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Working on tearing apart my 69 400 engine. Still trying to decide if I want to do a full rebuild or freshen things up a bit. Engine has not run in 15 years, but best I can tell it looks fairly clean. I am waiting to get a leak down test kit to check things out before I decide. I have never seen the engine run and so have not been in the position to do a compression check.
I pulled the oil pan yesterday to find it fairly clean except for 1/4" bits of plastic in the pan. Most pieces were wedged in between the pickup tube and screen to the oil pump. What I am trying to figure out is what they came from? Any ideas? See pictures. The individual piece has some sort of ridge on it.
Here is a thread incorrectly labeled as neoprene. The sprockets were made of nylon. In any case, what you found in your oil pan are remnants of your timing gear nylon sprockets after having been chewed down like a canine's teeth. It isn't endemic to Oldsmobile, many manufacturers employed the same nylon material - it doesn't last forever.
Thanks for the replies. I didn't know they had nylon on the timing chain sprockets. I do plan to replace the timing chain. Not sure if the one in the engine is original or not. The gear has a TGC written on it. See picture.
I can't recall if its Timken Gear Company or Torrington Gear Company - I think it's one of them they both made gears. OEM gears were nylon, replacements (you could at some point get nylon replacements but no one wanted to replace a nylon gear). I believe you already have an aftermarket timing gear. So, it sounds like the original timing gear and chain were changed at some point, but the leftover salad (complete with croutons & sunflower seeds) remained w/in the oil pump screen & oil pan? That's kind of a mystery. Good thing you're cleaning it all up. If you're pressing modestly hard on that timing chain then that timing chain is in good condition and the sprockets look good. I can't tell from the picture of the proper alignment on the scribe locator marks. I'd turn the crank to ensure they line up.
Well after looking at the "neoprene" thread, I am guessing that my timing gear set has been replaced at one point. Guess it was too much work to drop the oil pan at the time to clear out the debris. So what are some common tell tail signs to determine if the engine had been rebuilt?
The biggest indicator is aftermarket pistons and a larger-than-factory bore diameter.
And I can't help it, it just bothered me to read it - the cam gear is not MADE of nylon; the gear itself is made of aluminum and the teeth have a nylon layer for noise reduction.
Last edited by Fun71; January 1st, 2022 at 04:53 PM.
The biggest indicator is aftermarket pistons and a larger-than-factory bore diameter.
And I can't help it, it just bothered me to read it - the cam gear is not MADE of nylon; the gear itself is made of aluminum and the teeth have a nylon layer for noise reduction.
Well after looking at the "neoprene" thread, I am guessing that my timing gear set has been replaced at one point. Guess it was too much work to drop the oil pan at the time to clear out the debris. So what are some common tell tail signs to determine if the engine had been rebuilt?
Hardly anyone drops the pan just for a timing set replacement if the engine is in the car. I'm going to say it's doubtful your engine has been rebuilt simply because of all those bits of plastic still being in the pan.
Thanks for all the help! It was a mystery to me to find all those pieces in the oil pan. I was looking for metal pieces and fortunately did not see any. No glitter.
After I do the leak down test, I plan to pull the heads and inspect the cylinders.
The cam appears to look good. Some dried oil on it but no wear.
Agreed. As noted earlier, the factory head gaskets were thin .017" stamped steel, whereas aftermarket replacement head gaskets are .040" or so, which would reduce the compression ratio quite a bit.
Thanks for all the help! It was a mystery to me to find all those pieces in the oil pan. I was looking for metal pieces and fortunately did not see any. No glitter.
After I do the leak down test, I plan to pull the heads and inspect the cylinders.
The cam appears to look good. Some dried oil on it but no wear.
if the engine had a oil filter on it, cut it open. If the engine suffered any damage from oil starvation you wil find the evidence in the filter pleats.
Has anyone ever heard or noticed a noise after a nylon chain is replaced with steel?
if the engine had a oil filter on it, cut it open. If the engine suffered any damage from oil starvation you wil find the evidence in the filter pleats.
Has anyone ever heard or noticed a noise after a nylon chain is replaced with steel?
Clean that stuff out. It will clog the pickup and starve the engine of oil. I spin the bearings in my 70 W30 in 1978 due to nylon from the timing gear getting into the pickup. I was in college at the time and had no money for the rebuild. So, I put a 350 in and drove it as my daily until I got out of school and had enough to rebuild the 455.
Thanks again for all the feedback. I have never fully rebuilt an engine, so I am learning. A more experienced friend had suggested pulling the heads to inspect the cylinders. So what I am hearing is if the leak down test is good, then don't mess with the heads. What else should I do? Already planning to replace the timing chain/gears and the oil pump. RV type cam? The cam looks good as far as I can tell. See picture.
RV type cam? The cam looks good as far as I can tell. See picture.
I think the recommendation was to do a moderate camshaft upgrade as long as you had the engine apart. The factory cams were a bit lazy and a cam change is an easy gain in power, as long as you don't go overboard with a radical profile.
The usual "RV" cam is usually the 204/214 .448/.472 cam, very mild in 400 ci. Pretty sure your 400 came with a 217/217 .472/.472 minimum, the "RV" cam would be a step down. Even the 214/224 cam is a questionable upgrade. Unless the coolant is really nasty, the factory shim head gaskets should be OK. I had one fail that sat for years with the last owner and the coolant looked like mud.
I just looked at the Comp Cams website and there are lots of cams to choose from that would be a slight upgrade. The thing I did notice that they all said "available soon".
Camshaft technology has come along way in 50 years. If your in no hurry to get it together, definitely upgrade the cam. Keep in mind a cam change will probably require valve spring replacement also.
Since the engine is out and easy to work on, it might not be a bad idea to pull a few rod and main bearing caps for an inspection. Now would be the time to see if the engine was starved for oil with the oil pickup partially clogged with nylon.
If you do pull the heads, have them milled at least enough to compensate for the added thickness of the new head gaskets. If I remember correctly, the steel shim head gaskets measure around .018, the advertised compressed thickness of Fel-Pro gaskets are .038. Milling the heads .020 should put everything right back where they should be.
I think the factory cams were considered "lazy" because the valve opening and closing rates were about .005" per degree of duration. They were easy on valve trains.
The "new technology" has many facets. Increasing the opening and closing cam rates (thousanths per degree) gave more "effective duration". Lunati figured that out more than 50 years ago. Thats why you saw "Lunati cam" stickers on most every NHRA stock class winner. Since the "factories" didn't publish camshaft data beyond degrees of duration and total valve lift, there was lots of room to "improve" a factory cam. Roller rocker arms are a great piece of new hardware.
"So what I am hearing is if the leak down test is good, then don't mess with the heads. What else should I do?"
Inspect a few crankshaft bearings. If you do this do it one bearing at a time and put every piece back exactly where it was and torque it accurately. Replace the valve seals without removing the cylinder heads
Good luck!!!
Last edited by Sugar Bear; January 3rd, 2022 at 10:11 AM.
There is a company that makes thinner head gaskets and I can't think of the name. I believe it starts with a C but all I can think of is covid and that sure ain't it. Somebody will probably speak up with the name. I think they may be a little pricey but cheaper than milling your heads.
you need a complete rebuild. plastic is probably in the oil galleys.. you need to clean out everything.
you need to take apart everything and inspect each item carefully take apart oil pump..
the notorious oil galley end plugs with little hole probably plugged.. if this hole is not open your distributor area or timing chain wont be lubricated properly
you probably can reuse most stuff like the pistons, rods, block, heads etc but a throrogh cleaning and magmafluxing would be in order.
check all tolerances with micrometer..
I would recommend a light clean up of bores with a flex hone and new piston rings and crank/rod bearings , head/intake gaskets, timing chain, etc cheap insurance
remove grit after clean up of bores has to be squeky clean..
Get an engine builder person to help you with special tools, micrometers, etc
now is the time to get it right for long term reliable service
once done you should expect many many miles.. problem free.
Clean clean with soap and water and oil galley brushes.. keep it wet continuosly as long as it is wet rust will not form. then spray down tranny fluid in squirt bottle so rust does not appear.. wipe down with paper towels. this will take about 4 hours to do everything.. get a friend to help..Clean clean clean !!!with soap and water and oil galley brushes..
now is the time to get it right for long term reliable service
once done you should expect many many miles.. problem free.
There is a company that makes thinner head gaskets and I can't think of the name. I believe it starts with a C but all I can think of is covid and that sure ain't it. Somebody will probably speak up with the name. I think they may be a little pricey but cheaper than milling your heads.
Your not going to find a thinner gasket than the factory steel shim gasket.
you need a complete rebuild. plastic is probably in the oil galleys.. you need to clean out everything.
you need to take apart everything and inspect each item carefully take apart oil pump..
the notorious oil galley end plugs with little hole probably plugged.. if this hole is not open your distributor area or timing chain wont be lubricated properly
you probably can reuse most stuff like the pistons, rods, block, heads etc but a throrogh cleaning and magmafluxing would be in order.
check all tolerances with micrometer..
I would recommend a light clean up of bores with a flex hone and new piston rings and crank/rod bearings , head/intake gaskets, timing chain, etc cheap insurance
remove grit after clean up of bores has to be squeky clean..
Get an engine builder person to help you with special tools, micrometers, etc
now is the time to get it right for long term reliable service
once done you should expect many many miles.. problem free.
Clean clean with soap and water and oil galley brushes.. keep it wet continuosly as long as it is wet rust will not form. then spray down tranny fluid in squirt bottle so rust does not appear.. wipe down with paper towels. this will take about 4 hours to do everything.. get a friend to help..Clean clean clean !!!with soap and water and oil galley brushes..
now is the time to get it right for long term reliable service
once done you should expect many many miles.. problem free.
Anything small enough to get thru the oil filter pickup would be caught by the oil filter.
If the engine suffered from oil starvation, the bearings will show the evidence. No point in any further testing, it’s time for a complete yet down and proper overhaul.
With the engine on a stand, it’s pretty easy to remove/clean the oil squirters.
With the engine on a stand, you could bolt a starter to the engine and use a battery and jumper cables to do a compression test. If that passes, it’s really easy to do a leak down test.
If everything looks good, knock out the old freeze plugs. Clean out as much of the crap as possible from the water jackets. Install new freeze plugs. Now is the time to replace all the common wear/potential headaches, things like water pumps, rear main seal, fuel pump, things you would hate to have to fix once the engine is back in the car.
I have done dozens of junkyard engine swaps like this.
Those are the ones. I believe Summit carries those.
Matt69, where are you going to find factory gaskets?
I’d try 1980!!! 😂
Thats why I suggested milling the heads to compensate for the thicker gaskets. If the replacement gaskets measure .020 thicker, milling the heads .020 should put the head the exact same distance from the deck.
January 1st, 2022, 03:27 PM
