dounome Posted January 5, 2007 Report Share Posted January 5, 2007 My 408 is cursed!!!!!! HELP! -------------------------------------------------------------------------------- Ok so I dropped in the 408, and as you guys know I had electrical problems for over a month, thats done now. Here is the problem. LOUD vlave train now. On start up from a cold motor it is making a really bad sound and it does not sound good at all. After about 3 seconds and a little gas it goes away. But then even when the engine is warm Im getting a noisy valve train. Im running nothing crazy Patriot stage 2 LS6 heads with dual springs, stock lifters and stock length push rods, stock rockers. Here is what Im thinking, bad oil pick up tube O-ring??? Or dead lifter? The O-ring was the only gasket that I had to re-use on the entire motor and Im worried about it. I get 38-40psi oil press. at idle and a slow increase of 55-60 with a stab at the pedal. Im going to take the heads back off this weekend and also drop the front dif. and oil pan. Where would you guys start. BTW if this thing was running I would sell it so fast, Im sick of it! Quote Link to comment Share on other sites More sharing options...
Krambo Posted January 5, 2007 Report Share Posted January 5, 2007 What injectors are you running? Your absolutely sure that the injectors are not just real noisy? I know on my Typhoon, I almost didn't buy it because the 50#rs sounded terrible,...even with the hood closed! I have since swapped them out for the stockers and they are still noisy but deffinately less. You can do the wooden dowel scope trick (Mr. P can help) and pinpoint the noise. Quote Link to comment Share on other sites More sharing options...
Bowtie70SS Posted January 5, 2007 Report Share Posted January 5, 2007 My first guess would be a bent pushrod or two. Have you taken a valve cover off and rolled the engine over to see what's happening yet? Assuming you can tell which side the noise is on start there. I have also heard horror stories about those darn oil pump O-rings, although your oil pressure dosen't seem excessively low. Keep us posted. Dave Quote Link to comment Share on other sites More sharing options...
H8R Posted January 5, 2007 Report Share Posted January 5, 2007 (edited) Well, Do you have these springs shimmed in any certain way? That would be my first question. Secondly , did you replace the lifters when you built this engine, ls stlye lifters are known to fail. . What did you TQ the Rocker arms down to (ft lbs) I think they should be 18-22 ft lbs. Also in this 408 was the proper push rod length checked? P-V clearence? I think we need some more info on you set-up the give a better idea of what to check.I really dont know why you would use stock pushrods in an engine set-up for hi performance Unless this engine is shifted very early( under 6000) Also needle bearings have been known to fly out of the Rockers when used at VERY high RPMS. Is there any misfire associated with this noise? If so you might want to check for a bad/ bent valve, this could result from an improper degreeing of the cam. Another thing to remember is just because parts are new , that dosent mean the can't be defective, Patriot Gold springs I am guessing is what you have and I have heard some shady things about there older cnc progrmas/ and parts failure. It seems you may have some issues with valve train geometry have thinking about this further. Who set it up? Edited January 5, 2007 by H8R (see edit history) Quote Link to comment Share on other sites More sharing options...
misterp Posted January 5, 2007 Report Share Posted January 5, 2007 (edited) There's nothing wrong with the bottom-end of the motor; if you've got 40psi at idle that's *plenty* to pump-up the lifters. I would not tear the bottom-end of your truck apart, the problem sounds most certainly in the valvetrain. If you have already sold yourself on the idea of just going ahead and pulling the heads off then there is no need to even discuss diagnosing the problem. But I would diagnose it first, because maybe you only need to remove one head and it would be nice to know which - Krambo is right, use a mechanic's stethescope or wooden dowell to at least figure out which head is the noisy one if not pinpointing the actual valve, one bad valve can make a surprising hell of a lot of racket. Mr. P. edit - just wanted to add that I'm not trying to harsh on you, I've been in the this same situation before and it totally sucks. Edited January 5, 2007 by misterp (see edit history) Quote Link to comment Share on other sites More sharing options...
SS_bnoon_SS Posted January 5, 2007 Report Share Posted January 5, 2007 Did you use a push rod length finder for those heads? Typically someone porting heads will have them "cleaned up" on the mating surfaces and may require non-stock length pushrods. Also, double check that you tightened the rockers properly. If I remember right from an LS1 cam install how-to, it's 20 ft pounds, rotate crank about 1/3 of the way and torque them again, then rotate the crank 1/3 turn again and torque them a 3rd time... something like that anyway... Quote Link to comment Share on other sites More sharing options...
dounome Posted January 5, 2007 Author Report Share Posted January 5, 2007 Well I want to say first, thanks so much for the help guys. One thing to note about this motor. This motor is Tony's (2bseen) old motor, which was a long block, that I bought from him when he put in the 427. I know that Tony and Scott would not send me a crap motor, so Im not about to question that. What I did do was take the heads and the oil pan off of the motor before I installed it into my truck. I wanted to check everything out before I installed. I cleaned the heads up and the tops of the pistons. I then installed new ARP head bolts and reinstalled the valve train. Everything was torqued to the specs in the book except for the head bolts. This called for a one time torque, instead of that torque to yeld crap, or atleast thats what ARP box said. So when I first fired the motor up it would only run for about 15 seconds due to the codes I was getting with the TB and it would starve it self of fuel and sound really bad as it tried to idle at 300rpm. I finally drove it (baby steps) and when I went to start it back up thats when the really bad start up noise came about. If Mr.P is telling me not to worry about the bottem end then I will just pull those damn heads. I know that the bottom is solid, its all forged and proven, but me reinstalling the top end may have caused something to go wrong. Quote Link to comment Share on other sites More sharing options...
misterp Posted January 6, 2007 Report Share Posted January 6, 2007 How long have you had this motor running? Not very long I take it? It would help if you can email me a sound clip. And about the bottom-end, I'm just advising to save yourself some effort, there is no sense jumping in to a complete in-the-frame rebuild! Mr. P. Quote Link to comment Share on other sites More sharing options...
n2opwr Posted January 6, 2007 Report Share Posted January 6, 2007 If I had to make a educated guess, I would say your push rods are too short. The reason the noise is loud at first and get's quieter after it runs is because your lifters pump up and take up some of the "slack" in the valvetrain. Is the cam you are using a reground stock cam with a smaller base circle? Quote Link to comment Share on other sites More sharing options...
dounome Posted January 6, 2007 Author Report Share Posted January 6, 2007 Maybe just maybe I put in my push rods out of my old motor, and all the while Tony had longer push rods in the motor due to the decking of the block and the cam he has in it. So this would mean the push rods I am running are a tad too short and cause so much noise under normal conditions and really loud at start up. Ok so whats the best way to see if my push rods are too short. I guess I could pull one of them and grab one thats laying on my work bench. Quote Link to comment Share on other sites More sharing options...
Bowtie70SS Posted January 6, 2007 Report Share Posted January 6, 2007 I would think that you could bring the lifter to the back side of the lobe and check the clearence between the valve tip and the rocker arm. Of course this would not be 100% accurate since the lifter will bleed some when the engine isn't running. Consider it similar to setting mechanical lifters...somewhere around .025 cold. I'm sure there is a tool to check this but without specifics like how much the block has been decked, the thickness of head gaskets used, and whether or not the heads have been resurfaced and lastly the base circle of the cam. Lots to add up and it's tougher because the old school small blocks had completely adjustable valvetrain. I can't remember for sure but I think adjustable valve train is available for the LS1 series engines. Good luck Dave Quote Link to comment Share on other sites More sharing options...
Jonmalibuss Posted January 6, 2007 Report Share Posted January 6, 2007 This sounds like a problem with lifter to lifter bore clerance. We have had a lot of problems at work with aftermarket parts no matter whos they are they are almost all nearly .002" smaller in diameter than a stock lifter which will increase your clearance and cause the them to be very loud because they will be all over the place in the bore much like a piston with too much clearance. This would also be a huge reason they take so long to pump up especially if you think about how much increased clearance you would have x16. I would say if your going to have a head off you need to find a dial bore gauge so that you can measure the lifter bores compared to the lifters and see how much clearance you actually have. If you don't have a way to check the bores with a dial bore gauge and you know for a fact that the lifters are aftermarket I would say get yourself a stock set of lifters and put them in to see if the noise goes away. If you are running stock lifters right now I would still reccomend checking the clearance. As far as what the clearance should be depends on the lifter manufacturer. Quote Link to comment Share on other sites More sharing options...
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