383 spun main?

[PRHeads]

Well, not necessarily.
383’s don’t have tons of V/P clearance....... so if the cam is kinda big, and there is minor contact..... and the pushrods aren’t up to the task...... you can end up with what you see.

I’d be surprised if it’s not related to V/P clearance though...... for whatever the reason.

Although, I’ve seen heads that had been reconditioned where the new guides were installed and actually left taller than the originals...... which means you get retainer to seal contact at a lower lift.
However, the seals usually just get mashed up when that’s the situation.

It’ll be interesting to see what the problem turns out to be.

 

[Cranky]

Does the engine have that stale old gas smell?

 

[RebelRider]

Does the engine have that stale old gas smell?

Edit: no sir.....

 

[RebelRider]

The bottom picture is where the lifter wasn’t spinning. As far as I know, it’s a stock purple cam.

 

[PRHeads]

If you put #1 on TDC during overlap....... then take a pic showing how even the tops of the lifters are, it should help narrow it down.

Several of those lobes look like they don’t have adequate taper.
Or the lifters don’t have adequate crown.

Btw...... do you know what the cam is?

 

[RebelRider]

I’ll get a picture of it on tdc. I was told it’s a stock purple cam.

 

[PRHeads]

Unless something has changed...... it’s not a Mopar cam.
Mopar hasn’t parkerized cams in many years.
(I haven’t bought one in ages, so that may have changed)

TDC on the overlap...... not TDC firing.

 

[RebelRider]

the Car was originally pulled from a junk yard in the early 80s, then parked around 1990. The cam itself was re-used on the rebuild in 2000.
Please learn me on what you mean not firing? Overlap is 180 from that?

 

[PRHeads]

You’re at TDC twice in the 4 strokes.
When the cylinder is firing the valves are closed.
Rotate the crank 360* more, you’re back at TDC....... but both valves are partially open....... the time when both are open is called the overlap period.

This is actually where the cam is in relation to the crank when you “line up the dots” on the timing set.

With “most” cams, there will not be a lot of difference in how much the lifters are up off the base circle at TDC.
So, if there is a big discrepancy in the lifter height at TDC...... the cam is likely phased(installed) incorrectly.

 

[RebelRider]

Thanks. I’ll give it a shot.

 

[PRHeads]

The Mopar branded cams I’ve laid my hands on were not parkerized.

 

[RebelRider]

If you put #1 on TDC during overlap....... then take a pic showing how even the tops of the lifters are, it should help narrow it down.

Several of those lobes look like they don’t have adequate taper.
Or the lifters don’t have adequate crown.

Btw...... do you know what the cam is?

Number 1 is on the right.

 

[RebelRider]

Another question. Does this style valley not use separate gaskets?

 

[PRHeads]

I needed to turn the pic to really see it.
The cam does look to be advanced, but there doesn’t appear to be enough differential to have the cam off 2.5 teeth.
Even on a mild hyd cam, when the timing set is off 2.5 teeth, the lifters will be off like 1/8th inch from each other.



From the factory, there are no gaskets on the valley pan.
That is the gasket.

 

[PRHeads]

I guess “if it were me”, my next test would a leak down test on a couple of those cylinders where the pushrods came out.
If the intake valves leak, then it’s a safe bet they had been hitting the pistons....... and that’s why the pushrods failed.
If the valves don’t leak........ well, it doesn’t mean they didn’t hit....... just that they didn’t hit hard enough to bend the valve.
It’s inconclusive.

One of those little bore scope/camera things would come in handy.

 

[copper67sat]

I had a similar issue on my 383 not long after a rebuild while I was driving home from work. Turns out that the new valve guides did not have enough clearance and #3 intake valve started sticking open. Pushrod fell off rocker and bent up underneath. Oil pressure was erratic as lifter rode up in its bore. Thankfully it stayed in the bore and I was able to limp home. I found brass from the guides smeared all over the valve stems. There was also a nick in the top of the piston from contacting the valve, but the valve was fine.

Machine shop fixed the guides. Got a new pushrod and put it back together. No problems 30k miles later.

 

[RebelRider]

Before I buy any parts for it, I’m going to look down into the cylinders to see if there is any substantial damage. If there are any markings, I will then move to a leak down test.

 

[RebelRider]

I needed to turn the pic to really see it.
The cam does look to be advanced, but there doesn’t appear to be enough differential to have the cam off 2.5 teeth.
Even on a mild hyd cam, when the timing set is off 2.5 teeth, the lifters will be off like 1/8th inch from each other.

View attachment 968688

From the factory, there are no gaskets on the valley pan.
That is the gasket.

So the cam doesn’t look advanced enough to be a tooth off? Should I look any further into the timing? I’m just trying to wrap my head around why it did what it did. I’m already almost at the tipping point on the engine itself and hate for it to grenade more parts.

 

[PRHeads]

Since we don’t really know what the cam is, we don’t know how much difference at TDC would be “normal”.

A run of the mill HFT cam that was installed 4* advanced would have the intake lifter at .020-.030” more lift than the exhaust at TDC.

A tooth is about 14*...... which would increase the differential by another .080-.090.

Your lifters don’t look like there’s that much difference.

 

[RebelRider]

Since we don’t really know what the cam is, we don’t know how much difference at TDC would be “normal”.

A run of the mill HFT cam that was installed 4* advanced would have the intake lifter at .020-.030” more lift than the exhaust at TDC.

A tooth is about 14*...... which would increase the differential by another .080-.090.

Your lifters don’t look like there’s that much difference.

Thanks again for your help, sir.