ugh. problems getting the truck to run after putting my old engine back in -Timing? Valve lash??

[scouthead]

1988 TBI 5.7 manual trans


I am beat up and sore. ended up spending most of the weekend swapping my old motor back into the blazer. something is wrong.

the few times I've been able to get it running -seems like a timing issue. scratching my head and could use some help. Its parked at my office and cant stay here - needs to move tonight or tomorrow.

the motor that I just put back in had low compression in one CYL, but was actually still running well when pulled. It had a broken piston ring. I replaces the rings on that piston and did a quick hone job on that CYL only. the cam never came out or moved... I put the head back on and adjusted the valves. pulled the knocking motor sat morning- put this "repaired" engine back in.
I spent all day yesterday trying to get it to run.

-its getting fuel. injectors are spraying.

i have had it running (horribly rough- backfiring - stumbling) and it sounds like a timing issue.
- i shocked myself trying to turn the distributor when my hand was swetty... was off one of the plug wire terminals- not the coil thankfully - its definitely sparking...

i twisted the distributor counter clockwise and was able to get it to idle, but it sounds RETARDED - last time I had an issue like this, the timing was retarded by 20-30 degrees, and the computer was trying hard to catch up, but ran out of adjusment. after fixing the base timing, I was able to get it running well - NOT THIS TIIME. Im twisting the distributor way farther than i think should be necesssary. it feels like im turning it so far that #1 terminal and plug wire are crossing over into #2s territory. The wiring on the coil and the length of the plug wires prevents me from twisting the distributor any further...

When I disconnect the ESC wire - you would normally be able to set timing to 0 degrees - the engine dies- its not capable of running when the computer isnt helping with timing. i cant even see the mark on the balancer when my timing light is going. ive set the motor to TDC about 10 times and pulled/ reinstalled the DIZZY and rewired the cap... checked/doublechecked the firing order.

I have tried another distributor (with what is probably an incorrect ICM) and not having much better luck.

 

[scouthead]

dont want to chase the same things over and over and over...

Im going to restab the distributor ONE MORE TIME tonight, and try to make sure its the correct dizzy that went with this motor and ecm. after that I am going to assume that on the 15th try, there is no way the timing is 180 degrees out.

I had help swapping the motor- the guy is very eager to help, which is great, but when something goes wrong, i always worry about anything that i didnt see, or that was not done by MY HANDS... but I'm also worried some of the components may have gotten mixed up with what was laying around from a 1995 auto trans suburban...


havent been able to find any broken or frayed wires yet- map sensor, and everything else looks to be plugged in... vacuum hoses look good.

 

[scouthead]

I have tried to move the distributor up and down a tooth on the cam to see if that makes a difference. rotor position @ TDC was tried in several places as shown here.

 

[Bent77]

Tbi is timing picky. Put the engine and TDC for cylinder 1
Put the dizzy in, rotor pointed at 1
Snug dizzy down, and start it with the wire disconnected. Set it at 0
Turn it off
reconnect it
Start again

 

[max 02]

Tbi is timing picky. Put the engine and TDC for cylinder 1
Put the dizzy in, rotor pointed at 1
Snug dizzy down, and start it with the wire disconnected. Set it at 0
Turn it off
reconnect it
Start again

Why leave #1 disco Mark?

 

[Bent77]

Why leave #1 disco Mark?

Leave the timing disconnect wire for the ecm disconnected. (Not the plug wire,sorry)

The ecm doesn’t process it being manually plugged or unplugged as a service item, it processes it as an electronic malfunction and won’t time it as you set it

 

[scouthead]

ive never done the initial start up with that disconnected- in the past, always started it, let it run until warmed up, and then disconnected and set the base timing to 0

usually the computer compensates very well for the timing being 10-15 degrees advanced or retarded? so ive never had this problem in the past, other than the time i had a distributor installed 180 degrees out

 

[scouthead]

at this point, I'm wondering if the valves are too tight. I was having a hard time finding zero lash when I adjusted them- usually spin the pushrods in my fingers, but this motor sat for a year and i assume the lifters were dry after spinning the motor by hand a bunch of times, and having upside down on the stand a bunch of times? I felt like several of the lifters were plunging and i was not getting any change in the "feel" while I spun the pushrods... i did several of them 2-3 times to make sure i was confident...

now that im having problems, im not so confident anymore...

Lets say the valves have been overtightened... I should be able to put my compression tester in each spark plug hole and know immediately after spinning the motor 8 times?

I would assume that if the valves being tight were causing some of this problem, and if i measured 165psi last year on 7 cylinders, and then pulled the motor and removed a head... at least the head I did not disturb should still have similar compression numbers to what i recorded last time? -that is unless the valves are too tight?

 

[Wes Harden]

Was my first thought, tight valves.
If you've restabbed the dizzy a few times, you will need to double check it after readjusting the valves. Did you adjust both sides?
Use the procedure. Set number tdc do intake # so n so and exhaust x y z, then roll it over to #6 tdc and do the rest.
While it's on # 1 tdc check the dizzy, I like tbi pointing straight forward.
Good luck don't let this issue get flustered easier to miss something

 

[scouthead]

Was my first thought, tight valves.
If you've restabbed the dizzy a few times, you will need to double check it after readjusting the valves. Did you adjust both sides?
Use the procedure. Set number tdc do intake # so n so and exhaust x y z, then roll it over to #6 tdc and do the rest.
While it's on # 1 tdc check the dizzy, I like tbi pointing straight forward.
Good luck don't let this issue get flustered easier to miss something

yup- entire motor got the valves adjusted. and that was with the lifters "dry". they had just been sitting a while and the motor had been turned over a number of times by hand.

lifters were probably new (when i bought them 40-50 thousand miles ago) -comp cam's version of GM standard vortec hydraulic rollers.

when i adjusted them about a week ago - i noticed some lifters had quite a bit more resistance than the others- maybe some still had oil in them, or the internal springs are getting week on a few? I may have got a false "feel" trying to spin some of the ones that were weaker than the rest.

this was the only time i ever adjusted the valves using the "cheaters" method outlined in the hanes books... adjust to #TDC, and then do half the valves as listed... then spin the motor and adjust the other half as listed...

it may not matter, but i usually verify that piston is at the top of its travel before adjusting both valves above it... all 8 sets, one at a time.

 

[scouthead]

but, on the thought of valves being too tight- that would make it run terribly, or not at all... but not affect electrical timing? shouldn't the ICM still fire a spark at the correct time- compression or no compression? I would think I would still see the timing marker in the strobe flash from the timing light?

the only time I had it running well enough to check yesterday - the timing marker was flashing at 12 o'clock high (and the timing disconnect plugged in at the time) ... which is waaaay off the scale, and hard to see without sticking your head in the engine bay and trying to look at it from below.

none of my attempts to disconnect the timing lead on the firewall went well - by the time i got to the timing light the engine was barely running. most of the tries it quit immediately... on the few tries where it stayed on- I could not even see the timing mark , which made me think it was 180 degrees out... but I crawled under the truck with the timing light, and couldn't see the mark on the other side either when the strobe went off... the mark had to have been somewhere blocked by the water pump or another accessory at the time? which would mean it was way off from where it is supposed to be?

 

[centexk5]

They shouldn't unless it's causing knock and the computer is trying to retard the timing. Now that you've had the engine running and the lifters have pumped up, go back and recheck the valves to make sure they are good.

 

[scouthead]

probably have to pull the spark plugs if I'm going to be turning the motor for valves... maybe I will put the compression tester in all the cylinders first... then if I get rock solid numbers, I might look elsewhere first and avoid stripping the top of the motor to get at those valve covers... cant remember how much has to move to get the valve covers to come off - but I'm pretty sure its a can of worms.

if a couple of cylinders arent holding pressure, that might be an instant notification that the valve covers need to come off

 

[Wes Harden]

IDK about cheater ver, this is the way I do it always, this the way gm service manual says to do it. I suppose if you had a radical cam or 7-4 swap cam you could get into trouble.
Stick the dizziy with rotor pointing straight forward. align the timing marks at 0 put the rotor dead center of #1 cap tower, lock down dizzy. double check firing order, esp 5 and 7.
All of this provided the damper hasn't turned and is correct 1 for timing cover pointer. If you suspect the damper marks are off, time it using a vacuum gauge on manifold vacuum. Set the timing for highest vacuum. Not perfect solution but truck will run.

 

[scouthead]

Prayed - that didnt work this time.
stared at it- no change.
yelled at it. no change.

I ripped half the stuff off the top and front of the motor so i could get the valve covers off. I went through all the valves- no more trying to spin the pushrods to feel zero lash. this time I backed the nuts off, let them sit for a few min, and then adjusted them down until the pushrods no longer wiggled up and down... this left them looser than what i would typically consider zero lash when i spin the pushrods. Then I added 1/3 of a turn to the nut (everything i see in print says 3/4 to one full 360 revolution- and I see things on the interweb claiming 1/4-3/4). I assume I'm on the loose end of valve adjustment now?

left it on TDC#1 as i put everything back together... couldnt hurt right? absolutely sure ive got the motor in the correct position to check the distributor timing...
yeah but, i hadn't put the spark plugs back in yet, and when i was tightening the fan down to the water pump (belt was on), I must have turned the motor. I looked down at the timing mark, and it was not THERE anymore! WTF?! after looking at it for a minute, im pretty sure i spun the fan clockwise, which spun the crank counterclockwise... so i spun the crank clockwise again to get it lined up again.
-pulled dizzy cap
-everything looked GREAT- seriously the rotor was pointed EXACTLY where it needed to be- straight at #1 cylinder. the cap and body of the distributor was lined up Perfectly, so I left it all alone and put the cap back on.

reconnected battery - jumped in... 5-7 seconds of cranking without so much as an attempt to fire up and run. tried a second time- same thing, but with a couple of pops out of the intake. it was already 11pm and i had to get that truck off our loading dock, so i cranked the hell out of the distributor and advance the bejeezus out of it like last night. It started, sounds like a boat. barely idling, wont let me rev it up... with the TC in low range, i was barely able to coax the thing outside and get it parked. had to leave it outside in a bad neighborhood.

There is still a very small chance that the dizzy is 180 degrees out. I was pretty sure i knew which direction from TDC the engine had been accidentally turned, but im not 100 percent sure.
I will take a look at the dizzy again tonight, but unless i find some miracle wire thats broken, or a hose thats hanging off of something... IM SPENT. I havent had a full nights sleep in almost a week, and this truck was not supposed to be stranded here at my office.

If i cant figure it out in a couple hours tonight- i will have to beg the boss for forgiveness and ask if i can limp it inside the warehouse over night until this weekend. I have a trailer up for sale - a few interested parties want to see it this week. if it sells, I will ask a friend to tow me and the blazer over there, so it can be off the street and rot for a while.

 

[scouthead]

guess im going down the rabbit hole to start looking at what sensor/computer/ICM could have been damaged, or somehow just failed over the last couple days.
really really did not have time to do this- had hoped for a a quick start up after getting the "old" motor put back in the truck.

Ive not had this much trouble firing up a TBI 5.7 - EVER.

 

[scouthead]

soooo as a recap:
engine 1 had low compression in one cylinder, but still ran very well. if you got the RPMs up it would eject oil from dipstick tube... BUT, it still ran well. no problems with timing or fueling. I pulled the engine and set aside.


engine 2 was well used with about a hundred thousand miles. good compression and oil pressure... swapped it in, and after getting the timing set, it ran well for about 5-7 thousand miles, and then developed a knock. pretty sure it spun a bearing. I unplugged a spark plug wire on the cylinder that seemed closest to the noise, but the truck still ran very well as a 7 cylinder (just parking and moving it around town). No timing or fueling issues.


engine #1 is back in the truck.
it had one head pulled off, broken rings replaced one the cylinder that had low pressure. that was it - no disturbing the timing chain.
now having horrible timing issues, or some other kind of problem. 3 days ago. engine 2 was still in the truck running fine on 7 cylinders with its bearing knock.
Everything on #1 should be good to go. not sure what to look at next.

 

[Wes Harden]

Eng # 1, how old is the timing chain? Does it still have the nylon tooth cam gear? If so it may have been worn enough when pulled and decided to slip since install. Esp if engine has been coughing, spitting, and front firing.
The distributor, is the same for both engines?
Has cap been checked for cracks? You said you got bit when holding cap, crack is suspect.
I have run my last 4 or 5 sbc hrd cam builds at 0 lash + 1/2 turn. No issues.

 

[scouthead]

Eng # 1, how old is the timing chain? Does it still have the nylon tooth cam gear? If so it may have been worn enough when pulled and decided to slip since install. Esp if engine has been coughing, spitting, and front firing.
The distributor, is the same for both engines?
Has cap been checked for cracks? You said you got bit when holding cap, crack is suspect.
I have run my last 4 or 5 sbc hrd cam builds at 0 lash + 1/2 turn. No issues.

engine one has a billet "baby lt1" roller cam from a b-body in it (think Vortec 5.7 truck cam specs, but billet- not cast) no nylon that im aware of- pretty sure its part of the cam shaft and is cut into it? I robbed the oil pump drive gear from the same 5.0 LT1 as the cam (steel gear), and swapped it to my original 1988 distributor, so the cam and drive gear are still "matched". distributor total milage over the years is prob around 120K now... cam and gear from prior life plus the use in my engine is probably closer to 150K now.

timing chain is a comp cams double roller - had to shave the face of the block down so it would fit, but it should be a lot longer lived than a stock timing chain? It was new, and installed when I first built engine #2 -has about 60K on it now. fairly certain that there was no nylon on those gears.

distributors between the 2 engines have been kept with their respective camshafts... just trying to prevent premature wear. I'm not sure if their is a difference between the 2 pick up coils and ICM modules (they have different numbers on them), but i HAVE tried both over the last couple days and neither seems to be any different.

 

[Wes Harden]

Nylon coated cam gear would be factory or oem only, I am not aware of any aftermarket nylon cam gears. I doubt that the double roller chain slipped. inspect the cap, have differnt caps and rotors been tried