Philbert

iTrader: (2)

Subscribed!

Here's a dumb question I've been meaning to ask....

When doing a rebuild, it seems you guys often send the block to a shop to get cleaned, but also to get the cylinders re-bored. Sometimes the top of the block gets shaved down as well.

1) Why is this done and is it always done?
2) When it's done, you need to buy a thicker HG, and then get pistons (or just the rings?) that are 30 one thousands, 40 one thousands, or whatever, larger than stock, to fit in the wide cylinders.

Just wondering why this is done, and what determines how large one goes with the pistons/cylinders....are there advantages/disadvantages to either? Is staying "stock" not always an option and not recommended?


OK, that was not just one question, sorry

Learn me please!

JonnyBoy

Why the cylinders usually need to be bored .020, .030, etc oversized is because of wear between the pistons and cylinder walls. Even on a straight up and down engine like an r motor, the side to side motion of the crank/rods puts a slight load against 2 sides of the cylinder, so it can be very slightly ovaled. Also, the rings do wear into the block after a good while, so sometimes there can be a lip at the top of the cylinder where the rings stop on their way up. A properly oiled engine reduces this wear, but it still happens eventually.

If the block needs to be decked, however, it means the head mounting surface may have warped and is no longer flat enough for the head gasket to seal. Same for the head, which is more likely to warp. I've never removed and reinstalled an alum head without having it machined flat again, especially if the motor ever ran hot.
Solutions to decking the block or machining the head could be thicker head gaskets, but most people I know would rather get an adjustable cam gear(in the case of an OHC motor) or just slightly shorter pushrods(on an OHV motor)

Philbert

iTrader: (2)

Thanks JonnyBoy - that makes sense and is very clear - appreciate you taking the time to explain.

/end threadjack

txclimber

My block had a lip on the #4 cylinder you could feel with your finger. The rest felt smooth to the touch. The guy at the machine shop said that was common that the back is the worst. He said it runs a little hotter back there. Not sure why.

txclimber

I got some green r134 air conditioner gaskets today. Also picked up the adapters. I'm going to start trying to put an entire air conditioning system into my 86 which came from the factory without it.

I'm still unsure of what all is involved. I know I'm supposed to drain the compressor of oil, but not sure how.

Also, still don't know exactly what goes on under the dash. Anyone have any advice on this?

txclimber

Just ordered an LC Engineering header and a Marlin Crawler 1200lb clutch. They should get here by the end of the week. Still waiting on machine shop for block, crank, and flywheel.

Just about got the A/C figured out. Only one problem. Apparently they changed the A/C wiring harness from 86 to 87. Everything plugs in except one plug. My 86 has a 4 prong receptacle up top, but the 87 has a 5 prong. Anyone know what's up here?

hilandfrog

You may notice I ran into the same thing when I posted earlier, I found 2 articles that explain that the AC is mostly grounding stuff out.

Good luck, I know I'm going to need it

Repo

txclimber

hilandfrog- So we're both in limbo. Do you have a plan of attack? Track down proper harness? I called Toyota just to check--part discontinued. I wonder if we could just wire it direct and ground the stray wire out with another one? Way out of my element here.

txclimber

I've got the 86 FSM. A/C system circuit wiring diagrams show the 4 wires in my harness are for:

brown-vsv
light blue-vsv
black and white-magnetic clutch
black-ignition coil


Anyone have the 87 FSM? If so please check what the fifth wire is for. Thanks!

hilandfrog

I'm missing 2 wires from the AC to the Truck....

I'll need to figure out the ones that are x-tra and either splice them in add a switch or leave it blank and go for it.

I'm thinking the amplifiers get better and need more wires??

I suspect knowing what Year the donor AC was from could be helpful, just one more mystery

Best of luck.

Repo

txclimber

Big day. Went to pick up my block, crank, and flywheel, from the machine shop. Bored 40 over. Crank checked out within specs. Flywheel turned.

Also, when I got home there was a big box on my porch. LC Engineering header.

Called engnbldr, ordered a full rebuild kit with 40 over rings and pistons and standard bearings. I'll try to get some pictures up soon. It's about to get exciting.

hilandfrog

Nice :clap

Let the games begin.....

Buy 2 more cans of parts cleaner than you were planning
I completely soiled 10 gal of mineral spirits

Grab some fun tunes and get to it.

Repo

Blue 89 Runner

Post up pics of the header .

93YotaGuy

Maybe you could just replace the AC box with the one specific for your year from the junkyard? I purchased my whole system for about 80 bucks. I'm sure you could get the box for about 20 or so? I would also make sure that you replace the expansion valve because those are usually the first to go. I wrote a thread about it here.

https://www.yotatech.com/forums/f116...issues-186810/

spokane.yota.man

What did you spend at the machine shop, if you don't mind me asking? Was the block decked at all? I'm in the process of a 22r rebuild as well and just trying to gather as much info as possible. Along with oe seals I would get an oe head gasket too. I've heard some not so good things about the rock ones. Post some pics of the clean block and header!

txclimber

Got my injectors back from witch hunter. Wow. They look brand new. He said they were pretty rusty inside.

txclimber

Header pic will have to wait a bit longer. It's still all wrapped up in plastic. It'll come. Don't worry. But, I do have a little engine porn for you...Check it....



And to top things off:



I don't think blue adds as much horse power as red, but it should help. It matches the blue on my old factory clutch m/c perfectly. Duplicolor Chrysler blue. aka aisin blue?

txclimber

Machine shop work. $235.

$100 Bore and hone.
$35 two step flywheel turn
$100 Vat and mic crank

Steep? I don't know. I expected as much, but I was surprised it took almost 3 weeks.

Block checked out ok, so it was not decked.

txclimber

93yotaguy: thanks for the link I'll check it out. I don't think the box is different. It's the small wiring harness that connects the box to the main wiring harness. Everything plugs in an is super easy except one of the plugs that go into the main harness.

I've called and searched everywhere I can think of with hopes for a fix. I see two options: Get the small harness that matches my truck (yeah right) or figure out what the extra wire on the one I have is for and either ground it, forget it, or wire it in with one of the other four. Still hoping someone with an 87 fsm can look the mystery wire up for me.

spokane.yota.man

thanks for sharing that. That's about what I was recently quoted. 3 weeks does seem a little long though. As long as they did good work, that's what really matters. paint looks good! I like the black "Toyota" on valve cover. Ttora has a fsm for an 88 that might help you some with the a/c install.