Trying to evaluate this 400ci motor. 511 block and stock heads (3973493) with 2bbl carb. Smokes like crazy. Pulled the valve covers to fix leaks and there was a good bit of sludge. Compression on all cylinders is between 160 and 165 psi. What's normal compression? Any truth to the rumor that valve seals can be changed with the heads on? I just want to drive it until Nov, then the whole thing comes apart. Thanks

Yes, 165 or so is normal for that motor.

Yes, valve seals with the heads on is cake. They make a compressor that looks like an L shaped lever, with a fork and a hole in the short end. Get one, and some clothesline. Pull the plugs and valve covers. Turn it by hand till #1 is on it way up on compression, stuff a few feet of clothesline in the spark plug hole, and turn it till it won't turn any more.

Take off the rockers, bolt the compressor to the rocker stud and pull to compress the spring. The clothesline will keep the valve from falling into the cylinder. Pop the keepers, replace the seal, put it back together.. do em both, put the rockers back on, tighten to zero lash, wrench it backwards till u can get the clothesline out.
Repeat 8 times, by the firing order and you're done.

btw... bad valve seals mostly smoke when you let off the throttle. Also, I've seen sludged up engines smoke simply because the oil return holes were clogged. Use some engine cleaner to get the sludge out. I had on Olds once that blew so much white smoke you'da thunk it was on fire... I put half a gallon of kerosene in the crankcase, let it idle for 30 min, then changed the oil and filter 3 times, it was good as new.

I too have added a quart of diesel fuel to a motor once! It was the old 221 Ford V-8 I replaced my 260 with in my '64 Fairlane S/W and it did clean her out nicely, but don't go driving her b/c she might just VOC vapor your points dead and strand you like it did me one evening.

BUT it DID work fine de-sludging the old motor! I ran it until I got around and did a $150 "shade-tree", dingle-berry hone, overhaul job on the 260 several years later and then I put probably a 100,000 miles on the 260 before I gave the old car to the Church back about '85..

pdq67

I've heard of the kerosene bit for cleaning. Any scraping sounds though?

No, you just let her fast idle and it works out pretty good.. Or at least it worked fine for me anyway!!

Some guy's say that cleaning one that is really badly sludged up thisw way may break so much crud loose that there is a chance of plugging the oil pump sucker screen but mine didn't AND I will say it was crudded up pretty darn good!!

An old man musta owned the '63 Merc Meteor that the little motor came out of b/c it was dinged on all four corners and when I cleaned her out some the first time by hand, (under the valve covers that is), she was all sludged up!!

pdq67

I've only used that trick once, but it did work. Kept the car 2 years after, no problems. The thing was so sludged up you couldn't see the valve springs!!