Builds Welcome home Matilda - faded like your favorite pair of jeans

[overhanger]

Couple of things.
Squishier brakes: Your vacuum readings are lower than the worn out stock motor was giving you. Less vacuum equates to less brake boost. As the rings seat in vacuum will increase and braking should improve.
Changing valve lash specs: Dude, give the engine time to settle in before trying to “improve” anything. Be happy with the newfound power and just let things be for now. Learn what it tells you in its present state. Congratulations on your success.

 

[samc2447]

Anybody know how to read this balancing sheet?
View attachment 3946794

Left and right are normally used as the end references on the crankshaft when balancing - so think front and back, not side to side. Due to the rotating imbalance, different forces will be exerted outward on each end of the crank in the radial direction. The goal is to reduce the delta between the 2 ends and smooth out the rotational imbalance.

The first readings show that it exerted a lot of force at each end which had a fairly large delta at high RPM. Once they added or removed weight to smooth out the imbalance, and in essence make it rotate more freely, that size of the external force and the delta both decreased as seen in the Final Spin sheet.

Too much imbalance and a delta between the two would cause serious issues on the bearings at higher RPM.

So basically, if your valvetrain could handle it, you could rev to 10,000 rpm and you'd be exerting substantially less force on the bearings than the unbalanced crank at 4000 RPM. This is why as you noted it seems to spin up so quick and effortlessly.

You have evidence to raise the redline on your tach now

 

[CruiserTrash]

If you have the space keep the block and head, you'll likely never need them but if you part with them then need a block or head in the future finding one will be difficult to impossible. If you have a space OEM carb keep that and have it rebuilt by a guru. Starter, distributor, coil and ignitor are other useful spares to retain, and the alternator.

I generally travel with a spare alternator and starter and have had to swap those parts out while traveling.

I have a spare carb on hand that’s ready to go, and I’m getting fairly good at rebuilding them myself too. I actually find it pretty enjoyable! I have all those spares and those travel with me. There was a thread recently about the spares people carry and I think I had the longest list haha. All that Boy Scouting when I was young… so probably best to keep the motor. I’d like to autopsy it anyway.

@overhanger I put 100 miles on the truck yesterday. Went to work and back, then to the shop, the up Coal Creek Canyon to Robinson Hill Road, over to 119, and back down Hwy 6. In the morning idle vac was at 8-9. After commuting (before the mountain drive) I noticed idle vac was at 3.5 for the same 900rpm idle speed. It remained there after the mountain drive. The truck really suffers at altitude, especially just off idle like starting from a stop. Bogs super hard.

@samc2447 Thanks for the explainer. The left/right was confusing me. It looks like at 4000rpm I now have about 2lbs of imbalance on either end of the crankshaft versus 36lbs on the left and 15lbs on the right before. Smooth!

So like I mentioned to overhanger above, my idle vac suddenly dropped yesterday, with all other conditions remaining the same. While at the shop (after commuting during the day, before the evening mountain drive) I tried goosing the static advance - no change - and then returned it to where it was. I unplugged the brake booster vac hose from the manifold and capped it. No change, then I put the hose back. I adjusted the idle speed up and down - change was 0.5inHg - then put it back. I sprayed around the engine bay with carb cleaner and nothing happened. So I’m a little concerned that there was a sudden change in idle vacuum. If nothing else, it’s strange.

Last night I sat on the couch letting my brain overthink, something it’s too good at, and read about degreeing camshafts. Something I have no business reading about haha.

 

[overhanger]

I have a spare carb on hand that’s ready to go, and I’m getting fairly good at rebuilding them myself too. I actually find it pretty enjoyable! I have all those spares and those travel with me. There was a thread recently about the spares people carry and I think I had the longest list haha. All that Boy Scouting when I was young… so probably best to keep the motor. I’d like to autopsy it anyway.

@overhanger I put 100 miles on the truck yesterday. Went to work and back, then to the shop, the up Coal Creek Canyon to Robinson Hill Road, over to 119, and back down Hwy 6. In the morning idle vac was at 8-9. After commuting (before the mountain drive) I noticed idle vac was at 3.5 for the same 900rpm idle speed. It remained there after the mountain drive. The truck really suffers at altitude, especially just off idle like starting from a stop. Bogs super hard.

@samc2447 Thanks for the explainer. The left/right was confusing me. It looks like at 4000rpm I now have about 2lbs of imbalance on either end of the crankshaft versus 36lbs on the left and 15lbs on the right before. Smooth!

So like I mentioned to overhanger above, my idle vac suddenly dropped yesterday, with all other conditions remaining the same. While at the shop (after commuting during the day, before the evening mountain drive) I tried goosing the static advance - no change - and then returned it to where it was. I unplugged the brake booster vac hose from the manifold and capped it. No change, then I put the hose back. I adjusted the idle speed up and down - change was 0.5inHg - then put it back. I sprayed around the engine bay with carb cleaner and nothing happened. So I’m a little concerned that there was a sudden change in idle vacuum. If nothing else, it’s strange.

Last night I sat on the couch letting my brain overthink, something it’s too good at, and read about degreeing camshafts. Something I have no business reading about haha.

That engine is making you work for your bliss. This too will be figured out. You know what I would do: starts with B and ends with B.

 

[Skniper]

Sounds like you’re about to do a burnout at the strip! This has been a fun read.

 

[CruiserTrash]

Sounds like you’re about to do a burnout at the strip! This has been a fun read.

For as cool as it sounds I really want to sort out the issues and be done with it haha.

 

[overhanger]

For as cool as it sounds I really want to sort out the issues and be done with it haha.

Yup, something changed as it didn’t sound this racy the other night. Does sound good though.

 

[CruiserTrash]

Ok … took stuff apart and found one of the four brass vacuum fittings on the back of the carb was loose. These are press fit at the factory when Aisin made them. Those particular one is for the decel fuel cut system and I verified it ports to below the butterfly. Hoping this is my vacuum leak issue. Going to try to get the press fit plug out , clean it up, and then JB Weld it. Barring that I’ve got a couple other carb bases I can swap in. Fingers crossed this is the smoking gun.

I did verify that all the rockers are moving, so a quick check shows I don’t have a stuck lifter or totally wiped cam lobe.

 

[CruiserTrash]

We’re so back.

This is the same 9inHg I had before but at 750rpm rather than 900 - so this is even better. My theory is that the vac nipple on the back of the carb was leaking the whole time, but then yesterday it must have gotten jostled loose even more. Pulled out the brass piece, slathered in anaerobic sealer (not enough to plug the passage) and jammed it back in. I then covered the base of all the brass nipples with gasket shellac. I used that to seal up some leaky press fit plugs on the carb a little while ago and it worked great. Hopefully everything’s nice and sealed now.

Off idle acceleration is much better. I think we’ve got a winner on our hands. Time to rack up break in miles on it before SAS, with maybe a little fine tuning.

 

[CruiserTrash]

Looking back at the post above, I see the amount of vacuum is indicated as "poor" on the gauge.

5000' altitude yields 18% less vacuum than sea level and the cam is lowering vacuum as well. "Poor" is a relative term. With the previous motor I had 15.5-16.5inHg at idle depending on the weather and that's considered pretty great for a 2F motor here in Denver. If you adjust that 18% altitude drop backwards, that's 19.5 at sea level. If you adjust the current ~10inHg backwards you get 12.2inHg at sea level. Other forums are full of hot rod guys with huge cams in their old muscle cars asking if 7inHg at sea level is acceptable - just as an example. For me the minimum requirements are no off idle bog and the brake booster works. I will keep adjusting things over time to see if I can squeeze some more vac out of it too which would slightly decrease bog and give me a buffer for the further vac loss on high elevation trails.

I think it was @overhanger that said he thinks the idle vac and compression will both go up as the motor breaks in as well.

 

[4runner2FJ60]

Makes me want a Vac gauge!

 

[cps432]

Makes me want a Vac gauge!

You own and work on a Land Cruiser without one?!?!

 

[4runner2FJ60]

I have one for diagnostic use....but not a real-time in the dash style

 

[cps432]

I have one for diagnostic use....but not a real-time in the dash style

Okay! I was about to say, other than a ratcheting socket wrench, a vacuum gauge was the first tool I bought for my Land Cruiser!

 

[CruiserTrash]

The in-cab vac gauge has been so handy. It’s indicated exactly where to look for problems on many occasions. Instead of stabbing in the dark I could verify that my guess from the vac was right and then fix the problem.

 

[4runner2FJ60]

Where are you pulling the vacuum from as far as installing this gauge?

 

[CruiserTrash]

Where are you pulling the vacuum from as far as installing this gauge?

There are three lines that come off the “gas filter” in the manifold. I have a tee on one of those lines that’s zip tied to the spaghetti hardline cluster. So basically directly from the manifold. Gas filter is 2 years old new Toyota part. Just to be sure, I used a handheld vac gauge with a different vac hose and put it on the AC idle up fitting at the back of the manifold - same reading, so I know my in-cab gauge is accurate.

 

[cps432]

The in-cab vac gauge has been so handy. It’s indicated exactly where to look for problems on many occasions. Instead of stabbing in the dark I could verify that my guess from the vac was right and then fix the problem.

When I ran my sniper set up I had a boost gauge in the cabin. It was essential for the sniper imo. When my fuel pump failed I was very quick to diagnose it because I knew vacuum was 100% fine when it died. I will be reinstalling it when the truck goes back together…. Eventually.

 

[4runner2FJ60]

Its nice to have two capped off ports on that 3 way split port on the manifold after desmog!

 

[CruiserTrash]

Its nice to have two capped off ports on that 3 way split port on the manifold after desmog!

I actually just capped the ends of the vac lines where they go to the ABV and such. Looks sloppy but makes for easier reinstall when I have to smog in 2027.