would get it all back in shape.
I would not just junk the engine without first doing a proper diagnosis.
If it were my engine, I would feel the same as Mark regarding modifying a knocking engine.
Again if it were me, I would pull the pan and do a little exploratory surgery. Determine the problem, then formulate a plan from there. It very well might be that turning the crankshaft and replacing the bearings would get it all back in shape.
I would not just junk the engine without first doing a proper diagnosis.
Senior User
Joined: Oct 2005
Posts: 271
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From: Gresham Oregon
^^ What they said. I would do anything considered "performance" to the motor until it is healthy. Depending on what you plan to do with the truck, you might be able to find a replacement for cheap and keep this one as a rebuilder. Is your truck a 4x4? Stick or Auto?
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Lead Driver
Joined: Apr 2008
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Yea, my grandpa had one that knocked for 20 years... then finally just died from being wore out. This summer/fall im putting a 7.3 in it... thats kinda why i need to do towing and running. Its a 4sp 4x4. Lol.. and the trans is shot to boot. Thanks guys, thats what i was thinking, but if for $30 bucks i could gets a little more power.. i would.
