SlowMaro

i just now thought about this, when i was taking the valves out, i dropped two of the springs, intake and exhaust, i didnt think there was a height difference and just slapped em back on and put the heads on......so is there a height difference? also, the head gaskets i used were .45 thick. that bad? only one i could find .15 thick was copper, and 100 for a set....when i did my compression check they all checked out to be 150. however they didnt instantly hit 150 on the first engine revolation, it wa slike 100 on the first revolation, then to 125 on the second, then up to 150 on the third. when i say this i mean i never let the air out, it just went up 25 more psi per revolation after the first. until it was at 150, wouldnt go up anymore. if anyone doesnt understand what i mean please ask.

so i assumed my valves are fine? i mean whats up with the pressure only going to 100 then jumping up 25 more per revolation? valves leaking? head gasket? they ALL did this. and i had the tester tightened up pretty good.

im just confused why my timing needs to be jacked up so high after the port n polish. thats crazy. idle is weird too and the car feels like it just over all runs rough.

Tom84L69

In a race engine, valvesprings are matched by installed height. There is no difference between a spring on the intake or exhaust.

About your compression test, you are right on. What you describe is exactly what is supposed to happen, and 150 is a decent number.

SlowMaro

ok ...so my compression is good....why is my car still running like *** lol..i think ive ruled out the heads being messed up.

so where should i start looking now??

Vader

I'm almost afraid to ask, but did you degree the cam when it was installed?

RB83L69

On a set of stock heads, the I & E valves are the same height, and the springs themselves are the same; but the Es have that stupid dysfunctional rotator dead weight thing stuck up on top of them, which is about .100" thick. So they machined the exhaust seats an extra .100" deep. So when you do the right thing and throw all that trash in the garbage where it belongs, you usually have to shim up the exhaust springs an extra .100".

In the process of correctly working up a set of heads for performance use, the spring pockets get cut out to some large diameter anyway, so you can put real springs in them; by doing that, you can make the seats the same depth. Then you use shims to get the correct installed height, after the valves and seats are ground to their finished depth.

Of course, if you're using a bunch of old worn-out stock springs, or stock replacements, the heights could easily have significant variation from one to another, just depending on how much each one has given up the ghost over the years.

SlowMaro

....--smack--.....lol even i know to do this... i lined up the dots on the gears before i took out the old cam, cam went in the exact same, and my car ran great up until i swpaped the heads, so i doubt the cam or the harmonic balancer is an issue ...my timing was set at 8 degree advance after the cam and the car seemed to like that a good bit...

so i woke up, went outside, torqued the heads down to 70 lbs...looked at everything, scratched my head....and went W..T...F

i cant seem to figure out whats wrong here....compression is fine..plugs are brand new, should i gap them more than 50? wires are new, car ran fine before i took it apart....so where should i start looking now?? intake manifold??? random vaccum leak that i know is non existant? ive been looking over and over and i cant find anyhing wrong, yet there is something definatly wrong.

So it shouldnt matter if i mixed up two springs, and no more?

kevinc

The springs shouldn't matter, and if they were of significantly different rates you'd only likely see it at high revs when one valve would float (pop out the exhaust, feels like a misfire).

I suspect all the airflow mods, between the cam and heads, is out of spec for the software your ECM is running. That and your whacky timing problems are about all that's left, unless one of the steps you think you did right really isn't. Example: your lifter preloading description doesn't mention having done it in the #1 @ TDC, then #6 @ TDC sequence...if you just zero-lashed all the rockers then added 3/4 turn, they're not set anywhere near right.

You got a good compression test, you're not seeing coolant in the oil right? Not overheating or bubbling-up your coolant reservoir right? Head gaskets are likely ruled out if these are true.

I'd dig up an old laptop and get set to capture ALDL data, plenty of discussion on this in the DIY-PROM forum here. Cheap DOS laptop and a Mattei cable, plus software, gets you access to the ECM so you can see what's happening inside the engine. Being able to post the data will help others help you also, might even catch the cause of your timing problems.

SlowMaro

i adjusted the valves with the car running, ...back the nut up til it clicked, then turned it til it stopped, then 3/4 a turn.

i still think my idle problem is some retarded ecm thing changing the air/fuel mixture. i just need a good chip made i suppose.

everything seems mechanically fine.
other than the mystery oil leak i have still, DAMMIT

kevinc

Unless you're running aftermarket ignition components which specify the big spark plug gap, I'd set them to the factory spec as my next step. I run mine at 0.040" running Delco coil and ignition module. Only something like an MSD or Jacobs box would push you to a bigger than stock gap.

SlowMaro

oh ok...well thatll work then, ill set them back to 40....i wanna fix this oil leak,its etiher the intake or the heads.....i dont feel the urge to buy 2 intake gasket sets if it turns out ot be the heads ya know..then again id hate to yank the heads off for the intake leaking....im pretty much sick of taking this car apart and putting it back togather.....its annoying now. once i get this runnign right it stays togather, other than something stupid like under drive pullys.

its a bitch having a leak somewhere by the firewall, hard to see anywhere around it, and it only leaks with the car running, so its hard to *feel* for a leak....

Question, do i have to be driving the car to data log on aldl, or does it work the same at idle....cause if i can do it at idle then ill drag my pc to the garage for a day


my head gaskets are .45, this a bad thing, cause the thin ones *.15* are like 80 a set heh...

Twilightoptics

Maro: I didn't degree my cam. Some people think it's a HUGE NO NO to have installed the cam straight up like you and I do, even though many many many many people do. Comp Cams told me to install mine straight up. IT's built with 4deg advance in it. If the cam was like some generic brand, then I might degree it, but Comp is good stuff.




Your head gasket can't be .45 thick, it has to be .045.

If you did not Zero Deck your block, meaning that a machinist milled the deck (top part of the block where the pistons come up to) to make the deck even with the top of the piston, the .045 gasket is pretty bad.

If you have dish pistons it's not as bad.

Stock head gaskets are .015 thick steel shims, and deck height (piston top to deck top) is .025.

Deck height Plus gasket thickness = Quench

For Best performance and least posability of knock/ping/pre ignition Quench needs to be between .035 and .045 .040 being optimum.

If you still have stock deck height of .025... and put a .045 gasket on it your quench is .07! thats huge. This means that alot of your A/F mixture is not getting completely into the combustion chamber which is only 3/4 of the cylinder bore, and stuffed under the head on the flat spot.


Fel-1094 are .015 steel shim gasket that many people use and have great luck with. 19.95 ea ($40 for the set not 80-100) You need to buy a can of Copper Coat from napa or an autoparts store.

Bet that helps your running problem too. Atleast you'll ping less, have higher compression for more power, and have more power from optimum quench.

Hope that came out clear enough for ya!

BTW I gap my plugs at .045 with MSD Box and Coil. Stock ignition do NOT gap bigger than spec.



You can datalog at idle, but you'll only get readings at idle. If your engine does bad stuff at cruise, then you have to cruise with a laptop and datalog.


Your intake manifold gaskets... did you use RTV for the Block Ribs (front and back between the heads) or the little strip of cork/rubber that the kit comes with? If you used the strip they have a huge tendancy to leak. If not, you may have not used enough RTV to seal. Could also be your oil pressure sending unit in the back leaking oil. Doubt your head gaskets are leaking the oil.

SlowMaro

yeah i ment .045 , sorry about that. also, my deck wasnt milled, i had the head shaved but not enough to make ANY diff, just smoothed out..... i guess ill go get the good copper ones ....i just use the copper gaskets and spray them with the sprayon stuff. and nothing more, correct? are the prone to leak at all?

will it be worth it to switch them over?? i ask this because its abitch to replace head gaskets *as we all know* and i wanna know if itll be worth it to do it, before i yank them off.

the gaskets i usedfor the intake were from napa, as all my gaskets are. i used the silicone sealant all over the rubber pieces front and back, and around the coolant passages, and nothing more.

i have the stock pistons in there, ...they have those lil cresent moons type things on the pistons...

SlowMaro

PS....i wish someone woulda told me to get the gaskets, the FIRST TIME!!!! @#$#@%@$#%T bastards!! lol

dans82bird

Question if I may; so what your saying is that all stock sbc heads have the exhaust valve seat cut an extra 1/10th" depth?

Twilightoptics

Yep, get the gaskets, spray copper coat on one front to back both sides (I held it in mid air with a screw driver) let it get tacky for about 3 minutes, then put it on the block, the the head.

I can tell you I did the same thing. Rebuilt the motor with a rebuild kit didn't know anything about Quench. I can tell you that my spark plugs looked like aliens. The porcelan was buldging, I was getting quite a bit of knock.

You have dish pistons however, and I've read that Quench is not THAT big of a deal, because no matter how close you get that tip of the piston dish to the head, you still have that dish that makes the quench bigger.

if your piston has a dish like this: I wouldn't worry about it: DISHED


If it looks like this: I might think about changing it: FLAT TOP


I was always under the impression springs are the same height.

RB83L69

That is correct. The springs are the same height. And the exhaust seats are cut .100" deeper to accomodate the useless blob of dead weight commonly referred to as a "rotator".

A typical "performance" head job will include either spot-facing the intakes to the same depth as the exhaust, or simply shimming up the exhausts an extra .100". Actually people use .105" alot... one .060", one .030", and one .015" shim.

Valves will rotate just fine without the "rotator", if the heads are assembled correctly. I have no clue why the factory found it necessary to add that extra expense; I would assume that at one time they must have had lots of trouble with heads being incorrectly assembled, and that at the time it was cheaper to add that than it was to actually fix the problem; and that either whatever the root problem was hasn't been fixed, or that it's more expensive to change back than it is to continue to add the extra part.

SlowMaro

lol you know whats sad, i dont remember if they were flat top or not....whatever they are, they are the Stock pistons. i dont think the L03 came with flat top pistons seeing how flat top is better , i think the L03 came with the worst of the worsts.

maybe someone on here can tell me if they are dish or flat top if they are stock.

as far as the oil leak problem, we will see what the deal is after i put my intake manifold back on....the silicone ont he back rail looked pretty thin so im betting thats where the oil was comming from, *i hope*

id hate to have taken everything off that needs to come off , to get the heads off....then put it all back on ya know. but this at least eliminates doubt.

RB83L69

I believe the L03 came with flat-tops; perhaps someone else who has worked on one can verify.

Rather than taking stuff apart indiscriminately to fix the leak, go clean the motor up at the quarter car wash; then you'll be able to see any fresh leaks.

SlowMaro

see i tried that , and the leak is super hard to spot, its either the back of the manifold or the back of the passenger head....and itll only leak with it running so its even more hard to feel for the leak with my hands....basicly what im saying is, its in a tough place to visually see where its comming from lol .....i just took off the manifold and replaced all the gaskets and speared a 1/2 thick rail of stv all along the front and back rails and the coolant passages....none around the intakes....lets see if this helps any....and if that doesnt work, ...its definatly the heads, and i feel stupid, for i had the intake, headers and y pipe off today....then put it all back on today.....heh