Low vacuum and compression? (1 Viewer)

[TroutFJ]

Hey folks,

I finally got Babe pretty much put back together and installed a new gauge pod over the weekend and started running some diagnostics because she seems sluggish.
Here is some quick information on what I've done to her (that would affect the numbers)

I live at 9000'
33"x12.5 BFG AT's
New H55F
New HEI dizzy set 14 degrees advanced with new plug wires
New spark plugs set at .040
Weber 38 DGAS installed with heat riser plate (PCV valve ties in below the carb)
New PCV valve
MAF Headers and straight (no cat) exhaust
Desmog with BVSV#1 run to VCV, to air cleaner, to EVAP can. Other BVSV port capped (#2 removed)

Now on to symptoms and the numbers:

-Seems sluggish on acceleration, especially no power in 4th much less going uphill (could be the 33's just expected a bit more after all the mods and tranny)
-Slightly rough start after dropping in altitude (live at 9000' but work in Denver so almost 4k' lower) Need to pump the gas once or twice to get her started up then idles just fine.
-Somewhat of a rough idle until she warms up then evens out at 650-700 rpms (this I can adjust)
-Some oil sprays out of the exhaust as well as a puff of blue smoke after it's been sitting for awhile

Numbers:
Compression: 1:105, 2:105, 3:109, 4:105, 5:105, 6: 112 Dry tested. Wet test raised all numbers by about 4-5
Vacuum: Once she warms up it sticks right around 12-15 but when I rapidly engage and let off the throttle, or at 80% throttle on the highway, the vacuum drops down to 0-2 and jumps back up after releasing the throttle. At cruising speed (when throttle is engaged but not aggressively accelerating) the vacuum actually rides about 15-17.

So, based upon this article Vacuum 101 - Land Cruiser Tech from IH8MUD.com it would seem I'm losing vacuum and maybe compression from the piston rings being worn.

Does this sound consistent with what you guys think? If it is piston rings do you folks feel it's ok to drive until winter when I can get back to spending money and time on the old gal? I know I will have to keep up on the oil since I am losing some through the exhaust but I check that before every trip out anyway. There is no coolant in the oil and no leaks or drips anywhere right now.

 

[Output Shaft]

Both compression and vacuum will be lower at 9000 ft because the air is thinner. Check it at 4000 ft or lower. But 105 psi compression is low.

Any old 2F at 9000 ft (especially one that spits oil & blows blue smoke) with 33 inch tires and stock 3:70 differential gears is going to have the acceleration of an ox cart. A brand new one will too.

The H55 transmission won't do anything for power. It just has a lower 1st & 2nd gear and an overdrive.

If the cruiser lives at altitude, rejetting the Weber carb to make it run leaner will help. Also advance the timing just before it pings. Don't use regular gas. Use mid grade & adjust the timing accordingly.

But the elephants in the room are:

1. Worn out engine
2. 9000 ft elevation
3. Wrong gearing for 33" tires
4. Carb jetting

(And possibly 500 lbs of bolt-on added gear.. Bumpers, winch, sliders, dual batteries, roof rack, crap in the car)

 

[TroutFJ]

Thanks output! And yeah I have added a ton of weight to the gal. I can live with the lower power and figured that there wasn't much to be done about that with all the crap I've done. I guess my main concern, being a noob, is that if I continue to use it as a weekend warrior is there a possibility of getting stranded somewhere cause I didn't take care of something when I had to and if there was a way to squeak out a couple more horses lol.

That's good advice on using mid grade fuel. I will swap it out and adjust the timing accordingly. Are there any additives that may help with smoking/sealing up the rings some? Doubt it but figured I'd ask.

I'm planning on re-gearing this winter and may do an engine swap depending on finances and time. Mainly I just want to have fun out in the hills with it till then and not worry about destroying my engine cause I didn't take care of something that was urgent.

 

[micruz60]

You could try adding ZDDP (zinc additive) to the oil, it is intended to prevent wear, however, the wear may have already occurred. There are several threads on this... Research bob the oil guy.
I got up to 304,000 miles on the original 2F before I decided it was too tired (bluesmoking) to pull the ten percent / one mile grade at 8200' asl. Usually if I could get up to 2200rpm and maintain momentum I was happy. Another thing you could try is a heavier weight oil, such that it won't squeeze past the rings - 20-40w delo
And it never will pull too hard uphill in fourth, that is just the nature of a fast tractor.
hth