Recently put a new cam in.

When I installed the new intake manifold gasket, I didn't use any rtv around the intake ports. I didn't think I needed to. This is the gasket I used.


I have never used RTV on an intake gasket like this and I've never had a problem.

Vacuum gauge reading is showing about 8 in, bouncing up to 9 and down to 7 rapidly. I think this might mean an intake manifold leak.

I sprayed carb cleaner around the intake manifold and it had no stutter, so I'm guessing it's between two of the ports somewhere. I'm thinking with this cam I should be at about 14-16", I'd even be happy at 12-14" if it ran good. Idle is tuned to 800 RPM.

Compression test showed 115-120 on each cylinder, compression was lower than I thought it would be, but it's consistent (What's optimal, btw?). All rockers are adjusted 1/2 turn past zero lash.

I have triple checked the firing order, and all is well. No arcing wires, plugs and wires are new. Recently filled the tank with 93 octane fuel.

I have reset the PCM and the problem is still there.

No SES light.

I've gone over everything so many times, I'm about ready to take a few hours and pull the intake manifold to see if it helps.

Any other suggestions before I do this? I'm doing it early tomorrow. I'm thinking opti, but it's too much of a coincidence for it to die right after I did the cam install. No fluid of any kind ever touched the opti. I had the radiator and block drained when I pulled the water pump, and the opti was covered in towels (I went the way extra mile to keep the thing protected.

Thanks.

 

was your compression test done with the tb blades held wide open? if it was, its your valve adjustment thats off. 115-120lbs is pretty weak-suck even for a huge cammed lt1. mine cranks about 215-220, but i have higher comp.

 

Throttle was open all plugs out.

Does this mean the valves are too tight? Or too loose? They were at about 3/4 turn, I put them to 1/2 turn, then 1/4 turn, then back to 1/2 turn. Pretty much same results, except with 1/4 turn it was a little noisy.

However, since getting my tune (which I think I needed from the start), I've only set the valves from 1/2 to 1/4, then back to 1/2.

Could the valves not be tight enough? 1.6 comp RR w/poly locks, 7.2 pushrods, stock head height, comp 918's.

Confusing the hell out of me.

 

I bet your intake is leaking.What did you torque it to?Mileage?Out of curiousity-Stock lifters?ZYou sure the comp. guage is accurate?

 

that means the valves are too tight. causing them not to close completely under normal circumstances because the lifter plunger pumps up too much and doesnt allow them to fully seat. also what method did you use to find zero lash and what method did you use to set your lash.

while we're at it what size cam is this? cause if its not your valves being too tight which it doesnt sound like. and your cam isnt some monster sized deal.. you've got your cam in off a tooth and its a whole crap pile retarded because of it and bleeding off compression. probably not what you want to hear. unless you've got a shot of the dots being lined up like this.



i dont know what else it could be being 80psi low on cranking comp is probably about 2pts worth of comp being bled off. if you tell me what cam it is i'll calculate what yours should be be near with the right specs, and then with some severly retarded and see what happens.

 

110k miles, stock lifters, cam is 226/231 559/569 @1.6, intake torqued to 35 ft lbs.

When you told me how far my numbers were off, I went and did another cylinder test, on an easy access plug. I did the comp. test wrong, plus my god damn battery is non stop dying and it's annoying the hell outta me. I don't think I cranked it over enough last time. I used to do it just little spurts of the crank until it got to a set point (on my last car 125 would have been beautiful compression so when it got there and didn't move much I assumed it was ok), this time I did longer cranks.

Here is a new number, and the battery died so I couldn't crank it anymore. I might have been able to get more. Went out there in the pitch black to do this, I had no idea compression was supposed to go that high in this car.


Once I got it to that point, I tried cranking it over again and it clicked.

I'm gonna go pick up a battery charger tomorrow and leave it hooked to my battery so I can actually do stuff to the car. This is probably the most annoying thing I've ever dealt with. Dead batteries man... Cause I adjusted the rockers, then I'd start the car w/out the alt. Stupid I know, I didn't realize I could leave the alt on and remove the valve covers until AFTER the battery was dead.

To find zero lash, I just spun the rod while I tightened the poly lock, until it stopped spinning, then I set my preload 1/2 turn. Also, it seemed as tho everytime the poly lock was finger tight, it was at zero lash.

I had considered it was the timing, so I pulled the cover (waste of time) to find this...


Might be hard to see, but the timing was perfect, just like in your pic above.

 

Is the car still popping when you drive it? Does it feel down on power?Are you sure the vac. lines are all connected and not cracked?

 

It's been popping since I did the install.

Car runs like a total dog, does not run right at all. I can drive it, but I can't give it much throttle, it's just barely driveable. All the vac lines are in great shape and connected correctly. Sprayed carb cleaner on them to test for leaks, and there are none. Even so, there are only 2 lines that could affect vacuum THAT much, and that's brake booster (perfect), and the line that runs into the D/S of the intake (goes into rubber grommet on intake), and that's perfect as well.

I will do another compression test tomorrow. If that checks out OK, and the valve lash is OK (Which I'm assuming it is, because when I was at 1/4 turn it was too loud and not running right, worse than now, so I set it another 1/4 turn (1/2) and it was quiet and runs better, but not good), I'm going to assume it's the intake manifold leaking.

 

I'm willing to bet when I have a battery that I can crank the car with, I'm going to get about 175 psi out of that cylinder, minimum. I know it has to have great compression.

If you can't see it in that pic, it was at 150 psi.

 

The popping makes me think that it is your valves too tight.I set mine at 1/3 of a turn. 1/4-1/2 should work fine.Do them one cylinder at a time.Spin the motor with a socket.Watch one valve go down all the way and adjust the other valve for that cylinder.Its a lot of turning of the motor,but its always right. Hope that helps.

 

well, the only other thing i got for you is to try relashing your valves again. the pushrod spinning method is something i have never used. i usually just pull at the fulcrum of the rocker up and down, or i pull from the pushrod side toward the valve back and forth until i feel the slack run out, which is usually on well oiled threads the first sign of resistance then go 1/2 turn on stock lifters. i also adjust one cylinder at a time, exhaust opening i adjust the intake, intake closing i adjust the exhaust. i do that on every cylinder until i get em all, and i have never had to readjust valves after installing an engine with any type of hyd lifter.

i would think an intake leak would be adjusted for by the computer, like if you leave a vacuum line off the car will just take that as unmetered air and try to adjust for it and throttle up. you'd probably also notice a bit of oil burning if it was leaking from the valley.

 

The way to check for a vac leak between the runner and the lifter valley is to cap off the PCV line, then tighten the oil fill cap and then unplug the breather tube from the TB and zip tie a baggie on it, if it tries to suck the baggie into the breather tube, then vac leak...it may suck it in a little and then spit it back out, thats ok...this is while engine is idling.
If you have a breather on the oil fill, then cap the breather tube to the TB from the DS valve cover and put the baggie on the breather o the oil filler.

 

Well, I had my buddy adjust the rockers once, he's a pro engine builder, that's all he does (SBC's). After I adjusted them a few times, he did them.

Same results, so I thought maybe they're too tight.

So today I adjusted them to 1/4 turn, and it was too loose clattering, and valves weren't opening, car was very dead, so I added another 1/4 turn, which made the car run the same way it did with my buddy's adjustment.

I would think that the computer is only reading the metered air and providing fuel for that air, any air that's leaking from in the intake is not metered and that's whats throwing it off.

I really don't feel like adjusting those rockers again. I do it 8 valves at #1 tdc, and 8 at #6 tdc.

The way my buddy did it was one cylinder at a time. I turned the crank a little bit until he said stop, and he set the lash and preload.

I'm thinking it's the intake, but I'm wondering what I did wrong in installing the last set of gaskets.

 

I don't understand 100%

Cap off the pcv line coming out of the passenger side valve cover? (Or do you mean the pcv line going into the intake on the drivers side?)

Then put a baggie over the port on the TB that I pulled it from?

 

PCV is on the driver side, and then there's a breather tube coming off the pass side vc going to the TB, and the oil filler cap....thats the only 3 ways for pressure or vacuum to enter the crank case if everything is sealed right.
Alot of folks remove and cap off the breather tube so oil doesn't enter the TB and put a breather filter on the oil filler cap/hole...so depending on how your car is currently configured, cap the PCV line or pinch it closed with vice grips, then cap one of the 2 other entry points and put the baggie on the other.
Don't be suprised if the baggie blows up some from piston ring blowby if there is no vac leak in the under side of the intake runner.