I can see why the 390 is so legendary, the torque of this thing is unbelievable! At 1800 RPMs it it'll pull anything.

Sam

 

One more question, is the PCV valve suppose to be all the way open at idle? The engine idles a bit rough and when I plugged the PCV with my thumb it smoothed out.

Sam

 

I hate to say it, but it's not over yet... I was driving it today and noticed a definate drop in power and the miss is back, not quite as bad, but it is back. The engine also has a lot of blow-by, if you pull out the pcv valve it starts puffing smoke from both valve covers.

One more thing, I'm pretty sure it's a lean miss, I cranked out the idle screws all the way (any farther and they would fall out) and the motor ran noticeable smoother, but still missed. With the standard 2 1/2- 3 turns out it misses bad and runs real rough.

Sam

 

I think I finally have found what's been giving me grief, a warped head. The passenger side head had a big high spot in the middle of the intake surface. It looks like the shop goofed and missed that. The passenger side had had at least 0.013 in a 5 inch section. Driver's side had about 0.004 of warp over the length of the whole head.

So back to the shop they went, hopefully this will end my problems. I'm also going to pick up a stock iron 4bbl intake (the offy's power band was too high for me) and stick that on.

I'll report back when it's running again, hopefully I'll have some good news!

Sam

 

Unfortnately, I don't have any good news this time... I've lost 10psi of oil pressure over night and now I've got a knock. Oil is full of metal particles.

I hate to say it, but I think this is the end of the line for this motor.

I never did get that misfire to go away either...

Sam

 

Wonder what happened that metal started getting into the oil? Might be the heads weren't cleaned after shaving, if this is the same machinine shop that sold you the heads. Losing 10 lbs of pressure is troubling too, especially when you didn't change anything with the crank. Where could the new leak be?
puttster

 

The heads were cleaned up real good, I talked to the machinist and he says it's most likely from the knock. Either way, we'll know more on monday. The motor is up at the shop and they're going to do a full autopsy.

Sam

 

Sounds like things are going to end badly. Maybe valve vs piston. I hope not.

 

Unfortunately, the story isn't over yet.

I got the motor back from the machine shop last August or so, they changed the bearings due to pinging, but the knock was the fuel pump to chewing up the timing cover.... Nobody was happy when we found that.

So I put it back in and ran it around for a while, and the rockers kept getting noisier. No idea what was doing it, and then coolant kept showing up on one of the heads. Tried to fix that, and it slowed down a bit, but couldn't stop it. Then last week, it started pinging, pinging bad. Even running premium it would ping, normally I run regular. Pulled the plugs and several have aluminum flakes on them, but the #3 was especially bad. Did a compression test and #3 was 30-40lbs below the others. Plugs looks lean, so did the pistons.

I suspect my engine builder used the print-o-leaks on the intake and they're causing the coolant leaks. And if they're leaking coolant, I suspect they're leaking vacuum too.

I got a new truck to drive now, so I'll tinker with the old Ford, I'd like to put a diesel in it and put some patch panels into it for the rust.

Any idea what a fair price for the 390? Fresh rebuild, Edelbrock performer intake, Holley 570 carb some other goodies, potentially major pinging damage. $500 sound fair? I want rid of it.

Sam