TDC timing marks on flywheel

[Marine T]

1975 FJ40 F2 - first time posting. I’ve owned this truck for about 2 months, it runs very rough and I figured it could be timing. flywheel doesn’t have a BB, but has a hole and I read the hole serves as the same purpose. There are no gradient marking, only another line that someone else marked. I’m trying to time my truck, I know the hole incdicates TDC, but what could this other line represent? I have a HEI DUI distributor but something is off with the timing, a lot of valve clatter, weak motor. Any help would be appreciated. Mike

 

[charliemeyer007]

Do you have a book? If your valves are set wrong it will not run right. If your engine is worn out it will not run right.

Do at least a dry compression test. Set the valves. Now you can do the timing and carb adjustment. Is your gas fresh and the fuel filter new?

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[CruiserInProgress]

1975 FJ40 F2 - first time posting. I’ve owned this truck for about 2 months, it runs very rough and I figured it could be timing. flywheel doesn’t have a BB, but has a hole and I read the hole serves as the same purpose. There are no gradient marking, only another line that someone else marked. I’m trying to time my truck, I know the hole incdicates TDC, but what could this other line represent? I have a HEI DUI distributor but something is off with the timing, a lot of valve clatter, weak motor. Any help would be appreciated. Mike

View attachment 4174857

It looks like the hole might be where the BB should be (7° BTDC). If so, TDC (0°, for static timing and for valve adjustments) should be a, hard to see, fine scribe just below the window.

Once you've verified static timing and initial valve adjustments, you can move on to set timing when idling at 650rpm (vacuum advance plugged at carb. Most find around 12° BTDC good starting point.

Of course you'll also want to verify carb settings, air gap settings and voltages for your DUI, check for any manifold vacuum leaks, fuel flow, spark plug conditions, compression, etc. among other things.

 

[Marine T]

It looks like the hole might be where the BB should be (7° BTDC). If so, TDC (0°, for static timing and for valve adjustments) should be a hard to see, fine scribe just below the window.

Once you've verified static timing and initial valve adjustments, you can move on to set timing when idling at 650rpm (vacuum advance plugged at carb. Most find around 12° BTDC good starting point.

Of course you'll also want to verify carb settings, air gap settings and voltages for your DUI, check for any manifold vacuum leaks, fuel flow, among other things.

Thanks, @charliemeyer007! I’ll make sure I do the basics before moving on! I Appreciate the tips!

 

[Pighead]

Here's mine, too far apart to see both in the window. Maybe get underneath, drop the clutch cover and take another look. Maybe clean it up with some sandpaper or similar.

 

[Marine T]

Here's mine, too far apart to see both in the window. Maybe get underneath, drop the clutch cover and take another look. Maybe clean it up with some sandpaper or similar.

View attachment 4174956

View attachment 4174957

That’s a great picture and good advice. Your picture also looks like there are gradient markers next to the timing needle, so that’s helpful too - I didn’t see anything like that on mine, so another reason I should clean up my area and get a close look for the other marks. Thanks, @Pighead!

 

[Marine T]

It looks like the hole might be where the BB should be (7° BTDC). If so, TDC (0°, for static timing and for valve adjustments) should be a, hard to see, fine scribe just below the window.

Once you've verified static timing and initial valve adjustments, you can move on to set timing when idling at 650rpm (vacuum advance plugged at carb. Most find around 12° BTDC good starting point.

Of course you'll also want to verify carb settings, air gap settings and voltages for your DUI, check for any manifold vacuum leaks, fuel flow, spark plug conditions, compression, etc. among other things.

Thanks, @CruiserInProgress! I’m now taking steps to do static timing and check valves and manifold vacuum leaks.

 

[pb4ugo]

You could remove #1 plug and stick something long in the hole and carefully watch it rise while turning the crank by hand as the piston reaches tdc, then look for the flywheel mark.

 

[Pighead]

Your picture also looks like there are gradient markers next to the timing needle, so that’s helpful too - I didn’t see anything like that on mine, so another reason I should clean up my area and get a close look for the other marks.

No gradient marks on the flywheel, there are teeth on the flywheel...

 

[Marine T]

You could remove #1 plug and stick something long in the hole and carefully watch it rise while turning the crank by hand as the piston reaches tdc, then look for the flywheel mark.

Thanks, @pb4ugo!