I confirmed my suspicions today that my 390 jumped time. It's a 74 390 4V out of a F-350. It looks like I've only got one bent push rod but I'm planning on replacing them all.


My questions:

1. The catalogs only show push rods for 61-68 FE's. Will these work in my motor?

2. Is there a certain year that was better than others for the timing set? or do I need to just order one for a 74?

3. Is it possible that the piston contacted the valve? The push rod that was bent is for an intake valve.

 

It is possible that some contact was made. If it were me, I'd pull the head and take a look see.

The year doesn't really matter on the pushrods. They come in .060 increments. I would recommend checking the valve clearances and make sure you have the correct length(s). Here's a link for setting preload and checking clearances FE's That Bend Push-rods, A Dirty little Secret .: Articles

You'll need tool T58P-6565-A to bleed the lifters down.

You should either get an aftermarket timing set or a factory set from 71 and earlier. Both will be straight up, or in the case of the aftermarket it will often have 3 keyways (4° retarded, straight up 0°, and 4° advanced). The latter years, 72 or 73 and on factory sets were retarded 4°.
You generally want it straight up.

 

A quicky way to check for problems is put a compression tester fitting in the plug hole and fill with air and see what pressure it will hold while continuing to fill with air (quicky leakdown test).

Check between all the cylinders, with both the rocker shafts off the heads (so all the valves should be closed) - also a quick check to see if all the valve stems are up and somewhat level. A ruler across the tops of the valve stems will show anything obvious pretty quick.

 

Well, I tore into it more today and it doesn't look like it jumped time. It had a double roller timing set in it, installed at 0 and the marks lined up. It did notice quiet a bit of chain slack but the teeth on the gears showed a little wear but none were missing or damaged. Is it possible it could have jumped time and jumped back? what would cause a push rod to bend like that if it didn't jump time?

The truck sat for 6 years or so, I bought it, tuned it up, and it started and ran perfectly. It had about 30 mins of run time on it when I shut it off. I tried to restart it the next day and it was very hard to start and then ran really rough. I checked the timing and it was waaay retarded so I adjusted the timing and it started much better but still ran rough. That's when I found the bent push rod so I assumed it had jumped time.

 

If it sat for that long, a lifter maybe stuck and bent that rod.

 

Well as it turns out, it had several stuck valves. I don't see how it could run perfect for a week after redirecting it out of the field then the valves decide to stick. I would have thought they would be stuck from the beginning.

On a side note, several of the exhaust valves are recessed in the seat. Can this be fixed? What causes it?

 

FEs were good at burning valves even with leaded gas. With unleaded, non-hardened seats erode, especially under heavier loads.

'74s should have hardened seats, but your motor could have been fiddled with years ago, or may have just worn through.

 

I got my heads back from the machine shop today. Everything looks good now, they had to replace 6 exhaust seats, one intake seat, and one intake valve. They also had to mill the mounting surface.

I do have one question though, when I lay a straight edge on the top of the valve stems, should they all be level? It seems the intake valve stems are a tad higher taller than the exhaust valve stems.