Rough idle, compression test... head gasket at 3 and 4? (1 Viewer)

[MoaByte]

Don't adjust carb until valves and timing are good. A stethoscope can tell you a lot. This is the fun part.

 

[MoaByte]

I admire that that the emissions didn't scare you into handing it off. This is a cool thread.

 

[DFXR]

Thanks all. The thing about the emissions stuff - after 10 years it is less scary than it is aggravating. Getting all of it off and then on again (especially the EGR) bookends any engine/manifold project with time and headache. Looking at a desmogged or older 2F just makes me wistful. Sh*t like this could almost be fun. But then you find yourself wrestling with the EGR "won't flex" hose and thinking about selling the thing as soon as you're done.

I have timed with my vac gauge before, and it's fun in an old hot rod way, kinda like pouring water into your carb (google that), but I get better results with my really basic timing light. I usually time it, then hook up the vac gauge and set the idle to best reading on that. That's the plan at least!

I'll keep you all posted.

Thanks again to @lcolon for his great head removal thread-

 

[MoaByte]

Thanks all. The thing about the emissions stuff - after 10 years it is less scary than it is aggravating. Getting all of it off and then on again (especially the EGR) bookends any engine/manifold project with time and headache. Looking at a desmogged or older 2F just makes me wistful. Sh*t like this could almost be fun. But then you find yourself wrestling with the EGR "won't flex" hose and thinking about selling the thing as soon as you're done.

I have timed with my vac gauge before, and it's fun in an old hot rod way, kinda like pouring water into your carb (google that), but I get better results with my really basic timing light. I usually time it, then hook up the vac gauge and set the idle to best reading on that. That's the plan at least!

I'll keep you all posted.

Thanks again to @lcolon for his great head removal thread-

You are golden. Slightly better than chrome and way better than chrome painted with plasti-dip. Lol

 

[DFXR]

You are golden. Slightly better than chrome and way better than chrome painted with plasti-dip. Lol

Checked the valve lash and yeah, most were a little tight, not crazy tight, but maybe just an ass hair past dead on... Opened up all intakes a tiny bit, all exhausts a little more.

Idle has now smoothed out at 750, and that’s without any carb adjustment. Valves nice and loud. Took it for a longer drive, including a nearby “test hill,” and the warm vacuum reading was a steady 19.

I may advance the timing from 7* to 9* for a little more pep but mostly I just need to drive it.

 

[MoaByte]

Checked the valve lash and yeah, most were a little tight, not crazy tight, but maybe just an ass hair past dead on... Opened up all intakes a tiny bit, all exhausts a little more.

Idle has now smoothed out at 750, and that’s without any carb adjustment. Valves nice and loud. Took it for a longer drive, including a nearby “test hill,” and the warm vacuum reading was a steady 19.

I may advance the timing from 7* to 9* for a little more pep but mostly I just need to drive it.

Did you adjust them with the engine running? . I tried that.. checked them with engine running but adjusted them with ignition off.

 

[DFXR]

Did you adjust them with the engine running? . I tried that.. checked them with engine running but adjusted them with ignition off.

Yeah man, I hold the flathead in my teeth, next to my unfiltered Pall Mall. The smoke keeps my mind off the pain!

I do them cold, because I work slow, and I also wantted to check the torque on all the head bolts before doing the valves.

 

[Zjohnsonua]

Somewhere there's a kid that needs to read this thread to realize that this is what old cars are all about. No computers, scan tools, etc... just ol' reliable diagnoses, repairs, and recommissioning. I'm getting ready to yank both of my 2Fs, but I'll admit that threads like this one at least give me pause before I do it.

Happy wheeling.

 

[MoaByte]

Yeah man, I hold the flathead in my teeth, next to my unfiltered Pall Mall. The smoke keeps my mind off the pain!

I do them cold, because I work slow, and I also wantted to check the torque on all the head bolts before doing the valves.

Then adjust your timing by setting a cold glass of whiskey on the air cleaner. Lock it in when the waves are smoothest

 

[DFXR]

Then adjust your timing by setting a cold glass of whiskey on the air cleaner. Lock it in when the waves are smoothest

Update here. Got about 100 miles on the new head, no big long “crucible” to truly test it but all is still well. Running at normal temps according to the little digital temp gauge I installed when I put it all back together.

What I’ve done this week:

Switched back to stock Denso plugs from NGK BPR4ES
Advanced timing from 7 to 9 degrees
Re-torqued head bolts ( a couple moved a hair)
Re-torqued rocker bolts
Checked valves after all that
19.5hg and steady

There is a little exhaust leak somewhere. I am pretending not to hear it.

AND... I bypassed my rear heater a while ago, so before I put the head back on I put in the slick little Toyota SS “joint” to replace the stock heater cactus thing. Turns out that if you still have your air rail in place, the new joint puts the heater hose really close to it. I know the air rail doesn’t get nearly as hot as the manifold but it was still making me think about it, so I switched back to the cactus (with a pipe plug in the side port). That puts the hose back up where it belongs.

Maybe these before and after pics will help explain:

 

[DFXR]

500 miles in and I got two problems now, maybe related, maybe just next to each other. Doesn't seem like either is head-related, except in a roundabout way.

In order of importance-

1) Fuel leak right here. Above the slow cut valve, at the black spacer/insulator thing (RED CIRCLE). It only leaks when running - the bowl doesn't empty overnight. But I do see a little bubble/gurgle come out of that seam intermittently at idle. Obviously a fire hazard though it looks to evaporate before it hits the big heat shield under the carb.

I also see what looks like a crack (GREEN CIRCLE) but I don't have another carb to compare this to. Is it just a casting thing or could that be an actual crack?

As for the black insulator, my FSM shows it but does not name it, and SOR calls it the "EGR Block Insulator." Do they crack? Any other ideas on why I might get a leak here?

2) I'm getting a lean condition (too much oxygen, not enough fuel) under load that causes a slight misfire. I felt it recently, a little misfire like some dirt flopping around one of the jets and getting sucked in at higher RPMS, then smoothing out or releasing when I lay off the gas. I put it on the sniffer at a smog shop and indeed, at 1500 RPMS my NOX and residual oxygen both spike with the misfire. HCs and C0 stay OK. If I did try to smog test it for real, I'd fail on NOX.

Timing is at 9*BTDC, vacuum at idle is a steady 19hg, running temps are totally normal. Valves are set to spec and have been checked and re-checked very recently.

So I will definitely be pulling the carb to deal with the leak, and cleaning the jets. But here's a question - could a leak at the spot above actually suck in air under load, and cause that lean condition? Trying to figure out if the two problems are one problem.

 

[NeverGiveUpYota]

The slow cut valves are notorious for leaking. Many drill and tap closed and go w/o. Their are plenty of threads describing how.
Green circle is a casting mark.
Back sorry, I half read, distracted by a bare Chevy block and it’s talking owner. The block “could” be on the wrong way. They do have a right and wrong way. But I kinda doubt it, unless that’s why it’s leaking there. @mwebfj60 did a thread on it. But the slow cuts ARE notorious for leaking too.

 

[DFXR]

The slow cut valves are notorious for leaking. Many drill and tap closed and go w/o. Their are plenty of threads describing how.
Green circle is a casting mark.
Back sorry, I half read, distracted by a bare Chevy block and it’s talking owner. The block “could” be on the wrong way. They do have a right and wrong way. But I kinda doubt it, unless that’s why it’s leaking there. @mwebfj60 did a thread on it. But the slow cuts ARE notorious for leaking too.

i think this may be the only slow cut that is NOT leaking... though some of the ends up there and that’s what I originally thought.

This one is from up higher. I don’t know if that black block cracks or what. But I think it’s on right bc it’s been that way for 8 years.

I’ll have the carb off shortly and I’m thinking that after 8 years it might be time for a rebuild anyway.

 

[MoaByte]

i think this may be the only slow cut that is NOT leaking... though some of the ends up there and that’s what I originally thought.

This one is from up higher. I don’t know if that black block cracks or what. But I think it’s on right bc it’s been that way for 8 years.

I’ll have the carb off shortly and I’m thinking that after 8 years it might be time for a rebuild anyway.

Effing carbs... Stick with it or go EFI. Honestly, I miss the carb. It worked well until it didn't.

 

[DFXR]

Effing carbs... Stick with it or go EFI. Honestly, I miss the carb. It worked well until it didn't.

I’ll be sticking with it, no choice if you want to keep it registered here. When the carb is dialed in I feel like a champ beyond my actual abilities, but when it falters I want to huck the thing down the driveway.

 

[DFXR]

Long-overdue update here. This went from a head gasket thread to a carb thread a while back and then just went silent.

Anyway, WAY back in January, I sent the carb out for a rebuild due to the leak from the phenolic gasket. I used a well-known and loved guru for the rebuild, and throughout the saga that followed he was a complete and total stand-up guy. But because it was a saga, I am not saying his name because I don't want anyone associating him with any kind of BS.

In short, the carb went back and forth to him 3 times, each time with the same leak appearing after re-install and a hard test run. He planed the phenolic gasket twice but could not get a good seal on it. Finally he gave up and rebuilt another core that he had, and all has been well for months.

He turned all of the re-rebuilds around quickly, charged me for exactly one rebuild and covered all the shipping. As mad as I was at the carb, I was never mad at him.

Speaking of shipping, FedEx managed to lose the carb three times. It was packed and heavily padded in a 2.5 Gal bucket but the little throttle return spring hanger got progressively more thrashed with each adventure. At one point the hanger needed to be welded in place (thanks @joebattle1 and Chopper Bob). Even the replacement showed up with a bent hanger. I think FedEx just hates non-traditional packaging and goes full gorilla on it.

Here's a photo album of that poor carb's final days before becoming a paperweight:

Original leak:

Leaking again:

Ouch:

Welded at the weak point:

Leaking again:

After that final leak we just gave up and went with another carb.

Since getting the replacement carb on I have just been driving it. Passed smog a couple weeks ago. I won't say everything is great, because that would just jinx me.

..

 

[ToyotaMatt]

The reason F and 2F and 3FE / 3F all have the same issues on cylinders #3 and #4

is :

#1 # 2 and #5 #6

are surrounded with 3 coolant jackets sides and rear or front


# 3 and # 4 have only 2 sides coolant jackets , hence the exhaust valves and guides always burn up first