after pull the heads won't start

[John_S]

Re: after pull the heads won't start

Should be able to tell compression stroke by watching rocker arms (if you have cover off) or the compression gauge and turning over by hand.

 

[Windykid]

Re: after pull the heads won't start

Ok I am going to throw this out there. Dont stick a screw driver in the spark plug whole. Use a straw or the balancer mark.

Did you do a valve adjustment when you replaced the head gaskets?

Is the engine turning over fast enough to start?

And the distributer controls the spark as to which one fires and what order.

Have you spark timed the engine?

 

[rodbolt]

Re: after pull the heads won't start

easiest way to set the distributer, rotate the engine in its normal rotation,watch the #1 cylinder intake valve or rocker, when it closes continue rotating until the TDC marks line up. your now on #1TDC compresion stroke.
now set the disrtibuter in place with the rotor pointing at the position the #1 cap tower is at. remember as the dist falls in it will rotate. now rotate the engine 2 revolutions,recheck the rotor to #1 tower alignment. if its very close on to the next step.
hook up all wiring, turn the key on, with an old plug or a spark tester in the #1 plug wire boot rotate the dist CCW and CW. you should see a spark.the last rotation should be in aCCW rotation, now the dist is set close enough to run.
as far as valve adjustment some late GM engines use a shouldered stud and you simply torque the nut, others still used a 1 turn past 0 lash.
if yours are the 1 turn past 0 lash then rotate the engine in its normal rotation, watch the intake valve for the cylinder your going to adjust, when it closes and the lifter is on the cam heel then rotate the pushrod between 2 fingers while tightening the rocker nut, at the fisrt reistance your at 0 lash, turn 3/4 more and then do that cylinders exhaust valve, move on and repeat with the next cylinder.
there is a method to do this only rotating the crank twice but for the novice its very confusing.
but first you need to identify the correct rocker tightening procedure for the particular engine being worked on.

 

[Don S]

Re: after pull the heads won't start

120ish give or take 5 on all

One question about your compression readings. Were those done BEFORE or AFTER you pulled the heads? If it was done before, it means nothing, need to know what it is now.
If you have valves misadjusted, it won't fire at all.

Here is the other method rodbolt was mentioning.

 

[John_S]

Re: after pull the heads won't start

Unfortunatly, we can not link to the online merc manuals anymore Copy and paste is rather ugly and no graphics. I highly recommend getting the Merc manul over Selec. Assuming a late model vortec and manual 31:

OK - YOU CAN IGNORE THIS BECAUSE DON CAN POST A PIC QUICKER THAN I CAN CUT N PASTE AND RE-FORMAT!


3A-38 90-864260 OCTOBER 2001
Valve Adjustment
Engine Stopped With valve cover removed, adjust valves when lifter is on low part of camshaft lobe.

1. Turn engine in direction of engine rotation until mark on crankshaft balancer lines up with center “0” mark on timing tab.
NOTE: Ensure engine is in cylinder number 1 firing position by placing fingers on cylinder number 1 valves as mark on crankshaft balancer comes near “0” mark on timing tab. If valves move as marks align the engine is in cylinder number 6 firing position and should be rotated 360 degrees to cylinder number 1 firing position.

2. With engine positioned as in Step 1., adjust the following valves.
Description Cylinder Number
Exhaust Valves 1-3-4-8
Intake Valves 1-2-5-7

3. Adjust the valves indicated as follows:
a. Loosen rocker arm nut until valve lash is felt at valve pushrod.
b. Tighten rocker arm nut until all valve lash is removed. Zero valve lash can be felt by moving the valve pushrod up and down between the thumb and forefinger until there is no more vertical movement of the pushrod.
c. Tighten the rocker arm nut an additional turn (360 degrees). No other adjustment is required.

Engine 5.0 l (305 cid) / 5.7 l (350 cid) / 6.2 l (377 cid)
Intake and Exhaust Rotate the valve rocker arm nut clockwise
360 degrees (1 turn) from zero clearance

4. Turn engine in direction of engine rotation 360 degrees until timing tab “0” mark and crankshaft balancer mark are aligned. This is cylinder number 6 firing position. With engine in this position, the following valves may be adjusted as previously outlined.

5. With engine positioned as in Step 4., adjust the following valves.
Description Cylinder Number
Exhaust Valves 2-5-6-7
Intake Valves 3-4-6-8

6. Adjust the valves indicated as follows:
a. Loosen rocker arm nut until valve lash is felt at valve pushrod.
b. Tighten rocker arm nut until all valve lash is removed. Zero valve lash can be felt by moving the valve pushrod up and down between the thumb and forefinger until thereis no more vertical movement of the pushrod.
c. Tighten the rocker arm nut an additional turn (360 degrees). No other adjustment is required.

 

[JustJason]

Re: after pull the heads won't start

Ok, been there, done that, but how do you know if the cam is set to fire, #1, or #6,? They're both at TDC at the same time?

ok, what i personally do is pull #1 plug, disable ign system, hook up remote starter and put my thumb over the hole. I'll then "bump" it till i feel compression. Then i'll remove the remote starter, put a socket on the balancer, stick whatever i have handy thats solid down the cylinder, and SLOOOOOOWLY spin it up to tdc by hand. I have to put on my imaginary "machinist" gloves for this one because you have to be gentle and aware of what your hitting on top of the piston. you certainly don't want to sticking something in the ring gap, but on top of the piston. obviously a dial indicator is the best... but unless your looking for a bent crank, who has one. if you go slow, and don't rush it. my method (as taught to me by the elders) works every time.

 

[Don S]

Re: after pull the heads won't start

You don't have to stick anything into the sparkplug hole to feel the piston.
Once you start feeling compression building in #1 cylinder, then you know it's coming up (that is what causes compression) continue turning till the timing markes line up on 0. That is 0? TDC on #1 cylinder on the compression stroke.
You don't have to pull the valve covers to see the valves, both will be closed on #1 cyl. or you wouldn't be able to build compression.

 

[JustJason]

Re: after pull the heads won't start

i still do the screwdriver out of habit.... reason being is i was chasing a devil a few years back that the final result turned out to be a broken key and a spun balancer... i was called out for a "runs ruff" situation. I rebuild the carb (which it did need badly) but when i reinstalled it i couldn't get the dam thing right. It was all because I wasn't timing it correctly because of the spun balancer. The timing was previously "adjusted" by hand by the owners "expert friend" to compensate for the carb issue until the carb got fouled enough not to run. (i practically had to beat that one out of the guy)
So either way... it only takes me 5 minutes to do... and whenever its suspect i just do it that way. i'd rather know its at tdc vs having the balancer tell me it is. 99% of the habit comes from outboards... i've only seen 1 key sheared on an I/O and it was the 1 in the story above... but i've had quite a few OB's that have had sheared keys (can you say johnson!!)

 

[MikDee]

Re: after pull the heads won't start

ok, what i personally do is pull #1 plug, disable ign system, hook up remote starter and put my thumb over the hole. I'll then "bump" it till i feel compression. Then i'll remove the remote starter, put a socket on the balancer, stick whatever i have handy thats solid down the cylinder, and SLOOOOOOWLY spin it up to tdc by hand. I have to put on my imaginary "machinist" gloves for this one because you have to be gentle and aware of what your hitting on top of the piston. you certainly don't want to sticking something in the ring gap, but on top of the piston. obviously a dial indicator is the best... but unless your looking for a bent crank, who has one. if you go slow, and don't rush it. my method (as taught to me by the elders) works every time.

I'd rather do it this way, then just the finger method,,, It works better for me, besides sometimes there might be other issues like a sheared key, as jason mentioned.
(Hey jason, by the way there's a word missing in your signature, "be")

 

[Windykid]

Re: after pull the heads won't start

At least use a straw so you dont put a hole in the piston.

 

[JustJason]

Re: after pull the heads won't start

DOH... thanks mike!

 

[Don S]

Re: after pull the heads won't start

doesn't mean it's supposed be to that way

Ya put the "be" in the wrong place!

Might want to stay away from moving parts today Jason

 

[MikDee]

Re: after pull the heads won't start

To be, or not to be, that is the question,,, lol

 

[JustJason]

Re: after pull the heads won't start

its this dam flu i got... makes paying attention verrrrrry hard. i guess it's a good thing i have you guys watching!! that means i don't have to.

thank god for promethazine with codiene

 

[flabum]

Re: after pull the heads won't start

When you checked for spark, were you checking it out of the coil lead or out of a spark plug lead? Asking because if you checked it at the coil lead, a bad rotor can give you no spark at the plug leads.

 

[krisnowicki]

Re: after pull the heads won't start

ok so todays results :
So when i started I justed turned the engine over to see where we are at ... . Compression is at 151-170 I check it with a different gauge that is newer and better. So I turn the engine over with the plugs an it back fires out the carb.... I look at the valves at when I am at 1 TDC on the dist. I am at 6 TDC on the Valves. So I pulled the dist and rotated the engine to 1 TDC both valves down and place the dist in aligned the rotor and cap to 1 and began to turn it over. Now all i am getting is a back fire out the exhaust not carb ( big bang).
Also my fire now red on the numnber 1 plug. Tommorrow I will pull each plug and test them indvidually as i did before to make sure they are all blue ... I did this with a fresh charged battery what would cause the spark to be red not blue? So tommorrow I will pull all the plugs and check agian. All wires are in the firing order and Timing is set to 1 TDC..... thanks again for the help and spirited method debate.

 

[krisnowicki]

Re: after pull the heads won't start

i just wanna go fishing hehe

 

[Don S]

Re: after pull the heads won't start

If you have spark to all 8 spark plugs, then you have a timing problem. you just haven't found it. All the info you need to make it run is in this thread, you just need to find out what is wrong on your engine.

 

[krisnowicki]

Re: after pull the heads won't start

what is the most common cause of a cam timing slip?

 

[krisnowicki]

Re: after pull the heads won't start

forget the last comment the cam is fine has to be.. I am going to start from scratch tommorrow ...