Builds 1974 FJ40 Restoration Build Thread

[JohnJL]

There was also this

Could I confirm the cam timing is correct and not slipped by checking the intake/exhaust lift specs from Delta I suppose? The cam gear looked in new condition, I had to take it off and press it back on so had a good close look at it. Here is a pic of reinstallation last month with the white paint line marking its alignment when removed from the running motor before the rebuild. I didnt check vacuum before shutting the truck down before rebuild.

 

[JohnJL]

Could I confirm the cam timing is correct and not slipped by checking the intake/exhaust lift specs from Delta I suppose? The cam gear looked in new condition, I had to take it off and press it back on so had a good close look at it. Here is a pic of reinstallation last month with the white paint line marking its alignment when removed from the running motor before the rebuild. I didnt check vacuum before shutting the truck down before rebuild.

View attachment 2536665

PS yes I later changed the bolts out to new OEM matching ones.

 

[FJ40Jim]

If the gear is good, when the timing dots are aligned on the outer gear, the inner hub holes will allow access to the 3 bolts.
As the elastomer in the gear fails, the inner hub will drift backwards (CW), making it difficult/impossible to get a socket on the bolts when dots are aligned.

Earlier it was noted that the AFR was lean at idle, but if the idle vac is <14", then the AFR will be lean, as the low vac signal is not pulling much fuel out of the idle slot.

Since some smog stuff is currently disconnected, try the baseline non-smog setup:
Choke breaker gets connected to manifold vacuum (vac port on carb base).
Idle ignition timing should be 7-10*BTDC, vac hose disconnected, at 650RPM.
Vacuum advance gets connected to ported vacuum (carb base, valve cover side).
No vacuum goes to the Vac switching valve on fender.

Check the vac reading in the above baseline configuration, and test drive if it runs OK.

If the vac reading is still very low, then the engine is not pumping air efficiently at idle. Could be the cam timing is late, or could be the cam regrind is too radical for the engine, or...?

 

[JohnJL]

If the gear is good, when the timing dots are aligned on the outer gear, the inner hub holes will allow access to the 3 bolts.
As the elastomer in the gear fails, the inner hub will drift backwards (CW), making it difficult/impossible to get a socket on the bolts when dots are aligned.

Earlier it was noted that the AFR was lean at idle, but if the idle vac is <14", then the AFR will be lean, as the low vac signal is not pulling much fuel out of the idle slot.

Since some smog stuff is currently disconnected, try the baseline non-smog setup:
Choke breaker gets connected to manifold vacuum (vac port on carb base).
Idle ignition timing should be 7-10*BTDC, vac hose disconnected, at 650RPM.
Vacuum advance gets connected to ported vacuum (carb base, valve cover side).
No vacuum goes to the Vac switching valve on fender.

Check the vac reading in the above baseline configuration, and test drive if it runs OK.

If the vac reading is still very low, then the engine is not pumping air efficiently at idle. Could be the cam timing is late, or could be the cam regrind is too radical for the engine, or...?

Thanks, I will go try that.

I also ordered a NOS cam gear from the local dealer.

 

[JohnJL]

If the gear is good, when the timing dots are aligned on the outer gear, the inner hub holes will allow access to the 3 bolts.
As the elastomer in the gear fails, the inner hub will drift backwards (CW), making it difficult/impossible to get a socket on the bolts when dots are aligned.

Earlier it was noted that the AFR was lean at idle, but if the idle vac is <14", then the AFR will be lean, as the low vac signal is not pulling much fuel out of the idle slot.

Since some smog stuff is currently disconnected, try the baseline non-smog setup:
Choke breaker gets connected to manifold vacuum (vac port on carb base).
Idle ignition timing should be 7-10*BTDC, vac hose disconnected, at 650RPM.
Vacuum advance gets connected to ported vacuum (carb base, valve cover side).
No vacuum goes to the Vac switching valve on fender.

Check the vac reading in the above baseline configuration, and test drive if it runs OK.

If the vac reading is still very low, then the engine is not pumping air efficiently at idle. Could be the cam timing is late, or could be the cam regrind is too radical for the engine, or...?

Thanks again for this. I did another session out there.

Regarding AFRs, I have 1 wideband AFR gauge portable rig I use between cars and have that set up now, so I can see in real-time wideband 02 readings. I also have a narrowband AFR gauge hard-wired into the truck dash.

I followed those steps above. Base idle was set without vacuum to 7 degrees BTDC, then connected to the new port on the carb, where at a 700 rpm idle the timings goes to 9 degrees with the vacuum connected.

Took 1/6 turn out of the idle speed and 1/6 turn out of the mix screw, idles smoothly at 700 at 12.7-13.3 AFR.

But, still 7-8 in vacuum...

The cam gear was pressed on and removed 2x, perhaps that disturbed and was the last straw for the gear rubber isolator. I dont recall if it was pressed out with leverage on the gear perimeter or at the shaft collar. Ordered a new one from Toyota, that one will for sure be pressed by the collar and will examine the old one.

Also messaged Delta again about the cam profile and normal vacuum.

 

[FJ40Jim]

To recap:
Valve adjustment good.
Cam/crank timing marks aligned.
No vacuum leaks.
Idle mix around 13.0 (best idle vac setting)
Idle timing @ 9* with engine running in normal configuration.
Result: 7-8" vacuum.

In the absence of any other culprit, it almost has to be a cam with a lot of intake duration or a late cam (slipped gear).

 

[JohnJL]

Ugh. No obvious culprits. I called and spoke to Steve at Delta Cams, he confirmed either of their FJ40 cams still should expect 17" vacuum.

The cam gear looks correct. When the marks are aligned on the cam and crank gears, the bolts behind are evenly lined up behind.

When cylinder #1 is at TDC, distributor rotor is at #1, crank indicator is on the line, and the dots on the cam and crank are NOT aligned. Here you can see all of that.

With #1 at TDC on overlap, distributor is on #6 and the cam and crank marks are lined up. You can see all that here.

Everything here seems correct? Cam gear doesnt look to have slipped, timing marks line up as expected and dissy is aligned as expected.

Any more suggestions pls?

 

[FJ40Jim]

Which cam is installed, a Delta 250 or a 262?

It may be possible to get a vac reading from one of the more recent engine builds with steel gear & one or the other cam, then we'll have confirmation of typical vac readings for these cams.

 

[JohnJL]

Which cam is installed, a Delta 250 or a 262?

It may be possible to get a vac reading from one of the more recent engine builds with steel gear & one or the other cam, then we'll have confirmation of typical vac readings for these cams.

Jim, if this is the Delta 262, how would that change my jetting needs? I have what you sent back with the exception of a slightly larger main jet.

Thanks

 

[FJ40Jim]

It doesn't change the jetting.
The question is: what's a typical manifold vac reading for an open chamber engine with the 262 cam?
I'll see if a customer can get a reading from his similarly equipped engine.

 

[JohnJL]

It doesn't change the jetting.
The question is: what's a typical manifold vac reading for an open chamber engine with the 262 cam?
I'll see if a customer can get a reading from his similarly equipped engine.

Rkymtnflyhfisher responded on a thread here..What cam is this? - https://forum.ih8mud.com/threads/what-cam-is-this.1237308/#post-13575458.he gets 15" as Delta said also. I am wondering whether jetting is the issue here? Ignition checked out, and again I did compression tests with 148-150 psi (cold) and leakdown of 6-7% on every cylinder. Pulling the cam and lifters today. Even though the cam gear looks fine, i have a new one on the way so will pop that on there.

 

[JohnJL]

New timing gear in, lifters, cam all installed and everything back together. Still same vacuum.

While still working through that, I did some timing investigation. When at 10 degrees static, I measured 25 degrees advance at 1200 rpm, and 35 degrees at 2000 rpm! I measured again without vacuum advance connected and saw 17 degrees advance at 1200 rpm and it wouldnt run to 2000 rpm without the vacuum attached. So I am getting 7 degrees of mechanical advance and 8 degrees of vacuum advance already at 1200.

That is way too much at part throttle. The DUI had no adjustment to the vacuum slope or range. Its obviously working, and appears to have ~10 degrees of range.

I checked the springs and weights on the DUI, and they are very fine wire, tightly coiled and obviously lighter. I removed the weights and found them to be quite heavy compared to the generic HEI ones I have, at 16 gms.

I ordered some Spectre springs and put in the heaviest springs. When it isnt -10 degrees outside, I will warm her up and see how the timing curve has changed. I'll experiment with the springs to fine-tune.

That is the funkiest graph ever...left-handed and backwards...

 

[JohnJL]

 

[flee]

With regard to the graph, it is graphing advance, so degrees before TDC. It makes sense, kind of.

 

[JohnJL]

Graphing standards would dictate RPM on the x axis on an increasing scale with degrees advance in y axis on increasing scale. Theirs has degrees advance in the x axis on decreasing scale and rpm on y axis on increasing scale. Accurate but not conventional.

 

[JohnJL]

Here's the rough, initial timing graph I observed in a conventional scale:

Hahaha, no axis labels...degrees advance in y axis, rpm in x axis

 

[flee]

Your graph has degrees BTDC, which are minus sign, inverted from their logical place below the zero axis. Just sayin'.
In fact, if the odd behavior you show with no vacuum was to continue past zero at 2000 RPM, you would be plotting
positive degrees below the zero (x) axis where one would conventionally plot negative values.

Your graph is the way I've seen most advance curves plotted, though.

Your investigation of the advance curve makes me want to check mine now.
I'm also using an HEI.

 

[JohnJL]

Taking notes for myself here....started her up and ran around a bit. I still get backfiring off throttle occasionally, but much better. Accelerator pump works properly, but wideband O2 sensor shows very lean at part throttle (~5-15%). Found notes that I have a slow jet drilled to 0.75mm and 150 main jet.

Ignition curve was adjusted with that spring change: now idle is at 14 degrees with or without vacuunm. It is still 14 degrees at 1200. I didn's measure further at it was so lean at part throttle, 19 AFRs and misfiring.

 

[FJ40Jim]

Solid data.

Has the idle vacuum reading increased?

 

[JohnJL]

Just a bit, but not where I expected it. With a high idle ~1000 the AFR's are ~13:1, timing 14 degrees and 11 inches of vacuum. When closing down the throttle plate and adjusting the mixture screw so idle is ~700n the AFRs are 13:1, timing is 14 degrees and vacuum is 9 inches.

I also notice it is very lean at part throttle. When opening throttle and cruising at ~15% throttle, after the initial accelerator pump squirt the AFRs go way high, to like 19:1. I checked the primary main jet, that is 130 and the slow jet is 75. I wouldnt think part throttle should be so lean, are my jets undersized?