Volvo 4.3GLPHUB Cranks Won't Start

egrims

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Long time lurker, first time poster.

Been having quite a time getting the 4.3GL back up and running after a cylinder head rebuild. We ended up with the wrong spark plugs and one of them cracked off inside the engine and broke one of the exhaust valves. We pulled the heads off and got them professionally rebuilt. After putting everything back together the motor will crank but it will not turn over. Below is a list of things we've confirmed.

Spark plugs are correct now. Installed Champion RV15YC4's gapped at .045". Verified there is spark running the engine with the plugs pulled out (one at a time) and grounded. I'm not the best at confirming 'good' spark but it is sparking.
Replaced distributor cap and rotor.
Set timing on cap/rotor to rotor pointing to Cylinder #1 with Cylinder #1 at TDC.
Verified fuel pump is operating correctly, pulled line connected to pump and saturates a towel when trying to crank the engine.
Verified fuel is getting into the carb visually.
Dropped the carb and verified float / jets are operating as should be.
Verified compression on the cylinders after the rebuild. Was around 140-150.

We didn't touch anything else to do with timing besides taking off the distributor when putting the new cylinder heads on. At this point I'm completely at a loss for what else it could be. Compression, gas and spark are present. It should at least turn over for a few seconds. We even tried putting some gas directly in the carb and it wouldn't kick over. Also tried starting fluid on multiple occasions. We are getting some puffs back up through the carb during starting that is slightly concerning but I'm assuming the timing isn't completely perfect yet but I feel it should be close enough to at least run for a couple seconds.

Any help would be greatly appreciated. Thank you.
 

alldodge

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First stop using starting fluid, it can damage things

Need to clear up some terms

I'm seeing it will crank but not turn over, for me these terms are the same. The motor won't crank or the motor won't turn over, both say the starter is not cranking/turning over the motor. I believe your saying the motor will turn over but it will not run.

Backfire thru the carb means its out of time.

If your on No 1 compression stroke then the distributor points to 1 and rotates clockwise. Keep in mind you can also be 180 degrees out and firing on 4



V6 firing order.gif

If all is in order, I would get a spark gap tester so you can verify the spark is white or blue and is large enough to jump .045 gap
 

egrims

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Thank you very much for the quick response AllDodge. Sorry on the terms, you are correct. The starter motor is cranking, I'm getting spark but it will not run.

As for the timing order at one point I believe we were pointing at 4 and it was rough turning over. Started getting sparks at the battery and lots of heat through the battery cables due to the power being dumped into the starter. When we re-adjusted the distributor that went away but it now just won't run.

Good call on the spark gap tester. I will pick one up and confirm the spark color.
 

alldodge

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This sounds like your way off on timing. Can you remove the port side valve cover, then bump the starter until bort valaves close on No1, then continue until the timing mark aligns? If you can do this then drop the distributor in and if should start.

If not, move the distributor more, until it starts to fire, or if it gets worst, go the other direction. May need to pull dissy a couple times if need be to turn it far enough
 

Scott Danforth

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you need to properly stab the dizzy

first, pull the dizzy
then with all the plugs out, put your finger over cylinder #1 hole. when your finger pops off the hole, back the motor up until the timing marks line up

then when you drop the cylinder in, make sure the rotor is pointing to #1 tower on the cap. due to the helix of the dizzy gear you will need to account for this. also, once you drop the dizzy in, you will need to turn the motor over until the dizzy drops onto the oil pumpshaft

install dizzy hold-down clamp, loosely

then use the timing light to set timing, and lock down dizzy
 

egrims

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Thanks for continuing to share ideas. We did pop the plug out of Cylinder #1 and put a straw down in. Rotated until the straw was sticking out the most and then aligned timing mark and put the distributor in and pointed it to #1. I will verify that again though while I'm waiting for the carb gaskets to come in since when we verified that we were also doing what seemed like a dozen other things.

Thanks again for all the help, much appreciated.
 

alldodge

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We did pop the plug out of Cylinder #1 and put a straw down in. Rotated until the straw was sticking out the most and then aligned timing mark and put the distributor in and pointed it to #1.

That will either be on 1 or 180 out on 4
 

Lubak572

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Will it even "run" 180 off? My 6.2's wouldn't just backfired thru the exhaust. I will be doing this procedure soon.
 

Saline Marina

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So the basic conundrum is that the full 4-stroke combustion cycle takes 720 degrees of crank rotation to complete. It seems like every TDC is the same but there's a "correct TDC" for setting timing and an "incorrect TDC". Consider on the "correct TDC" both intake and exhaust valves are closed and the upward piston is compressing the charge. On the "incorrect TDC" the exhaust valve is just closing and the intake valve is just opening. I recommend taking the rocker cover/valve cover off the #1 side and observe the motion of the rocker arms on the #1 cyl. At "correct TDC" the valves will be "quiet" or not-moving on both sides of the piston apex.

The procedure Scott posted is also good, to "feel" the compression stroke of the air pushing out the spark plug hole.

Once you get the correct TDC, then align the distributor rotor with the #1 post (it can be any of the 6 possible) and continue adding plug wires around. I forget which way the distributor rotates. This should be good enough to start the engine.

Then you need the timing light and the little harness which applies 12vdc to one of the pins on the ign module (I extended the +12vdc lead-to-alligator-clip on mine to make it easier) to take out the variable effect of the ignition module and put it in "base timing mode" where it can be accurately set by gently rotating the distributor base as the engine idles. As you get more advance the engine slows way down and seems like its going to stall, but that will go away when the timing-harness is removed. If it does stall, its a good idea to unclip the +12vdc alligator clip before restarting.
 

egrims

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Alright so a couple things. First you guys are awesome. Second you pretty much were all correct. In my case it ended up being timing. I'll post a link to a video below that helped me visually understand what was going on as well. I took over the valve cover and popped all the spark plugs out. I rotated until Cylinder #1 valves stopped moving and then advanced to the timing mark. My original timing alignment with the cap/rotor was out. So I took the distributor out and realigned it to be where I needed it to point to #1 at this point and still have my cable reach. Bolted everything together and it tried to run but was still struggling. Bumped the cap a little bit until it ran and then fiddled with the distributor cap while it was running to hear it smooth out a little bit. Went back later with a timing light and timed it out properly.

Thanks for all your help, it is greatly appreciated.

https://www.youtube.com/watch?v=O8H54pKeNEc
 
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