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Nockenwelle
Nockenwelle Reader
12/21/23 6:51 p.m.

Well, like I mentioned in the prior post, it's because the cam has almost no valve lift at TDC exhaust (low duration, low overlap, low lift, low RPM top-of-the-page cam), and whatever lift it might have is usually sucked up by hydraulic lifters compressing because there's no oil pressure sitting still. It would be hard to see a few thou valve lift thru the hole with a scope anyway.

A more reliable method requires two humans, or someone with very long monkey arms, or a bump switch. Rock-paper-scissors to see who gets to turn the key, and who gets to hold a finger in the #1 spark plug hole. Bump it over, and when the motor blows the finger holder's finger out of the hole, it's approaching the right TDC. Make sure not to crank quickly and blow past the mark.

A 401 CJ
A 401 CJ SuperDork
12/21/23 7:49 p.m.
wae said:

Okay...  I flipped the plug wires around and then with a tiny twist of the distributor, it started up.  It's trying to bounce the distributor up and out of its hole, though, so I need to figure out how to get around the fuel lines to the hold down bolt.

 

Here's my question, though:  how the berkeley did I have that wrong?  My first thought was that it was 180 out, but both valves were closed in #1.  Apparently there is more to it than what I thought, so please learn me.

Ummmm...aren't both valves closed at the top of (beginning) both the power stroke and intake stroke?  You'd have to bar it over past TDC and then see what happens to the valves.  If the intake starts to open then you're 180 out.  
 

I usually set it up just like you did and if it acts like yours did, then I switch it around.  I'm right 50% of the time.

Cousin_Eddie (Forum Supporter)
Cousin_Eddie (Forum Supporter) SuperDork
12/21/23 7:51 p.m.
Nockenwelle said:

Well, like I mentioned in the prior post, it's because the cam has almost no valve lift at TDC exhaust (low duration, low overlap, low lift, low RPM top-of-the-page cam), and whatever lift it might have is usually sucked up by hydraulic lifters compressing because there's no oil pressure sitting still. It would be hard to see a few thou valve lift thru the hole with a scope anyway.

A more reliable method requires two humans, or someone with very long monkey arms, or a bump switch. Rock-paper-scissors to see who gets to turn the key, and who gets to hold a finger in the #1 spark plug hole. Bump it over, and when the motor blows the finger holder's finger out of the hole, it's approaching the right TDC. Make sure not to crank quickly and blow past the mark.

To add, when working solo, a guy can screw his compression tester hose into #1 hole and he will be able to hear the air coming out of the hose as the compression stroke happens. 

(This post was written by a lone wolf who always works alone.)

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
12/22/23 5:38 a.m.
wae said:

Okay...  I flipped the plug wires around and then with a tiny twist of the distributor, it started up.  It's trying to bounce the distributor up and out of its hole, though, so I need to figure out how to get around the fuel lines to the hold down bolt.

 

Here's my question, though:  how the berkeley did I have that wrong?  My first thought was that it was 180 out, but both valves were closed in #1.  Apparently there is more to it than what I thought, so please learn me.

Lifters bled down so it looked like they were on the base circle when really they were just during the overlap period when the lift was extremely low.

The way around this is to rotate the engine, watch the exhaust open and close, watch the intake open and close, and then roll around to the next TDC.

wae
wae PowerDork
12/23/23 9:28 p.m.

I appreciate the education!  My first instinct was that it was 180 out, but I trusted my eyeballs instead of my gut!

Finally got the wrench for the distributor hold down and I'm doing the break in now, but the temp gauge is getting awfully close to red.

With it fully warmed up, though, I've got 30+ psi of oil pressure, so that's good.

wae
wae PowerDork
12/23/23 9:47 p.m.

Ooh.  Well, it didn't overheat but I think I may have been making more oil pressure than the gauge registered.  It blew a giant puddle of oil out from where the gauge apparently want screwed in quite tight enough.  Like, a lot a lot.

wae
wae PowerDork
12/26/23 11:23 a.m.

Fresh oil is in along with a new filter.  I discovered that I left the oil drain pan right under the exhaust when I was doing the break-in, though:

Oops.

I set the ignition timing via a vacuum gauge and it's sounding pretty darn good.  I'm still getting oil everywhere whenever I rev the engine though.  Of course I can't rev the engine while sitting underneath the RV but it's coming from the left side from probably the front of the engine and the only thing I can think of that I touched there is the oil pressure sensor.  But the gauge was pretty well screwed in as it turns out and I'm pretty sure I've got the sensor back in as far as it will go, so I'm a bit perplexed.

Edit: ah-ha.  I'm 99 44/100 sure that the leak is in the oil cooler line.  It had a tiny dribble before and it looks like it's flowing out around the crimped connection.  I suspect that this isn't some standard part and I'm going to have to figure something out here.

wae
wae PowerDork
1/21/24 3:20 p.m.

So here's a weird one...  The oil cooler lines are all hooked up and not leaking.  I took it for a little driver around the "block" and it's not shifting.  Hard to tell if it's stuck in 1st or 2nd, but my assumption is that I knocked an electrical connection loose and the TCM is in limp mode.  It'll do 35-40, so I'm assuming that's second gear, not first.  I'm trying the battery disconnect trick first to see if it's just a little confused with trying to start on a pretty low battery and needing the jump box.  Then I'm going to check the fuses.  If those are all good, I'll start it up and see if it will blink any codes at me.

Stampie
Stampie MegaDork
1/21/24 5:02 p.m.

In reply to wae :

That should have a 400 or 475 trans right?  Check the vacuum line from the engine to the vacuum modulator on the right side of the trans.

wae
wae PowerDork
1/21/24 6:59 p.m.

In reply to Stampie :

It's the 4l80E so more speed sensors and TPS than vacuum lines.  I was able to fix it by either disconnecting the battery cable for a while or by unplugging the transmission connector and plugging it back in again.

Stampie
Stampie MegaDork
1/21/24 7:13 p.m.

In reply to wae :

I didn't know those had the 4L80E that early.

wae
wae PowerDork
1/31/24 11:24 p.m.

Well, the coach made the trip to Daytona and back and sounded great the whole time.  After 1700 or so miles, I think I'm willing to call this fixed.

I did have some trouble with the trans going into limp mode in Atlanta, but I think a couple exposed wires touched and blew the TCM fuse.  A bit of tape to keep things from touching and everything was fine.

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