I approciate any help i can get on this car, it's an 88' Pontiac Firebird 2.8L V6 Vin S

I've changed several parts for a semi-rebuild nothing internal such as rocker's, lifters, cam, but all the externals such as sensors, booster, lines, vac lines, tune-ups all that over 1,500 in parts

I took my car out on the highway yesterday and floored my gas pedal and only got up to about 65 then it would slowly build up to faster speeds after awhile, now i know it's not normal since i also struggle to make it up hills if i floor it i might make it up to 40 overtime which isn't normal, and i took care of the cat converter (test pipe didn't help)

I've been messing with the valve lash since i did do a head job just to get rid of all those 20 yr old gaskets, i would lossen them all put the crank on TDC do the correct # cylinder's intake and exhuast turn 360* samething do the correct # cylinder intake and exhaust as stated in Haynes and also tighten untill all lash is gone ( this is what i do i push it up/down feel for lash, i also look at the rocker and nut and if i see oil shimmer through between the bolt and rocker i tighten it untill that oil isnt able to shimmer or move, then i tighten 3/4 that's how i find zero lash or do you think that method is wacko?) My valves also don't tick.

The car has 193,000 miles on it, it has been previously honed and had some internal repairs done ( not sure how long ago can't tell ya didnt own it then)

ANY advise is nice, thank you.

Im going to run a compression test tommorow morning.

 

#1- 118-120
#2- 120
#3- 65-70 Ouch!
#4-86-90
#5- 90
#6- 105-110

I put a teaspoon of oil in each spark plug hole after getting the numbers above and gained barely if any compression, maybe 1 PSI or so.

New head gasket, so think its my lash adjustment?

maybe it's my cam =((((((((((((((((((((

 

have the heads been skimmed to make sure there true ???

 

No, btw i have new numbers with spark plugs (all 6 removed)

#1-127
#2-140
#3-80-85
#4-95-100
#5-100-105
#6-105-110

#3-#4 are adjacent cylinders so what could the low compression be due to worn push rods?

I used the old push rods i might of mixed 1 or two from there original positions think it might be that?

It starts it runs just has poor driveability

 

the pushrods should be fine, try loosing all the rockers 1/4 turn and test drive they may be on the tight side.

 

maybe #3 has a bad exhaust valve, but are my other readings ok?

 

#3 and #4 are not adjacent cylinders. They are on the opposite sides of the engine. Soundsto me like you didn't do the valves properly.

 

watch the intake valve open/close then place the timing marker on TDC aka 0.

adjust valves number 1,5,6 Intake 1,2,3 Exhaust
Turn 360*

adjust valves number 2,3,4 Intake 4,5,6 Exhaust

Adjust to zero lash i would remove all slack from rocker arm then tighten very slowly so the push rod has zero movement up/down movement

then tighten 3/4 to preload

what am i doing wrong?

and im not up to par with my terms lol, but they are opposites, since they are new head gaskets, and oil doesn't raise compression my valves are leaking or my springs are weak.

If i shoot compressed air into my cylinder were do i listen for hisses?

 

that wouldnt work, and its a bit pointless. your making this too complecated. id slacken the rockers off, then do the test again, wont hurt having your engine a bit tappety just for compression test then at least you can take that out of the equation. check the torq settings on the head bolts too. if that dont work and as you say oil didnt help then youve got some bad valves. i would have thought even bad springs get the valves shut just not as fast as they used too, so i wouldnt worry about them either.

 

Hooked up a vacuum gauge got a reading of 4-7 hg the needle was bouncing somewhat, once it went into closed loop i got a reading of 14-15 hg, and the needle was a tad bouncy, not incredibly bouncy just a tad.

Not sure if i did the crank test correctly but I unhooked the distributor wire to ignition coil, unhooked the fuel pump fuse, hooked the gauge with a T up to the back left of the plenum on the other side of the brake booster line, and cranked the engine my reading was 0, the needle jittered in the zero mark but didnt move at all.

maybe i did that test wrong.

 

Have you ever considered worn cam lobes?.or a lifter not pumping up..valves not opening fully will also give you low compression results.

 

Really if they didnt open fully wou;dnt the compression be higher? worn cam lobes hmm no i havent good idea, and the lifters seems to be ok.

for the cam it requires a tear down to check clearance correct?

 

You can get more air into a cylinder if you have a valve opening fully..less air if its only opening part-way.Think of a engine as a air pump.Its has to compress air and the only way to get air into that cylinder is by the opening of the valve.You could pull the valve covers off and rotate the engine around by hand watching the rocker on each cylinder open and compare them to a known good cylinder?A dial indicator with magnetic base works well too then you can actually watch the needle move.Otherwise yes you would need to pull the cam and measure the lobes.

 

maybe im looking toward the wrong place, maybe its my ignition system i mean the car runs fairly good in closed loop alittle rough in open loop, but it just doesnt have that quick power it has that slowly building power (hence why i think it's compression related)

 

I dont think its your ignition system..usually the car will run rough when warm or closed loop you said it runs fairly good.The ignition will break down when it gets warm.When a car is idling it takes more power to jump the spark gap then at high RPMS.I used to do this test to every car that came in with performance problems and its real easy.If you have a auto trans...put the car in drive and hold one foot on the brake pedal and the other on the gas and give it a little gas (your putting a load on the engine) and if it starts to run rough your ignition system has a weak component.Dont floor it or do it for a long period of time either cause we blew up a transmission like that.I was going to say check your converter but you stated you removed it?.A blocked air filter or plugged exhaust will starve an engine of power.Not enough air in and not enough out....thats why I said think of an engine like an air pump.

 

yes i have a gutted cat on for temps as it was clogged, but i then realized that wasnt my power problem, it runs decent idle (maybe because i replaced everything out the waaaazooooo on it) but when going up in rpm's (in drive) and driving the power seems to be missing and it can't get above a certain point without excessive travel, my vacuum is about 17hg warm idle (closed loop rechecked)

 

Just out of curiousity have you checked your fuel pressure?.or fuel system?.17 inches is good..if that checks out then I would have to say you might have your valves too tight.After driving the lifters will pump up and increase lash possibly holding the valves slightly open creating less cylinder pressure?.I just got done redoing mine again..4th time.I really feel like an idiot...had them too tight.I push up and down on the push rod until I dont feel any play and you can tighten them an additional 1/4-1/2 I think 3/4 is too much.Personally I think 1/2 would be too much..but that my opinion..I havent tried them there so I shouldnt say too much.

 

No Joke, I've done valve lash so far 9 times, it should of been right at least once? I have tried 1/4 1/2 3/4 at zero lash eliminating all up/down movement then pre-loading the lifter, i know what i'm doing i just can't diagnose this thing correctly..

I've never had a tick and i have about 45 PSI fuel pressure.

 

3 and 4 arent adjacent. Are you sure you have your cylinders correct? That could screw you up bad, especially with the method of valve lash adjustment you are using. On the drivers side of the car, the farthest forward cylinder is #1. The next one behind that, still on the drivers is #3. The next is #5. On the Passenger side head, the first is #2, the next is #4, and next #6. If your valves arent adjusted properly you could get the compression results you have. Even if youve done it 20 times the exact same way, it still wont be right. Make sure you dont mix up exhaust and intake as well. Maybe you should try doing it one cylinder at a time, and turn the crank at the front with a ratchet. Adjust the valve when its fully closed, and you can see its fully closed.

As far as your compression, you will never have good fuel mileage and power with that compression. You need to worry about that. Your low vacuum is definetly because of your low compression. You need to figure out why your compression is low. I recommend a leakdown test. You say your motor has been opened up and honed. If the person who did that did a crappy job, it may have ruined the motor. Your rings may be worn, cylinders may be worn, block could be warped, various other things. That block has to be cleaned really well after honing for it to last.If your motors gone, its gone. You can get a remanufactured long block for $1000. Youd spend that on machine work and new parts, plus youd have to do all the work.