...Some time's ya win...sometimes ya lose. I'm a loser, lately.

The 400 that I'm putting together for the KART UPGRADE, is giving me a little heart burn. I bought it as a good running, rebuilt engine. Was it really rebuilt? Who knows, but I wasn't going to buy it w/o seeing it run, and the seller did run it for me. It was run on an engine stand, it had stock manifolds, ~30" of pipe on each side and turbo muff's on it so it was pretty quiet and I could hear the mechanical nature of it when it ran. And? It sounded great! Fired instantly, idled good, smooth, quiet, throttle responsive. Sounded healthy and good, so I bought it.

When I started changing parts over onto it from the L98, I found some things that caused concern.
First, it was REALLY tight, to turn by hand. Too tight for a fresh rebuild, IDK...maybe not.
Second, the front timing cover seal was rock hard. Weird.
Third, there was some weird damage or blems on one of the cyl walls....like the rings had sat in that spot and rusted, then flaked off the wall when turned. (?)



So...^that^ sucks. I was able to dress it up some and it might be O.K.
Since the front seal was basically hard plastic, I figured I should replace the rear main seal and sure enough, it was toast, too. Weird. OTOH, the inside of the engine was super clean, pistons looked brand new, had a double roller timing chain that wasn't stretched at all, and it was bored .020" over, so? Apparently is WAS, "rebuilt". Cool? Maybe?




Fourth...way weirder, and annoying, is that when I pulled the rear main bearing cap to R&R the seal, the bearing is pretty much toast. So, I pulled the rest of the main caps and a couple rod caps and? They're toast too! Only on the loaded sides, but WTF!? How could this thing be so low mile and the bearings are DUNZO?? Even the flat tappet cam that was in it was in good shape (lifters too), but the bearings are gonzo. Freakin' irritating. Also, the crank is turned 20/20, so someone was there and did replace the bearings....I'd guess when they replaced pistons and bored it .020 over.


...and have a look at those THRUST surfaces!! Yikes.


Here are the two rod caps...


....and here is what the rod side of the bearings look like. Same with the mains, but "upside down"....




Wish the bearings looked as good as the pistons do. :-/




Soooo...IDK, I'm going to buy new bearings, plasti-gauge 'em and move forward anyway, if the plasti-gauge shows reasonable clearances. Grrrrrr......

 

Yikes! Was it in a manual transmission application ith a lot of engine braking or is that detonation without breaking ring lands? Yowza

 

Are you refering to the bearing issue? Or something on the piston? IDK...there is no evidence of detonation on the piston crown. It's weird all the bearings are gone but everything else looks fine.

 

Looks like oil starvation to me, possibly clearences too tight. Are the back sides of the bearings discolored from heat? What do the cam bearings look like? Are all the oil galley plugs in place? Did this have the external oil cooler adapter on it? I have seen a 350 square body truck engine do this when it briefly ran with no oil pressure because a neglected ancient factory oil cooler hose blew at highway speeds.

I had a junkyard 5.3L I paid $125 for that had a cylinder wall that looked like that. It went into a truck I bought with a grenaded 4.8L that I did not really care about, just needed it up and running. I scotch bright pad cleaned up the rust with some penetrating oil, threw it in and ran it. I later tested the compression after it had run ~1,000 miles, it was no different than the other cylinders and did not use oil.

 

Bet the oil pump died and lead to this

 

...And then it sat for a few years before it landed on Craigslist. That could be just long enough to turn the seals into glass after being baked and run without oil pressure.

 

I didn't answer this earlier, it had a flex plate on it, so not a manual.

I haven't pulled the shells out...I'll do that and take pics....but clearances too tight was the first thing that I thought of. If oil starvation were the issue, I'd THINK that the cam/lifters would have suffered too....but IDK, for sure. Cam bearings looked good. WAY better than the upper rods and lower mains.

I love this story. I LOVE it when people pull off something that "shouldn't work"....but then it does.....and keeps on working. Here is how far I got that cylinder dressed up....



it will be interesting to see what compression numbers it generates initially, and then later on after some running.


Totally makes sense about the seals. I considered that it got rebuilt then sat for years....decades. . I'll pop open the oil pump and have a look. I've never seen an oil pump wear out (other than buicks and AMC's -aluminum housings)....it's the most well lubricated part of the engine!

,

 

Popped the rear main bearing out of the cap and, not seeing any overheating looking at the back of the shell.












...Can anyone see the pics? When I hit "EDIT", I can see 'em. When I hit "Save"....I can't. (?)

 

I see 'em...

 

Cool.... thx. I can too....now.

 

Welp...looks like .003" to me, so the bearings weren't too tight.




Maybe even a little proud of .003".

Could've run too thin oil for that much clearance, but I'm going with, it wasn't primed on initial start up. The hard/brittle seals, the cyl blems from the rings (?) and all the other things... I think it was put together decades ago, sat and sat and sat and finally someone started it up without priming the oil pump.

I'm going to move forward with this pile. I think it'll be all right.

 

Was the pickup still in the oilpump or was it in the bottom of the pan?

 

It was and still is, in the pump. I rolled the new crank bearings into it today (obviously), the next session I have to work on it, I'll get the rod shells in and then take the pump apart and have a look at it...

 

Hmmm....








The mains might be on the loose side...the rods are TIGHT. Less that 0.001" if the plastigauge is right. I don't think someone knows how to turn a crank. Oh well...the crank will "turn" the bearings!

My goal for the afternoon was to get through all of those bearings, get the oil pump inspected (see pic below) and get the pan on and be done w/the short block "Rustoleum Rebuild". UNFORTUNATELY....things went south with the oil pump install. I put the pump on, dropped the bolt in, snugged it, then grabbed my digital Snappy tq wrench to tighten to spec....65 lb-ft. As I pulled on the handle, I watched the tq #'s climb so that I could stop right at 65....it never made it. It peaked at ~59, then started to drop. "****." I removed the bolt, it looked "fine", put it back in and snugged it, then w/teh tq wrench, couldn't get more than 45 lbs out of the thing. Removed the pump, threads in the cap look fine...IDK if I'm stretching the bolt or pulling the threads out of the cap. I'll order a bolt tonight and see what that one does. Grrrrr.....


Oil pump is the Melling m55, most likely installed with the rebuild the engine received who knows how long ago? Looks to be like new inside essentially. Don't think that was causing any issue related to the bearings.

 

Well, shyyyyit....it WAS pulling the threads in the cap.










As we say in Utah...Bull fetchin' Shnikies.

 

That happens soooooo often

 

No kidding? I've never heard of that one. A helicoil would be a proper fix...BUT...since this is "project junk show" and there are so many other problems with the engine that I won't fix, why waste money on a Helicoil?

I removed the cap, shell and found about 4 good threads "down at the bottom". I threaded a bolt through them and out into the bearing cradle to ensure that those 4-ish threads were good and would take a bolt and they did...and those threads didn't come out with the bolt when I removed it. . So that's good...ish.
I coated the ARP oil pump stud that I had bought w/ red loctite and installed into the cap, threading right to the very edge of the bearing shell surface, to get as much thread engagement as possible. Put the shell back in, cap back on/tq'd then the oil pump. B/c the stud was now threaded so deep in the cap, I didn't have full engagement of the nut. I discarded the ARP washer, and applied blue Loctite to the nut, put it on and torqued it to 50 lbs....which it took. I'm calling that...."Good enough". Put the pan on and moved on to the heads now.

 

Well, I had a minute, so I pulled the valves out of the heads, and (keeping to the UT theme) Holy Shnikies!! These got dandruff someofititches intake ports!! Can anyone here believe that this junk made 290 RWHP!?? I can't. We're looking at the outside radius here....not the inside....

 

I can't believe that no one has commented on these things!! Those ports are an abomination.

 

Those are pretty bad. The reputation of shotty quality exudes from those and the stuff of the era. I'm glad I came up in the roller cam era.

 

You only need ~170 cfm of intake flow to make that. Check out how poorly the ET7Es on the 5.0L Mustang flowed sometime.

 

Even w/a stock cam?

Whatever the numbers, I think that it's appalling to look at...and that people at GM thought that was "OK". In the book, "Heart of the Beast" about the development of the LT5 for the '90 ZR-1...there is a noticeable amount of text given, covering the "problem" or "limits" of the Gen I small block and thus the need for help from Lotus, 4 valve heads etc to get above 250hp and the looming threat of 300 hp Asian sports cars.

I mean....FIX ^THAT^!! Start there! "Oh boo-hoo....we can't get 300 from a small block and meet emissions....boo-hoo the Asians are coming!....Call Lotus and $pend the money$".

I bet....I BET, that if they'd just cleaned up the machining/casting slightly, put a not-sh!tty exhaust (the "T-pipe", for example) on these things, and generally GAF about some low hanging fruit details, they could have met the goals of the era. I mean, we already know that b/c that's what they did in '92...anyway. But my god, I can't believe that some engineer, some manager, some production leader....saw this dog-**** coming out of production and thought, "Yeah, that's good enough. Hmmm, I wonder why we can't meet our perf goals?...." And, yeah, ALL heads were like that then -Ford, Chrysler, GM. I get it on cost, left-over casting/machining tooling from the 50's and 60's that still worked. And I "Get it" for use on cast iron junk heads in junk cars -Caprice's, Electra's, Town cars...whatever. But on a flag ship halo sports car....while they were simultaneously wondering why they couldn't meet performance goals? Yikesies. There was no one who GAF at the wheel.

I'm just ranting I guess. I've seen plenty-a-domestic 80's head ports, but I've always assumed that the 113 head would have had quality casting/machining similar to the LT1 head. Then I saw this junk.

 

Strange how that two years later the LT1 was meeting emissions and producing 330HP in stock form. I guess the engineers sharpened their pencils, or retired.

 

300 in '92, the 330 didn't come along until '96/LT4. But yeah, BIG jump. That is actually addressed in the book mentioned above, in a quote from Dave McLellan; the paraphrase is something like,
"When the power train guys learned what we were doing with the LT5, they said, 'Hey, WE can to that!', to which we replied, 'Then do it!'" Apparently, the LT5 was motivating to someone, to step up the SBC program. That was some expensive motivation.

Maybe someone(s) DID retire, to allow that to happen?

 

I do not disagree. The 113s GM sold over the counter that came on the ZZx crate engines were far cleaner and the set I had looked to even have some factory bowl work on them. I feel like exactly what you are speaking is why one car would be a ripper and another a dog. That was every single US automaker though in that era. Nobody had decent quality or GAF and that is why the Asian/European car makers got such a foot into the US market. I had an Acura Legend years ago that was designed in ~1991 with a 3.2L V6 SOHC engine that had as much HP as a L98, it was seemlessly smooth all the way to like 6,500 rpm and it was extremely reliable. It would get off the line and RUN for a front wheel drive 4 door sedan with a V6. Nissans VH V8 that was in the Infiniti Q45 back in the day was even more powerful and more refined than the Acura V6.

 

Hey... sorry for the tangent... is engine braking bad for an engine? I'd never heard this before.

I have a couple of stick shift cars, and **** if I don't like to brake with the engine because it sounds so damn nice as it's decelerating...

Just curious, thanks!

 

No, it's not bad for it. On a car with an automatic, I've heard/read that the tq converter pushes forward on the crankshaft with substantial force, while decelerating in a manually selected gear. IDK why the trans or tq converter would do that but if it does, then that would push on the thrust bearing for the crank shaft. However that bearing should be able to tolerate that. With a stick shift car, that thrust on the crank doesn't exist, so there is no reason why down shift decel should hurt anything.



Now...in other junk-yard news, I finished converting the 400 to an "OEM roller block", tonight. How do I feel about the conversion/results? Eh....pretty good. I think it'll work. I didn't drill/tap the main oil galley as some do, instead, I made threaded stands by welding nuts together, heated the block and welded the nuts (and one broken off OEM stand that "came with" my junk-yard spider plate) to the top of the galley/rail. Unfortunately, I couldn't get that area of the block as hot as I wanted to, even using two propane torches; the heat got soaked up by the rest of the block too fast for my heat source. But the welds are good enough and it'll work.