Multiple cylinders with no compression.

DHale_510 · Posted: Fri Jun 12, 2015 7:27 am Post subject:

- I believe I am at TDC with aftermarket crank pulley. However I did not install the pulley myself. When I set to what the pulley says #1 TDC the #2 exhaust valve is in rocking position. I guess this is not exact enough eh?

#1 is at TDC ;and full compression] when #3 has the valves both moving [no compression].

Dennis

ORANGECRUSHer · Posted: Fri Jun 12, 2015 9:23 am Post subject:

you can also slide a screwdriver down into the spark plug hole, turn the engine over by hand and you'll be able to see exactly when it's at TDC because the driver will quit pushing out.

Make sure you have the actual #1 cylinder as it is common for some engine tins to actually be marked wrong.
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dcj63000 · Posted: Fri Jun 12, 2015 12:26 pm Post subject:

Im going to attempt to start this weekend. Ty

I Ride Sand · Posted: Sat Jun 13, 2015 9:47 am Post subject:

71StandardReduction · Posted: Sat Jun 13, 2015 6:17 pm Post subject:

I wish you good luck, too.
Like Dale said, get you some run time on your engine before compression checking again.
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ORANGECRUSHer · Posted: Mon Jun 15, 2015 6:17 am Post subject:

And let it warm up quite a bit before stopping and starting again.

I ruined a sportbike engine rebuild just because I was trying to tune the carbs while the motor was breaking-in. Too many short heat cycles glazed the cylinders and it would not seat the rings.
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I may not know everything,but I will try to help if I can
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HERC · Posted: Mon Jun 15, 2015 6:34 am Post subject:

Hopefully the distributor is not 180 degrees off.
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dcj63000 · Posted: Mon Jun 15, 2015 5:10 pm Post subject:

We have compression! There were a couple of causes.
1. I wasn't using the adapter on the compression tester. The tester seemed tight in the spark hole but I don't think it was spot on. Got readings when I used the adapter.
2. I went ahead and actually looked at the piston placement to determine TDC when setting the valve clearance. I set the valve clearance to .006 at actual TDC for each cylinder.
3. Discovered I had compression in all cylinders with the valve covers off. When I put the covers on to attempt a start I noticed i had no compression again! THis is why...

Image may have been reduced in size. Click image to view fullscreen.

The small indents on the first picture are actually where the rocker arms were hitting the valve covers not enabling the valves to close correctly. I was tightening the bolts down too far. I set them to 7 ft lbs and now we have compression. Maybe this will help someone in the future.

The engine is not exactly purring like a kitten but it is firing when you turn the key. It hasn't actually started. Ive been through and through the carb so im guessing it is the timing.

I know the Bosch is set at (roughly) 7.5 - 10 degrees BTDC at idle speed but what to set it at to try and get the engine to start? Does the compufire change this? Thanks all

Dale M. · Posted: Mon Jun 15, 2015 6:52 pm Post subject:

Put the bolt on valve cover up on shelf... Go back to stamped steel valve covers with spring bails... Alloy covers are pretty but that is about all.... The bolt on covers are going to be a continuing source of grief becasue if not tight enough they will leak and if too tight (but leak stops) they will hit valves valves...

Even with steel cover I had issue of rocker hitting valve cover and had to shave a little bit off of rocker so it did not scrape/hammer on valve cover... This occurs on exhaust valves for #1 and #4 cylinders... The hitting also cause valve cover to move and let oil out...

UMMM by the way where your upper cylinder tins...

Dale
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All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

dustymojave · Posted: Mon Jun 15, 2015 7:00 pm Post subject:

Ok. Good work finding those issues.

Have you tried static timing the distributor?
- connect a simple 12V light with alligator clips to the same side of the coil as the small wire to the distributor (negative "-" side) and to ground anywhere on the engine.
- remove the distributor cap
- turn the ignition to "on" as it would be if the engine were running, but do NOT crank the starter.
- turn the engine over clockwise looking at the crank pulley.
- the light should light up when the engine is in firing position.

It's possible for it to be firing when the pistons are up and the valves are open if the distributor is out of place. So you need to make sure that when the light is lit, the valves for that cylinder are closed. When # 1 is at TDC and the valves for #1 are closed, the distributor rotor should be pointing at about 4:30 to 5:00 where there SHOULD be a little notch in the top edge of the distributor body. The #1 plug wire should be in the cap at that location. I've seen VW mechanics of LONG experience get them in the wrong order or get the distributor drive shaft oriented wrong. It can happen to the best.
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dcj63000 · Posted: Mon Jun 15, 2015 9:40 pm Post subject:

The tins are sitting in my shed. Took em off to work on engine lol. I cant afford to shelf those covers right now but thats good to know for later. The wife wasn't not exactly thrilled I bought new P/C's Shocked

The way i have set static timing is a little different. Instead of turning the engine until the light turns on I have set the pulley to 10 degrees BTDC (also tried it today at 7.5) then checked the light by turning the distributor clockwise until it turns off, then counter-clockwise until it just turns on. Will this get the same result?
And I did check all the plug locations and rotor location to ensure i was on #1. I will make sure the valves are fully closed and try static time the way you described to make sure its firing when I think it is.

Aerindel · Posted: Mon Jun 15, 2015 10:10 pm Post subject:

Dale M. · Posted: Tue Jun 16, 2015 3:15 pm Post subject:

Set pulley at 7.5 ° BTDC (#1 cylinder top of compression stroke)

You want to turn dist. counter clockwise till it goes off them back clockwise to point it just comes on...

This is point where points open and current flow stops in primary winding of coil, at this point the magnetic field in primary winding collapses educing a magnetic field across the secondary winding of coil to produce high voltage arc to fire plug(s)...

Also at this point if you are timing on #1 "TDC" the rotor should be pointing the #1 tower on dist cap...

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

dcj63000 · Posted: Tue Jun 16, 2015 4:34 pm Post subject:

Accelerator pump is working, I can see it squirt fuel when throttle is hit.

dcj63000 · Posted: Tue Jun 16, 2015 4:52 pm Post subject:

I know this thread has gone past the original topic but I noticed the the degrees on my crank pulley are not spot on TDC compression stroke. When the #1 piston is at real TDC the crank pulley shows 4 degrees BTDC. I know it is not ideal but is it OK to do the ignition timing using the 4 degree mark at my *TDC* or 0 ?

Dale M. · Posted: Tue Jun 16, 2015 7:34 pm Post subject:

ORANGECRUSHer · Posted: Wed Jun 17, 2015 5:06 am Post subject:

I Ride Sand · Posted: Wed Jun 24, 2015 2:12 pm Post subject:

Well, its been a week. got it running yet?


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Multiple cylinders with no compression.
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