noisy valvetrain under load

[import convert]

well this may be a dumb quesion but when im on the highway and i try to step on it in third my valvetrain is a little noisy. also on ly seems to do it above 2500rpms.

my question is if it could be loose rocker bolt? i did rebuild the motor a few months ago so im wondering if i need to retourqe the rocker bolts and it may help.

i am using 10w30 oil and i got new lifters. if im easy on the throttle its fine but still, going up hills on the highway i can here them rattle. course having 4th gear blown on my tranny doesnt help

[1987cp]

What rocker arms did you use? My Explorer motor has had noisy rockers ever since I built it due to excessive clearance. One of these days I will pull it into the garage, swap to a less-worn set of stock rockers, and stab in my length-checking pushrod to see if the replacements I got were even close.

[grandpaslincoln]

You sure it's valvetrain noise and not pinging?

[import convert]

i used a stock set but i looked at the spot the pusheod would sit in and it was barely worn on each one.

i thought of htat too. i can fill it today with 89 or 93 and see if its better, then ill know i ned ot back the timing off

[gadget73]

Sounds like spark-knock. If it was valvetrain, you'd get the same noise regardless of load, it would be RPM dependant. Too much timing will do that.

[mrltd]

That's preignition. Check your timing, and fuel. Too lean will do that also.

[import convert]

yea. i put 89 in it and it felt better on even back roads. tomorrow ill have to back the timing down form 15* to 10*.

[trwp72]

Another thing that will cause excactly what you described is a fuel pump that is not putting out enough pressure... Mine used to spark knock really bad when I was driving it excactly the same way.... I put a new fuel pump in it... it went away.... And had alot more power...

Tom...

[import convert]

i know its not from a bad pump. i chnaged it last year and my car is carbed and im using a regulator with the stock FI pump.

i drove her on the highway last night with 89 int he tank and i didnt here anyhting. i didnt think knock would sound like a bad lifter. i heard it sounded like a bunch of little hammers banging on the block but now i know what it sounds like.

i think ill still back the timing down though.

[91waggin]

Also, if you're running EGR, make sure it's operating properly. And if you're running cats, make sure they aren't messed up in some way. I had horrible spark knock problems until I repaired these two items. The bunch of hammers you're talking about sounds like a comparison of a bearing or rod knock. Spark knock sounds like a miniature diesel motor to me.

[1987cp]

No cats or EGR, as I recall ............ I do remember a bunch of discussion about vacuum advance, which Dave claims isn't necessary with a non-EGR engine (mine run great with it disconnected).

[import convert]

well i did the same trip that i did the last time when i noticed htis problem and put 93 in the thing before i left like i did before and i never heard hte noise again. actually i saved like a 1/4 of a tank and i drove faster too this time so i shouldve used more gas.

i had one guy tellme that detonation sounds like little hammers hitting the block but i guess it sounds like a small diesle too.

but yea, i need to either run 93 all the time or back the timing off

[1987cp]

Yeah, I'd definitely back the timing off to 10 degrees initial with no vacuum advance, at least for the time being. I got used to running lots of advance on my Explorer motor, presumably since it has slightly lower compression, and when I tried the same light advance springs on my 351 I ran into lots of little tapping noises under certain driving conditions, so I hurried and swapped out my centrifugal-advance limiter (20 instead of 36!) and backed the initial back to 10 for now. That means I'm currently running with only 30 degrees total advance, but the carb isn't entirely happy right now either so that's probably OK.