I could use some help. I've been doing a lot of reading, but I think I'm just going in circles at this point and I haven't seen anything with combo I have at the moment. Its a bit of a long story but I'll put cliffs at the end.

Heres where I am now. I have a 90 z51 6 speed. It started making noise at the end of last autocross season that sounded like bad lifters. Took off the valve cover and found that one of the valves was sticking a bit just before it closed. I figured that must have been it.

My mechanic took the head off and ground off a bit of the end of the valve guide that caused it to stick. Wish I had just replaced them in hindsight. Also, replaced lifters because I found new ls7 lifters for $25.

Car was quiet for a day and then the noise returned. Took off valve over to check if it was sticking again, but it wasn't. The valve that was once sticking is just like the others. Ran it with the valve cover off and oil was coming out of all the pushrods the same.

So not sure where to go now. It definitely sounds like it coming from just under the valve cover, but with new lifters and valve not sticking, not sure where to look.

Cam bearing was mentioned as maybe the culprit, but now we are talking about taking the engine out.

If thats the case I'm going to travel down the "while its out path". Sooo, what would you do for more power? The car has some good upgrades and it does run great, but since its out.

Engine has been rebuilt recently and all parts except whatever ones are making the noise look great. It has:

long tube headers and free flowing exhaust

edelbrock tpi intake

unknown cam

113 heads with upgraded springs

3.33 rear

removed air pump and a/c


Now its not a show car so I want to be budget conscious but not cheap. If I were to change the cam to something like a lt4 hot cam (which people seem to like), what would be the next thing holding the engine back?

If I had a stock intake, I'd go miniram, but is the edelbrock good enough? I've seen some people say that the 113 heads are pretty good and others say sell them and get afr heads. Are they good enough? What could I get for the 113s to offset the cost?

I imagine I could do the cam now and change heads or intake later if needed.

What do you think would get me the most bang for the buck or is it a bit of a waste to change one or two things without changing all?

Or, do I just sell the car and use my miata?

Thanks if you've made it this far.

Cliffs: Engine looks like it may have to come out. What upgrades could or should I do while its out to get more power.

Thanks,
Jared

 

I think the stock heads get trashed talk too much, but modern aftermarket heads are real nice! It really depends on your long term goals, how much power you want/need/allowed and how much $ you want to sink into this car. The intake will hold you back but can be changed easier later if you can't afford to do both now. I don't like a lot of the short runner intakes and l think they give up too much low end for when you want a wide operating range, so I'd try cutting down the dividers a few inches, maybe get a superram or mod a stealthram(or your hood, might be a good idea if it's allowed to have a hole for some venting). You can find take out cams for cheaper and if you do use one with your current heads then you pretty much have a zz4.

Has the car been tuned for the mods? Any major changes will need tuning and you'll have to factor that cost.

edit: A road style oil pan would be a good idea, but you can also do that later in the car and that's one thing I like bout vettes.

 

Has the car been tuned for the mods? Any major changes will need tuning and you'll have to factor that cost.

edit: A road style oil pan would be a good idea, but you can also do that later in the car and that's one thing I like bout vettes.[/QUOTE]



The car has been tuned, not sure by who but it does run well. I also have a canton road racing pan on it. The car appears to have had some money spent on it, which makes me wonder more about what may have happened.

To be honest, I wasn't really looking to mod it, but if I have to change parts, I'd like to go faster. Cam, intake, and heads are probably not an option right now, but if I can change one or two now without having completely mismatched parts I could do that.

If I just did a cam now, what would you do next, heads or intake?

 

Did you save the old lifters? If any of the rollers show any damage or wear, I can pretty much guarantee that the corresponding cam lobe is bad.

 

The 113 heads are about as good as the old fuelie heads..nothing special except a 40 pound weight saving total. Used 133 heads go for around 300 bucks and up. AFR 180s or 195s are darn good heads , giving much more power than stock heads. If you change heads, you gotta take off the intake anyway. you can take off the intake without taking off the heads.. your call.

 

I have the lifters and we did check them. They looked good all pretty much the same. Looked at cam as best you can and didn't see anything unusual. I only changed the lifters because I got the new ones for such a deal and figured why not.

 

Depends how often you wanna pay for tuning or labor. I know it's apart now so anything is kinda easy, but your not gonna feel it like those three so I'd save up. Shoot for as much at the same time as you can when you go back into it, intake has to come off for heads.

 

If it runs good now Id try and find the source before tearing it apart
To get a big difference in power it will cost. With all parts the same a fresh 350 doesnt run much different than a worn one.

Sometimes engine noises can travel around and fool ya.
I assume the noise in time with the cam not the crank?

Have you tried pulling plug wires off one at a time while its running to see if the noise stops?

No exhaust leaks?

A worn guide, broken spring, needle bearings in rockers going south etc

If you have aftermarket rockers sometimes they can touch parts of the valve cover internally either the top or wall facing intake. Makes a racket


If youre impressed with the miatas handling price a supercharger for it and compare $ pros cons etc.

Lots to think about and price

 

Your car already has a pretty extensive list of mods.

Speaking personally, I always considered the cam to the brains of the engine. Start with a cam and work out from there; and lets face it, a cam is one of the most wear prone part of the engine, especially as spring pressures go up; so , yes by all means do a cam swap.

I did an LT4 Hot Cam swap. I was pleased with the results and it breezed through the California smog test.

I drive an LT4 with a 3.45 rear end with a zf six speed, which has a 50 percent overdrive in 6th gear (2,000 rpm = 80 mph). A lot of members here consider a 4.10 rear ratio much more "usable", depending, I guess, on what you're using it for. With a 3.30 rear gear, a rear end swap might be amongst your future mods.

 

I assume the noise in time with the cam not the crank?

appears to be

Have you tried pulling plug wires off one at a time while its running to see if the noise stops?

will try later today. sorry to have to ask, but if the noise changes what should that mean?

No exhaust leaks?

not that I can tell. gaskets were replaced a couple years and only a few thousand miles ago.

A worn guide, broken spring, needle bearings in rockers going south etc

springs are good and different rockers have been tried. The funny thing is that the guide appears to be original when all the others have been changed. Its diameter is a bit smaller. However, it doesn't seem to have anymore play in it than the others.

If you have aftermarket rockers sometimes they can touch parts of the valve cover internally either the top or wall facing intake. Makes a racket

Made the noise with the valve cover off too


If youre impressed with the miatas handling price a supercharger for it and compare $ pros cons etc.

I respect the miata, but only have it because my father in law gave me a great deal. 96 with 65k miles new top and great paint to $1000. Just got some 15x9 rims with too 888s for $300.

Lots to think about and price[/QUOTE]

 

A little update. I pulled the plug wires one a t a time and the noise didn't seem to change. That would most likely mean its not a bottom end problem, correct?

Thanks

Jared

 

here is a video of the noise

 

Sounds like collapsed lifter, too loose rocker or small exhaust leak.

FYI those are SLP runners, did you mean eddy base? Yellow injectors I thought those were like 19lb ford? I'm not efi/injector expert maybe someone can name them.

 

We thought it was lifters too. Replaced them with ls7 ones. Had rockers adjusted and then tightened then a bit more but no change in noise. Replaced header gasket same time as lifters and still no change in the sound.

Car came with intake on it. I can now see its an Eddy base. Was told they were Bosch III injectors.

I really appreciate the help. I really don't want to tear into it.

 

What type of rockers, they may be contacting the valve cover just.

 

Ran it without the cover and still mad the noise.


Would it be possible to take the rocker off and use a magnet to hold the lifter up off the cam to see if it will make the noise still?

 

That may create a major oil leak and a gm block is not priority main oiling, so that would be a real bad idea.

edit: Could be trash in the lifters, had an engine that was cleaned up with the no-no fiber disk and that engine always had clicky lifters.

 

my wife said the "engine made a horrible noise"....turned out to be the gear on the bottom of the oil pump stub drive stripping it's teeth,

 

A worn valve guide will sound like a bad lifter.

Run the engine with the valve cover off.
Stick some cotton in one ear & use a length of hose in the other ear. Listen @ each rocker/valve to identify the noise maker.
On car valve guide check: Engine off, valve closed, lever the retainer towards the intake manifold with a flat bar or screwdriver etc. Watch the valve stem for movement if you can see movement the guides are toast.

Changed heads on my 89 due to worn guides @ 100K miles.

 

If the mechanic cut part of the guide off something caused it to get like that. Wondering it a valve didnt kiss a piston at some point and hurt something. Guides dont get bent on their own.
Good thing is guides are cheap bad part is may require a valve job..and your labor.
If your rockers arent touching covers, no broken springs, lifters are good has to be it. Think Churchkey is on to something

If they are truly that worn best to rip it apart before you drop a valve