Well, It was good while it lasted, but something internally broke and the motor has got to come out of the van chassis to fix it. After a long period of down hill 2nd gear engine braking at about 2000 RPM I noticed a miss when it was time to pull the next hill.

At first I thought I might have burned a valve fiddling around with the new tune, but a cold compression test with the throttle closed shows the middle two cylinders on the passenger side at 30 PSI each… making me wonder if the head gasket is blown between the two cylinders. In spite of it being down two jugs it still ran the 120 miles back home surprisingly well, so maybe there’s some kind of synergy between them and together they’re not completely dead?

The driver side bank read 115 psi per across the board (and I imagine it’d be higher with a warmish motor and the throttle open) so in theory I could try pulling just the passenger head in chassis, but that still doesn’t fix the awful exhaust manifold leak on the driver side, or the oil leak at the back of the oil pan. Nope, Noline’s next big adventure is engine out, heads off, inspect the bores and bearings and see where the road takes us from there… and up-power Modification-Town!!! has always been a tempting destination.

The machinist has a pair of DOVE-C heads for sale for $300. I don’t know if that includes serviceable rockers, and setting up the rockers and pushrods to run the early cast heads sounds fiddly, expensive, and may be too much compression for pump gas. Otherwise there are some spend-y modern aluminum head, intake, and cam combo packages that promise lots of beefy low end torque. You can even retro-fit hydraulic roller lifter$ and cam$!

However, back in Reality-Town the wife’s car needs stuff and so does my dailey so project 460 will probably be more along the lines of a valve job, broken exhaust bolt extraction, true up the stock exhaust manifolds, new oil pump, aluminum intake, fresh 650 cfm carb, maybe a little more cam, and we’ll just have to see about the rest.

 

Huh?

Since when do you perform a compression test with the throttle closed? What were the other cylinders from this closed throttle “test?”

Then you did a warm test with the throttle open like you are suppose to do but didn’t tell us what you got on the passenger side so were cylinders 2 & 3 still low?

 

Here are the results of the compression test. With two cylinders at 30 psi and a big miss under power, is there really any point in perfecting the test? Otherwise I can play with a leakdown test when the motor is on the stand and the rockers are off.

 

One word of caution:

Not sure how true it may be, but this doesn’t always work out when an engine has some miles on it. Bump up the power with top end work such as new heads, increased compression, etc. and suddenly the existing lower end is overloaded and fails in short order.

 

When you are looking at the general health of a engine, you want it to gulp lots of air during the compression test. But in this case I think you are right, there is no purpose in re-doing the test, the problem is obvious.

 

I do all my compression tests with the throttle closed. As long as all of the test is done with it closed what difference does it make.
I am sure he also did the full test with the throttle closed and it found a problem, well done.

Have you done a compression test on the same engine both ways, WOT and closed and what was the difference?
How do you hold the throttle open? Tell me how you do that on newer motors with a drive by wire motor?
Dave ----

 

My point is that the OP only told us the closed throttle results from cylinders 2 & 3 and open throttle results on the driver’s side. 30psi isn’t good but what if the drivers side was 40 psi?

No I have never done a compression test with the throttle closed but I was taught to have the throttle completely open for the same reason Franklin2 stated.

Drive by wire wasn’t out when I worked at the dealership. I assume you would use a diagnostic scanner to “tell” the computer to open the throttle. Back on the 90’s you would use the NGS tester to actuate different modules to make the wipers, chime or other systems to operate to test them.

 

On the newer stuff, drive by wire, most "home mechanic" dont have the high dollar scanner that you can turn on & off different things so again the throttle would be closed.
I have not done a side by side test but I cant see it being all that different as it is still pulling in air all be it maybe a little less but when doing a compression test you are looking for a big change between holes when you got a miss.
Now if you are low on power then you may want a open throttle test but when you have a 8.5:1 motor how high would compression be?
Dave ----

 

Progress report. Just need to pull dizzy, disconnect exhaust, torque converter, motor mounts, and bell housing bolts. Lift, split the motor from the x mission, and remove.

I also need to jack up the front of the RV, just to accommodate the height of the engine hoist. I don’t think they make short ones for vans, I’ve seen pictures, but you have to shorten them yourself. I also need to call around to see if I can rent a transmission jack. I’ve been thinking that once I have the engine supported by the lift plate attached to the intake, maybe that would be the perfect time to pull the transmission. Then all that’s left is to pluck the motor up off the mounts and roll it out the front.

Since I knew I’d have to crack it open, I had the operational AC system evacuated before I started, but who knew this trip would take me on a detour through AC system refurbishment town. Better budget for a compressor, o-rings, AC oil, refrigerant, dryer, expansion valve, and maybe a new condenser too.

Meanwhile, the biggest performance modification I can think of would be to swap out the C6 for an E4OD. Curious to know if anyone here has done the conversion and how it went.

Also on the engine out list is upgrading the alternator to 3G and getting a nice little alternator bracket.

 

Never done the E4OD swap. But I do know you will need to buy a aftermarket transmission controller if you do get one.

What are your plans for this RV? Drive a couple of times a year but mostly stay in a RV park? It may not be worth it to change the trans if it sits in a RV park most of the time. You can figure the payback. Estimate how many miles you will be driving a year, and figure at best 3mpg more with the overdrive trans.

 

I would also check the rear gear ratio because when in OD and converter locked the RPM may be too low at cruising speed and hurt MPG and performance.
I would also look at the first gear ratios between the 2 transmissions It would be nice to have a lower ratio to get that heavy truck moving from a stop.
Dave -----

 

Just saying, isn't it easier to pull the engine and tranny as a unit, then take them apart on the floor ?

Make sure you drain the tranny fluid first and cap the tailshaft outlet.

 

I'm not an expert on 460s, but I'm kinda thinking that's a tad on the low side.


Pulling a 460 out of a van! Fun project! Have you seen the YouTube video where they found it was faster and easier to just lift the whole body off, rather than trying to snake the engine out?

 

I'm not sure it's even possible to take them out as a unit, when they are mounted in a van. Clearance is not your friend on that vehicle. Dropping the trans is pretty easy.

 

You can see he has the whole frontend off. It should come out forward as a assembly with a little finagling. Only thing is you have to put your chains more to the rear of the engine to balance the weight of the transmission still on it.

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