What the frickity frack is happening with my timing? (1 Viewer)

[midknightc3]

So I actually have questions on both my trucks, as I've never been able to advance my timing beyond 7-10deg BTDC. However, I'm going to avoid questions on the properly running truck at the moment and concentrate on the FJ40 that just suddenly decided to not run right. Quick backstory, I've done this rigamarole previously and thought I had everything sorted after replacing everything in the ignition setup. Engine is (by SN) a 1976 2F with a dented side cover, FJ60 large cap dizzy and Celica igniter. When I installed this setup it fixed some very poor performance issues I had from the previous heavily worn OEM points dizzy out of the F155 that was originally in the truck. Didn't think much of it until last week when my wife barely made it home because the engine kept backfiring and stalling.

Much trouble shooting later, I threw a timing light on it and couldn't find the timing mark. Spun the engine around until TDC compression and theres the mark and rotor is pointed at the #1 plug on the distributor cap (roughly 10 o'clock). Painted the TDC line and BB white, put the gun back on, and I can JUST see the TDC line at the top of the sight window (vac advance is disconnected and tubing plugged, RPM @750). So, I'm estimating maybe 2-4deg AFTER TDC, and dizzy is exactly where I had last set it at full advance (which 9mo ago got me to 10deg BTDC). This explains why she's suddenly running like dookie and backfiring, BUT HOW THE HELL DID THIS HAPPEN? FJ60 dizzy was a rebuilt model from @4Cruisers, along with the ignition module. I'll pull the dizzy tomorrow, but he had put a new gear on it and everything looked beautiful before stabbing it in. Engine was rebuilt by the PO, maybe they reused some internal parts with worn gears? Could they have reused F155 parts in the 2F and that could be the issue?

Hoping this doesn't involve tearing down the engine, but if it's suddenly jumping timing I'm guessing that is where this is headed. Anyone local to central AZ interested in beer for mechanical knowledge in the driveway?

Thanks!
Clark

Edited for clarity

 

[4Cruisers]

Post a photo of the distributor after you pull it. Hopefully we can rule that out.

 

[midknightc3]

Absolutely, but I highly doubt it is your distributor. This feels like the exact issue I was trying to fix when I installed it thinking the previous dizzy was worn out. To be clear, everything I'v purchased from you has been fantastic in both my trucks, I was only tagging you so that one: others won't think I had Bubba down the street to it, and two: hoping you might have some magical insight! I'm guessing theres no magic here though, just lots of engine work.

 

[Skreddy]

Do you have good gas in it?

How’s plugs and plug wires? How long ago was the distributor replaced? Cap and rotor good?

When you say rotor pointed at plug 1; do you mean physically pointing to the plug at cylinder 1 or pointing to the spot on the cap where #1 plug wire connects (could be both). Do you have all the plug wires to the right spot in the right order?

 

[pb4ugo]

What Skreddy asked. What's the rotor pointing at? I'd check the dist. Is advance plate moving freely and working? Are the mechanical advance springs still attached to the weights? Make sure the clamp holds the dist in place. I doubt the engine skipped time. I would think the timing gears would eat themselves if it did.

 

[midknightc3]

@Skreddy and @pb4ugo, at TDC compression the rotor is pointed at the location on the cap where plug #1 connects, about 10 o'clock or so. Cap and rotor were replaced with the rest of the dizzy about 9mo ago and barely 3k miles ago. I'm certain the plug wires are all in the correct order, plus I'v had a couple other people go through everything just to make sure I didn't miss something obvious. Plugs are Denso V groove, wires are also Denso, also replaced at the same time 9mo ago. Vac advance is working fine, I can get a better view today when I pull the dizzy and I'll check the mechanical advance springs. Running 89 octane from Frys, she's a DD so the gas is always fresh.

Clark

 

[Pighead]

BUT HOW THE HELL DID THIS HAPPEN?

Cam gear de-bonding?

 

[bikersmurf]

I’d start by adjusting the timing to Toyota specs (7* BTDC) and seeing how it runs. I haven’t touched a distributor in an F series since my 1.5F died in ‘96.

My best guess would be that a plastic bushing has worn out or other parts have worn causing this change over the last 9 months. Alternatively, electrical connector(s) have corroded or come loose causing increased resistance causing the electronics to work slightly differently.

I know I’m flying blind, but if it was something simple and straightforward, you’d have found the solution already. There’s a big difference between my SBC points distributor with heavy weights, light springs, and a Crane Cams trigger. I have messed with things so much that I don’t even have a starting point to set it to. I advance the timing till I get ping and then retard it till it goes away. After that, I adjust till the performance feels right.