Well it's on a stand right? Easy to get to now.

It may have been running before, that doesn't mean a whole lot. Somebody claims it was "rebuilt" 30 years ago, that ... means even less.

A compression test first thing kind of takes the guesswork out of whether it's worth buying a gasket kit or balancer and the rest of it, know what I mean?

 

I'm smellin' what you're sellin'. I bought the truck for $250, so that's taken the sting out of some of the bigger purchases, but I'll do the test first thing if I'm ever in this position again.

 

In stead of a compression test do a leak down test as it will tell you a lot more.
Dave ----

 

I don't think I have the right equipment to do a leakdown test, but I do have a compression tester.

I read that I can do the test by hand cranking and that each cylinder may be a little lower than expected due to the manual nature of the test. Does that sound right?

 

You need to turn it over on the starter motor. Trying to do it by hand is too slow and most of the compression pressure will bleed off past the rings.
So, no.

 

To do the test you'd need to pull it off the stand ( Oil pan and timing cover installed and oil in it) . Install the block spacer plate, flywheel, bellhousing and starter. Get a good car battery and some jumper cables. Set the engine on the ground, with it some how supported/blocked up so it wont tip over. Then pull all the spark plugs, install the tester in the first cylinder. Hook up the jumper cables, one end of the negative cable ( black ) to the engine block and the other negative clamp on the negative battery post ( - ). Then hook up the one positive clamp ( red ) to the positive battery post ( + ) making sure the other side doesn't arc out to the engine or battery. Then when you are ready put the other positive clamp on the main terminal post on the starter to spin the engine over ( stop by removing clamp off starter when the needle on the gauge pretty much stops climbing ) . Wear some good work gloves because depending on the cables the clamps may get hot. Right the # down and move on to the next cylinder. You may need to charge the battery between cylinders depending on the size and condition of the battery you are using.

Once you have done all the cylinders you will have the results for a dry compression test.

 

I'm waiting on a new harmonic balancer to get it, but in the meantime, I'm replacing seals and gaskets. Thanks for the guidance on compression testing.

I'm trying to replace the seal on my timing cover - the service manual says to drive the seal out with a pin punch. I can't tell if I should be driving it out from the front or the back. This is a 1978 engine and the manual looks like a new seal is installed from the inside of the cover. I'm assuming I need to drive the old seal out from the outside, but I've seen videos on older models doing it the opposite way. Has anyone removed the crankshaft oil seal from the timing cover on 78ish 300?

 

Disregard my last message - it had to be punched out from the outside of the cover. Took some close inspection to find the seam, but it came right out after a few whacks.

 

First, I can't tell you folks how thankful I am to have this forum as a resource. You guys are lifesavers.

I've pulled the cylinder head and am down to the block now. What's the best method / method you prefer to clean everything? There's a little carbon buildup on the piston head, but it doesn't look too bad to my novice eyes.

 

From what I've read, it's ok to use a degreaser and a scouring pad to clean the cylinder head and valve train. I'm going to try to knock that out today and replace the valve stem seals. Nothing is aluminum, so I'm assuming Purple Power will be ok to use here. I have some Ultra Slick I can use to follow up with on the cylinders. Is that considered superior to regular oil or WD-40?

Thanks!

 

With the head off the engine already the best solution is to take it to a machine shop to have it cleaned, milled flat, valves ground/valve job, etc.

 

It would be nice to do so, but I'm trying to keep the cost low and get it on the road before I move this spring. I don't think there was any warping or a blown head gasket or overheating.

 

I'd want run a dingelberry hone across the cylinders for crosshatch and install new rings?

And then, so long as you're in there might as well... and then... and then... and then...

 

If you don't want to or can't deal with a machine shop on the head, clean it thoroughly, visually inspect the head for cracks. You should see if there are any major cracks, won't catch the smaller ones without magnafluxing the head. Also check the valve guides. If they are worn, bite the bullet and have them replaced by a machine shop. Lap the valves, if you can get a nice seal by lapping them then you are good on the valves ( if there are not any sunken seats ) . And check the head with a straight edge for warping. The head is off so check it! The guys/gals that say "it'll be fine" are the same people pulling it apart later to fix it again because they didn't do it right the first time. You can do things on a budget and still do them right.




That's why I always prefer to get the engine running good before I tear it down to re-gasket/reseal it.

Get it running the best you can, do a compression test and throw a good oil pressure gauge and vacuum gauge on it. If the compression and oil pressure are good, then there is a pretty good chance that the bottom end is solid. And you don't need to tear into the short block except the gaskets and seals. Just tearing it down first you are going in blind and that means you need to check everything or hope you are lucky.

 

It's gonna take a lot of flowers and chocolates for me to add anything else to the 'and then' list.

Does this procedure look accurate? How To Lap Valves