I heard a weird clacking noise at certain rpms. So i removed the valve cover and looked at the valve springs. a few were damaged. the damper inside the spring was shredded and laying inside the head. i replaced all the springs and seals and there didnt seem to be any other noticeable damage. when i put it all back together it sounded fine. but as i was driving the car home the noise started again. i havent looked at it yet due to extreme frustration. but would anyone have any ideas on what to look for? i know im gonna have to take the head off but im no mechanic.

1992 z28 5.7 with vortec heads

 

pull the valve covers and make sure that's your problem first.

-What cam do you have? Comp what? Part number please...
-What have you done to your heads?
-What springs were on there originally, and what springs did you put back on there? (not "z-28", or "double" but part number, and source if applicable)

Coil bind is typically what would cause this, but you'd need a big cam to do that. Lets get some info first...

 

Methinks you are on to something there. Too much lift.

 

Did you have the large bases of the valve guides machined smaller so that the dampener coils will fit around them? Factory vortec heads don't use those dampener coils and most (all?) replacement 1.25" performance/replacement springs which have them they won't fit down over that large base. Essentially, you bind up only the inner dampener coil.

Cheap fix? Take the dampener coils out and run without them. Done it myself now several times using Comp 981 springs on stock Vortec heads. They work fine.

 

Odds are you're running too big of a cam for the unmodified vortec heads. Factory Vortec heads can't run over .470 ( I think, could be .480) of lift because of the valve guides being too tall. If you run a cam with more lift than that, you have to have the valve guides milled.

 

The heads are out of the box Vortec as far as i know.
Comps cam part #08-304-8

i replaced the valve springs with stock type. Maybe thats the prob? i appreciate the help and patience guys. I wish i knew more about the issue.

 

i took off the valve cover yesterday only to find that one of the valve spring locks popped out and the rocker was off. my dumbass must have forgot to "set" that one when i was replacing the springs. but in my defense i did say im no mechanic.
as far as the springs go. i replaced them with off the shelf springs. and you guys have told me that i will run into probs with them. if i just drive the car normally for now could i get away with not doing the performance springs until it gets warmer??

 

.510" lift is too much for stock Vortec or stock replacement springs.

 

ok thanks. can i drive it this way or do i have to replace them with Comps recomended springs?
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right away i mean. like could i baby it for a month or 2. i barely drive it anyway

 

By too much lift on factory vortec's, he means that the bottom of the retainer is slamming into the top of the guide boss, physically preventing the valve from opening any further. Vortecs max out around .460" stock. This is bad. Bent pushrods, wiping of cam lobes, not good stuff.

 

reason 1,000,001 not to buy a car that already had work done. what are my options here? replace the cam or have the heads modified? and if it ran fine for months before is it possible that the heads are worked? im sorry for all the questions. i feel like a douche

 

You wouldn't have been able to run it for months if the retainers were hitting the guides. But, it has to be marginal.

You're coil binding the springs, though. You either need to get offset retainers, or pull the heads and get everything set up properly with cut guides, proper springs, etc.

At this point, I'd be pulling the heads.

 

Now that I think about it, he would have been hitting the valve seals, not the guides.

+1 on what 57 said, though.

 

1 last question before i would have the heads pulled. is it possible that this whole prob could have just happened from and over revving burnout quite a few times? it hit 7k a couple times on accident.(i got too excited) the prob began shortly after this. when the Phillies won i got a little out of control with the car(stupid).

 

It's possible. I no longer care about youre issue since I was pulling for the Rays. Joking.

Either way, though, the cam needs room to open the valve, and with the Vortecs in stock config, the room just isn't there. It's not a matter of high RPM the valve will lift more (well, unless you're tossing the lifter, which who knows..) Where were the Vortecs aquired from?

 

haha well the better team won lol.

i bought the car with the work already done from the previous owner. i do not like doing it that way but it was clean and a good price. all the work he had done was very clean and done right. he paid attention to detail which is why i would like to think he had the heads set up right. but i just dont know. and im very low on funds right now due to being laid off. so i couldnt really have the car dropped off somewhere to check these things for me

 

If you have the ability, pull off one of the valve spring assemblies and get down to the valve seal. Vortecs use an odd diameter seal. Like .560" or something. If they were machined, chances are, they would be cut down to a .530" diameter. They would also be have that machined look, not the as-cast. Looking would be the next best thing to find out. Would be in your best interest.

 

I will def take a look as soon as i get a chance. i just need to get my hands on an air compressor. thanks for all the help i will let you know how i make out

 

check the rocker studs, with that much lift on Vortecs theres a good chance they are starting to pull out or bend from the increased tension on them. .450" is the max i would go on a stock set of vortecs. get some good springs, machine the valve seat if needed, and check coil bind and installed height.

 

Very likely, actually.

While a good idea, studs pulling out wouldn't damage springs.

 

ok so this dummy is in need of more of your guys expertise. i ordered comp cams valve springs that are the req. part number for my cam. i just received them today and opened them and they are double springs(spring with a smaller loose spring inside). the springs on the car now are single. will this be an issue? or maybe this is why i had the issue? greatly appreciate the feedback as always. thanks

 

What springs?

 

comp cam #08-304-16
grind number cs 266h-r14
gross valve lift .500 .500


comp springs #986-16

 

Those are 1.45" diameter springs. They won't fit the Vortec spring pocket (designed for stock 1.25" diameter springs) without machine work. And they probably still won't fit over the base of the stock Vortec valve guide boss without work there as well. They also won't open up your retainer-to-guide seal clearance for higher lift clearance. You're heading in the wrong direction here if you're looking for a bolt-on solution without doing machine work.

The ONLY solution that would work here without machine work is going with a fairly pricey set of beehive-style springs and matching retainers. That will fit your stock spring pockets, fit the stock valve guide boss AND open up your retainer-to-seal clearance good for about .525" lift. It's more money for the parts, but zero money and zero hassle for machine work. Contact Comp's tech line and they will be able to recommend the exact springs and retainers that will work with your cam.

 

well this sucks. how can i find out(cheaply) if my heads have been machiined? i bought this car with its current setup and i have paperwork for all the parts but that is all. im beyond broke right now so i cant be spending money on the car

 

As I posted above.

 

im sorry i forgot all about that. i will look tom. morning weather permitting.

 

update: i re-installed the valve spring started the car and it was knocking pretty bad. so i tore it apart. i removed the TPI,intake manifold and head. (and a billion other parts just to get the head off) visually the pistons looked normal but i gave them a push and the piston below the valve spring i had issues with dropped down about 1/4 inch. the others stayed where they were. so we are guessing its the rod? my mechanic(who is a very close family friend) thinks i should just look for another motor or block. or take it to get machined.

what do you guys think?

-i know a guy who recently built a fresh 350 with keith black forged pistons and gmpp heads he wants 2k. but i wanted to retain the TPI setup and im not sure if its possible with that motor.


thanks in advance yet again guys

 

Either way, pretty much sounds like the engine is going to have to come out. I would pull and do a tear down and see what's actually happened down there. Sounds like bad juju to me, though.

As for the fresh build, if you trust the work, then it might be worth looking into. There's nothing as far as the TPI goes, though, that won't work with any form of block. You can put whatever cam you'd like in it. TPI won't care what the compression is, obviously assuming it's a streetable ratio. Find out what's in it - get a parts list if you can. Then you'll be able to make a better decision as to if you want to pursue it.

 

thanks for the feedback. i have to go back tomorrow to get the car towed AGAIN bc i can't keep it there. so i will find out more info on the motor's build and post it. if you don't hear back from me its bc i attempted to rob a bank

 

If you have the means, just jack it up and pop the oil pan off. You'll be able to see FUBAR.

 

i will do that and let you know. ty

 

turns out i spun the rod bearing. there was alot of chewed up metal shards in the pan. so instead of tearing it apart i decided on buying this setup:
89 2 bolt 350 bored .040 over (357) 1 pc rear main block
New Scat crank
New KB hyper pistons
5.7 reconditioned rods New ARP bolts
New rings & bearings
New cam bearings & freeze plugs
New Howard hyd roller cam 280/292 dur 504/504 lift 112 centerline
New hyd roller link lifters
New Comp Cam double roller timing chain
New Alum timing cover
New balancer
New HV oil pump & pickup w/steel shaft
New Moroso oil pan w/1 pc oil pan gasket
New flexplate w/bolts
Balanced rotating assy prof built ready for your topend over $2,800 invested

and I will have the vortec heads ported w/total valve job and resurface.
my intake is the SDPC manifold with edelbrock siamesed runners and 52mm throttle body.

any thoughts or suggestions ?

 

You might want to search for my thread titled "062's". Bunch of good info about prepping Vortec heads.

 

i checked it out. theres alot of useful info. thank you