Very loud clacking sound

lilpiston8 · #1 (**permalink**) 08-29-2010, 10:24 PM

So my engine's valvetrain was very loud so i suspected a bad lifter. I got a set of the short travel hydrolic roller lifters, installed them with a new set of pushrods to correct the geometry. Lash is set at 1/8 turn past 0 lash as per comp tech guys. So my problem is that now its super loud, runs super hot, and idles like crap. Checked ignition timing and it is spot on. what gives??? Motor is a 388 sbc with full hydrolic roller valvetrain.

iwannagofaster · #2 (**permalink**) 08-30-2010, 11:48 AM

If the ignition timing is where it needs to be, the engine would not be running hot, nor would it idle like crap unles there is a fuel issue. Where is the timing set at, and who told you where it needs to be? Our hydraulic rollers are noisy by nature and if you use any type of roller rockers, that will add to the noise as well. What cam are you using? How did you set the lifter preload? We do not recommend any timing settings because every engine wants something different. You may also want to check to make sure the balancer didn't slip. I have seen that more times than you can imagine and you will be reading 18 degrees by the marks on the balancer, but you may have a lot less than that in the engine.

lilpiston8 · #3 (**permalink**) 08-30-2010, 03:01 PM

I suppose that the timing is off but it matches on the balancer dead on and in the fast system. Timing at idle is set to 21 . All i did was change pushrods and lifters. To set preload I went to 0 lash and a 1/8 turn past like i said following the comp cams method . If the lifters were bottomed out it would run really ruff as in the valves would hang open. The thing i cant figure out is all this clacking. I have heard solid roller motors run and is about 20 times louder. The crank is not hitting anything nore are the cam lobes. there is no interference any ware just this clacking sound. Could it be a spring issue?

iwannagofaster · #4 (**permalink**) 08-30-2010, 05:13 PM

I suppose it could be a spring issue, but there is one thing that also concerns me with what you have going on here, what weight oil are you using and how much piston to wall clearance do you have?

lilpiston8 · #5 (**permalink**) 08-30-2010, 08:26 PM

I currently have 20/50 in for the summer. And im not sure what the piston to wall clearence is as the short block was built for me.

lilpiston8 · #6 (**permalink**) 08-31-2010, 01:25 AM

Ok, so tonight i ripped her apart again checked every valvespring, all good. Reset lash to 0 lash and left it there to see what happens. Fired it up and what do you know, still clacking away. So i crawled underneath to see if anything had loosened up and nothing under there looked out of the ordinary. I pulled the distributor (just to check) but ran out of time in the day. The sound sounds like it is coming from the center of the intake about half back and when i put a timing light on it i get about 2 clacks ish to 1 lite flash. this sound pretty much has always been there but not even close to as loud. Im starting to look at other things like rockers? oilpump? cam walk? my brain is fried. Ill talk to my builder tomorrow to get the piston to wall clearance measurement.

iwannagofaster · #7 (**permalink**) 08-31-2010, 12:17 PM

I was originally thinking it could be piston slap, but now that you tell me there are two'ish clacks to every light flash, I am thinking it is rod bolt to camshaft interference. There are two rods (#2 & #6) that come really close to (and most times hit) the camshaft on a 3.750" stroke engine. Number 6 is really close to half way back in the engine. At speed, the camshaft can flex, so even if it didnt hit rotating the engine by hand, it could easily hit at speed when the camshaft is flexing. What cam, and what rods are you using?

lilpiston8 · #8 (**permalink**) 09-01-2010, 01:01 AM

I am pulling the motor tomorrow, hopefully we will see what is up and get to the bottom of this clacking.