1986 Chevrolet 4.3L Engine Rebuild/Buildup

This is the buildup of my 1986 4.3l (262cu in) engine. It was in a 1986 Chevrolet C10 pickup. It used to be very reliable and got about 22mpg, but towards the end it started missing and the exhaust started popping (burning fuel in the exhaust) and after swapping out various ignition and carb components, I performed a compression and leakdown test, which showed something terribly wrong in the No.3 cylinder. The truck had 143,578 miles on it.

Here were my compression and leakdown numbers

No.     dry     wet   Leakdown
1         167     175   15%
2         165     178   14%
3         120     145   35%
4         168     180   13%
5         168     175   15%
6         157     168   15%

The loss in No.3 was coming back through the carb.

    So, I pulled the motor, and after teardown I find a massive buildup of oil sludge in the lifter valley.  I snapped some pictures and asked around what that could be from, the first several responses were "Are you using quaker state or penzoil?" I did use QState 10w40 since I bought the truck at 85500mi, and the orginal owner gave me a stack of reciepts from a penzoil oil change place dating back into the late 80's. I guess the old rumor goes that QState and penziol both tend of buildup parrofin wax throughout the engine.  It's a little hard to really believe that rumor though, they are both owned by the same company now, it's a big reputable company, I'm quite sure thev've done tests running engines and tearing them down afterward, so I guess the engineer in me just can't believe the rumor. But then again, several people said the same thing in an instand in looking at the pictures, and they've seen that many times in the past with Qstate and Penzoil.

    The only real problem I could find were the lifters on No. 3, the intake espcially sticky, ok it took a vice to compress it, the exhaust was a little sticky, the others all compressed normally. The valve guides or seals were leaking pretty badly, lots of carbon buildup on the head chambers and piston heads. The bottom end looked really good, everything down there was within spec still.

    Anyhow,  on with the buildup. This is my first complete engine buildup. So some research was in order. Hours and hours of reading. Finally I took my block, heads, rods and crank to a machine shop. I called around to a couple different shops in the area, since I don't know many people who have machine work done, it was kinda of crap shoot in picking one. My decision would later be a little regrtablle, but how was I to know. I told the guy my situation, that it was my first buildup, what went wrong with the engine. The orders were, bore as nessesary, hone, tank, magnaflux, install cam bearings, and re-do the heads and I'd buy his Victor Reinz master kit, and I said I'd defer to him on the crank after he checked it. He said about a week, they'll call when it's done. Cool.

A couple days later, I started calculating what the cost of the heads would be, and was looking around to just exchange them at one of the head exchange places, one is near my house that I've used before for head jobs, never had problems with them. But then, I found these really nice brand new Vortec heads, casting number 12557107, supposedly the same as the 772 casting found on 96-97 heads, but with a hardened exhaust seat. Brand new painted, finished with stock valves, seals, springs, keepers, locks for $275 to my doorstep. So I bought those and went and picked up my old heads at the machine shop. I can't find much information on this casting number, I had my brother who works for General Motors attempt to lookup the application for that number, he said he could find much of anything, he did find it was a valid number, but other than that, just some chmafer specs and wall thickness. Looking at some specs for stock 350 heads from an old drawing I had kept from the mid-90's for a 97 head when I used to work at a tooling shop as a process engineer,  they specify a wall thickness, then note marine heads got a tad thicker casting, and the thickness they mention matched the thickness of the heads I got. That, and the fact that they are painted from the factory as a bare head, kinda of tells me that they are marine heads. But it's a little intriging because all the Mercruiser heads I find are the same casting numbers as automotive applicaiton, I thought they stopped making marine specific block and heads back in the early 80's.

    Now, the deal with putting Vortec heads on an older block is you need to change your manifold because the heads have a different mounting bolt pattern. I saw a writeup out there on how ot modify your existing manifold, and your new vortec heads to use your existing old style manifold, but I wanted to dump the old manifold anyway, so I just bought Edlebrocks 2114 manifold, it's a carburator to vortec head style, so perfect for my application, and didn't cost anymore than the Edlebrock 2111 manifold I was going to buy to fit the older heads. You should use vortec style gasket too, so I had to procure GM's gasket no. 12xxxxxxx because the gasket in my master kit would be for the old heads. Other than th e manifold, everything else is a bolt up, I had some concerns over pushrod length, but we'll see.

    Ok, on with the engine buildup, I did a lot of research into what parts I should get. There's a specific reason for each part, but here's what I eneded up with:
So there's the parts I got. Now, back to the machine shop. Two and a half weeks go by, I call them and they say, "yeah those were done last week." Gee, thanks for calling, then taking a tone with me for picking them up late. Anyhow, I go to pick everything up,  when asked how much he  bored it,  "we always bore 0.030 over", I had told him not to bore more than really nessesary, and the condtion of the walls was pretty good, my check indicated really only  a 0.010 would have been sufficient. Then I asked what was done to the crank, he said, "well, it was just written to polish it here", I said, umm, didn't you check it first? No response. So I get my stuff home, I mic the journals on the crank, they end up being within spec, although they are on the edge, they are all within the range. I look at the gaket kit in the master, it's for a 1985 engine. Great, my 1986 engine was the first year for a 1 piece rear main seal, so the seal and oil-pan gasket are different. Then I look at the piston rings, they are listed for a Ford 6cyl engine from the late 60's.. I call the guy back up, he says bring it by, and he'll square me away. When I get back there, he tells me the Hastings 592 rings he gave me are right, and they'll fit. I correct him with my printed sheets from the www.hastingsmfg.com website, a cross reference chart by piston manufacture shows I should have 4721, not 592's. That and the box on the 592's says "Ford 6cyl".  He insists the 592's work, "he's used them many times before". The difference is pretty subtle. The pistons I got are silvoite 3445, hastings chart specifically lists 4721 for a silvolite 3445 pistons.  Hastings lists 592's as 2 5/64", and 1 3/16. Hmm..lets see,  3/16" = 0.1875, 5/64"=0.0781.  The 4721 rings list 2-2.0mm, 1 4.75mm. 2.0mm=0.0787, 4.0mm=0.1870, differeneces of 0.0006 for the compression rings, and 0.0005 on the oil ring. So I decide to test fit them, the compression rings fit, and are within spec for ringe side clearance. The oil ring fit, but I have to jam it in there, there is no clearance, and due to my jamming, the other end of the oil ring assembly is spread apart (I didn't install the rings, just placed and edge of them into the grove from the side), so I'm not sure if one could actually install the oil ring without compressing  it a little.. Book says I should have 0.002 and 0.007 clearance for the oil ring, I have 0.0000. So now I'm worried, I mean, if 592's and 4721's are the same, why would hastings have 2 different numbers. There must be differences. I called the guy back again, he finally gives in and orders the more expensive and less used 4721 ring set
    Out of curiosity, I emailed Hastings tech support, asking what the differences in 592 and 4721 ring sets were. I got a very nice response, noting not only the differnce in ring thickness, but also they have different ring edge taper that works with the type of skirt for a particular piston. The 592's are designed to work with a different piston skirt design, for oil retension and control. They made it clear not to use 592 rings on my 3445 piston, and if I did I would have a much lower MPQ (miles per quart) oil economy rating and probably increased friction.  Glad I checked! Now I'm just concerned with the quality of the machine work on my block.

    On with assembly. I started assembling based on a book "How to build a small block chevy". First, the crank. Dropped right in, torqued up the caps, perfect, spins nice and free. Checked endplay. Next, the rings. I layed out all the rings for each piston, we put each ring in it's bore to check gap, the book says this is time consuming, and it is, but a nessesary step cause if one it out, you got big troubles. All good. Installed the first set of rings on No.1 piston, checked endplay,  dunked the head and wrist pin in oil, and pushed it through my 0.030 over tapered ring compressor into the bore. Lined up the rod to the crank, and bolted on the rod cap. The book I use says to rotate the crank a full turn or two after each item is installed to ensure the assembly rotates freely. I go to turn mine, and I can barely barely turn it. Uh oh, major problem. After I struggle to get 1/4 turn out of it, I notice small metal shavings on the underside of the piston near the wrist pin. Great. I take it out, can't seem to find anything wrong with it, then my friend who's helping me notices a small lip, like casting flash, on one of the faces that would meet the fore-aft face of the rod wrist. Installed it again and we notice the rod wrist  is close to that side. After thinking for a while, we notice if we install this piston on the other bank the rod wrist will be closer to the other face, so we did that, and had 0.08 clearance from the tit to the wrist pin. Still feeling a little uncomfortable, but continued on none-the-less. All the other pistons installed without problem and the assembly rotates freely. Next we installed the cam, timing chain. No problems. Oil pump, dipstick tube, and oil pan were next. Timing chain cover, then lifters. Put the heads on, torqued 'em down. pushrods, rockers next. I got to lash the valves and notice that I'm not building any compression in No1. Uh oh again. After carful inspection, I notice that intake valve is not closing all the way. I actuate the valve with a pry-type compressor, I blew compressed air in there thinking it was a piece of debris. Still not closing all the way. What the heck. So I remove that head, valve is definatly not seating, so I take off no. 1 valve spring and remove it's valve. No sign of damage. A small little piece of something seemed to be in there when I took the valve out, so I clean everything good, lubed  up the valve stem and re-installed it. Seals good now. Whew...well hopefully, still a little worried about it, but I think it's ok. Procured another head gasket, cleaned up the block and head surfaces, and re-installed the head. Lashed all the valves using the TDC procedure  for each  cylinder. This procedure says to find  TDC on compression stroke, then lash both valves,  that is to  tighten to zero lash then 1/2 turn more. Finding 0 lash takes a little getting used to. I went around the motor three times before I felt comfortable I had it right. I ensured to leave the motor at TDC on compression for No.1  Next put on the intake manifodl using the newer vortec style gaskets which came with instructions in the GM bag to only torque to 11ft/lbs (this really doesn't feel right, but I followed the instructions). Installed exhaust manifolds, with new studs and doughnut gaskets, installed carb square-bore to spread-bore spacer,  and installed carb. Fabbed up a custom accelerator linkage bracket and bolted it on. Filled up oil filter, installed it, cleaned heads one last time. Next using my friends tool, I prelubed the engine, it's a tool that installs into the distrubtor hole, meshes with the oil pump and you spin it with a drill. I did that for several minutes until oil started coming out all the pushrod ends over the rockers. Then I installed the valve covers and distributor, pointing it at no.1  Brought over the hoist, lifted off the stand and installed the clutch and bellhousing. Then it was back into the truck

    Finally all bolted down in the truck, everything hooked back up, exhaust, wiring, hoses, power steering, radiator, coolant added, oil level checked. I go to crank it over and it fired right up on the first keystroke after a couple of cranks. I couldn't believe it. The moment called for a beer. The celebration however, was short lived, after adjustments and timing, it was idleing a little rough. After reaching operating temp and watching coolant flow, and shut it down. It was almost impossible to start again and when it did, black smoke coming from the tailpipe for 3-5 seconds. Bad news, running very rich. COuld have a fuel wash problem. We don't want that. Drove it around, definetly more power, but not like it should be, and still hard to start hot and black smoke. Must be carb. After tinkering for a bit, I decide I don't know enough about quadrajets, and I drove it to a carb shop in Flint. Within 30minutes they called and said there was a hole in the bottom of my fuel bowl. Not the fuel wells where they normally get them, but in between the wells. They said they've never seen that before. They patched it up, let it dry 478hours, fired it up, dialed in the idle mizture, fast/slow idle and timed it again. Went to pick it up and she's running very good now. Idles smooth, pwoerful through the whole RPM band, excellent throttle response. Very happy. After it's broke in, there's a speed shop that will do dyno tests, 3 pulls for $75. I might take it there to see what kind of numbers I'm pullin. Stock was 150hp and 210ft/lb at the flywheel. So at 13% loss for manual transmission vehicles, taht would be 130hp and 182lb/ft at the wheels. I would guess or hope anyway, I would be seeing 150-160hp and 200ft/lbs. We shall see.....